Yanli Zheng

Background: Tuber indicum is a rare edible and medicinal ectomycorrhizal fungus, and the polysaccharide fractions have attracted extensive research attention owing to their potent immunomodulatory potential. Objective/Methods: To systematically characterize the structural features and gut microbiota-mediated immunoregulatory mechanisms of water-extracted polysaccharide (TIWP) and alkali-extracted polysaccharide (TIAP) from T. indicum, two polysaccharide fractions were prepared and comprehensively structurally characterized in this study. Results: The maximum molecular weight of TIWP reached 2.65 × 10⁷ Da, which was dominated by glycosidic linkages of →3)-Glcp-(1→, →2,4)-Glcp-(1→ and →3,6)-Glcp-(1→. TIAP possessed a higher molecular weight up to 3.87 × 10⁷ Da, with predominant glycosidic bonds of →3,6)-Glcp-(1→, →4)-Glcp-(1→ and →2,4)-Glcp-(1→. In vivo bioactivity evaluation results demonstrated that both TIWP and TIAP significantly restored the proportions of CD3⁺ T and CD19⁺ B lymphocyte subsets in peripheral blood and spleen, and alleviated pathological damage in splenic and colonic tissues. Distinct regulatory patterns of gut microbiota were observed between the two polysaccharides: TIWP markedly enriched the genera Lactobacillus and Ruminiclostridium, whereas TIAP elevated the relative abundances of Lactobacillus and Alloprevotella. Untargeted metabolomics combined with KEGG pathway enrichment analysis revealed that TIWP and TIAP activated the pantothenic acid and coenzyme A biosynthesis pathway and the linoleic acid metabolism pathway. Conclusions: Collectively, TIWP and TIAP alleviated CTX-triggered immunosuppression through distinct “gut microbiota-metabolite-immunity” regulatory networks due to their structural disparities. This study provides a theoretical basis for the development of gut microecology-targeted functional foods with immunomodulatory functions.

This paper introduces a novel cold storage: phase-temperature storage, which is characterized by its distinctive coupling jacket structure that connects the sub-storehouse units to the main storehouse. This innovative design facilitates heat transfer while effectively inhibiting mass transfer. Experimental results indicate that polyethylene film, with a thermal conductivity of 0.42 W/m·K, is a more suitable material for constructing sub-storehouses. Enhancing the surface area of the sub-storehouse and increasing convective wind speed are identified as key factors for improving convective heat transfer within the sub-storehouse. Moreover, the optimized design ensures a more uniform temperature distribution inside the sub-storehouse. In contrast to conventional cold storage, the defrosting unit in phase-temperature storage consumes only 5.72 units of energy under equivalent conditions, compared to 154.02 units for conventional cold storage. This demonstrates that the energy expenditure during the defrosting process of phase temperature storage is less than 4% of that required by conventional cold storage, achieving an energy savings rate exceeding 96%. Under identical circumstances, conventional cold storage consumes a total of 36.359 units of electrical energy for defrosting, with 34.231 units being released as defrosting waste heat into the cold storage environment, resulting in a loss rate of approximately 94.13%. Based on apple preservation experiments, phase-temperature storage exhibited significantly superior performance compared to conventional cold storage in terms of apple respiratory peak, weight loss rate, hardness, and TSS content, with respective values of 17.05 CO₂ mg·kg⁻¹·h⁻¹, 2.89%, 9.29 N, and 16.3%. In contrast, the conventional cold storage group recorded values of 18.15 CO₂ mg·kg⁻¹·h⁻¹, 5.16%, 8.42 N, and 14.9%. These results highlight the exceptional freshness-retention capabilities of phase-temperature storage, underscoring its considerable potential for application in storage systems.

