title: Solid state fermentation of rapeseed cake with Aspergillus niger for degrading glucosinolates and upgrading nutritional value.
abstract: BACKGROUND
  Rapeseed cake is a good source of protein for animal feed but its utilization is limited due to the presence of anti-nutritional substances, such as glucosinolates (Gls), phytic acid, tannins etc. In the present study, a solid state fermentation (SSF) using Aspergillus niger was carried out with the purpose of degrading glucosinolates and improving the nutritional quality of rapeseed cake (RSC). The effects of medium composition and incubation conditions on the Gls content in fermented rapeseed cake (FRSC) were investigated, and chemical composition and amino acid in vitro digestibility of RSC substrate fermented under optimal conditions were determined.
  
  
  RESULTS
  After 72 h of incubation at 34°C, a 76.89% decrease in Gls of RSC was obtained in solid medium containing 70% RSC, 30% wheat bran at optimal moisture content 60% (w/w). Compared to unfermented RSC, trichloroacetic acid soluble protein (TCA-SP), crude protein and ether extract contents of the FRSC were increased (P < 0.05) 103.71, 23.02 and 23.54%, respectively. As expected, the contents of NDF and phytic acid declined (P < 0.05) by 9.12 and 44.60%, respectively. Total amino acids (TAA) and essential amino acids (EAA) contents as well as AA in vitro digestibility of FRSC were improved significantly (P < 0.05). Moreover, the enzyme activity of endoglucanase, xylanase, acid protease and phytase were increased (P < 0.05) during SSF.
  
  
  CONCLUSIONS
  Our results indicate that the solid state fermentation offers an effective approach to improving the quality of proteins sources such as rapeseed cake.
authors.affiliation: Animal Nutrition Institute, Sichuan Agricultural University, Xinkang Road 46#, Ya'an, Sichuan Province 625014 People's Republic of China.
authors.forename: Changyou
authors.initials: C
authors.lastname: Shi
authors.affiliation: Animal Nutrition Institute, Sichuan Agricultural University, Xinkang Road 46#, Ya'an, Sichuan Province 625014 People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: He
authors.affiliation: Animal Nutrition Institute, Sichuan Agricultural University, Xinkang Road 46#, Ya'an, Sichuan Province 625014 People's Republic of China.
authors.forename: Jie
authors.initials: J
authors.lastname: Yu
authors.affiliation: Animal Nutrition Institute, Sichuan Agricultural University, Xinkang Road 46#, Ya'an, Sichuan Province 625014 People's Republic of China.
authors.forename: Bing
authors.initials: B
authors.lastname: Yu
authors.affiliation: Animal Nutrition Institute, Sichuan Agricultural University, Xinkang Road 46#, Ya'an, Sichuan Province 625014 People's Republic of China.
authors.forename: Zhiqing
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Animal Nutrition Institute, Sichuan Agricultural University, Xinkang Road 46#, Ya'an, Sichuan Province 625014 People's Republic of China.
authors.forename: Xiangbing
authors.initials: X
authors.lastname: Mao
authors.affiliation: Animal Nutrition Institute, Sichuan Agricultural University, Xinkang Road 46#, Ya'an, Sichuan Province 625014 People's Republic of China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zheng
authors.affiliation: Animal Nutrition Institute, Sichuan Agricultural University, Xinkang Road 46#, Ya'an, Sichuan Province 625014 People's Republic of China.
authors.forename: Daiwen
authors.initials: D
authors.lastname: Chen
keywords: Aspergillus niger; Glucosinolates; Nutritional value; Rapeseed cake; Solid state fermentation