Joseph Hubert Galani Yamdeu | Canterbury Christ Church University (original) (raw)

Publications by Joseph Hubert Galani Yamdeu

Frontiers in Sustainable Food Systems, 2022

Biophysical evaluations of climate-smart agriculture (CSA) often overlook the potential interacti... more Biophysical evaluations of climate-smart agriculture (CSA) often overlook the potential interactions with and implications for biodiversity and ecosystem services, which are important determinants of food system resilience and sustainability. Drawing on a case study in the East Usambara Mountains, Tanzania, we compare the impacts of CSA with other agricultural management practices on invertebrate pest and natural enemy diversity, and the associated effects on crop damage and crop yield. We found that the most common CSA practices in the region, terracing and trenching with live and compost mulches, provided the best outcomes for crop production, pest suppression and agricultural income. However, greater diversity of pests was observed when neighboring fields planted improved crop varieties, suggesting that the use of improved varieties by farmers creates increased vulnerability to pest damage among neighboring farmers that used local varieties. Also, greater natural enemy diversity was found when neighboring fields were either intercropped or left fallow highlighting spatial flows of ecosystem services between fields. Landcover heterogeneity was positively correlated with pest diversity, whilst landcover richness was positively associated with higher pest volume, highlighting the importance of landscape characteristics in pest and natural enemy dynamics. Finally, we found that crop damage was most severe when pest communities had low species richness, suggesting that a small number of key crop pests contribute to most yield losses. Our findings illustrate that those varied combinations of agricultural management practices lead to heterogeneous biodiversity outcomes and trade-offs, and highlight the importance of local management, neighborhood effects and landscape characteristics. CSA evaluations must therefore look beyond productivity as a measure for success, as trade-offs with invertebrate biodiversity, food production, and environmental sustainability often interact and feedback in complex and unexpected ways.

Intech Open Book Chapter , 2022

Yam is a labor-intensive and weed-sensitive food crop. The labor-intensive nature of the yam mean... more Yam is a labor-intensive and weed-sensitive food crop. The labor-intensive nature of the yam means that the production process requires the attention of the farmer all year round. However, the dwindling labor situation and the proliferation of weeds have forced farmers to think of modern ways of controlling weeds on their farms, that is, the adoption of chemical (herbicides) weed control. Even though the adoption of these chemicals has no doubt brought relief to the farmers and has resulted in increased yam production over the years, it has also brought in its wake, negative externalities of environmental pollution, human health effects, and food quality issues. The study was thus designed to investigate how yam is produced, the human and environmental health effects of how yam is produced, and food quality effects of how yam is produced. This was done through literature review, and field and laboratory experiments. It was revealed that, in recent years, new innovations have been introduced in yam production, the manner in which farmers handle herbicides in their yam production process exposes them to high doses of pesticides, thereby endangering their lives. The study findings also suggest that the use of herbicides in yam production does not affect the quality of the yam.

Frontiers in Sustainable Food Systems, 2022

Climate change will put millions more people in Africa at risk of food and nutrition insecurity b... more Climate change will put millions more people in Africa at risk of food and nutrition insecurity by 2050. Integrated assessments of food systems tend to be limited by either heavy reliance on models or a lack of information on food and nutrition security.

Accordingly, we developed a novel integrated assessment framework that combines models with in-country knowledge and expert academic judgement to explore climate-smart and nutrition-secure food system futures: the integrated Future Estimator for Emissions and Diets (iFEED). Here, we describe iFEED and present its application in Malawi, South Africa, Tanzania and Zambia.

The iFEED process begins with a participatory scenario workshop. In-country stakeholders identify two key drivers of food system change, and from these, four possible scenarios are defined. These scenarios provide the underlying narratives of change to the food system. Integrated modelling of climate change, food production and greenhouse gas emissions is then used to explore nutrition security and climate-smart agriculture outcomes for each scenario. Model results are summarised using calibrated statements - quantitative statements of model outcomes and our confidence in them. These include statements about the way in which different trade futures interact with climate change and domestic production in determining nutrition security at the national level.

To understand what the model results mean for food systems, the calibrated statements are expanded upon using implication statements. The implications rely on input from a wide range of academic experts – including agro-ecologists and social scientists. A series of workshops are used to incorporate in-country expertise, identifying any gaps in knowledge and summarising information for country-level recommendations. iFEED stakeholder champions help throughout by providing in-country expertise and disseminating knowledge to policy makers.

iFEED has numerous novel aspects that can be used and developed in future work. It provides information to support evidence-based decisions for a climate-smart and nutrition-secure future. In particular, iFEED: i. employs novel and inclusive reporting of model results and associated in-country food system activities, with comprehensive reporting of uncertainty; ii. includes climate change mitigation alongside adaptation measures; and iii. quantifies future population-level nutrition security, as opposed to simply assessing future production and food security implications.

International Journal of Environmental Research and Public Health, 2022

Despite the fact that several cases of unsafe pesticide use among farmers in different parts of A... more Despite the fact that several cases of unsafe pesticide use among farmers in different parts of Africa have been documented, there is limited evidence regarding which specific interventions are effective in reducing pesticide exposure and associated risks to human health and ecology. The overall goal of the African Pesticide Intervention Project (APsent) study is to better understand ongoing research and public health activities related to interventions in Africa through the implementation of suitable target-specific situations or use contexts. A systematic review of the scientific literature on pesticide intervention studies with a focus on Africa was conducted. This was followed by a qualitative survey among stakeholders involved in pesticide research or management in the African region to learn about barriers to and promoters of successful interventions. The project was concluded with an international workshop in November 2021, where a broad range of topics relevant to occupational and environmental health risks were discussed such as acute poisoning, street pesticides, switching to alternatives, or disposal of empty pesticide containers. Key areas of improvement identified were training on pesticide usage techniques, research on the effectiveness of interventions targeted at exposure reduction and/or behavioral changes, awareness raising, implementation of adequate policies, and enforcement of regulations and processes.

Scientific Reports, 2022

Climate change is causing problems for agriculture, but the effect of combined abiotic stresses o... more Climate change is causing problems for agriculture, but the effect of combined abiotic stresses on crop nutritional quality is not clear. Here we studied the effect of 10 combinations of climatic conditions (temperature, CO 2 , O 3 and drought) under controlled growth chamber conditions on the grain yield, protein, and mineral content of 3 wheat varieties. Results show that wheat plants under O 3 exposure alone concentrated + 15 to + 31% more grain N, Fe, Mg, Mn P and Zn, reduced K by − 5%, and C did not change. Ozone in the presence of elevated CO 2 and higher temperature enhanced the content of Fe, Mn, P and Zn by 2-18%. Water-limited chronic O 3 exposure resulted in + 9 to + 46% higher concentrations of all the minerals, except K. The effect of climate abiotic factors could increase the ability of wheat to meet adult daily dietary requirements by + 6% to + 12% for protein, Zn and Fe, but decrease those of Mg, Mn and P by − 3% to − 6%, and K by − 62%. The role of wheat in future nutrition security is discussed.

