Evaluating the Performance of Peroxide and Conjugated Diene Values in Monitoring Quality of Used Frying Oils (original) (raw)
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International Journal of Food Science and Technology, 2007
Most of the present regulations or guidelines on used frying fats and oils for human consumption establish that the content of polar compounds should not be higher than 25% of the oil weight. The standard method for the determination of polar compounds, which is based on adsorption chromatography, is time-consuming and needs laboratory facilities. Thus, rapid and simple methods are necessary to evaluate the quality of frying oils in fried food outlets. In this study, rapid tests based on chemical reactions (Fritest and Oxifritest) and on physical properties (Viscofrit and food oil sensor) have been evaluated in a set of 105 used frying oils as alternative methods to the determination of polar compounds. The results demonstrated that any of the rapid tests assayed are of great utility to determine the point at which frying fats and oils should be discarded. The tests based on physical properties showed better results than those based on chemical reactions, as the number of false results was lower. Furthermore, they can be useful to gain information on the changes in the frying oil quality, as their results showed high correlation coefficients with the determination of polar compounds.
Archives of Hygiene Sciences, 2018
Background & Aims of the Study: The quality of the edible oils is made with chemical compositions and percentage of the degree of unsaturation fatty acids. The peroxide value (PV) always measures the extent of primary oxidation (rancidification) of oils. Oils Rancidity can produce potentially toxic compounds associated with health effects such as heart and neurological disorders. In order to investigate initial oxidative rancidity of the oils, PV will be measured. The aim of this paper is determination of PV and the acid number taking place in oils during frying process and its relationship with demographic characteristics and environmental conditions. Materials &Methods: In this study, the statistical populations are sandwich and fast food shops of Qom city, Iran. Samples were conducted, using cluster sampling. For data collection, a questionnaire and chemical tests were used. Samples were transferred in the laboratory under cool conditions for PV and acid number (AN) examination. A hundred fifty different sample of oil were collected. Statistical analysis was performed by SPSS. The ANOVA, T-test and Pearson coefficient were used for data analysis. Results: From the points of view of PV, 80% of oils were consumable and 20% were not. The lowest and the highest number of PV were 0.6 to 16.5, respectively. The minimum and the maximum number of AN were 0.028 to 0.2, respectively. With the assumption of equal variances (p>0.05), a significant relationship between the increase after the age of the chefs and the lack of obtaining a health card was shown. The small correlation between the temperature of the oils and PV, r(150)=-0.21, p=0.009 is shown. There wasn't seen any relation between the type of oils with PV and AN. Discussion: Antioxidants, oil saturation and the reduction of temperature can reduce the production of peroxide; thus, PV was reduced. Due to the results, temperature increasing lead to increases the peroxide content. In this case, 3.3% of the edible oil samples were in rancidity conditions. Conclusion: This study has indicated that PV in almost sample was lower than the standard amount. However, removing the oil absorbed into the food leads to reducing the peroxide content and other hazardous compounds by fast-food consumers. This survey indicated that some cookers are not completely aware of government regulation and control procedures for PV and AN of frying oils.
2018
Continuous surveillance and monitoring of used materials in food processing is a tool for achieving to food safety assurance. Peroxide and Acid values are common indicators to detect fat oxidation, frequent and longtime heating and usage of edible oils in cooking or frying of food. This study aimed to quality assessment of used edible oils in restaurants and fast food centers (Sandwich centers) of Zanjan, Iran by determination peroxide value (PV) and acid value (AV). A total 60 oil samples were collected randomly from restaurants (27 samples) and fast food centers (33 samples) based on cluster sampling plan of the Zanjan city. Titration methods were used to determine Peroxide and Acid values according to Iran national standards protocols No. 4179 and 4178. Peroxide value in 22 (81.48%) and 24 (80%) of oil samples and Acid value in 22 (81.48%) and 30 (90.9%) of samples taken from restaurants and fast food centers were higher than standard limit, respectively. Present investigation ha...
Earthline Journal of Chemical Sciences
Recent studies have shown that heating oil to high temperature causes oxidative degradation of the oil, consequently producing characteristics odour, taste, colour and texture. However, this study was conducted to evaluate the stability of four different samples of edible oils. Acid value was found to be 5.22, 3.50, 0.73 and 1.29 mg KOH/g oil in fresh Melon, Bushmango, olive and Palm olein oils samples respectively. When the four oil samples were used for frying, the acid value was found to be; 6.73, 3.90, 2.24 and 2.24 mg KOH/g oil (24 hours after frying), 11.22, 7.86, 4.49 and 3.3 mg KOH/g oil (2 weeks after frying) and 19.17, 13.22, 5.82 and 4.4 mg KOH/g oil (4 weeks after frying), for melon, Bushmango, olive and palm olein oils samples respectively. Saponification values were ranged between 196.70-240.00 mg KOH/g oil in fresh oils of the samples, and between 197.80-252.33 mg KOH/g oil in the oils after using them for frying. Furthermore, Peroxide values ranged from 2.65 to 3.20 ...
Quality Changes of Common Edible Frying Oils during Frying of Traditional Foods
Asian Food Science Journal
This study aimed to examine the impact of the frying process on the physical and chemical properties of widely consumed edible oils. Soybean, palm, and mustard oils, as well as raw dulpuri and singara products, were procured from the nearby marketplace. The oils underwent five consecutive frying cycles at temperatures exceeding 160°C and were subjected to five hours of heating. Analyses including determination of free fatty acid (FFA), peroxide value (PV), saponification value (SV), iodine value (IV), and optical density (OD) at a wavelength of 425 nm were performed. Following multiple rounds of frying and heating, the levels of FFA, PV, and oxidative stability index exhibited an increase, whereas the IV demonstrated a decrease across all three types of oils. The OD of soybean and palm oils exhibited an upward trend, whereas that of mustard oil initially displayed a decline, followed by a gradual ascent. In comparison to soybean and mustard oils, palm oil exhibited the most notewort...
