Ziziphus jujuba Mill. is nutritious and used as food and medicine for more than two thousand years. It has many pharmacological effects, such as elimination of fatigue, dilation of blood vessels, etc. The polysaccharide in it is one of the bioactive substances. In this paper, the ultrasonic extraction effects on the yield and activity of polysaccharide were studied.

Protein derived from purple wheat bran was hydrolyzed sequentially using alcalase proteases for the production of antioxidant peptides. Purple wheat bran protein (PWBP) hydrolysates were fractionated using size-exclusion (G-25) and ion-exchange chromatography methods to identify the structure of antioxidant peptides. The free radical scavenging activity of peptides purified from PWBP hydrolysates was evaluated using superoxide anion radical-scavenging activity and determination assays of Trolox equivalent antioxidant capacity (TEAC). Results demonstrated that purple wheat bran peptide F4-4 exhibited the highest antioxidant activity among other hydrolysates. F4-4 was further identified as Cys-Gly-Phe-Pro-Gly-His-Cys, Gln-Ala-Cys, Arg-Asn-Phe, Ser-Ser-Cys, and Trp-Phe by high performance liquid chromatography (HPLC) spectrometer coupled with Orbitrap Elite™ mass spectrometer (LC–MS/MS). Antioxidant peptides 2 and 4 showed improved stability when the temperature was lower than 80 °C. These peptides also demonstrated good digestive stability in vitro system by simulating gastrointestinal digestion.

This research aims to assess the effect of Pichia guilliermondii treatment on the improved disease resistance of the peach fruit and to explore the biocontrol mechanisms. Infection rate and lesion diameter of the yeast-treated fruit were substantially inhibited after Rhizopus stolonifer and Penicillium expansum infection, respectively. A significant increase in endogenous salicylic acid (SA) content was stimulated in peach fruit treated with P. guilliermondii. The activities of defense-related enzymes and the SA synthase in peaches were also improved after P. guilliermondii treatment, and the expression of pathogenesis-related genes was activated. Thus, P. guilliermondii may be a biological elicitor-activated systemic acquired resistance by the SA signaling pathway. The new understanding regarding the mechanism of antagonist yeast could could be conducive for controlling fruit postharvest diseases in the future.

The effects of individual and combined Pichia guilliermondii (at 1 × 108 CFU mL−1) and hot air (at 38°C for 96 h) treatments on the three major postharvest diseases Botrytis cinerea, Penicillium expansum, and Colletotrichum gloeosporioides, as well as the quality and antioxidant content of Red Fuji (Malus pumila var. domestica) apple fruit, were investigated in this work. Results suggested that the combined hot air and antagonistic yeast (P. guilliermondii) treatment effectively and completely inhibited the infection of apple fruit wounds by the three major postharvest diseases. Furthermore, apple fruit treated with antagonistic yeast or heat alone maintained better quality, which included mass loss, firmness, solid/acid ratio, and ascorbic acid content, than the control. The combination of the two treatments yielded the optimum apple quality. Moreover, the combined hot air and P. guilliermondii treatment also maintained or enhanced the antioxidative enzyme activities and total phenolic content o...