In order to solve the problems with semi-dried blunt snout bream such as short shelf life and difficulty of circulation, the effect of glycerol combined with preservatives on the quality of semi-dried blunt snout bream during storage was investigated by determining total viable counts (TVC), total yeast and mold counts, microbial composition, total volatile basic nitrogen (TVB-N) content, thiobarbituric acid reactive substances (TBARS) value, pH and sensory evaluation scores. The results showed that with increasing storage time, the sensory scores of both the glycerol combined with compound preservative (0.075% potassium sorbate + 0.025% sodium dehydroacetate) treatment and control groups decreased continuously, and TVC, total yeast counts, the relative abundance of Lactobacillus, TVB-N content, TBARS value and pH increased continuously. Compared with the control group, the combined treatment slowed down the decline of sensory scores, inhibited the growth of bacteria and yeasts, reduced bacterial diversity, lowered the relative abundance of Lactobacillus, reduced the accumulation of TVB-N, slowed down the rate of fat oxidation, and prolonged the shelf life of semi-dried blunt snout bream by 2, 4 and 7 d at 25, 15 and 4 ℃, respectively. This study provides a reference for the quality control and shelf-life extension of semi-dried blunt snout bream.

The effect of different water activity (a_w)-lowering agents on the water state and quality of semi-dried blunt snout bream was studied by measuring its a_w, water state, total viable counts (TVC), yeast count, total volatile basic nitrogen (TVB-N) content, thiobarbituric acid reactive substances (TBARS) value, and sensory scores. The results showed that the type and amount of a_w-lowering agents had a significant impact on the a_w, water state and physicochemical indicators of semi-dried blunt snout bream, the latter effect being more pronounced than the former one. Trehalose, sorbitol and glycerol reduced the a_w, glycerol being the most effective among the a_w-lowering agents. When 6% glycerol was added, the a_w was reduced from 0.917 to 0.873. With increasing amounts of added trehalose, sorbitol and glycerol, the T₂₂ significantly decreased (P < 0.05), but the T₂₃ did not significantly change. The proportion of immobilized water increased significantly (P < 0.05), whereas the proportion of free water decreased significantly (P < 0.05). Relative to the control group, the TVC, yeast count, TVB-N content, and TBARS value were significantly reduced (P < 0.05) with increasing addition of a_w-lowering agents, and the optimal values of these parameters were obtained with the addition of 6% glycerol. To sum up, the addition of a_w-lowering agents could effectively reduce water freedom and fluidity and slowed down the quality deterioration of semidried blunt snout bream.