2018
Background: Frying is one of the most popular methods of food preparation. Since in fast food restaurants the oil is heated for prolonged and repeated periods of time, toxic compounds in oils likely go up to very high concentrations. In this study, we investigated chemical quality of oils that was used for frying in fast food restaurants. Methods: Oil samples were collected from 42 fast food restaurants located in Shiraz, Iran. Samples were obtained from oils that were being heated in fryers at the peak of fast food restaurant activity between 10:00 and 12:00 PM. Acid and peroxide values and total polar compounds were measured according to standard procedures. Results: Acid and peroxide values of 27 samples (64.3%) were higher than the permitted values for oil health (Table 1). This number for total polar compounds was 19 (45.2%). Conclusion: In many fast food restaurants of Shiraz, Iran, oils that are in use contain high levels of toxic materials that may imperil consumers as well ...
Journal of the American Oil Chemists' Society, 2011
In this study, the effect of deep fat frying on oil degradation, total phenols (TP) and total antioxidant activity (TAA) of hazelnut, corn, soybean and olive oils were investigated. Oil degradation and oxidation were monitored by measuring the total polar compounds (TPC) and the peroxide value (PV). The amount of TPC in corn, soybean and olive oils increased significantly with the time increment (p \ 0.05). The PV of the oils did not exceed the maximum acceptable limit of 10 mequiv O 2 /kg after 125 min frying except for hazelnut oil (10.64 mequiv O 2 / kg). Deep-fat frying did not cause any significant change in the TP of corn oil, soybean oil and olive oil (p \ 0.05). A significant decrease in the antioxidant activity was observed after 50 min frying using hazelnut oil and corn oil (p \ 0.05). However, the antioxidant activity of soybean oil and olive oil significantly decreased after 75 and 25 min frying, respectively.
Quality Assessment of Frying Oil from some Restaurants in Al-Ahsa City, Saudi Arabia
Basic and Applied Sciences - Scientific Journal of King Faisal University
The oxidation and hydrolysis products of frying oil greatly affect human health. The qualities of twenty-one samples of both fresh and in-use frying oils collected from some restaurants in Al-Ahsa, Saudi Arabia were assessed. In fresh oil, the free fatty acids (FFAs), p-anisidine value (p-AV), total polar compounds (TPCs), and value of total oxidation (TOTOX), were of acceptable quality, while their peroxide value (PV) in some sample was above the recommended limit. For the in-use oils, 9.5% had an FFA level above 2%. Additionally, the PV of in-use oil was 38% above the suggested limit, whereas 81% of in-use oil was beyond the recommended level for TOTOX. The inuse oil contained more conjugated diene and triene than fresh oil. The refractive index, viscosity, and color increased in all in-use oil samples compared to fresh oil. Significant correlations between most parameters were observed. Institutions responsible for food control and inspection should consider these results for consumer health.
RESEARCH ON QUALITY OF FOOD FRYING OILS USED IN COMMERCIAL RESTAURANTS
The aim of this research is to evaluate the quality of oils used in the frying process in commercial restaurants. Oil samples were collected from deep fryers in two commercial restaurants in the area of Bosnia and Herzegovina. One of the restaurants used partially hydrogenated oil and the other sunflower oil. The analysis samples were collected during one 12-hour shift, in two-hour intervals. Physico-chemical parameters, changes in fatty acid composition during frying, and the presence of metals were analyzed. The research results have shown that there is a statistically significant difference (p < 0.05) between all analyzed parameters, for both types of oils. During frying, the composition of fatty acids for both oils changes significantly. Total oxidation value for partially hydrogenated oil was increased from 2.165 to 55.983 mg/kg oil, and for sunflower oil from 15.332 to 153.888 mg/kg. During frying, there is an increase in the metal content (p < 0.05) in the tested oils.
International Journal of Food Properties, 2011
In the present study, the quality of frying oil, as affected by commercial pan fish frying, was investigated. The quality of fresh frying oil, null replenishment (NR) oil, and discarded frying oil were evaluated by drawing out the oil samples from the fryer at the initial stage, just before the addition of new frying oil for level make-up and used oil of the last frying cycle, respectively. The parameters used to assess the quality were the fatty acid composition including trans fatty acid (TFA), free fatty acid, and peroxide values of frying oil. Gas chromatography-mass spectroscopy (GC-MS) was used to examine fatty acids profiles of the frying oils. Trans fatty acid in fresh oils varied from 2.5%–3.8% (except oil-6, which contained 13%), whereas NR oils and discarded oils contained 5.6%–14.8% and 7.3%–20.8% trans fatty acids, correspondingly. Free fatty acid in fresh, NR, and discarded oils were 0.12%–0.24%, 0.22%–1.74%, and 0.80%–3.39%, respectively. Peroxide value in fresh, NR, and discarded oils were determined to be 1.15–3.93, 2.71–7.51, and 2.84–14.68 meq of O2 /kg oil. It was observed that commercial fryers were not using the proper oil for frying. Furthermore, the last frying cycle just before discarding the oil may be dangerous for the health of consumers due to their significant level of TFA, free fatty acid, and peroxide values.