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Two hot pepper hybrids; 'Wonder King' and 'P-6' were grown under high plastic tunnels and fruits were picked at their horticultural maturity stage i.e., full green color with uniform size and shape. The study was conducted to determine the best polyethylene packaging material and low temperature treatment to maximize the shelf life of green hot peppers. Freshly harvested fruits were stored at a range of temperatures; 7, 14 and 21°C in a range of packaging; 7, 15 and 21 µm thick polyethylene bags or unpacked (control) and their post harvest quality was assessed. Minimum weight loss for 'P-6' was observed for fruits stored at 7°C in 7 µm thick polyethylene bags, whereas for 'Wonder King' minimum weight loss was for fruits stored at 7°C in 21 µm thick polyethylene bags. Maximum ascorbic acid in 'P-6' was 53 mg 100 g-1 when stored at 14°C packed in 15 µm thick polyethylene bags whereas in the case of 'Wonder King' maximum ascorbic acid was 107 mg 100 g-1 at 7°C with 7 µm thick polyethylene bags. Total phenolic compounds were 53.62 mg 100 g-1 for 'P-6' when stored at 7°C unpacked while no significant differences were found in 'Wonder King'. No significant carotenoid differences were recorded for 'P-6' whereas maximum total carotenoids (5.93 mg 100 g-1) were found for fruits stored at 7°C with 7 µm thick polyethylene bags. Total sugars, reducing sugars and non reducing sugars in 'P-6' were estimated at 9.16, 2.71 and 2.59% whereas in the case of ‘Wonder King’ these were 6.53, 1.37 and 1.27% at 21°C in open conditions, respectively. Maximum shelf life (20 days) was recorded for 'P-6' at 7°C in 15 µm thick polyethylene bags while in 'Wonder King' maximum shelf life was 10 days at 7°C using 15 µm thick polyethylene bags.

Given the increasing importance of organic produce, a study was carried out to find out how organic production methods affect postharvest and storage quality of ‘Conference’ pears (Pyrus communis). When fruit were taken out of cold storage and artificially infected either with Monilinia fructigena or Penicillium expansum disease development was significantly slower in organic pears than in conventional pears. The effects were more marked for M. fructigena which is the more aggressive pathogen (about 20% inhibition of lesion growth rate), compared with a smaller, but significant effect on P. expansum (5-10% inhibition of lesion growth rate). Organic pears had higher dry matter content (15.6% compared with 14.7%) and were firmer than conventionally-produced fruit, which may affect the rate of pathogen growth. Analysis of total phenols indicated an increase induced by infection by either pathogen, but no significant differences either before or after infection between organically and conventionally-produced pears.

Chlorophyll fluorescence has been tested by many researchers as a non-invasive method to assess physiological damage in chlorophyll containing fruits and vegetables. The characteristic Fv/Fm is most commonly considered. One draw-back of this method is that the fluorescence signal is affected primarily by the state of photosystem II, which is one of the components most sensitive to stresses, including heat, chilling and oxidative stress, so that the Fv/Fm may be more sensitive than the overall tissue. A more reliable strategy may be to look at the ability of the tissues to resynthesise photosystem II after damage, by looking at the rate of Fv/Fm recovery. This strategy shows promising results in predicting chilling injury in peppers and cucumbers, and heat stress in asparagus. Trials are also reported that attempt to predict low temperature injury in apples, but the results are not definitive.

Alternative methods for disinfestation of asparagus against thrips (Thrips tabaci) need to be developed for the Thai export trade, ensuring efficient thrips’ mortality, while maintaining quality and environmental safety. Hot air/water using temperatures of 40-60°C and high CO2 treatments were studied at laboratory level. An appropriate treatment involving hot water at 45°C for 15 min, with or without high CO2 treatment, followed by hydro-cooling with water at ambient temperature (~20°C) was identified. Methods to assess quality, such as objective tests (% mass loss, force measurement, colour measurement) and subjective tests (appearance, decay, off-odour, snap-test for texture) gave no indication of significant quality deterioration. Chlorophyll fluorescence and ion leakage measurements were used to assess physiological stress. The Fv/Fm ratio which indicates the intactness of photosystem II was shown to decrease immediately after all heat treatments tested, but recovered over 24h for non-damaging heat treatments (42.5 and 45°C). A rise in % K+ leakage was observed that increased with treatment temperature but recovered over 24h following treatment at 45°C. High CO2 showed neither significant detrimental effect nor indication of physiological stress, and could kill thrips although not at a sufficiently high rate. Confirmatory trials to demonstrate the efficacy of these treatments in Thailand using naturally infested asparagus were carried out. The mortality rate of thrips was as high as when this method was tested in the UK. Adoption of the selected disinfestation method into existing process lines in Thailand would not be too complicated.

An understanding of the control of sprouting of sweetpotatoes (Ipomoea batatas) is important, both for marketing of sweetpotatoes in the developed world and for the role of the crop for food security in the developing world. Long-term storage of sweetpotatoes requires inhibition of sprouting, while stimulation of sprouting is necessary for the production of planting material. Many studies have been conducted on the control of sprouting/dormancy of potatoes whereas sprouting in sweetpotatoes is less studied. Recently, exposure to ethylene has been introduced as a commercial method for controlling of sprouting in potatoes. Data presented here show that 20 ppm ethylene is effective in controlling sprouting in sweet potato over 4 weeks of storage at 25°C. Gibberellins appear to have a key role in stimulating sprout growth in potato. Trials using gibberellins and gibberellin synthesis inhibitors suggest that gibberellins are likewise involved in the stimulation of sprouting in sweetpotatoes.