Optimisation of solid-state fermentation process of sunflower meal based on response-surface methodology

Context. Some studies have investigated the application of sunflower meal (SFM) in feeding livestock and poultry. However, there have been few researches related to fermenting SFM.Aims. In this experiment, the neutral detergent fibre degradability and increase rate of crude protein were used as rapid evaluation indicators of solid-state fermentation (SSF), and the response-surface methodology was used to optimise the process conditions for SSF of SFM with the mixed fermentation agent (Bacillus subtilis H-12, Saccharomyces cerevisiae Y-5 and Trichoderma longibrachiatum).Methods. Box-Behnken design with three factors and three levels was adopted. The process conditions were fermentation temperature (28?, 32?, 36?), duration of time (48 h, 72 h, 96 h), and moisture to substrate ratio (MSR; 50 %, 100%, 150 % (v/m)). The nutritional quality and feeding value of the original SFM and fermented SFM were evaluated under the optimal process conditions according to response-surface methodology.Key results. The results showed that the optimal process conditions for SSF of SFM were as follows: fermentation temperature 31.7?, duration of time 72.2 h, and MSR 106.4%; the contents of crude protein (44.82%), true protein (42.40%) and total amino acid (36.77%) in fermented SFM were significantly increased compared with those of original SFM (P < 0.05); the neutral detergent fibre, crude fibre and chlorogenic acid contents were decreased significantly (P < 0.05); the index values of metal elements, vomitoxin, aflatoxin and coliform were all lower than the national limit standards.Conclusion. The nutritional quality and feeding value of SFM were improved by microbial SSF, while the potential risks of harmful toxins and microbial contamination were reduced.Implications. The results of this study will contribute to the research on the development of protein-feed raw materials and explore the application of SFM in feed industry.