The Technology Of Monascus Fermentation On Semi-dry Tilapia

In this paper, the Monascus was used to ferment semi-dry Tilapia. The Monascusfermentation agent was prepared and the ferment processing was optimized. Thevolatile compounds of fermented Tilapia was identified by solid phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS); theeffect of Monascus fermentation on storage characteristic was investigated and itsinfluence of Tilapia muscle protein was also analyzed.(1) The effect of inoculation amount, rice powder addition, fermentation time andfermentation temperature of the fermentation were analyzed by single factor test andorthogonal test. The optimal fermentation condition of red Monascus GIM3.445was:inoculation amount25%, rice powder addition4.5%, and fermentation temperature34℃, fermentation time9h; the optimal fermentation condition of purpureusMonascus GIM3.439was: inoculation amount35%, rice powder addition4%, andfermentation temperature34℃, fermentation time7h. The Monascus fermentationagent was packaged in vacuum and it can be stored for15days in4℃. The number ofMonascus is relatively stable during storage.(2) The semi-dry Tilapia was fermented by Monascus, which was obtained the typicalbacon flavor fermented products. The volatile compounds of the unfermented andfermented Tilapia were identified by SPME-GC-MS.51volatiles were detected inunfermented group, while75volatile compounds were identified in fermented group.The contents of aldehydes and alcohols in fermented group were higher than theunfermented group. Amine compounds were increased in fermented group. Nonanal, octanal, octanol,1-octene-3-alcohol and ethanol is the main flavor compounds infermented Tilapia.(3) The Monascus fermented and unfermented samples were stored in25℃. The colorvalue, TVB-N value, amino nitrogen, acid value and peroxide value of the two groupswere measured from0to25day. The results showed that Monascus contributed a lotto inhibit the growth of microorganism and delay Tilapia spoilage. Meanwhile, theycould keep the lipids from oxidized and rancidity and obtained a satisfying color andgood flavor fish product. The processed fish products were storage in25℃, the shelflife of fermented and unfermented samples was determined by the physical andchemical index and the total number of bacteria. The results showed that Monascusfermentation could inhibit the growth of microorganism, improve the quality ofsemi-dried Tilapia and extend the product shelf-life.(4) The Tilapia muscle protein has changed significantly. SDS-PAGEelectrophoretogram showed that the macromolecules bands of water-soluble proteinsin fermented group has almost disappeared. In addition, the distribution and quantityof the salt-soluble protein in fermented and unfermented samples are significantchanges. Therefore, it can be concluded that the Tilapia muscle protein was degradedby microorganism during Monascus fermentation and storage process.