Isolation, identification and characterization of yeast species from coffee waste collected from Sidama and Gedio zone (original) (raw)
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Coffee processing environment harbours different microbiota of fungi and bacteria, some of which are of great economic value. This study isolated, screened and identified indigenous yeast associated with ethanol production potential in coffee processing environments of Mbinga in Ruvuma region and Hai in Kilimanjaro region using standard procedures. Yeast identification was done by amplification and sequencing D1/D2 domain of the gene 26S rDNA. A total of 21 yeast isolates were obtained from both sites and only 8 of them were able to ferment glucose. All 9 isolates fermented coffee pulp waste to ethanol at varying levels. Highest ethanol production was observed by isolate M4, which produced 3% (v/v) ethanol, followed by PDA4MB (2.8% v/v), PDA3 (2.6% v/v) and the least was by M2 which produced only 1.1% (v/v).Three isolates showed good attribute to ethanol production (2.76 to 3.56% v/v) even after an addition of higher sugar concentrations to coffee pulp waste. The basic local alignment search tool (BLAST) and phylogenetic analysis revealed the identity of the yeasts as Pichia kudriavzevii, Issatchenkia orientalis, Clavispora lusitaniae, Pichia guilliermondii, and Pichia anomala, all of them known to be associated with ethanol fermentation. Their attributes towards ethanol fermentation are taken to be potential for further investigation for bioethanol production.
International Journal of Food Microbiology, 2014
During wet processing of coffee, the ripe cherries are pulped, then fermented and dried. This study reports an experimental approach for target identification and selection of indigenous coffee yeasts and their potential use as starter cultures during the fermentation step of wet processing. A total of 144 yeast isolates originating from spontaneously fermenting coffee beans were identified by molecular approaches and screened for their capacity to grow under coffee-associated stress conditions. According to ITS-rRNA gene sequencing, Pichia fermentans and Pichia kluyveri were the most frequent isolates, followed by Candida Candida glabrata, quercitrusa, Saccharomyces sp., Pichia guilliermondii, Pichia caribbica and Hanseniaspora opuntiae. Nine stress-tolerant yeast strains were evaluated for their ability to produce aromatic compounds in a coffee pulp simulation medium and for their pectinolytic activity. P. fermentans YC5.2 produced the highest concentrations of flavor-active ester compounds (viz., ethyl acetate and isoamyl acetate), while Saccharomyces sp. YC9.15 was the best pectinase-producing strain. The potential impact of these selected yeast strains to promote flavor development in coffee beverages was investigated for inoculating coffee beans during wet fermentation trials at laboratory scale. Inoculation of a single culture of P. fermentans YC5.2 and co-culture of P. fermentans YC5.2 and Saccharomyces sp. YC9.15 enhanced significantly the formation of volatile aroma compounds during the fermentation process compared to un-inoculated control. The sensory analysis indicated that the flavor of coffee beverages was influenced by the starter cultures, being rated as having the higher sensory scores for fruity, buttery and fermented aroma. This demonstrates a complementary role of yeasts associated with coffee quality through the synthesis of yeastspecific volatile constituents. The yeast strains P. fermentans YC5.2 and Saccharomyces sp. YC9.15 have a great potential for use as starter cultures in wet processing of coffee and may possibly help to control and standardize the fermentation process and produce coffee beverages with novel and desirable flavor profiles.
Journal of Food Science and Technology, 2020
Different types of yeasts and lactic acid bacteria dominate in spontaneously fermented products (food, beverages, and condiments) that are commonly consumed in Ethiopia. The aim of this study was to identify efficient fermentative yeasts from fermented foods, fermented beverages, honey and molasses using genotypic methods. Out of the 70 samples tested, 180 distinct wild yeast isolates were recovered. A total of 23 isolates were selected for genomic analysis based on their basis of biomass yield, fermentation capacity, and leavening performance. The nucleotide sequence analysis of the internal transcribed spacer ITS-5.8S rDNA region revealed that the indigenous yeast isolates had close relatedness to Saccharomyces cerevisiae, Candida humilis, Kazachstania bulderi, Pichia fermentans and Pichia kudriavzevii with greater than 97% nucleotide similarity. The study shows a high diversity of indigenous wild yeasts in fermented products and that potent strains had higher biomass yield, good gas production and remarkable leavening capacity that indicates their inherent potential for use in the baking industry.
Food Control, 2013
Introduction. Bissap (Hibiscus sabdariffa L.) is a common plant in the tropics. In Senegal, the calyces are used to make a popular juice. In the food industry, small and medium-sized enterprises (SMEs) are responsible for the transformation of bissap calyces into drinks, concentrates, jam, etc. In spite of the very low pH of the juice (pH < 3), problems of contamination and fermentation are often observed in the final products post-pasteurization. They are mainly due to Pseudomonas spp., E. coli, Klebsiella spp. and Pichia opuntiae. To solve this issue, monitoring of the microbial ecology was performed during the full process of bissap products. Methods and results. Fresh calyces and dried mixed calyces of the two varieties of Hibiscus sabdariffa ('Koor' and 'Vimto'), as well as juice samples, were collected at every stage of the processing of a bissap drink and syrup in a Senegalese SME. The monitoring of microbial flora was performed by using molecular fingerprinting. The molecular technique PCR-DGGE was employed to evaluate the microbial dynamics using bacterial 16S rDNA, yeast 26S rDNA and 28S rDNA mold profiles at each critical stage of the process. Results and discussion. The genetic profiles generated contributed to identifying the critical points in the manufacturing processes. A multivariate analysis based on the presence or absence of spots in the denaturing gradient electrophoresis gels (DGGE) showed that the microbial flora (bacteria, yeasts, molds) of bissap evolved during the following phases: harvest (fresh flower), drying (dried calyces) and processing (before filtration, after pasteurization and before packaging). Conclusion. Our work contributed to determining the microorganisms responsible for the microbial contamination of the final products, and highlighted the origin of these contaminants. The most important critical point was identified as the pasteurization step.