Flat peach, a predominant fruit consumed in China, is highly susceptible to softening and perishable. The impact of 1-methylcycloproene (1-MCP) fumigation combined with ε-poly-L-lysine (ε-PL) on softening and postharvest reactive oxygen species (ROS) and phenylpropanoid pathway metabolisms in peaches and its relationship to disease resistance were investigated. Findings revealed that a combination of 1 µL L⁻¹ 1-MCP and 300 mg L⁻¹ ε-PL effectively suppressed the activity of cell-wall-degrading enzymes and the disassembly of cell wall structure, thus maintaining higher firmness and lower decay incidence. Compared to the control group, the synergistic approach bolstered enzymatic responses linked to disease resistance and ROS-scavenge system, consistently preserving total phenolics, flavonoids, ascorbic acid, and glutathione levels. Concurrently, the accumulation of hydrogen peroxide and malondialdehyde was significantly diminished post-treatment. These results show that there is good synergistic effect between 1-MCP and ε-PL, which could effectively maintain the quality of flat peach fruit by modulating cell wall metabolism and enhancing the resistance.

Apple juice that is designated ‘Not from concentrated’ (NFC) is now increasingly popular with consumers due to its unique taste and rich nutritional value. However, layered precipitation and instability have emerged as serious technical problems that restrict the viability of the NFC apple juice industry. This study researched the influence of water-cored ‘Fuji’ apple fruit storage under different temperatures (0, 20 °C) and times (0, 9, 18, 30, 60 days) on the turbidity stability of NFC apple juice. Changes in the physicochemical properties (juice yield, pH, total soluble solids and titratable acid), turbidity stability (turbidity and particle size) and precipitation sensitive substances (insoluble starch, total phenolics, soluble protein and pectin) of NFC apple juice were determined, combined with the respiratory rates and ethylene release of apples, in order to study post-harvest regulation and control of processed fruit. Results indicated that fruit storage temperature and time significantly guided the turbidity stability of NFC apple juice. As a typical respiratory climacteric fruit, apple fruit stored 45 days at 0 °C and 15 days at 20 °C gained the best juice stability, respectively. This is basically consistent with the respiratory peak of fruit when processing raw materials. During the post-ripening process, the insoluble starch in apple gradually hydrolyzed into fructose and glucose, while total phenolics diminished and water-soluble pectin content increased. On the other hand, the amounts of pectin, soluble protein and phenolics in fruit juice declined as the fruit aged in the late storage period (stored 75 days at 0 °C and 40 days at 20 °C). Meanwhile particle size became larger and the turbidity stability of cloudy juices also decreased. This study’s results will provide a sound theoretical basis for improving the turbidity stability of NFC apple juice by regulating the physiological state of processed raw materials.

Chilling injury, tissue browning, and fungal infection are the major problems of peach fruit during post-harvest storage. In this study, a precise temperature control cold storage with low-temperature fluctuation (LFT) and internal circulation flow system is designed. An ozone (O₃) generator and a (titanium dioxide) TiO₂ photocatalytic reactor were applied to cold storage to investigate the variation of LFT combined with ozone fumigation and a TiO₂ photocatalytic reactor in the efficiency of delaying ripening and maintaining peach fruit quality. Results showed that the temperature fluctuation with the improved control system was only ±0.1 to ±0.2 °C compared with that of ±0.5 to ±1.0 °C in conventional cold storage. LFT significantly reduced the chilling injury of peach fruit during storage. Although LFT combined with fumigation of 200 mg m⁻³ ozone periodical treatment slightly damaged the peach fruit after 40 d of storage, its combination with the TiO₂ photocatalytic system significantly improved the postharvest storage quality of the fruit. This treatment maintained higher titratable acidity (TA), total soluble solids (TSS), better firmness, color, microstructure, and lower decay rate, polyphenol oxidase (PPO) activities, total phenol accumulation, respiratory intensity, ethylene production, and malondialdehyde (MDA) content during 60 d of storage. All the results show that LFT combined with the TiO₂ photocatalytic system might be a promising technology for quality preservation in peach fruit storage.