EFFECT OF CHILLING AND SUBSEQUENT STORAGE AT 20-DEGREES-C ON ELECTROLYTE LEAKAGE AND PHOSPHOLIPID FATTY-ACID COMPOSITION OF TOMATO PERICARP

Mature green tomato fruit (Lycopersicon esculentum cv. Caruso) were st ored at 1-degrees-C or 20-degrees-C and analyzed on day 0, 18 and 22 f or electrolyte leakage, ripening-associated changes in pigmentation an d phospholipid fatty acid composition. Chilled fruit were also analyze d 4 days after they were returned to 20-degrees-C. Fruit did not ripen significantly during chilling and subsequent storage at 20-degrees-C, and showed visible chilling injury symptoms only at 20-degrees-C. Ele ctrolyte leakage increased in control and chilled fruit, indicating en hanced membrane permeability during both ripening and chilling. Return ing the fruit to ambient temperature gave an apparent decrease in elec trolyte leakage. Phospholipid and linolenic acid content and double bo nd index decreased during ripening at 20-degrees-C. The small changes in phospholipid fatty acid composition during chilling cannot account for the enhanced membrane permeability. The significant decrease in pe rcentage of linolenic acid and in double bond index in the total lipid s, but not in the phospholipids, upon returning the fruit to 20-degree s-C suggests loss of galactolipid polyunsaturated fatty acids.