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

To investigate the feasibility of replacing the traditional chilled mackerel diet with a probiotic formula during the fattening stage of Chinese mitten crabs (Eriocheir sinensis), we compared the effects of the two diets on muscle quality, nutritional characteristics and flavor composition. Compared with the chilled mackerel diet, the probiotic formula significantly reduced muscle fiber diameter and improved hardness, resilience, elasticity and masticability of female E. sinensis muscles. Nutritionally, no significant differences were observed in crude fat, crude protein or moisture contents of the edible parts between the two diets (P>0.05). Regarding flavor, crabs fed off the probiotic formula exhibited significantly higher total free amino acids (TFAAs) contents; gonadal levels of umami amino acids (354.18, 85.27 mg/100 g) and sweet amino acids (442.93, 544.76 mg/100 g) were likewise signifcantly elevated (P<0.05). Additionally, gonadal inosinc acid (16.41 mg/100 g) and adenosine monophosphate (128.44 mg/100 g) in males were significantly higher with the probiotic diet (P<0.05). Volatile analysis further revealed higher contents of aldehydes (363.98 ng/g), oleines (123.16 ng/g) and oleic acid (42.79 ng/g) in the probiotic group, with mallow aldehyde and octadecaldehyde significantly exceeding control values (P<0.05). These results demonstrate that probiotic feed enhances muscle quality and flavor without nutritional value, providing a robust data and a theoretical basis for its practical adoption.