Investigation of pectolytic and PR genes expression, quality and phytochemical contents in organic and non-organic table grapes at harvest and during storage.

The demand for organic table grapes is increasing worldwide. However, comprehensive information of quality parameters and phytochemical compounds in organically grown fruit remain unclear. Furthermore, table grapes are perishable and postharvest quality retention and waste prevention is very important. In this study we have compared the differences between organic and non-organic table grapes in terms of phytochemical compounds and quality parameters as well as the changes in the expression levels of pathogen related and lytic genes during storage. Organic fruit showed higher levels of phenolics, flavonoids, caffeic acid, hydrogen peroxide, protein content, antioxidant and anti-stress enzymes and total antioxidant activities at harvest and during storage. Although, the expression levels of polygalactronases, pectin methyl esterase, chitinase and glucanase genes was lower in organically grown table grapes at harvest, but the expression of all these genes was significantly increased during cold storage. After 60 days of cold storage the expression levels of pectin methyl esterase, chitinase and glucanase genes was significantly higher than the conventionally grown grape berries in organic ones. The highest expression of polygalacturonase was recorded in organic samples after 30 days of storage. There was no significant difference between the two types of table grapes for decay extension and tissue deterioration rate. The results of this study indicate that due to higher levels of phytochemicals and antioxidant compounds the organic table grapes have a higher nutritional quality. Furthermore, the increase in PR and pectolytic genes expression levels is enough for decreasing the fruit susceptibility to decay pathogens and enhancing the postharvest life of organic grapes.

Extraction and activity of chemical constituents from Houttuynia cordata Thunb by ultrasonic method.

Polyphenols and flavonoids are phytochemicals that have essential roles in human nutrition. In this regard, the contents of polyphenols and flavonoids in Houttuynia cordata Thunb and their antioxidant activities were evaluated in the current study. Two Houttuynia cordata materials with the same chromosome number and chemical type were used to comprehensively assess the contents of total phenols and flavonoids in different parts of H. cordata. These chemical components were extracted by the ultrasonic method. The results showed that the total phenols and antioxidant capacity of different parts of H. cordata were significantly different. The content of polyphenols in roots and stems was low, the antioxidant capacity was weak, the total phenols in flowers and leaves were high, and the antioxidant capacity was strong. Therefore, different parts of H. cordata had different pharmacological and food effects. The whole herb can be used as Chinese herbal medicine, and its young leaves and roots can be used as vegetables. Flavonoids are the main phenolic components, and total phenols are the main components of antioxidant activity. It can explain a very significant positive correlation between total phenols and flavonoids. Therefore, in the further breeding work of H. cordata, the procedure can be simplified by determining one of the above indexes to predict the varieties with high total phenolic and antioxidant activity.

Evaluation of a Novel Phosphorylated Red Dragon Fruit Peel Pectin for Enhancement of Thermal Stability and Functional Activity.

Red dragon fruit peel, as a fruit waste, is rich in plant-based nutritional pectins that can be applied as food additives. The present study aims to characterize a novel phosphorylated red dragon fruit peel pectin (PRDFP-P) and to explore its functional activities. The thermal analysis, morphology analysis, antibacterial, antioxidant and antitumor activities of PRDFP-P were evaluated. The results showed that the phosphorylated derivative PRDFP-P had typical phosphate groups. Compared with the native red dragon fruit peel pectin (PRDFP), PRDFP-P possessed superior thermal stability and exhibited significant inhibition effects on Escherichia coli and Staphylococcus aureus. Moreover, the phosphate groups on the derivative PRDFP-P chains remarkably enhanced the scavenging ability of hydroxyl radicals and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. In addition, PRDFP-P showed a significant inhibition effect on growth of human hepatic carcinoma cells (HepG2) and the IC50 value was determined to be 248.69 µg/mL (P < 0.05). Our results suggested that the phosphorylated derivative PRDFP-P might be potentially applied as stabilizing, thickening and gelling agents with functional activities in the food industry.