Protein quality of Aspergillus niger-fermented palm kernel cake.

This study was conducted to evaluate the nutritional improvement especially on protein quality of Aspergillus niger-fermented palm kernel cake (fPKC). Results of proximate and chemical analyses showed an improvement in nutritional quality of fPKC compared to untreated PKC. The crude protein of fPKC (24.7%) increased significantly compared to the value in untreated PKC (7.5%). The total essential amino acid in fPKC was significantly increased (6.3%) compared to the value in untreated PKC. The fPKC contained 5.7% of total amino acid, accounted for 63.4% of the crude protein. Rat bioassay on protein quality was conducted for 28 days to determine protein efficiency ratio (PER), in vivo apparent protein digestibility and feed conversion ratio (FCR) of fPKC. Results showed that when fPKC was fed as the only protein source during the experiment, the diet did not support rats’ growth. Rats fed diets of fPKC recorded a mean body weight loss of 24.4 g PER, and FCR of fPKC also showed negative values(–.5 and –6.5, respectively), while the apparent digestibility value of fPKC was 22.6%. This indicated that fPKC may not be fed as the sole protein source in the diet of animals.