Spaghetti squash is one of the hard-shelled squashes in the cucurbit family. When cooked, the flesh can be pulled apart to form strands that resemble spaghetti, hence its name. The purpose of this paper is to investigate the relationship between pectic substances and the separation into strands during cooking of spaghetti squash. Spaghetti squash flesh separated into strands when boiled or soaked in 0.01N HCl solution of pH 2.0. Pectic substances of raw and cooked flesh were fractionated into three reagents. The galacturonic acid compositions of HCl-soluble pectin (PA), sodium acetate buffer-soluble pectin (PB) and sodium hexametaphosphate-soluble pectin (PC) of raw flesh were 69.0%, 28.9% and 2.1%, respectively. Also, the degree of esterification of pectin was greatest to least: PA > PB > PC, respectively and the DEAE-cellulose column chromatograms of PA and PB showed that they were comparatively in high methoxyl pectin. Therefore, about 50% of pectic substances in flesh were released into a cooking solution during 15～30 min of cooking. High methoxyl pectin was degraded by β-elimination during boiling or extracted by soaking in diluted HCl solution. Consequently, the flesh separated into strands. This suggests that high methoxyl pectin glues cells of strands together in the flesh of spaghetti squash.
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