The Effects of Fermentation Process with Acid and Lactic Acid Bacteria Strains on the Biogenic Amine Formation of Wet and Spray-Dried Fish Silages of Discards

Characterization and Evaluation of Proteolysis Products during the Fermentation of Acid Whey and Fish Waste and Potential Applications

Reduction of waste in the food industry is critical to sustainability. This work represents one strategy of valorizing waste streams from the dairy (acid whey) and fisheries industries (fish waste) using fermentation. The main approach was to characterize the peptides produced by this fermentation under three conditions: (1) fermentation without adding inoculum; (2) with the addition of a single lactic acid bacterial strain; and (3) the addition of a consortium of lactic acid bacteria. Previous results indicated that the rapid acidification of this fermentation was advantageous for its food safety and microbial activity. This work complements our previous results by defining the rate of peptide production due to protein digestion and using two-dimensional (2D) gel electrophoresis and proteomic analysis to give a more detailed identification of the peptides produced from different waste streams. These results provide important information on this process for eventual applications in industrial fermentation and, ultimately, the efficient valorization of these waste streams.

Bacterial Diversity Analysis and Evaluation Proteins Hydrolysis During the Acid Whey and Fish Waste Fermentation

The disposal of acid whey (Aw), a by-product from fermented products, is a problem for the dairy industry. The fishery industry faces a similar dilemma, disposing of nearly 50% of fish processed for human consumption. Economically feasible and science-based alternatives are needed to overcome this problem. One possible solution is to add value to the remaining nutrients from these by-products. This study focuses on the breakdown of nutrients in controlled fermentations of Aw, fish waste (F), molasses (M), and a lactic acid bacteria (LAB) strain (Lr). The aim was to assess the dynamic variations in microbial diversity and the biochemical changes that occur during fermentation. Four treatments were compared (AwF, AwFM, AwFLr, and AwFMLr), and the fermentation lasted 14 days at 22.5 °C. Samples were taken every other day. Colorimetric tests for peptide concentrations, pH, and microbial ecology by 16S-v4 rRNA amplicon using Illumina MiSeq were conducted. The results of the microbial ecology showed elevated levels of alpha and beta diversity in the samples at day zero. By day 2 of fermentation, pH dropped, and the availability of a different set of nutrients was reflected in the microbial diversity. The fermentation started to stabilize and was driven by the Firmicutes phylum, which dominated the microbial community by day 14. Moreover, there was a significant increase (3.6 times) in peptides when comparing day 0 with day 14, making this treatment practical and feasible for protein hydrolysis. This study valorizes two nutrient-dense by-products and provides an alternative to the current handling of these materials.