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Effect of mechanical damage of greenhouse lettuce on some biochemical processes occurring in it during storage

Maria Leja, Anna Mareczek

Department of Plant Physiology
Faculty of Horticulture, Agricultural University
29 Listopada 54, 31-425 Kraków, Poland

The effect was investigated of mechanical damage such as "squeezing" and "chopping" of greenhouse lettuce stored at high (20°C, 4 days) and low (5°C, 7 days) temperature on phenolics, polyphenoloxidase, and peroxidase activity, free amino acids, ethylene production, and cell membrane permeability.

A considerable increase in total phenols, enzyme activity and amino acids content was found during the storage of lettuce, irrespective of the storage temperature. In the autumn experiment a slight dominance of polyphenoloxidase and peroxidase activity in wounded lettuce leaves as compared with intact onces was observed. The increase in free amino acids in damaged lettuce was higher than in intact heads, particularly in lettuce stored at high temperature.

A rapid ethylene production was noted just after damage, significantly higher in wounded leaves than in intact ones. The membrane permeability of lettuce grown in the autumn cycle, measured either after wounding or during storage was drastically higher in damaged lettuce leaves than in intact ones. Lettuce cultivated in the spring cycle was significantly less sensitive to wounding than that grown in autumn.

Leja M., Mareczek A., 1995. Effect of mechanical damage of greenhouse lettuce on some biochemical processes occuing in it during storage. Folia Horticulturae 7/1: 75-89.