Impact of Bacillus stratosphericus strain G30 formulated mackerel feeds fattening on the quality, nutritional, and flavor attributes of chinese mitten crabs (Eriocheir sinensis)

To investigate the possibility of replacing traditional frozen mackerel diet with probiotic formula in the fattening stage of chinese mitten crabs (Eriocheir sinensis), and compared the effects of the two diets on muscle quality, nutritional characteristics and flavor composition of E. sinensis. The results showed that compared with the chilled mackerel diet, the probiotic formula diet could significantly reduce the muscle fiber diameter and improve the hardness, resilience, elasticity and masticability of female E. sinensis muscles. In terms of nutrition, there were no significant differences in the contents of crude fat, crude protein and moisture in edible parts between the two diets (P>0.05). In terms of flavor composition, the contents of total free amino acids (TFAAs) in the E. sinensis fed with probiotic formula were significantly higher than those in the chilled mackerel diet group, and the contents of umami amino acids (354.18, 85.27 mg/100g) and sweet amino acids (442.93, 544.76 mg/100g) in the gonad were also significantly higher than those in the control group (P<0.05). In addition, the contents of inosinc acid (16.41 mg/100g) and Adenosine monophosphate (128.44 mg/100g) in the gonads of male crabs fed with probiotic formula diet were significantly higher than those in the chilled mackerel diet group (P<0.05). The determination of volatile substances further revealed that the contents of aldehydes (363.98 ng/g), oleines (123.16 ng/g) and oleic acid (42.79 ng/g) in the crab fed with probiotic formula diet were higher than those in the chilled mackerel diet group. In particular, the contents of mallow aldehyde and octadecaldehyde were significantly higher than those of control group (P<0.05). This study showed that probiotic formula feed could effectively improve the muscle quality and flavor composition of chinese mitten crab, and there was no significant difference in nutrition compared with traditional chilled mackerel diet, which provided a strong data support and theoretical basis for the practical application of probiotic formula feed.