Coffee and Yeasts: From Flavor to Biotechnology
Fermentation
Coffee is one of the most consumed beverages in the world, and its popularity has prompted the necessity to constantly increase the variety and improve the characteristics of coffee as a general commodity. The popularity of coffee as a staple drink has also brought undesired side effects, since coffee production, processing and consumption are all accompanied by impressive quantities of coffee-related wastes which can be a threat to the environment. In this review, we integrated the main studies on fermentative yeasts used in coffee-related industries with emphasis on two different directions: (1) the role of yeast strains in the postharvest processing of coffee, the possibilities to use them as starting cultures for controlled fermentation and their impact on the sensorial quality of processed coffee, and (2) the potential to use yeasts to capitalize on coffee wastes—especially spent coffee grounds—in the form of eco-friendly biomass, biofuel or fine chemical production.
Fermentation, 2017
The aim of this study was to evaluate the yeast diversity and physicochemical characteristics of spontaneous coffee bean fermentation conducted in the coffee-producing region in Cerrado Mineiro, Brazil. During 48 h of fermentation, yeast population increased from 6.60 to 7.89 log CFU•g −1 , with concomitant pulp sugar consumption and organic acids production (mainly lactic (3.35 g•L −1) and acetic (1.27 g•L −1) acids). According to ITS-rRNA gene sequencing, yeast population was mainly represented by Saccharomyces sp., followed by Torulaspora delbrueckii, Pichia kluyveri, Hanseniaspora uvarum, H. vineae and Meyerozyma caribbica. SPME-GC-MS analysis revealed a total of 25 volatile organic compounds with predominance of hydrocarbons (9 compounds) and higher alcohols (6 compounds). The resulting fermented, roasted coffee beans were analyzed by diverse chemical analysis methods, including Fourier Transform Infrared (FTIR) spectroscopy and mineral and thermogravimetric analysis. The thermal decomposition of the coffee beans occurred in four stages between 90 and 390 • C, with significant mass loss (68%) after the second stage at 190 • C. FTIR spectroscopy confirmed the presence of the main organic functions associated with coffee aroma, such as aromatic acids, ketones, aldehydes and aliphatic esters. The results presented in this study enrich our knowledge concerning yeast diversity and physicochemical characteristics associated with coffee bean fermentation, and can be used to promote a controlled on-farm processing.
Isolation and identification of yeast from Manihot esculenta, Zea mays, Cola acuminata and Sorghum bicolor was done using the spread plate technique. Morphological, cultural, physiological and molecular characterizations were carried out resulting in determination of the species. Four isolates belonging to different genera which include Pichia, Kluyveromyces, Candida and Saccharomyces were identified. This present study showed that the yeast isolates have the potential to ferment both hexose and pentose sugars.
LWT, 2021
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Boletim do Centro de Pesquisa de Processamento de Alimentos, 2003
O objetivo deste trabalho foi isolar cepas de leveduras capazes de degradar a água de degomagem do beneficiamento úmido do café, caracterizando os metabólitos formados. A bebida preparada a partir de grãos tratados por via úmida é considerada de melhor qualidade quando comparada à elaborada com grãos tratados por via seca. No entanto, o alto potencial poluente da água residual do beneficiamento representa sério problema para o ambiente. A água de degomagem apresenta essencialmente contaminação orgânica, com taxas de demanda bioquímica de oxigênio (DBO) e demanda química de oxigênio (DQO) superiores a 20.000 mgO2/L. Candida tropicalis, C. lypolitica, C. guilliermondii, C. parapsilopsis, Kloeckera apiculata e Rhodotorula rubra, isoladas de cerejas de café, foram inoculadas em frascos contendo água de degomagem e esses, submetidos à agitação constante(120 rpm) por 48 horas, a 28oC. Candida parapsilopsis apresentou percentual de redução da taxa de DBO de 50,14% e de DQO de 29,81%, evide...
ISOLATION AND CHARACTERIZATION OF YEASTS FROM LOCALLY AVAILABLE FOODS
Journal of Agro-Technology and Rural Sciences , 2022
A study was conducted to identify different isolates of yeasts which are prospective to be utilized in various industries from locally available foods. Altogether 24 yeast isolates were obtained from fermented fruits and vegetables (banana, cabbage, grapes, lime and mango), pudding, bee honey, toddy and fermented fish samples using the pour plate method. Characterization of the yeasts using several biochemical tests (urease, catalase, liquid carbon and nitrogen assimilation and sugar fermentation tests) revealed that this pool was composed with yeast strains belong to genera of Saccharomyces, Kluvyeromyces, Candida, Pseudozyma, Cryptococcus, Rhodotorula and Debaryomyces. The most effective lactose fermenters were identified as viable candidates for bioethanol production and for manufacturing fermented dairy products for lactose intolerant people. Yeasts with the highest biomass production were suggested as the best viable candidates for industrial single cell protein production using whey, the major byproduct of the dairy industry. The five thermo-tolerant yeasts (Y55, Y57, Y58, Y59 and Y70) and Y069 which was optimally active under 10C were recognized as suitable for industrial applications. The isolates tolerant for high osmotic pressure conditions were identified as potential isolates to be used in highly concentrated food products. Sugarcane juice was recognized as a possible medium for the cultivation of these yeasts in industrial settings. The beneficial yeasts forecasting in this study are expected to screen using molecular biological methods to utilize them in industrial applications.