Maize is a major staple and plays an essential role in food and nutrition security in Sub-Saharan... more Maize is a major staple and plays an essential role in food and nutrition security in Sub-Saharan Africa (SSA). Conservation agriculture (CA), a climate-smart agriculture practise based on minimum soil disturbance, crop residue retention, and crop diversification, has been widely advocated but without extensive research on the impact it may have on maize nutrient composition, and food and nutrition security. This study assessed the grain yield, macro-and micronutrient mineral content, and nutrient yield of eight maize varieties grown in Malawi, and how these are affected by CA practises over two seasons. The minerals were analysed by inductively coupled plasma (ICP) coupled to optical emission spectroscopy (OES) and to mass spectroscopy (MS). Grain yield and Se content differed among the varieties, while C, N, Fe, K, Mg, Mn, P, and Zn were similar. The local variety Kanjerenjere showed lowest grain and nutrient yields. The open-pollinated varieties (OPVs) concentrated more minerals than the F1 hybrids, but the latter showed higher yields for both grain and nutrients. Typical consumption of the eight maize varieties could fully meet the protein and Mg dietary reference intake (DRIs) of Malawian children (1-3 years), as well as Mg and Mn needs of adult women (19-50 years), but their contribution to dietary requirements was low for Fe (39-41%) and K (13-21%). The trials showed that CA increased grain yield (1.2-to 1.8-fold) and Se content (1.1-to 1.7-fold), but that it had no effect on C, K, Mg, P, and Zn, and that N (1.1-to 1.2-fold), Mn (1.1-to 1.8-fold), and Fe (1.3-to 3.4-fold) were reduced. The high increase in grain yield under CA treatments resulted in increased yields of protein and Se, no effect on the yields of K, Mg, Mn, P, Zn, and reduced Fe yield. Conservation agriculture could contribute in reducing the risk of Se deficiency in Malawian women and children but exacerbates the risk of Fe deficiency. A combination of strategies will be needed to mitigate some of the foreseen effects of climate change on agriculture, and food and nutrition security, and improve nutrient intake.

(1) Background: Halogenated pesticides are abundantly used in Cameroon, but there is no informati... more (1) Background: Halogenated pesticides are abundantly used in Cameroon, but there is no information on the health risk of consumers from exposure to their residues in foods. (2) Methods: Residues of 20 halogenated pesticides were determined in 11 agricultural products collected in the 3 largest cities of Cameroon using QuEChERS extraction and gas chromatography with electron capture detector (GC-ECD), and health risk from dietary exposure was assessed. (3) Results: Organochlorines pesticides aldrin, p,p’-dichlorodiphenyl-trichloroethane (DDT) and β-hexachlorocyclohexane (β-HCH) found in 85.0%, 81.9% and 72.5% of samples, respectively, were the most frequently detected.
The highest average concentrations of residues were 1.12, 0.74 and 0.39 mg/kg for methoxychlor, alachlor and β-HCH, respectively, found in chilli pepper. Chili pepper (58.9%), cowpea (56.8%), black beans (56.5%) and kidney beans (54.0%) exhibited the highest residue occurrences. Levels above the European Union maximum residue limits (MRLs) were found for all the 20 pesticides, in 40.1% of the positive analyses, and the food samples contained 14 pesticides banned in Cameroon. Chronic,
acute, cumulative and carcinogenic risk assessments revealed that lifetime consumption of maize, black beans, kidney beans, groundnuts and chili pepper contaminated with aldrin, dieldrin, endrin, HCB, heptachlor, o,p’-DDT, p,p’-DDD, p,p’-DDT, p,p’-DDE and β-HCH, could pose health risks. (4) Conclusion: These results show that there is an urgent need of pesticide usage regulation, effective application of pesticide bans and management of obsolete pesticide stocks in Cameroon.

Scientific Reports, 2022

Climate change is causing problems for agriculture, but the effect of combined abiotic stresses o... more Climate change is causing problems for agriculture, but the effect of combined abiotic stresses on crop nutritional quality is not clear. Here we studied the effect of 10 combinations of climatic conditions (temperature, CO 2 , O 3 and drought) under controlled growth chamber conditions on the grain yield, protein, and mineral content of 3 wheat varieties. Results show that wheat plants under O 3 exposure alone concentrated + 15 to + 31% more grain N, Fe, Mg, Mn P and Zn, reduced K by − 5%, and C did not change. Ozone in the presence of elevated CO 2 and higher temperature enhanced the content of Fe, Mn, P and Zn by 2-18%. Water-limited chronic O 3 exposure resulted in + 9 to + 46% higher concentrations of all the minerals, except K. The effect of climate abiotic factors could increase the ability of wheat to meet adult daily dietary requirements by + 6% to + 12% for protein, Zn and Fe, but decrease those of Mg, Mn and P by − 3% to − 6%, and K by − 62%. The role of wheat in future nutrition security is discussed.

Natural agricultural inputs in sweet pepper cultivation can be beneficial for nutritional quality... more Natural agricultural inputs in sweet pepper cultivation can be beneficial for nutritional quality, and environmental and food safety. This research assessed the effect of the combined use of clove basil (Ocimum gratissimum) aqueous extract and cassava peel compost on the nutrients, pesticide residues, yield and antioxidant properties of sweet pepper fruits. The experiment was a split plot design of 04 blocks with 03 plots each and 03 repetitions, conducted in pots and in the field. The soil was amended with compost at 1kg/4kg and 2kg/3kg in pots, with 3kg/plot and 6kg/plot on field experiment, and 26.3 g of NPK (20.10.10) per plant was used as an inorganic amendment both in pots and field. Plants in both experiments were sprayed with clove basil extract, insecticide lambda-cyhalothrin or water. Sweet pepper fruits cultivated with composts and sprayed with clove basil extract exhibited the highest values of nutritional parameters, antioxidant properties and increased the yield by 93% in pots and 187% on field, as compared with synthetic fertilizer treatments. Organic fruits were free from pesticide residues and had the best values of Na/K and Ca/P ratios which are good indicators of their nutritional values. Sweet pepper plants sprayed with lambda-cyhalothrin or from farmers contained lambda-cyhalothrin at concentration of 0.0199 mg/kg. These results show that organic treatments improved the fruit nutrients, health-promoting properties and safety, and could be used to enhance the nutritional quality of sweet pepper while providing an efficient way of sustainable agriculture.

Aspergillus flavus is a pathogenic fungus associated with food safety issues worldwide. This stud... more Aspergillus flavus is a pathogenic fungus associated with food safety issues worldwide. This study investigated the antifungal activity of citrus peel extracts prepared using food-grade solvents (hot water or ethanol). Mandarin (Citrus reticulata) peel ethanol extracts inhibited the mycelial growth of A. flavus (39.60%) more effectively than those of orange (32.31%) and lemon (13.51%) after 7 days of incubation. The growth of A. flavus could be completely inhibited by mandarin extracts at 300-400 mg mL − 1 , depending on the extraction solvent. Solidphase extraction (SPE) separated the polyphenol-rich fractions, which showed up to 40% higher antifungal activity than crude extracts. Twelve polyphenols (2 phenolic acids and 10 flavonoids) were identified by HPLC-DAD, narirutin and hesperidin were the most abundant. In conclusion, citrus peels are promising bioresources of antifungal agents with potential applications in food and other industries.

