Pseudomonas lundensis is the main bacterium responsible for meat spoilage and its control is of great significance. 3-Carene, a natural monoterpene, has been proved to possess antimicrobial activities. This study aimed to investigate the antibacterial activity and mechanism of 3-carene against the meat spoilage bacterium P. lundensis, and explore its application on pork. After 3-carene treatment, cellular structural changes were observed. Cell walls and membranes were destroyed, resulting in the leakage of alkaline phosphatase and cellular contents. The decreased activity of Ca²⁺-Mg²⁺-ATPase and Na⁺-K⁺-ATPase showed the imbalance of intracellular ions. Subsequently, adenosine triphosphate (ATP) content and oxidative respiratory metabolism characteristics indicated that 3-carene inhibited the metabolism of the tricarboxylic acid cycle in P. lundensis. The results of binding 3-carene with the vital proteins (MurA, OmpW, and AtpD) related to the formation of the cell wall, the composition of the cell membrane, and the synthesis of ATP further suggested that 3-carene possibly affected the normal function of those proteins. In addition, the growth of P. lundensis and increase in pH were inhibited in pork during the 5 days of cold storage after the samples were pre-treated with 3-carene. These results show the anti-P. lundensis activity and mechanism of 3-carene, and its potential use in meat preservation under refrigerated conditions.

The contribution of rheological properties and viscoelasticity of the interfacial adsorbed layer to the emulsification mechanism of enzymatic modified sugar beet pectin (SBP) was studied. The component content of each enzymatic modified pectin was lower than that of untreated SBP. Protein and ferulic acid decreased from 5.52% and 1.08% to 0.54% and 0.13%, respectively, resulting in a decrease in thermal stability, apparent viscosity, and molecular weight (Mw). The dynamic interfacial rheological properties showed that the interfacial pressure and modulus (E) decreased significantly with the decrease of functional groups (especially proteins), which also led to the bimodal distribution of particle size. These results indicated that the superior emulsification property of SBP is mainly determined by proteins, followed by ferulic acid, and the existence of other functional groups also promotes the emulsification property of SBP.

Mango juice (MJ) was co-inoculated with Lactobacillus plantarum + Rhodotorula glutinis or Metschnikowia pulcherrima (LP + RG or LP + MP, respectively) and Lactobacillus casei + Rhodotorula glutinis or Metschnikowia pulcherrima (LC + RG or LC + MP, respectively) to evaluate their effect on the physicochemical characteristics, antioxidant capacity, and aroma compounds of MJ after 72 h of fermentation at 28 °C. Results indicated that among the fermented MJ, that which was fermented with LC + RG yielded the highest content of total acid (15.05 g/L). The pH values of MJ fermented with LC + MP, LC + RG, LP + RG, and LP + MP were 3.36, 3.33, 3.26, and 3.19, respectively, and were lower than that of CK (4.79). The juice fermented with LP + MP culture had the lowest sugar content (73.52 g/L), and those fermented with LP + RG and LP + MP had higher total phenol contents and stronger DPPH radical scavenging activity, ABTS radical scavenging activity, iron-reducing antioxidant capacity, and copper reducing antioxidant capacity than the others. Carotenoids in MJ had varying degrees of degradation after mixed fermentation by using all four combinations. Volatile compounds revealed that the co-fermentation of LP + RG produced increased norisoprenoid aroma compounds. The mixed co-inoculation method is a strategy to contemplate for MJ fermentation, but the modalities of inoculation need further investigation. Success depends on the suitable combination of non-Saccharomyces and lactic acid bacteria and consideration of strain variation.

This study aimed to optimize the brewing conditions of Shanlan rice wine (SRW) and select a suitable sterilization method. The response surface method experiment was used to optimize the brewing process of SRW. LC-MS/MS (liquid chromatography–tandem mass spectrometry) and GC-MS (gas chromatography–mass spectrometry) were used to analyze the physicochemical components, free amino acids, and flavor metabolites of the thermal-sterilized SRW and the SRW sterilized by intense pulsed light (IPL), respectively. Results showed that the optimum fermentation conditions of SRW were as follows: fermentation temperature, 24.5 °C; Qiuqu amount (the traditional yeast used to produce SRW), 0.78%; water content, 119%. Compared with the physicochemical properties of the control, those of the SRWs separately treated with two sterilization methods were slightly affected. The 60 s pulse treatment reduced the content of bitter amino acids, maintained sweet amino acids and umami amino acids in SRW, and balanced the taste of SRW. After pasteurization, the ester content in wine decreased by 90%, and the alcohol content decreased to different degrees. IPL sterilization slightly affected the ester content and increased the alcohol content. Further analysis of the main flavor metabolites showed that 60 s pulse enhanced the important flavor-producing substances of SRW. In conclusion, 60 s pulse is suitable for sterilizing this wine.

To explore the feasibility of pure yeast fermentation in whole Calamondin puree (FWCP) for the utilization of the whole fruit, yeasts were isolated from naturally fermented Calamondin, and their fermentation characteristics were evaluated. The results indicated that all yeasts were able to ferment FWCP, reducing the sour taste by degrading citric acid, increasing the contents of nutrients (such as phenols and limonins) and volatile compounds, and enhancing the antioxidant activity and inhibition of α-glucosidase activity (p < 0.05). Among them, P. terricola QJJY1 and H. opuntiae QJJY14 exhibited stronger abilities to degrade organic acids, with P. terricola QJJY1 enhancing the antioxidant capacity by releasing phenolic compounds such as phloretin-3′,5′-di-c-β-glucoside, vitexin-2″-O-rhamnoside, and isomargaritene. Moreover, H. opuntiae QJJY15 improved the contents of characteristic volatile compounds such as terpene hydrocarbons and higher alcohols. In total, 70 components were identified as differential metabolites based on their fold change in the metabolites, with 42 differential metabolites involved in 29 metabolic pathways across four strains. The main pathways related to phenol and flavor enrichment were flavonoid, flavone, and flavonol biosynthesis, monoterpenoid biosynthesis, and glyoxylate and dicarboxylate metabolism. Therefore, yeast fermentation is an effective method for utilizing whole Calamondin.

The present study aimed to evaluate the rheological and interfacial behaviors of a novel microbial exopolysaccharide fermented by L. starkeyi (LSEP). The structure of LSEP was measured by LC-MS, ¹H and ¹³C NMR spectra, and FT-IR. Results showed that the monosaccharide composition of LSEP was D-mannose (8.53%), D-glucose (79.25%), D-galactose (7.15%), and L-arabinose (5.07%); there existed the anomeric proton of α-configuration and the anomeric carbon of α- and β-configuration; there appeared the characteristic absorption peak of the phosphate ester bond. The molecular weight of LSEP was 401.8 kDa. The water holding capacity (WHC, 2.10 g/g) and oil holding capacity (OHC, 12.89 g/g) were also evaluated. The results of rheological properties showed that the aqueous solution of LSEP was a non-Newtonian fluid, exhibiting the shear-thinning characteristics. The adsorption of LSEP can reduce the interfacial tension (11.64 mN/m) well and form an elastic interface layer at the MCT–water interface. Such functional properties make LSEP a good candidate for use as thickener, gelling agent, and emulsifier to form long-term emulsions for food, pharmaceutical, and cosmetic products.