Relationship between pectic substances and strand separation of cooked spaghetti squash

摘要

Spaghetti squash is one of the hard-shelled squashes in the cucurbit family. When cooked, the flesh can bepulled apart to form strands that resemble spaghetti, hence its name. The purpose of this paper is toinvestigate the relationship between pectic substances and the separation into strands during cooking ofspaghetti squash. Spaghetti squash flesh separated into strands when boiled or soaked in 0.01N HCl solutionof pH 2.0. Pectic substances of raw and cooked flesh were fractionated into three reagents. The galacturonicacid compositions of HCl-soluble pectin (PA), sodium acetate buffer-soluble pectin (PB) and sodiumhexametaphosphate-soluble pectin (PC) of raw flesh were 69.0%, 28.9% and 2.1%, respectively. Also, thedegree of esterification of pectin was greatest to least: PA > PB > PC, respectively and the DEAE-cellulosecolumn 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 ofcooking. High methoxyl pectin was degraded by β-elimination during boiling or extracted by soaking indiluted HCl solution. Consequently, the flesh separated into strands. This suggests that high methoxyl pectinglues cells of strands together in the flesh of spaghetti squash.