European Scientific Journal, 2021

The involvement of pesticides in agriculture requires the implementation of best phytosanitary pr... more The involvement of pesticides in agriculture requires the implementation of best phytosanitary practices in order to guarantee the health of populations and preserve the environment. This study focused on the assessment of phytosanitary practices of tomato producers in Foumbot, Western Highlands-Cameroon, and evaluated the residues of 17 pesticides in tomatoes. The methodological approach consisted of field investigations by survey, collection of samples, pesticide residue extraction using QuEChERS method, and their analysis by gas chromatography tandem mass spectrometry (GC-MS). Survey of 100 farmers showed that, they did not comply with the instructions for the use of plant protection products: 56% of farmers interviewed increased the dose of products when they noticed its ineffectiveness; 93% did not the respect pre-harvest intervals; while 77% increased the application frequency at the time of fruiting. All the producers work without personal protective equipment (PPE) and 68% of them use empty packaging for packaging consumable including water, red oil and palm wine. The reuse of empty packaging could expose populations (producers and consumers) to numerous health risks. Regarding pesticides residues, 03 actives ingredients were detected and quantified in the samples, all the samples were contaminated by lambda-cyhalothrin, 86.66% by cypermethrin and 66.66% by acetamiprid. Moreover, residue concentrations above the maximum residue limit (MRL) were found in all the positive samples of lambda-cyhalothrin, and 92.30% of cypermethrin positive samples. This study shows that utilization of plant protection products in Foumbot requires extensive monitoring with producers, in order to reduce risk of consumers exposure.

Comprehensive Reviews in Food Science and Food Safety, 2020

Contamination of agricultural and food products by some fungi species that produce mycotoxins can... more Contamination of agricultural and food products by some fungi species that produce mycotoxins can result in unsafe food and feed. Mycotoxins have been demonstrated to have disease-causing activities, including carcinogenicity, immune toxicity, terato-genicity, neurotoxicity, nephrotoxicity, and hepatotoxicity. Most of mycotoxins are heat stable and cannot be easily destroyed by conventional thermal food processing or domestic cooking methods. Postharvest approaches to prevent growth of mycotoxin-producing fungi and detoxify mycotoxins from contaminated food are important topics in food safety research. Physical, chemical, and biological methods have been applied to prevent fungal growth or mycotoxin production, or to reduce mycotoxin content in the postharvest period and contribute toward mitigating against the effects of mycotoxins on human health. This literature review aims to evaluate postharvest approaches that have been applied to control both fungi growth and mycotoxin content in food and discuss their potential for upscaling to industrial scale.

Critical Reviews in Food Science and Nutrition, 2020

This paper reviews and analyses the importance of maize as staple food in Eastern and Southern Af... more This paper reviews and analyses the importance of maize as staple food in Eastern and Southern Africa (E&SA) and contributes in understanding the nexus between maize nutritional composition and prevalence of micronutrient deficiencies (MNDs) in these regions. MNDs remain a major public health concern particularly for women and children, with calcium, iodine, iron, selenium, zinc, fol-ate and vitamin A deficiencies being the most common. Estimates of their prevalence are among the highest in E&SA: iron-deficient anemia affected 26 to 31% of women of reproductive age, and deficiencies up to 53%, 36%, 66%, 75% and 62% for vitamin A, iodine, zinc, calcium and selenium, respectively, were measured in populations of these regions. Besides, these two regions show the highest worldwide maize per capita consumption (g/person/day) as main staple, with 157 in Eastern Africa and 267 in Southern Africa, including up to 444 in Lesotho. The analysis of food composition tables from these regions showed that 100 g of maize foods consumed by these populations could to some extent, contribute in satisfying dietary reference intakes (DRIs) of children and women in energy, proteins, carbohydrates, magnesium, zinc, vitamins B1 and B6. However, it provides very low supply of fats, calcium, sodium, selenium, vitamins C, A and E. The high occurrence of MNDs and considerable nutritional potential of maize consumed in E&SA can be explained by loss of nutrients due to processing practices, low food diversification and reduced nutrients bioavailability. Success cases of the main strategies to tackle the issue of MNDs in these regions by improving maize nutritional quality are discussed in this paper. Maize fortification was shown to improve nutrition and health outcomes of population. Increasing dietary diversity by complementing maize with other foods has improved nutrition through integration of micronu-trient-rich foods in the diet. Mostly, biofortification has successfully contributed in reducing vitamin A and zinc deficiencies in rural communities more than nutrient supplementation, fortification and dietary diversity.

Food Control, 2020

This study monitored 81 pesticides residues in 160 samples of 11 dry agricultural products collec... more This study monitored 81 pesticides residues in 160 samples of 11 dry agricultural products collected in the 3 largest cities of Cameroon, extracted using QuEChERS method and analysed by liquid chromatography tandem mass spectrometry (LC-MS/MS). Residues of 58 (71.6%) compounds were found in the samples, the most distributed pesticides were Imazalil, Triadimenol and Pyrimethanil, and those with the highest average concentrations were Cymoxanil, Thiamethoxam and Thifensulfuron. Half of the positive pesticides were above their European Union maximum residue limits (MRLs) among which Carbaryl, Carbofuran, Malathion, Metalaxyl and Propoxur are pesticides banned in the country. All the 11 food items contained pesticides, the highest contamination rates (12.8%-5.0%) were found in white pepper, maize, Egusi seeds and groundnuts, while groundnuts, Egusi seeds, maize and soybeans showed the highest residue concentrations (1.46-1.37 mg/kg). Pesticide contamination rates were similar in the 3 sampling cities, but Bafoussam and Yaounde had more samples above the MRLs than Douala. Using the food consumption data for Cameroon from the recent Sub-Saharan Africa Total Diet Study, dietary exposure was calculated and potential health risk of Cameroonian consumers was evaluated. Hazard quotient of Carbofuran in groundnuts was 22% above the safe value, the remaining food items could be considered safe for individual pesticide residues, although Triazophos and Metribuzin in maize were of concern. Groundnuts (0.531) and maize (0.443) showed high hazard index, with 17 highly contributing compounds, but there is no reason to be concerned about cumulative exposure to residues from the food items. While the food items are in general safe to eat, to minimize the increasing human health risk of consumers and ensure approval of Cameroon export produces on international market, this study suggests that authorities must regulate the usage of agrochemicals, strengthen the controls for effective implementation of the pesticide bans and implement strong control of obsolete pesticide stocks in the country.

Analytical and Bioanalytical Chemistry, 2019

In mass spectrometry, the type and design of ionization source play a key role on the performance... more In mass spectrometry, the type and design of ionization source play a key role on the performance of a given instrument. Therefore, it is of paramount importance to evaluate newly developed sources for their suitability to analyze food contaminants like pesticide residues. Here, we carried out a head-to-head comparison of key extraction and analytical performance parameters of an electrospray ionization (ESI) source with a new atmospheric pressure ionization source, UniSpray (US). The two interfaces were evaluated in three matrices of different properties (coffee, apple, and water) to determine if multiresidue analysis of 81 pesticides by QuEChERS extraction and LC-MS/MS analysis could be improved. Depending on the matrix and irrespective of the chemical class, US provided a tremendous gain in signal intensity (22-to 32-fold in peak area, 6-to 7-fold in peak height), a threefold to fourfold increase in signal-to-noise ratio, a mild gain in the range of compounds that can be quantified, and up to twofold improvement of recovery. UniSpray offered comparable linearity and precision of the analyses with ESI, and did not affect the ion ratio. A gain in sensitivity of many compounds was observed with US, but in general, the two ionization interfaces did not show significant difference in LOD and LOQ. UniSpray suffered less signal suppression; the matrix effect was in average 3 to 4 times more pronounced, but showed better values than ESI. With no effect on recovery efficiency, US improved the overall process efficiency 3 to 4 times more than ESI.

