The Role of Selected Lactic Acid Bacteria on Organic Acid Accumulation during Wet and Spray-Dried Fish-based Silages. Contributions to the Winning Combination of Microbial Food Safety and Environmental Sustainability.

Esmeray Kuley,João M Rocha,Mustafa Boga,Ismail Akyol,Fatih Özogul,Ilyas Özogul,Gulsun Özyurt

doi:10.3390/microorganisms8020172

Abstract

Organic acid contents of acidified and fermented fish silages made from gibel carp (Caracius gibelio) and klunzinger’s ponyfish (Equulites klunzingeri) fishes, and from fish processing residues or by-products, were determined and studied. The silages were undertaken in wet and spray-dried fish-based raw-materials for 3 weeks at room temperature (ca. 25 °C). Selected lactic acid bacteria (LAB) of Enterococcus gallinarum, Lactobacillus brevis, Lactobacillus plantarum, Pediococcus acidilactici, and Streptococcus spp. were employed to produce fermented fish-based silages, while acidified silage was prepared resorting to the addition of formic acid (3%, v/v). Lactic and propionic acids were the dominant produced organic acids, while succinic acid was formed at the smallest amounts in fermented silages. In the acidified silage, lactic and formic acids were produced in amounts higher than 800 and 1000 mg organic acid/100 g sample, respectively. Among the fermented fish-based silages, LAB strains unfolded considerable ability to presumptively produce propionic acid in gibel carp silage (>2370 mg organic acid/100 g sample). Spray-dried fermented silages displayed significantly higher organic acid content than wet silages. Propionic acid accumulation was found at the highest levels in gibel carp silage fermented with L. plantarum (6335.40 mg propionic acid/100 g sample). This research effort pointed out the good capability of various selected lactic acid bacteria strains to produce significant amounts of organic acids—especially lactic, acetic, and propionic acids—during the fermentation of fish-based silages. In terms of food safety and quality, such a production of relatively high amounts of organic acids in wet and spray-dried fish-based silages clearly indicated their suitableness to be used for animal feed.

Highlights

The fish processing industry generates a large amount of high quality protein food residues or by-products
Propionic, and lactic acids were the main metabolites produced in acidified wet silages, while lactic and propionic acids were the most abundant organic acids produced throughout the fermented wet silages
P. acidolactici in klunzinger’s pony fish wet silage and L. plantarum in both fish processing waste and klunzinger’s pony fish wet silages did not form formic acid. Apart from these bacteria, formic acid production by other lactic acid bacteria (LAB) strains were below 4 mg/100 g

Summary

Introduction

The fish processing industry generates a large amount of high quality protein food residues or by-products. Silage is recognized as being the most useful biotechnology for solving the utilization of discarded (no economic value) fish as well as the disposable fish-based wastes in the fish processing industry. Besides representing a high-value product for its protein content, the production of fish silages is a preferred processing biotechnology because it requires low inputs of energy, labor, and equipment. Fish without commercial value and fish-based wastes from the processing industry can be converted favorably into powdered/flour fish silage, since it is a relatively easy method to be implemented and provides relatively low operating and initial investment costs [3,4]

Methods

Results

Discussion

Conclusion