Coffee protein profiles during fermentation using different yeast inoculation methods

The objective of this work was to evaluate the protein profiles of natural and semidry fermented Coffea arabica, either subjected to treatments with different yeast inoculation methods with starter culture or to an uninoculated control. Saccharomyces cerevisiae CCMA 0543 and Candida parapsilosis CCMA 0544 were separately inoculated into coffee by directly spraying the cherries on a terrace or in buckets, for 16 hours before sun drying. Protein quantification showed a significant difference between the protein profiles of the samples collected after natural dry fermentation. The MALDI-TOF MS analysis generated a list of 96 peaks with different mass-to-charge ratios (m/z) in the samples collected at the beginning and the end of fermentation. The highest number of peaks in the natural dry coffee was observed at the end of fermentation in the samples inoculated with S. cerevisiae CCMA 0543, in bucket, and in C. parapsilosis CCMA 0544 sprayed on the terrace. However, in the semidry processed coffee, the highest number of peaks was observed in the initial fermentation, with a decrease in the peptide peaks after fermentation. The fermentation with different microorganisms, processing types, and inoculation methods affects m/z profiles, influencing the types of proteins found in coffee.

Control of Aflatoxin Production in Cassava Produced by Dry Fermentation in North Kivu, Democratic Republic of Congo

Traditionally, cassava (Manihot esculenta Crantz) is transformed by fermentation in water (retting) or in the open air (dry fermentation) in the DRC. In the east of the country (North Kivu), dry fermentation is the main technique for processing cassava for its detoxification and conservation. The Congolese farmers ferment the cassava to the open air using a preselected microferment contained in the scrapings of the fermented cassava previously called "MUSIYIRO". These fermentations are spontaneously directed by the microorganisms of the uncontrolled autochthonous flora. Unfortunately, toxinogenic molds are often more active in the fermentation process during which they also produce aflatoxins. This study was undertaken to help prevent the production of aflatoxins in cassava during this process. To do this, we substituted the traditional ferment with a strain of Rhizopus oryzae used as starter (microferment). Six successive replications, in controlled fermentation and uncontrolled fermentation, in a peasant environment (Beni, North Kivu) and fermentation directed by the strain of R. oryzae were carried out. Aflatoxins were then dosed in both groups of cassava flours. The results of the assay revealed an absence of aflatoxins in cassava fermented by scrapings from fermentation led by R. oryzea, while the non-directed fermentation controls were all contaminated with aflatoxins. These results show that it is possible to prevent the production of aflatoxins in cassava during fermentation when an aflatoxin-inhibiting microbial biomass is used which can progressively invade and colonize the fermentation site and thereby control the fermentation activities of cassava.