Horticultural Plant Journal, 2017

Storage of potato tubers at low temperature affects their metabolism and may alter their phytoche... more Storage of potato tubers at low temperature affects their metabolism and may alter their phytochemical properties. There is a need to elucidate the changes in antioxidant compounds, activity and enzymes during storage of tubers. Eleven Indian potato varieties were evaluated for antioxidant parameters, after 0, 30, 60 and 90 days of storage at room temperature, 15°C and 4°C. Total phenolics (0.0786-0.1546 mg gallic acid equivalents·g −1 FW) and vitamin C content (0.0828-0.2416 mg·g −1 FW) varied among the varieties and were different with storage temperature ; their levels fluctuated during storage but remained above the initial level until the last day of observation. Phenolic acid profiling by UPLC identified 12 compounds among which the most abundant was chlorogenic acid followed by gallic acid, sinapic acid and ellagic acid. Except para-coumaric acid which decreased at 4°C, all the phenolic acids increased with storage. Caffeic acid, chlorogenic acid, protocatechuic acid and gallic acid mostly correlated with total phenolic content (r = 0.456, 0.482, 0.588 and 0.620, respectively). Antioxidant activity against both DPPH and ABTS radicals increased during the initial days of storage and then dropped to a level comparable or lower than the original value, irrespective of the storage temperature. Correlation study revealed that chlorogenic acid, gallic acid and ferulic acid mostly contributed to an-tioxidant activity. Activity of both antioxidant enzymes, superoxide dismutase and ascorbate peroxidase, increased initially but then decreased to values lower than the initial level and were not influenced by storage temperature. Correlation with antioxidant activity indicated that the enhancement of reactive oxygen scavenging species in cold stored tubers could result mainly from ascorbate peroxidase activity. Our results demonstrate that storage temperature adversely influences the metabolism and the content of antioxidant compounds in potato tubers, with subsequent increase on their antioxidant capacity.

Food and Chemical Toxicology, 2017

For directing scientists, consumers, industry and stakeholders on mitigation strategies, there is... more For directing scientists, consumers, industry and stakeholders on mitigation strategies, there is a need to understand the acrylamide-forming potential of important Indian foods. Flour obtained from total 16 varieties of 9 Indian cereals, legumes and roots and tubers was heated at 160 C for 20 min, acrylamide was extracted and quantified by UPLC-UV. Acrylamide level was above the European Commission indicative value in potato-and cereal-based food products, it ranged from 3436.13 to 5562.56 mg/kg in roots and tubers (potato and sweet potato). Among the cereals, maize (2195.31 mg/kg) and wheat (161.12 mg/kg) had the highest and lowest contents, respectively, whereas rice, sorghum and pearl millet showed intermediate values. Among the 2 legumes, soybean contained higher acrylamide (337.08 -717.52 mg/kg) than chickpea (377.83-480.49 mg/kg). Analysis of variance revealed that roots and tubers acrylamide was highly significantly greater than the content in cereals (p < 0.0001) and in legumes (p < 0.0001) while there was no significant difference between cereals and legumes (p = 0.443). These results support the combination of pulses and minor cereals (chickpea, soybean, millets and sorghum) in cereal-based foods for improving the nutritional value and reducing acrylamide formation.

Foods, 2018

There is no information available on pesticide residue levels in major food commodities harvested... more There is no information available on pesticide residue levels in major food commodities harvested in Cameroon, especially from the western highlands region, the food basket of the country. Hence, this study evaluated the residues of 99 pesticides in 72 samples of 12 agricultural products collected in the region, using QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method extraction, and analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) and gas chromatography with electron capture detection (GC-ECD). This method was suitable for detecting the targeted compounds: For 81 pesticides by LC-MS/MS, the limit of quantification (LOQ) was between 0.0004 and 0.0537 mg/kg; and for 18 halogenated pesticides by GC-ECD, it ranged from 0.0012 to 0.2180 mg/kg. The residues of 62 pesticides, including 12 banned compounds, were found in the samples. Insecticides (39.7%) were the most prevalent group, with all the samples containing at least one pesticide. Twenty-one pesticides (34.4%) exceeded their European Union maximum residue limits (MRLs) and 22 pesticides (34.4%) were found in all 6 sampling locations. Malathion and p,p-DDT were the most distributed pesticides, found in almost all the samples and sampling sites. Food items with the highest rates of positive results were chili pepper (23.2%), white pepper (20.2%), kidney beans (17.3%), and soybeans (17.2%). Samples with residues above their MRLs represented 38% of all the positive analyses; chili pepper (6.4%) and kidney beans (5.5%) were found to have the most residues above their MRLs. The most critical food commodities were kidney beans, soybeans, chili pepper, and maize. This data presents scientific evidence that investigation into continuous monitoring and good regulation of pesticide usage in Cameroon is needed, and paves the way for health risks analysis.

Antioxidants, 2017

It is of paramount importance for consumers, scientists and industrialists to understand how low-... more It is of paramount importance for consumers, scientists and industrialists to understand how low-temperature storage of food items affects their bioactive compounds and properties. This study evaluated the effects of cold storage on total phenolics (TP), phenolic acids profile (PA), total anthocyanins (TA), total ascorbic acid (Vit. C) and antioxidant activity (AA) of 19 fruits and vegetables, collected from local Indian markets and stored in refrigerator (4 • C) during 15 days. Content of TP was highest in dill and amaranth and decreased (up to 29.67%) with storage. Leafy vegetables (amaranth, dill, onion, fenugreek and spinach) contained higher amounts of the 12 PA revealed by UPLC-UV; ellagic, gallic, sinapic and vanillic acids levels were the highest; chlorogenic acid (= 0.423), syringic acid (= 0.403) and sinapic acid (= 0.452) mostly correlated with TP; and the PA increased during storage. Highest contents of Vit C estimated by AOAC, DCPIP and DNP methods were found in amaranth, dill and pomegranate, and decreased with storage. Pomegranate showed highest TA levels and low-temperature storage did not significantly increase TA, which was the largest contributor of TP in fruits and vegetables (= 0.661). Storage induced a drastic decrease of AA, which mostly correlated with TP (= 0.808, 0.690 and 0.458 for DPPH, ABTS and FRAP assays, respectively). Spearman's correlation confirmed by principal component analysis demonstrated that dill, pomegranate and amaranth had the highest overall antioxidant capacity, whereas orange juice and carrot showed the lowest. The results provide support for a key-role of TP, followed by Vit. C and TA in antioxidant capacity of fruits and vegetables, which could be interesting dietary sources of natural antioxidants for prevention of diseases caused by oxidative stress.

American Journal of Potato Research, 2015

Cold-induced sweetening (CIS) characterized by reducing sugars (RS) accumulation during low tempe... more Cold-induced sweetening (CIS) characterized by reducing sugars (RS) accumulation during low temperature storage of potato (Solanum tuberosum L.) tubers remains a serious postharvest concern for the potato processing industry. Enzymes involved in carbohydrates metabolism and the genes modulating their activities are of paramount importance in the events associated with the development of CIS. Expression of vacuolar acid invertase gene StvacINV1, β-amylase gene BAM1 and invertase inhibitor gene INH2α and their consequence on acid invertase and β-amylase activities with resulting RS accumulation were followed in one CIS-tolerant (Kufri Jyoti) and one CIS-susceptible (Kufri Badshah) Indian potato varieties stored in cold conditions. Differential gene expression analysis showed that during cold storage, expression of StvacINV1 and BAM1 increased at low temperature and their transcripts were more expressed in the CIS-tolerant variety than the CIS-sensitive. Besides, correlation between BAM1 expression and β-amylase activity affirmed the hypothesis of several enzymes and pathways involved in starch degradation during cold storage of potato. Expression of invertase inhibitor gene INH2α however was higher in the CIS-tolerant variety than the CIS-sensitive. Correlating StvacINV1 and INH2α expressions with RS content and acid invertase activity established that post-translational regulation of acid invertase by the invertase inhibitor protein could be an important component of resistance to CIS.

