The effects of ultrasonic-assisted curing versus static curing as a control on the quality parameters and gel properties of minced pork were studied. Ultrasonic-assisted curing was carried out with different ultrasonic power (180, 240 and 300 W) and times (30, 60 and 90 min). The results showed that the pH and cooking yield of minced meat were significantly increased after ultrasonic treatment compared with the control group (P < 0.05), the chloride content increased significantly (P < 0.05), and textural properties were significantly improved. The 240 W/60 min treatment group had the maximum hardness, springiness and chewiness, which were significantly better than those of the other treatment groups (P < 0.05). The L* value of minced meat subjected to ultrasonic treatment at 240 W for 60 min was significantly higher than that of the 30 and 90 min treatment groups (P < 0.05); with increasing ultrasonic time, the a* value first increased and then decreased. Ultrasonic-assisted curing reduced the juice loss and imparted good water- and oil-holding capacity to minced pork. Compared with the control group, the total juice and water loss of the 240 W/60 min treatment group were reduced by 48.34% and 58.21%, respectively, which had the best emulsion stability among all the experimental groups. Meanwhile, this treatment group had the lowest apparent viscosity and the strongest flow performance. In conclusion, ultrasonic-assisted curing could significantly improve the quality of minced meat, and the optimal process parameters were 240 W and 60 min for ultrasonic power and time, respectively.

Peach fruit is sensitive to chilling injury during low temperature storage. In order to comprehensively study the regulatory effects of hot air (HA) treatment on the metabolic pathways in peach fruit during cold storage, the fruit subjected to HA treatment at 40 ℃ for 4 h, and then stored at (1 ± 1) ℃ for 35 days. Samples were taken after every seven days for the determination of soluble sugar, citric acid, malic acid, total phenols, total flavonoids and anthocyanins in peach fruit. Besides, peaches were selected for the analysis of transcriptomics and proteomics. Results showed that HA significantly inhibited the decreases in sucrose, citric acid, malic acid, total phenols and total flavonoids, and the increases in fructose and glucose. Furthermore, HA significantly promoted the synthesis of anthocyanins (P < 0.05). Transcriptomics and proteomics analysis showed that most deferentially expressed genes (DEGs) and proteins (DEPs) regulated by HA were mainly concentrated in carbohydrate metabolism and secondary metabolite metabolism. The metabolic changes of soluble sugars and organic acids were mainly related to the expression of invertase, sucrose synthase, sucrose phosphate synthase, malate dehydrogenase and citrate synthase. In addition, HA treatment promoted the production of phenols, flavonoids and anthocyanins by up-regulating the expression of phenylalanine ammonia lyase, 4-coumaric acid CoA ligase, chalcone synthase, dihydroflavonol 4-reductase, anthocyanin synthase and UDP flavonoid glucosyltransferase. In summary, HA treatment could effectively suppress the decreases in sugars, organic acids and phenolic substances, and promotes an increase in anthocyanins in peach fruit during cold storage.

A non-destructive method for the detection of gray mold in strawberry fruit based on odor information was proposed in order to monitor the decay process of strawberry fruit. A portable electoral nose (E-nose) was utilized to collect the odor information of samples every 24 h. Healthy strawberry fruit were taken as the control group. The volatile compounds of samples were then quantitatively detected by headspace solid phase micro-extraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS). Finally, a regression model for predicting the microbial load in artificially infected strawberry fruit was established based on E-nose datasets by partial least squares regression (PLSR). The results showed that after 120 h storage, the contents of esters, aldehydes and alcohols in infected strawberry fruit were significantly changed, and the content of alcohol (mainly ethanol) increased rapidly from 0.85 to 3.95 μg/g. Principal component analysis (PCA) showed a high correlation between the microbial load and the stable response of E-nose sensors. The optimal PLSR model for the microbial load showed a coefficient of determination for prediction of (R_p²) 0.815, and a relative percent deviation (RPD) of 2.270. Furthermore, the non-destructive detection method based on stable signals of E-nose sensors could identify early diseased strawberry fruit with an accuracy of 92.9%. These results can provide a reference for non-destructive monitoring and early detection of strawberry postharvest diseases.