Multi-strain sequential fermentation of tilapia bone meal and its quality characterization

To improve the bioavailability of tilapia bone meal (TBM), a multi-strain continuous fermentation process was designed to increase the soluble calcium content of TBM. Firstly, Bacillus subtilis YQ-XJ-2 was inoculated for half of the total fermentation time, and then co-fermentation was carried out by inoculating Lactobacillus plantarum ATCC14917 and Saccharomyces cerevisiae 336671 to synergistically degrade protein matrix and dissolve hydroxyapatite. The fermentation conditions were optimized using response surface methodology, yielding a soluble calcium content of 6000.72 mg/kg in the fermented product (FTBM), which represented a 74.8-fold increase compared to TBM. Furthermore, the content of peptide-calcium complexes and organic acid-bound calcium significantly increased to 1301.78 and 4867.69 mg/kg, respectively. Physical characterization revealed that fermentation markedly reduced the median particle size (D50) from 137.21 μm to 28.06 μm. Moreover, key fishy odor compounds such as hexanal, 1-Octen-3-ol, triethylamine and Nonanal were eliminated in FTBM. This sequential fermentation strategy provides an effective approach for the high-value utilization of tilapia by-products. • A multi-strain sequential fermentation strategy was developed for tilapia bone meal. • The soluble calcium content was significantly increased by 74.8-fold under the optimal process. • Fermentation concurrently eliminated fishy odor and generated favorable aroma compounds. • This strategy can promote the high-value utilization of tilapia by-products.