Frontiers in Sustainable Food Systems, 2022

Biophysical evaluations of climate-smart agriculture (CSA) often overlook the potential interacti... more Biophysical evaluations of climate-smart agriculture (CSA) often overlook the potential interactions with and implications for biodiversity and ecosystem services, which are important determinants of food system resilience and sustainability. Drawing on a case study in the East Usambara Mountains, Tanzania, we compare the impacts of CSA with other agricultural management practices on invertebrate pest and natural enemy diversity, and the associated effects on crop damage and crop yield. We found that the most common CSA practices in the region, terracing and trenching with live and compost mulches, provided the best outcomes for crop production, pest suppression and agricultural income. However, greater diversity of pests was observed when neighboring fields planted improved crop varieties, suggesting that the use of improved varieties by farmers creates increased vulnerability to pest damage among neighboring farmers that used local varieties. Also, greater natural enemy diversity was found when neighboring fields were either intercropped or left fallow highlighting spatial flows of ecosystem services between fields. Landcover heterogeneity was positively correlated with pest diversity, whilst landcover richness was positively associated with higher pest volume, highlighting the importance of landscape characteristics in pest and natural enemy dynamics. Finally, we found that crop damage was most severe when pest communities had low species richness, suggesting that a small number of key crop pests contribute to most yield losses. Our findings illustrate that those varied combinations of agricultural management practices lead to heterogeneous biodiversity outcomes and trade-offs, and highlight the importance of local management, neighborhood effects and landscape characteristics. CSA evaluations must therefore look beyond productivity as a measure for success, as trade-offs with invertebrate biodiversity, food production, and environmental sustainability often interact and feedback in complex and unexpected ways.

Intech Open Book Chapter , 2022

Yam is a labor-intensive and weed-sensitive food crop. The labor-intensive nature of the yam mean... more Yam is a labor-intensive and weed-sensitive food crop. The labor-intensive nature of the yam means that the production process requires the attention of the farmer all year round. However, the dwindling labor situation and the proliferation of weeds have forced farmers to think of modern ways of controlling weeds on their farms, that is, the adoption of chemical (herbicides) weed control. Even though the adoption of these chemicals has no doubt brought relief to the farmers and has resulted in increased yam production over the years, it has also brought in its wake, negative externalities of environmental pollution, human health effects, and food quality issues. The study was thus designed to investigate how yam is produced, the human and environmental health effects of how yam is produced, and food quality effects of how yam is produced. This was done through literature review, and field and laboratory experiments. It was revealed that, in recent years, new innovations have been introduced in yam production, the manner in which farmers handle herbicides in their yam production process exposes them to high doses of pesticides, thereby endangering their lives. The study findings also suggest that the use of herbicides in yam production does not affect the quality of the yam.

Frontiers in Sustainable Food Systems, 2022

Climate change will put millions more people in Africa at risk of food and nutrition insecurity b... more Climate change will put millions more people in Africa at risk of food and nutrition insecurity by 2050. Integrated assessments of food systems tend to be limited by either heavy reliance on models or a lack of information on food and nutrition security.

Accordingly, we developed a novel integrated assessment framework that combines models with in-country knowledge and expert academic judgement to explore climate-smart and nutrition-secure food system futures: the integrated Future Estimator for Emissions and Diets (iFEED). Here, we describe iFEED and present its application in Malawi, South Africa, Tanzania and Zambia.

The iFEED process begins with a participatory scenario workshop. In-country stakeholders identify two key drivers of food system change, and from these, four possible scenarios are defined. These scenarios provide the underlying narratives of change to the food system. Integrated modelling of climate change, food production and greenhouse gas emissions is then used to explore nutrition security and climate-smart agriculture outcomes for each scenario. Model results are summarised using calibrated statements - quantitative statements of model outcomes and our confidence in them. These include statements about the way in which different trade futures interact with climate change and domestic production in determining nutrition security at the national level.

To understand what the model results mean for food systems, the calibrated statements are expanded upon using implication statements. The implications rely on input from a wide range of academic experts – including agro-ecologists and social scientists. A series of workshops are used to incorporate in-country expertise, identifying any gaps in knowledge and summarising information for country-level recommendations. iFEED stakeholder champions help throughout by providing in-country expertise and disseminating knowledge to policy makers.

iFEED has numerous novel aspects that can be used and developed in future work. It provides information to support evidence-based decisions for a climate-smart and nutrition-secure future. In particular, iFEED: i. employs novel and inclusive reporting of model results and associated in-country food system activities, with comprehensive reporting of uncertainty; ii. includes climate change mitigation alongside adaptation measures; and iii. quantifies future population-level nutrition security, as opposed to simply assessing future production and food security implications.

International Journal of Environmental Research and Public Health, 2022

Despite the fact that several cases of unsafe pesticide use among farmers in different parts of A... more Despite the fact that several cases of unsafe pesticide use among farmers in different parts of Africa have been documented, there is limited evidence regarding which specific interventions are effective in reducing pesticide exposure and associated risks to human health and ecology. The overall goal of the African Pesticide Intervention Project (APsent) study is to better understand ongoing research and public health activities related to interventions in Africa through the implementation of suitable target-specific situations or use contexts. A systematic review of the scientific literature on pesticide intervention studies with a focus on Africa was conducted. This was followed by a qualitative survey among stakeholders involved in pesticide research or management in the African region to learn about barriers to and promoters of successful interventions. The project was concluded with an international workshop in November 2021, where a broad range of topics relevant to occupational and environmental health risks were discussed such as acute poisoning, street pesticides, switching to alternatives, or disposal of empty pesticide containers. Key areas of improvement identified were training on pesticide usage techniques, research on the effectiveness of interventions targeted at exposure reduction and/or behavioral changes, awareness raising, implementation of adequate policies, and enforcement of regulations and processes.

Scientific Reports, 2022

Climate change is causing problems for agriculture, but the effect of combined abiotic stresses o... more Climate change is causing problems for agriculture, but the effect of combined abiotic stresses on crop nutritional quality is not clear. Here we studied the effect of 10 combinations of climatic conditions (temperature, CO 2 , O 3 and drought) under controlled growth chamber conditions on the grain yield, protein, and mineral content of 3 wheat varieties. Results show that wheat plants under O 3 exposure alone concentrated + 15 to + 31% more grain N, Fe, Mg, Mn P and Zn, reduced K by − 5%, and C did not change. Ozone in the presence of elevated CO 2 and higher temperature enhanced the content of Fe, Mn, P and Zn by 2-18%. Water-limited chronic O 3 exposure resulted in + 9 to + 46% higher concentrations of all the minerals, except K. The effect of climate abiotic factors could increase the ability of wheat to meet adult daily dietary requirements by + 6% to + 12% for protein, Zn and Fe, but decrease those of Mg, Mn and P by − 3% to − 6%, and K by − 62%. The role of wheat in future nutrition security is discussed.

