Alginate with citrus pectin and pterostilbene as healthy food packaging with antioxidant property.

A new type of film packaging made from natural polysaccharide materials, with its environmental safety and friendliness, is considered as a potential substitute for plastics. Novel polysaccharide composite films based upon citrus pectin (CP) and sodium alginate (SA) were successfully prepared and characterized, containing pterostilbene (PTE) at various concentrations (0.2, 0.4, 0.8, 1.6, 3.2 mM). The rheological analysis displayed that all film-forming liquids performed no gelation behavior with G" > G' at low frequency and weak gelation with G" < G' at high frequency. The SA-CP films had good tensile strength (TS) and elongation at break (EB), while adding PTE as an antioxidant to the film reduced both the values. Of note, the SA-CP films with PTE had better moisture resistance than that of the pure SA-CP films, which was related to the changes of its microstructure. The increased roughness of the films containing PTE was observed by microscope. After calcium chloride cross-linking, the water solubility of the films was reduced, while its thermal stability was improved. Notably, the accretion of PTE expressively enhanced the antioxidant properties of the SA-CP films. Thus, the SA-CP composite films containing PTE could be utilized as an excellent antioxidant packaging material.

Based on RNA-Seq analysis identification and expression analysis of Trans-scripusinA synthesize-related genes of UV-treatment in postharvest grape fruit.

Stilbenes, an active substances closely related to resistance and quality of grapes, are rarely found in natural resources. However its cumulative amount is affected by ultraviolet radiation (UV). The purpose of this study is to screen key genes in biosynthesis of stilbenes Trans-scripusin A and explore its synthetic pathway. We tested content of stilbenes with UHPLC-QQQ-MS2, results revealed that stilbenes accumulation is positively correlated with UV-B exposure time. Then, we performed transcriptome high-throughput sequencing of grapes under treatments. Results shown that 13,906 differentially expressed genes were obtained, which were mainly enriched in three major regions (ribosome, plant-pathogen interaction and biosynthesis of flavonoid). Three genes of trans-scripusin A synthesis pathway key got by combining KEGG annotation and reference gene HsCYP1B1. Phylogenetic analysis showed that SAH genes had high homology with other hydroxylase genes, and distributed in two subgroups. Gene structure analysis showed that SAH genes contained four exons, indicating that gene has low genetic diversity. Chromosome localization revealed that SAH genes were distributed on different chromosomes, in addition, the number of gene pairs between Vitis vinifera and other species was not related to genome size of other species. The expression profiles of SAH genes in different parts of Vitis vinifera L. were analyzed using qRT-PCR analysis, results indicated that expression of SAH genes be specific to fruit part. These paper provide theoretical basis for further study of polyphenols biosynthesis pathway in grape fruits. The study provides novel insights for further understanding quality of grapes response to UV radiation.

New insights into the alleviating role of Melaleuca alternifolia oil on metabolites pathway disorder of grapes caused by Aspergillus niger, verified by corresponding key genes expression.

Grape berries are susceptible to Aspergillus niger (A. niger) infection during storage, leading to a significant reduction in its nutritional quality. However, most alternations in nutrient contents and related gene expression during fungal infection or treated with antimycotics remain unexplored. This work aimed to monitor and verify the metabolic changes in berries caused by A. niger or Melaleuca alternifolia oil (MAO) by using UHPLC-ESI-MS2 and Quantitative Real-time PCR (RT-qPCR). Results showed that sucrose, glucose, fructose, trans-resveratrol and pterostilbene levels were down and pentose phosphate pathway, glycolysis pathway and phenylpropanoid pathway were significantly down-regulated compared with healthy berries due to A. niger infection, all of which were alleviated by MAO treated. A. niger also induced down-regulation of key genes expression associated with metabolic pathways and magnitude of down-regulation was reduced by MAO. These results provide a theoretical basis for MAO used to control the risk of A. niger-mediated diseases.

Determination of metabolites of Geotrichum citri-aurantii treated with peppermint oil using liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry.

Sour rot is a leading disease of citrus fruit caused by the postharvest pathogen Geotrichum citri-aurantii. It has been reported that essential oils can be used as substitutes for synthetic fungicides to control the pathogen. In this study, changes in metabolites and antifungal effects of G. citri-aurantii treated with peppermint oil (PO) were investigated. The inhibition rate of the mycelial growth increased as the PO concentration increased, and 6 µl PO/disk resulted in a radial growth inhibition of 79.2%. The electrical conductivity of G. citri-aurantii treated with PO increased compared to the control. By comparing the metabolic profiles of treated and untreated G. citri-aurantii cells, a total of 53 distinct metabolites 9 were up-regulated and 44 were down-regulated were found, including 16 lipid metabolites, 6 carbohydrate metabolites, 2 amino acid metabolites, 5 alcohols, 2 glycoside metabolites, and 3 ketone metabolites, etc, and these metabolites are involved in 25 major metabolic pathways. PRACTICAL APPLICATIONS: Chemical fungicides can effectively control G. citri-aurantii during fruit postharvest period. However, synthetic chemical fungicides have gradually led to buildup of resistance of fungil, which seriously causes the frequent of food-borne diseases. PO extracted from natural plants can be used as natural additive in many foods due to their antioxidant, antibacterial, and antifungal properties. Therefore, PO can be considered as a promising bacteriostatic agent for the defense of G. citri-aurantii during fruit postharvest period.