Hot air drying is an alternative technique to either maintain or increase bioactive compounds in agricultural products because temperatures can be controlled. The effects of different hot air oven drying temperatures and times on the physicochemical changes, bioactive compounds (capsaicinoids, phenolic and flavonoid profiles and contents) and antioxidant activities in dried ‘Super Hot’ chili fruits were evaluated. The chilies were dried in a hot air oven at low (60–100 °C) or high (120–160 °C) temperatures for 30, 60, 120 min and at 12–13% moisture content (MC). The main compounds presented in chili fruits were capsaicinoids, limonene, pinene, tocopherol and oleic acid, regardless of drying temperature and time. Although the total flavonoid contents decreased during the drying process, the total phenolic contents increased (38–51%), and capsaicinoids, the primary pungent compounds, increased six-times at 120–160 °C compared to the fresh chilies. The phenolic profiles showed that chlorogenic acid was the most stable and abundant amongst the nine quantified phenolic compounds. In the flavonoid profile, both rutin and quercetin can be detected at a high temperature of 160 °C, with a decreasing trend. The main pungent compounds, capsaicin and dihydrocapsaicin, were found to increase compared to the fresh chilies, especially at 12–13% wet basis (w.b.). Although the antioxidant activities (ABTS• + and DPPH•) of dried chilies at all temperatures decreased with increasing drying time, these activities were still detected. Therefore, drying chilies at 160 °C (120 min) can not only maintain the capsaicinoids, phenolics and flavonoids that can be utilized by the pharmaceutical and food industry, but can also reduce the production time.

Carotenoids are considered to be important components in mango fruits. However, there is a lack of understanding about the regulation of carotenoids in mango. To gain an insight into the carotenoid metabolism pathway, carotenoid content and the expression of carotenoid metabolic genes were investigated in the peel and pulp of mango during fruit development and ripening in three cultivars, ‘Kaituk’, ‘Nam Dok Mai No.4′, and ‘Nam Dok Mai Sithong’, which are different in color. The highest carotenoid content was observed in ‘Kaituk’, followed by ‘Nam Dok Mai No.4′ and ‘Nam Dok Mai Sithong’, with the major carotenoid being β-carotene. The gene expression analysis found that carotenoid metabolism in mango fruit was primarily regulated at the transcriptional level. The changing patterns of carotenoid biosynthetic gene expression (MiPSY, MiPDS, MiZDS, MiCRTISO, MiLCYb, MiLCYe, MiHYb, and MiZEP) were similar to carotenoid accumulation, and ‘Kaituk’ exhibited a higher expression level than the other two cultivars. In addition, the differential regulation of carotenoid catabolic genes was found to be a mechanism responsible for variability in carotenoid content among the three mango cultivars. The expression of carotenoid catabolic genes (MiCCD1, MiNCED2, and MiNCED3) more rapidly decreased in ‘Kaituk’, resulting in a larger amount of carotenoids in ‘Kaituk’ than the other two cultivars.

Gamma irradiation is used as a phytosanitary treatment for tropical fresh fruit from some producing countries. An experiment was carried out to study the effect of gamma irradiation and season of harvest on the quality ‘Pattavia’ pineapple fruit. Fruit harvested in the summer and the rainy cool (winter) seasons were exposed to gamma radiation at dose levels of 0 and 400–600 Gy from a 60 Cobalt source and the fruit stored at 13°C and 90% RH for up to 21 days. Gamma irradiation did not affect the ratio of TSS/TA, antioxidant content, or ascorbic acid concentration. However, gamma irradiation did delay color development and also induced internal browning over 50% of flesh discolored in fruit stored for 14 days, especially harvested winter fruit. Moreover, harvesting fruit in different seasons had a significant effect on fruit quality after harvest and during stimulated sea shipment storage. The result showed that gamma irradiation can be used as a phytosanitary treatment with minor changes in eating quality. However, the internal browning was greater if fruit were stored longer than 1 week at 13°C.

The aim of this study was to evaluate the concentrations of sodium nitroprusside (SNP), a nitric oxide donor, on postharvest ripening and quality of mango fruit cv. Nam Dok Mai No.4. The fruits were dipped in 1 or 2 mM of SNP solution for 30 min while control fruits were dipped in tap water for 30 min. After treatment, all fruits were stored for 18 days at 13°C and RH 90%. Both SNP doses showed significantly reduced ethylene production and respiration rate, maintained the fruit firmness, decreased the changes in total soluble solids and titratable acidity, and reduced fruit weight loss. The treatments of SNP also delayed color development in fruit peel and pulp. SNP-treated fruits showed higher L* and hue angle values and lower a* and b* values in comparison with control fruits. No significant differences were found between 1 and 2 mM SNP treatments. SNP applying on dose of 1mM to postharvest ‘Nam Dok Mai No.4’ mango fruits and then stored at 13°C changed ethylene production and respiration rates, maintained firmness pulp, decreased weight loss and slowed the changes in fruit peel and pulp color, total soluble solids (TSS) and titratable acidity (TA). Key words: Mangifera indica L., sodium nitroprusside, biochemical changes, fruit quality.