Maize is a major staple and plays an essential role in food and nutrition security in Sub-Saharan... more Maize is a major staple and plays an essential role in food and nutrition security in Sub-Saharan Africa (SSA). Conservation agriculture (CA), a climate-smart agriculture practise based on minimum soil disturbance, crop residue retention, and crop diversification, has been widely advocated but without extensive research on the impact it may have on maize nutrient composition, and food and nutrition security. This study assessed the grain yield, macro-and micronutrient mineral content, and nutrient yield of eight maize varieties grown in Malawi, and how these are affected by CA practises over two seasons. The minerals were analysed by inductively coupled plasma (ICP) coupled to optical emission spectroscopy (OES) and to mass spectroscopy (MS). Grain yield and Se content differed among the varieties, while C, N, Fe, K, Mg, Mn, P, and Zn were similar. The local variety Kanjerenjere showed lowest grain and nutrient yields. The open-pollinated varieties (OPVs) concentrated more minerals than the F1 hybrids, but the latter showed higher yields for both grain and nutrients. Typical consumption of the eight maize varieties could fully meet the protein and Mg dietary reference intake (DRIs) of Malawian children (1-3 years), as well as Mg and Mn needs of adult women (19-50 years), but their contribution to dietary requirements was low for Fe (39-41%) and K (13-21%). The trials showed that CA increased grain yield (1.2-to 1.8-fold) and Se content (1.1-to 1.7-fold), but that it had no effect on C, K, Mg, P, and Zn, and that N (1.1-to 1.2-fold), Mn (1.1-to 1.8-fold), and Fe (1.3-to 3.4-fold) were reduced. The high increase in grain yield under CA treatments resulted in increased yields of protein and Se, no effect on the yields of K, Mg, Mn, P, Zn, and reduced Fe yield. Conservation agriculture could contribute in reducing the risk of Se deficiency in Malawian women and children but exacerbates the risk of Fe deficiency. A combination of strategies will be needed to mitigate some of the foreseen effects of climate change on agriculture, and food and nutrition security, and improve nutrient intake.

(1) Background: Halogenated pesticides are abundantly used in Cameroon, but there is no informati... more (1) Background: Halogenated pesticides are abundantly used in Cameroon, but there is no information on the health risk of consumers from exposure to their residues in foods. (2) Methods: Residues of 20 halogenated pesticides were determined in 11 agricultural products collected in the 3 largest cities of Cameroon using QuEChERS extraction and gas chromatography with electron capture detector (GC-ECD), and health risk from dietary exposure was assessed. (3) Results: Organochlorines pesticides aldrin, p,p’-dichlorodiphenyl-trichloroethane (DDT) and β-hexachlorocyclohexane (β-HCH) found in 85.0%, 81.9% and 72.5% of samples, respectively, were the most frequently detected.
The highest average concentrations of residues were 1.12, 0.74 and 0.39 mg/kg for methoxychlor, alachlor and β-HCH, respectively, found in chilli pepper. Chili pepper (58.9%), cowpea (56.8%), black beans (56.5%) and kidney beans (54.0%) exhibited the highest residue occurrences. Levels above the European Union maximum residue limits (MRLs) were found for all the 20 pesticides, in 40.1% of the positive analyses, and the food samples contained 14 pesticides banned in Cameroon. Chronic,
acute, cumulative and carcinogenic risk assessments revealed that lifetime consumption of maize, black beans, kidney beans, groundnuts and chili pepper contaminated with aldrin, dieldrin, endrin, HCB, heptachlor, o,p’-DDT, p,p’-DDD, p,p’-DDT, p,p’-DDE and β-HCH, could pose health risks. (4) Conclusion: These results show that there is an urgent need of pesticide usage regulation, effective application of pesticide bans and management of obsolete pesticide stocks in Cameroon.

Scientific Reports, 2022

Climate change is causing problems for agriculture, but the effect of combined abiotic stresses o... more Climate change is causing problems for agriculture, but the effect of combined abiotic stresses on crop nutritional quality is not clear. Here we studied the effect of 10 combinations of climatic conditions (temperature, CO 2 , O 3 and drought) under controlled growth chamber conditions on the grain yield, protein, and mineral content of 3 wheat varieties. Results show that wheat plants under O 3 exposure alone concentrated + 15 to + 31% more grain N, Fe, Mg, Mn P and Zn, reduced K by − 5%, and C did not change. Ozone in the presence of elevated CO 2 and higher temperature enhanced the content of Fe, Mn, P and Zn by 2-18%. Water-limited chronic O 3 exposure resulted in + 9 to + 46% higher concentrations of all the minerals, except K. The effect of climate abiotic factors could increase the ability of wheat to meet adult daily dietary requirements by + 6% to + 12% for protein, Zn and Fe, but decrease those of Mg, Mn and P by − 3% to − 6%, and K by − 62%. The role of wheat in future nutrition security is discussed.

Natural agricultural inputs in sweet pepper cultivation can be beneficial for nutritional quality... more Natural agricultural inputs in sweet pepper cultivation can be beneficial for nutritional quality, and environmental and food safety. This research assessed the effect of the combined use of clove basil (Ocimum gratissimum) aqueous extract and cassava peel compost on the nutrients, pesticide residues, yield and antioxidant properties of sweet pepper fruits. The experiment was a split plot design of 04 blocks with 03 plots each and 03 repetitions, conducted in pots and in the field. The soil was amended with compost at 1kg/4kg and 2kg/3kg in pots, with 3kg/plot and 6kg/plot on field experiment, and 26.3 g of NPK (20.10.10) per plant was used as an inorganic amendment both in pots and field. Plants in both experiments were sprayed with clove basil extract, insecticide lambda-cyhalothrin or water. Sweet pepper fruits cultivated with composts and sprayed with clove basil extract exhibited the highest values of nutritional parameters, antioxidant properties and increased the yield by 93% in pots and 187% on field, as compared with synthetic fertilizer treatments. Organic fruits were free from pesticide residues and had the best values of Na/K and Ca/P ratios which are good indicators of their nutritional values. Sweet pepper plants sprayed with lambda-cyhalothrin or from farmers contained lambda-cyhalothrin at concentration of 0.0199 mg/kg. These results show that organic treatments improved the fruit nutrients, health-promoting properties and safety, and could be used to enhance the nutritional quality of sweet pepper while providing an efficient way of sustainable agriculture.

Aspergillus flavus is a pathogenic fungus associated with food safety issues worldwide. This stud... more Aspergillus flavus is a pathogenic fungus associated with food safety issues worldwide. This study investigated the antifungal activity of citrus peel extracts prepared using food-grade solvents (hot water or ethanol). Mandarin (Citrus reticulata) peel ethanol extracts inhibited the mycelial growth of A. flavus (39.60%) more effectively than those of orange (32.31%) and lemon (13.51%) after 7 days of incubation. The growth of A. flavus could be completely inhibited by mandarin extracts at 300-400 mg mL − 1 , depending on the extraction solvent. Solidphase extraction (SPE) separated the polyphenol-rich fractions, which showed up to 40% higher antifungal activity than crude extracts. Twelve polyphenols (2 phenolic acids and 10 flavonoids) were identified by HPLC-DAD, narirutin and hesperidin were the most abundant. In conclusion, citrus peels are promising bioresources of antifungal agents with potential applications in food and other industries.

European Scientific Journal, 2021

The involvement of pesticides in agriculture requires the implementation of best phytosanitary pr... more The involvement of pesticides in agriculture requires the implementation of best phytosanitary practices in order to guarantee the health of populations and preserve the environment. This study focused on the assessment of phytosanitary practices of tomato producers in Foumbot, Western Highlands-Cameroon, and evaluated the residues of 17 pesticides in tomatoes. The methodological approach consisted of field investigations by survey, collection of samples, pesticide residue extraction using QuEChERS method, and their analysis by gas chromatography tandem mass spectrometry (GC-MS). Survey of 100 farmers showed that, they did not comply with the instructions for the use of plant protection products: 56% of farmers interviewed increased the dose of products when they noticed its ineffectiveness; 93% did not the respect pre-harvest intervals; while 77% increased the application frequency at the time of fruiting. All the producers work without personal protective equipment (PPE) and 68% of them use empty packaging for packaging consumable including water, red oil and palm wine. The reuse of empty packaging could expose populations (producers and consumers) to numerous health risks. Regarding pesticides residues, 03 actives ingredients were detected and quantified in the samples, all the samples were contaminated by lambda-cyhalothrin, 86.66% by cypermethrin and 66.66% by acetamiprid. Moreover, residue concentrations above the maximum residue limit (MRL) were found in all the positive samples of lambda-cyhalothrin, and 92.30% of cypermethrin positive samples. This study shows that utilization of plant protection products in Foumbot requires extensive monitoring with producers, in order to reduce risk of consumers exposure.

