Relationship between changes in texture of fruit and vegetables during cooking, drying or pressurization and pectic substances

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Relationship between changes in texture of fruit and vegetables during cooking, drying or pressurization and pectin was investigated. The flesh of spaghetti squash separated into strands by trans-elimination of pectin when cooked. Raw Chinese quince was firm. However, when cooked, it was softened by hydrolysis. The potatoes soaked-then-cooked in calcium rich tap-water (pH 8) were firmer than those in tap-water (pH 6). The pectin de-esterified by soaking was resistant to degradation by trans-elimination and increased the binding with calcium; consequently, tissues remained firmer. When the dried stem-lettuce (Yama-kurage) was cooked, it maintained a crisp texture. The demethoxylation of pectin during drying inhibited the degradation of pectin during cooking. High-pressure-induced marmalade was evaluated as better than heat-induced marmalade because a natural color and flavor were maintained.