Danai Boonyakiat

Effect of calcium infiltration on ripening of avocados of different maturities

Mature but unripe Fuerte and Hass avocados harvested at 3 stages of maturity were vacuum-infiltrated with 4 and 8% calcium chloride (CaCl2) solutions and stored at 20°C. The fruit were assessed for ripening and injury development and analysed for Ca content. Postharvest application of Ca to fruit harvested 2 weeks before prime harvest elicited a greater delay in ripening and caused less fruit injury than application at prime harvest or 2 weeks after prime harvest. Fruit maturity did not have a significant effect on the amount of Ca taken up by fruit when infiltrated with each CaCl2 solution. Vacuum infiltration with 8% CaCl2 solution greatly enhanced the uptake of Ca by both Hass and Fuerte fruit but did not delay ripening further than 4% CaCl2 treatment.

Application of Vacuum Cooling Technology and Active Packaging to Improve the Quality of Chinese Kale

This research studied the effect of vacuum cooling combined with active packaging on the quality of Chinese kale from an initial core temperature of 22-25°C to a final core temperature of 4±1°C. The study results illustrate that the optimum condition for Chinese kale under the vacuum cooling process is obtained with the best parameters at a holding time of 5 minutes. The total cycle time was 17 minutes and the electrical energy consumption was 0.017 kWh, with a resulting electricity cost of THB 0.06 per kilogram of Chinese kale. Precooled Chinese kale was then packaged in six different types of packaging material, namely perforated polyethylene, polypropylene and active packag- ing with different oxygen transmission rates (OTR): 10,000-12,000, 12,000- 14,000, 8,000-16,000cc m -2 day -1 and stored at 4±1°C. Subsequently, the effect of vacuum cooling with active packaging on the quality of Chinese kale was investigated. The results showed that the Chinese kale precooled under vacuum cooling process with the best active packaging (M1) had a longer storage life of 14 days compared to the normal storage life of non-precooled Chinese kale packaged in perforated polyethylene (Doi Kham bag) of 3 days.

Physico-chemical changes during growth and maturation of tangerine fruit cv. 'Sai Nam Phueng' and 'See Thong'

Several tangerine cultivars are popular and commercially produced in Thailand. Despite this, no published data exists on the physico-chemical characteristics of the Thai cultivars, assessing their quality, throughout the various stages of fruit development. This study will assess the quality of the physicochemical characteristics of two cultivars, ‘Sai Nam Phueng’ and ‘See Thong’, during growth and maturation. Chlorophyll degradation and carotenoid accumulation in peel resulted in changing color from green to yellow-orange throughout fruit development of both cultivars. Carotenoid accumulation in juice resulted in changing color from yellow-orange to deep orange. Titratable acidity (TA) and citric acid content of both cultivars peaked at the early growth stage, then rapidly decreased during growth and slightly decreased during maturation. Malic acid and vitamin C content were very high at early growth stage, and then declined toward fruit maturation. Isocitric acid content gradually decreased during maturation. The total soluble solids (TSS), TSS/TA ratio, sucrose, glucose and fructose content rapidly increased during growth and slowly increased during maturation. During maturation, ‘Sai Nam Phueng’ had higher TA, TSS, citric acid, vitamin C, sucrose, glucose and fructose content and lower peel carotenoid, isocitric acid content, juice pH and TSS/TA ratio than ‘See Thong’. Peel and juice colors, peel chlorophyll, juice carotenoid and malic acid content did not differ between the two cultivars during maturation.