Comprehensive Reviews in Food Science and Food Safety, 2020

Contamination of agricultural and food products by some fungi species that produce mycotoxins can... more Contamination of agricultural and food products by some fungi species that produce mycotoxins can result in unsafe food and feed. Mycotoxins have been demonstrated to have disease-causing activities, including carcinogenicity, immune toxicity, terato-genicity, neurotoxicity, nephrotoxicity, and hepatotoxicity. Most of mycotoxins are heat stable and cannot be easily destroyed by conventional thermal food processing or domestic cooking methods. Postharvest approaches to prevent growth of mycotoxin-producing fungi and detoxify mycotoxins from contaminated food are important topics in food safety research. Physical, chemical, and biological methods have been applied to prevent fungal growth or mycotoxin production, or to reduce mycotoxin content in the postharvest period and contribute toward mitigating against the effects of mycotoxins on human health. This literature review aims to evaluate postharvest approaches that have been applied to control both fungi growth and mycotoxin content in food and discuss their potential for upscaling to industrial scale.

Critical Reviews in Food Science and Nutrition, 2020

This paper reviews and analyses the importance of maize as staple food in Eastern and Southern Af... more This paper reviews and analyses the importance of maize as staple food in Eastern and Southern Africa (E&SA) and contributes in understanding the nexus between maize nutritional composition and prevalence of micronutrient deficiencies (MNDs) in these regions. MNDs remain a major public health concern particularly for women and children, with calcium, iodine, iron, selenium, zinc, fol-ate and vitamin A deficiencies being the most common. Estimates of their prevalence are among the highest in E&SA: iron-deficient anemia affected 26 to 31% of women of reproductive age, and deficiencies up to 53%, 36%, 66%, 75% and 62% for vitamin A, iodine, zinc, calcium and selenium, respectively, were measured in populations of these regions. Besides, these two regions show the highest worldwide maize per capita consumption (g/person/day) as main staple, with 157 in Eastern Africa and 267 in Southern Africa, including up to 444 in Lesotho. The analysis of food composition tables from these regions showed that 100 g of maize foods consumed by these populations could to some extent, contribute in satisfying dietary reference intakes (DRIs) of children and women in energy, proteins, carbohydrates, magnesium, zinc, vitamins B1 and B6. However, it provides very low supply of fats, calcium, sodium, selenium, vitamins C, A and E. The high occurrence of MNDs and considerable nutritional potential of maize consumed in E&SA can be explained by loss of nutrients due to processing practices, low food diversification and reduced nutrients bioavailability. Success cases of the main strategies to tackle the issue of MNDs in these regions by improving maize nutritional quality are discussed in this paper. Maize fortification was shown to improve nutrition and health outcomes of population. Increasing dietary diversity by complementing maize with other foods has improved nutrition through integration of micronu-trient-rich foods in the diet. Mostly, biofortification has successfully contributed in reducing vitamin A and zinc deficiencies in rural communities more than nutrient supplementation, fortification and dietary diversity.

Food Control, 2020

This study monitored 81 pesticides residues in 160 samples of 11 dry agricultural products collec... more This study monitored 81 pesticides residues in 160 samples of 11 dry agricultural products collected in the 3 largest cities of Cameroon, extracted using QuEChERS method and analysed by liquid chromatography tandem mass spectrometry (LC-MS/MS). Residues of 58 (71.6%) compounds were found in the samples, the most distributed pesticides were Imazalil, Triadimenol and Pyrimethanil, and those with the highest average concentrations were Cymoxanil, Thiamethoxam and Thifensulfuron. Half of the positive pesticides were above their European Union maximum residue limits (MRLs) among which Carbaryl, Carbofuran, Malathion, Metalaxyl and Propoxur are pesticides banned in the country. All the 11 food items contained pesticides, the highest contamination rates (12.8%-5.0%) were found in white pepper, maize, Egusi seeds and groundnuts, while groundnuts, Egusi seeds, maize and soybeans showed the highest residue concentrations (1.46-1.37 mg/kg). Pesticide contamination rates were similar in the 3 sampling cities, but Bafoussam and Yaounde had more samples above the MRLs than Douala. Using the food consumption data for Cameroon from the recent Sub-Saharan Africa Total Diet Study, dietary exposure was calculated and potential health risk of Cameroonian consumers was evaluated. Hazard quotient of Carbofuran in groundnuts was 22% above the safe value, the remaining food items could be considered safe for individual pesticide residues, although Triazophos and Metribuzin in maize were of concern. Groundnuts (0.531) and maize (0.443) showed high hazard index, with 17 highly contributing compounds, but there is no reason to be concerned about cumulative exposure to residues from the food items. While the food items are in general safe to eat, to minimize the increasing human health risk of consumers and ensure approval of Cameroon export produces on international market, this study suggests that authorities must regulate the usage of agrochemicals, strengthen the controls for effective implementation of the pesticide bans and implement strong control of obsolete pesticide stocks in the country.

Analytical and Bioanalytical Chemistry, 2019

In mass spectrometry, the type and design of ionization source play a key role on the performance... more In mass spectrometry, the type and design of ionization source play a key role on the performance of a given instrument. Therefore, it is of paramount importance to evaluate newly developed sources for their suitability to analyze food contaminants like pesticide residues. Here, we carried out a head-to-head comparison of key extraction and analytical performance parameters of an electrospray ionization (ESI) source with a new atmospheric pressure ionization source, UniSpray (US). The two interfaces were evaluated in three matrices of different properties (coffee, apple, and water) to determine if multiresidue analysis of 81 pesticides by QuEChERS extraction and LC-MS/MS analysis could be improved. Depending on the matrix and irrespective of the chemical class, US provided a tremendous gain in signal intensity (22-to 32-fold in peak area, 6-to 7-fold in peak height), a threefold to fourfold increase in signal-to-noise ratio, a mild gain in the range of compounds that can be quantified, and up to twofold improvement of recovery. UniSpray offered comparable linearity and precision of the analyses with ESI, and did not affect the ion ratio. A gain in sensitivity of many compounds was observed with US, but in general, the two ionization interfaces did not show significant difference in LOD and LOQ. UniSpray suffered less signal suppression; the matrix effect was in average 3 to 4 times more pronounced, but showed better values than ESI. With no effect on recovery efficiency, US improved the overall process efficiency 3 to 4 times more than ESI.

