Changes in Flavonoids and Nonphenolic Pigments during On-Tree Maturation and Postharvest Pericarp Browning of Litchi (Litchi chinensis Sonn.) As Shown by HPLC-MSⁿ

Abstract

Polyphenols, chlorophylls, and carotenoids were characterized by HPLC-DAD-MS(n) in the pericarp of unripe to over-ripe 'Hong Huey' and 'Chacapat' litchi fruit at harvest and during subsequent storage (5 °C, 90% RH, 21 days). (-)-Epicatechin and A-type procyanidins always predominated quantitatively. Besides these ortho-diphenolic compounds, minor novel litchi flavonoids included monohydroxylated structures. Chlorophyll degradation by 73-92% and 7-38-fold anthocyanin accumulation affected pericarp color throughout the last 15-20 days of on-tree maturation. Postharvest, anthocyanins and (-)-epicatechin largely degraded within the first 3 days, accompanied by severe pericarp browning. Without packaging of the fruit, desiccation initially accelerated polyphenol oxidase-induced oxidation of (-)-epicatechin, but then hindered its further progress. Constant levels of the monohydroxylated (epi)afzelechin indicated no involvement of peroxidase. Acting as antioxidants, anthocyanins retarded (-)-epicatechin degradation. Hence, pinkish-red fruit with a molar ratio of cyanidin 3-O-rutinoside to (-)-epicatechin of >3:100 retained flavonoids best. However, brown polymers masked remaining red pigments.

Effect of Steam Blanching and Drying on Phenolic Compounds of Litchi Pericarp

“…Therefore, it was selected for evaluation of the effect of the combination of steam blanching and drying methods on the individual procyanidin profiles as shown in Table 2. The procyanidin A2 and epicatechin were the major procyanidins, which was in agreement with previous literature [16,17].…”

Green Pepper (Piper nigrum L.) Extract Suppresses Oxidative Stress and LPS-Induced Inflammation via Regulation of JNK Signaling Pathways

“…The colors of the peppercorns are dependent on the chlorophyll content and various phytochemicals, which affect the flavonoid and phenolic contents and therefore, the antioxidant capacity. The contents of flavonoids and nonphenolic pigments are affected by the degree of the pepper fruit maturation and postharvest processing [39]. Our chromaticity analysis results showed that green pepper had high Hunter L* and b* values and low a* values, while black pepper had low Hunter L* and b* values and high a* values.…”

Effect of high hydrostatic pressure and storage in fresh‐cut cashew apple: Changes in phenolic profile and polyphenol oxidase activity

“…Storage of untreated samples did not modify the flavonoid profile of cashew apple pieces and this effect was similar to that observed on total polyphenols and phenolic acids (Figure 2a). The content of quercetin and kaempferol glycosides also remained stable in litchi fruits stored at 5℃ for 21 days (Reichel et al, 2011). Piljac-Zegarac and Samec (2011) evaluated total flavonoids in strawberry, raspberry, cherry, and gooseberry stored at 4 or 25℃ for 30 days and observed no changes in strawberry and cherry, while in raspberry and gooseberry it was observed reduction until 24% of initial levels.…”