THE EFFECT OF ENVIRONMENTAL FACTORS ON BIOSYNTHESIS OF CAROTENOIDS AND POLYPHENOLICS IN FRUITS AND VEGETABLES: A REVIEW AND PROSPECTS

Polyphenols Content in Capsicum chinense Fruits at Different Harvest Times and Their Correlation with the Antioxidant Activity

The aim of this work was to investigate the changes of the content of polyphenols in fruits of Capsicum chinense Jacq. at different harvest times and their correlation with the antioxidant activity. Habanero pepper plants grown in black soil (Mayan name: Box lu’um) and harvested at 160, 209, 223, 237 and 252 post-transplant days (PTD) were analyzed. The results indicated that subsequent harvesting cycles decreased the content of total polyphenols, catechin, chlorogenic acid and ellagic acid, while the content of gallic and protocatechuic acid increased. The antioxidant activity determined by DPPH (2,2-Diphenyl-1-picrylhydrazyl) radical scavenging and ABTS (2,2′-azino-di-3-ethylbenzthiazoline sulfonic acid) assay decreased through the harvest days. Linear correlation analysis between total polyphenol content and antioxidant activity in peppers resulted in a correlation of r²_DPPH = 0.8999 and r²_ABTS = 0.8922. Additionally, a good correlation of the antioxidant activity was found with catechin (r²_DPPH = 0.8661 and r²_ABTS = 0.8989), chlorogenic acid (r²_DPPH = 0.8794 and r²_ABTS = 0.8934) and ellagic acid (r²_DPPH = 0.8979 and r²_ABTS = 0.9474), indicating that these polyphenols highly contributed to the antioxidant activity in Habanero peppers. This work contributes to understanding the changes that take place during the development of Capsicum chinense, indicating that fruit harvested at earlier PTD showed the highest concentrations of total polyphenols and antioxidant activity, obtaining the best results at 160 PTD.

Could the reliability of classical descriptors of fruit quality be influenced by irrigation and cold storage? The case of mango, a climacteric fruit

BACKGROUND

Large improvements have been realized on the accuracy of the determination of fruit quality. The relevance of the relationship between commonly used quality descriptors and their related chemical contents was here questioned under the influence of water supply reduction and postharvest cold storage. The study relied on three analyses: (1) a correlation table between quality descriptors and compound contents, (2) principal component analysis using the selected variables to see the quality discrimination dictated by treatments; and (3) linear correlation between content and descriptors according to treatments.

RESULTS

The results indicate that abiotic parameters applied on mango fruits before or after harvest can affect the relationship between a quality descriptor and the content in compounds it is related to, here between titratable acidity and organic acid content and to a lesser extent between color, represented by hue angle values, and carotenoids, possibly creating bias in the final quality determination. A stronger relation between total soluble solids and total sugar content, were observed under mild abiotic stress.

CONCLUSION

Fruit growth and postharvest storage conditions, such as irrigation and cold storage, can influence the actual correspondence between the compounds contents and the descriptors used to estimate fruit quality, particularly for pulp color, sugars and acids. © 2019 Society of Chemical Industry.

Response of the physiological parameters of mango fruit (transpiration, water relations and antioxidant system) to its light and temperature environment

Depending on the position of the fruit in the tree, mango fruit may be exposed to high temperature and intense light conditions that may lead to metabolic and physiological disorders and affect yield and quality. The present study aimed to determine how mango fruit adapted its functioning in terms of fruit water relations, epicarp characteristics and the antioxidant defence system in peel, to environmental conditions. The effect of contrasted temperature and light conditions was evaluated under natural solar radiation and temperature by comparing well-exposed and shaded fruit at three stages of fruit development. The sun-exposed and shaded peels of the two sides of the well-exposed fruit were also compared. Depending on fruit position within the canopy and on the side of a well-exposed fruit, the temperature gradient over a day affected fruit characteristics such as transpiration, as revealed by the water potential gradient as a function of the treatments, and led to a significant decrease in water conductance for well-exposed fruits compared to fruits within the canopy. Changes in cuticle thickness according to fruit position were consistent with those of fruit water conductance. Osmotic potential was also affected by climatic environment and harvest stage. Environmental conditions that induced water stress and greater light exposure, like on the sunny side of well-exposed fruit, increased the hydrogen peroxide, malondialdehyde and total and reduced ascorbate contents, as well as SOD, APX and MDHAR activities, regardless of the maturity stage. The lowest values were measured in the peel of the shaded fruit, that of the shaded side of well-exposed fruit being intermediate. Mango fruits exposed to water-stress-induced conditions during growth adapt their functioning by reducing their transpiration. Moreover, oxidative stress was limited as a consequence of the increase in antioxidant content and enzyme activities. This adaptive response of mango fruit to its climatic environment during growth could affect postharvest behaviour and quality.

Evolution of phenolic compounds from color and flavor problems to health benefits

Early studies focused on the negative effects on color and flavor of foods, followed by exploration of the antioxidant properties and the associated health benefits. The growing body of evidence suggests that plant-based polyphenols may help prevent or delay the onset of a multiplicity of diseases. Newer work suggests that a variety of polyphenols can alter the expression of genes in the inflammatory pathway. Data also show that the absorption of the polyphenols is very limited. Insulin resistance and endothelial and mitochondrial dysfunction are hallmarks of the metabolic syndrome and aging and occur at the early stages of the disease. There is limited clinical evidence that certain polyphenolic metabolites by virtue of their anti-inflammatory activities can improve insulin sensitivity and endothelial and mitochondrial function, suggesting that polyphenols are good for disease prevention. The goal of this review is to summarize the evolution and emphasize the potential benefits of polyphenols.