Horticultural Plant Journal, 2017

Storage of potato tubers at low temperature affects their metabolism and may alter their phytoche... more Storage of potato tubers at low temperature affects their metabolism and may alter their phytochemical properties. There is a need to elucidate the changes in antioxidant compounds, activity and enzymes during storage of tubers. Eleven Indian potato varieties were evaluated for antioxidant parameters, after 0, 30, 60 and 90 days of storage at room temperature, 15°C and 4°C. Total phenolics (0.0786-0.1546 mg gallic acid equivalents·g −1 FW) and vitamin C content (0.0828-0.2416 mg·g −1 FW) varied among the varieties and were different with storage temperature ; their levels fluctuated during storage but remained above the initial level until the last day of observation. Phenolic acid profiling by UPLC identified 12 compounds among which the most abundant was chlorogenic acid followed by gallic acid, sinapic acid and ellagic acid. Except para-coumaric acid which decreased at 4°C, all the phenolic acids increased with storage. Caffeic acid, chlorogenic acid, protocatechuic acid and gallic acid mostly correlated with total phenolic content (r = 0.456, 0.482, 0.588 and 0.620, respectively). Antioxidant activity against both DPPH and ABTS radicals increased during the initial days of storage and then dropped to a level comparable or lower than the original value, irrespective of the storage temperature. Correlation study revealed that chlorogenic acid, gallic acid and ferulic acid mostly contributed to an-tioxidant activity. Activity of both antioxidant enzymes, superoxide dismutase and ascorbate peroxidase, increased initially but then decreased to values lower than the initial level and were not influenced by storage temperature. Correlation with antioxidant activity indicated that the enhancement of reactive oxygen scavenging species in cold stored tubers could result mainly from ascorbate peroxidase activity. Our results demonstrate that storage temperature adversely influences the metabolism and the content of antioxidant compounds in potato tubers, with subsequent increase on their antioxidant capacity.

Food and Chemical Toxicology, 2017

For directing scientists, consumers, industry and stakeholders on mitigation strategies, there is... more For directing scientists, consumers, industry and stakeholders on mitigation strategies, there is a need to understand the acrylamide-forming potential of important Indian foods. Flour obtained from total 16 varieties of 9 Indian cereals, legumes and roots and tubers was heated at 160 C for 20 min, acrylamide was extracted and quantified by UPLC-UV. Acrylamide level was above the European Commission indicative value in potato-and cereal-based food products, it ranged from 3436.13 to 5562.56 mg/kg in roots and tubers (potato and sweet potato). Among the cereals, maize (2195.31 mg/kg) and wheat (161.12 mg/kg) had the highest and lowest contents, respectively, whereas rice, sorghum and pearl millet showed intermediate values. Among the 2 legumes, soybean contained higher acrylamide (337.08 -717.52 mg/kg) than chickpea (377.83-480.49 mg/kg). Analysis of variance revealed that roots and tubers acrylamide was highly significantly greater than the content in cereals (p < 0.0001) and in legumes (p < 0.0001) while there was no significant difference between cereals and legumes (p = 0.443). These results support the combination of pulses and minor cereals (chickpea, soybean, millets and sorghum) in cereal-based foods for improving the nutritional value and reducing acrylamide formation.

Foods, 2018

There is no information available on pesticide residue levels in major food commodities harvested... more There is no information available on pesticide residue levels in major food commodities harvested in Cameroon, especially from the western highlands region, the food basket of the country. Hence, this study evaluated the residues of 99 pesticides in 72 samples of 12 agricultural products collected in the region, using QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method extraction, and analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) and gas chromatography with electron capture detection (GC-ECD). This method was suitable for detecting the targeted compounds: For 81 pesticides by LC-MS/MS, the limit of quantification (LOQ) was between 0.0004 and 0.0537 mg/kg; and for 18 halogenated pesticides by GC-ECD, it ranged from 0.0012 to 0.2180 mg/kg. The residues of 62 pesticides, including 12 banned compounds, were found in the samples. Insecticides (39.7%) were the most prevalent group, with all the samples containing at least one pesticide. Twenty-one pesticides (34.4%) exceeded their European Union maximum residue limits (MRLs) and 22 pesticides (34.4%) were found in all 6 sampling locations. Malathion and p,p-DDT were the most distributed pesticides, found in almost all the samples and sampling sites. Food items with the highest rates of positive results were chili pepper (23.2%), white pepper (20.2%), kidney beans (17.3%), and soybeans (17.2%). Samples with residues above their MRLs represented 38% of all the positive analyses; chili pepper (6.4%) and kidney beans (5.5%) were found to have the most residues above their MRLs. The most critical food commodities were kidney beans, soybeans, chili pepper, and maize. This data presents scientific evidence that investigation into continuous monitoring and good regulation of pesticide usage in Cameroon is needed, and paves the way for health risks analysis.

Antioxidants, 2017

It is of paramount importance for consumers, scientists and industrialists to understand how low-... more It is of paramount importance for consumers, scientists and industrialists to understand how low-temperature storage of food items affects their bioactive compounds and properties. This study evaluated the effects of cold storage on total phenolics (TP), phenolic acids profile (PA), total anthocyanins (TA), total ascorbic acid (Vit. C) and antioxidant activity (AA) of 19 fruits and vegetables, collected from local Indian markets and stored in refrigerator (4 • C) during 15 days. Content of TP was highest in dill and amaranth and decreased (up to 29.67%) with storage. Leafy vegetables (amaranth, dill, onion, fenugreek and spinach) contained higher amounts of the 12 PA revealed by UPLC-UV; ellagic, gallic, sinapic and vanillic acids levels were the highest; chlorogenic acid (= 0.423), syringic acid (= 0.403) and sinapic acid (= 0.452) mostly correlated with TP; and the PA increased during storage. Highest contents of Vit C estimated by AOAC, DCPIP and DNP methods were found in amaranth, dill and pomegranate, and decreased with storage. Pomegranate showed highest TA levels and low-temperature storage did not significantly increase TA, which was the largest contributor of TP in fruits and vegetables (= 0.661). Storage induced a drastic decrease of AA, which mostly correlated with TP (= 0.808, 0.690 and 0.458 for DPPH, ABTS and FRAP assays, respectively). Spearman's correlation confirmed by principal component analysis demonstrated that dill, pomegranate and amaranth had the highest overall antioxidant capacity, whereas orange juice and carrot showed the lowest. The results provide support for a key-role of TP, followed by Vit. C and TA in antioxidant capacity of fruits and vegetables, which could be interesting dietary sources of natural antioxidants for prevention of diseases caused by oxidative stress.

American Journal of Potato Research, 2015

Cold-induced sweetening (CIS) characterized by reducing sugars (RS) accumulation during low tempe... more Cold-induced sweetening (CIS) characterized by reducing sugars (RS) accumulation during low temperature storage of potato (Solanum tuberosum L.) tubers remains a serious postharvest concern for the potato processing industry. Enzymes involved in carbohydrates metabolism and the genes modulating their activities are of paramount importance in the events associated with the development of CIS. Expression of vacuolar acid invertase gene StvacINV1, β-amylase gene BAM1 and invertase inhibitor gene INH2α and their consequence on acid invertase and β-amylase activities with resulting RS accumulation were followed in one CIS-tolerant (Kufri Jyoti) and one CIS-susceptible (Kufri Badshah) Indian potato varieties stored in cold conditions. Differential gene expression analysis showed that during cold storage, expression of StvacINV1 and BAM1 increased at low temperature and their transcripts were more expressed in the CIS-tolerant variety than the CIS-sensitive. Besides, correlation between BAM1 expression and β-amylase activity affirmed the hypothesis of several enzymes and pathways involved in starch degradation during cold storage of potato. Expression of invertase inhibitor gene INH2α however was higher in the CIS-tolerant variety than the CIS-sensitive. Correlating StvacINV1 and INH2α expressions with RS content and acid invertase activity established that post-translational regulation of acid invertase by the invertase inhibitor protein could be an important component of resistance to CIS.