Low-cost dehydrated starter production: Protective effect of maize-based carrier materials and its application in a Cameroonian maize-based traditional fermented beverage (Sha'a)

The objective of this work was to produce a dehydrated starter from Saccharomyces cerevisiae LT16 and Nakaseomyces delphensis LT80 and to evaluate its impact on the quality of Sha'a, a straw-colored or yellowish, milky, alcoholic or non-alcoholic beverage, made exclusively from maize For this purpose, a suspension of each strain was added to the carrier material (maize flour, husks and starch), dehydrated at 40 °C and then stored at 4 °C and room temperature, and the viability of the strains was assessed for 90 days. Sha'a was produced by both the pure and co-fermentation in which the kinetic parameters were determined. The consumers' appreciation was assessed. The highest viabilities after dehydration were 80.58 and 70.47 % for LT80 and LT16 respectively in maize flour. However, after 90 days, viability was higher in maize flour (68.60 % at 4 °C and 62.04 % at room temperature for LT80 and LT16 strains respectively). As a stress marker, only glutathione was positively correlated with viability. In addition, the fermentation efficiency were negatively affected by drying. The strain LT80 significantly (p < 0.05) increased the palatability of the Sha'a. Sha'a produced with LT80, LT80+LT16 starters and the back slope were “quite pleasant”. Therefore, the LT80, LT80+LT16 starters would be of interest to standardise, guarantee hygienic and sensory quality, and meet consumer demand

Isolation, Characterization, and Effect on Biofilm Formation of Bacteriocin Produced by Lactococcus lactis F01 Isolated from Cyprinus carpio and Application for Biopreservation of Fish Sausage

The aim of this work was the screening of bacteriocin-producing LABs isolated from fish, the selection of promising/prominent strain(s), the characterization of the bacteriocin produced, and the evaluation of its potential to be used as biopreservative(s). Amplification and sequencing of the 16S rRNA gene of the bacteriocin-producing strain was performed. Then a partial purification of the produced bacteriocin, using a combination of ammonium sulfate and chloroform-methanol precipitation, was done. Its molecular weight was determined by SDS-PAGE. In addition, the action spectrum, the hemolysis test, and its ability to inhibit biofilm formation were analyzed. A total of 88 isolates of lactic acid bacteria (LAB) including one bacteriocin producer, which was identified as Lactococcus lactis F01, were collected. The bacteriocin was partially purified with an estimated yield of 40%. Regarding the SDS-PAGE profile, the secreted bacteriocin has molecular weight of about 3.5 kDa and was identified as class I bacteriocin. The antimicrobial test showed that the bacteriocin inhibits pathogenic and/or spoilage bacteria, 10 Gram-positive and 16 Gram-negative bacterial species. Moreover, it can inhibit biofilm formation from 1.3% (Escherichia coli) to 63.92% (Pseudomonas aeruginosa ATCC15692) depending on the strain. The hemolytic activity of novel bacteriocin was observed at the concentration of 10 μg/ml of bacteriocin crude extract, which was 0.7±0.0029%. In addition, it exhibited good thermal and pH stability with retained antibacterial activity of 85.25% after treatment at 121°C for 20 min, as well as at a pH range between 2.0 and 10.0. Moreover, this bacteriocin showed the ability to inhibit the growth of bacterial culture load in fish sausage stored at 8°C for 28 days. Considering the results obtained, bacteriocin could be potentially exploited as an alternative to chemical preservatives or as a substitute for antibiotics