L.S. Wong

The effects of 1-methylcyclopropene on the shelf life of minimally processed leafy asian vegetables

The effect of 1-methylcyclopropene (1-MCP) on shelf life and the ethylene sensitivity of detached leaves from six leafy asian vegetables (Chinese mustard, choy sum, garland chrysanthemum, mibuna, mizuna and tatsoi) commonly used in minimal processing was examined. All vegetables studied were significantly affected by the presence of 1 μl/l ethylene. This reduction was primarily due to yellowing except in mizuna and mibuna. In the absence of ethylene, 1-MCP treatment only increased shelf life for mizuna and tatsoi (21 and 67% increase, respectively). In contrast, 1-MCP treatment in the presence of ethylene significantly protected Chinese mustard, choy sum, garland chrysanthemum and tatsoi. 1-MCP may, therefore, be ideal for use on minimally processed leafy asian vegetables in situations of co-storage or co-retail with ethylene-producing commodities.

Screening sweetcorn for enhanced zeaxanthin concentration

BACKGROUND New varieties of fruits and vegetables, with higher carotenoid levels, are being developed to improve the potential health benefits to consumers. To assist the development of a new variety of high zeaxanthin sweetcorn, an analytical screening method was developed, including chromameter measurement of hue angle and optimized extraction for HPLC, and applied to 385 lines of a breeding population and six commercial varieties. RESULTS Saponification had no effect on carotenoid extraction. In the breeding population, carotenoid levels had a wide range with the highest levels of zeaxanthin being 11.9 mg kg(-1) fresh weight, which was at least six times greater than the tested commercial varieties. The regression of hue angle versus zeaxanthin was described by the equation, hue angle = 76.16 + 4.50 x exp(-0.24 x zeaxanthin) + 11.73 x exp(-0.24 x zeaxanthin), r(2) of 0.59. The top 6% of lines, with regards to zeaxanthin (zeaxanthin + beta-cryptoxanthin + beta-carotene) and total carotenoids, all had hue angles <or=84.1 degrees. CONCLUSION The use of a hue angle of 85 degrees as a maximum cut-off for liquid extraction will allow for much increased efficiency in screening further germplasm for high zeaxanthin lines. There appears to be significant opportunity to further increase the zeaxanthin concentration by selecting for lines which preferentially channel carotenoid synthesis towards zeaxanthin.