The flesh of spaghetti squash separates into strands when cooked. The purpose of this paper is to investigate the cause of strand separation （during cooking） by soaking for 24 h at 35 ℃ in solutions with three kind...The flesh of spaghetti squash separates into strands when cooked. The purpose of this paper is to investigate the cause of strand separation （during cooking） by soaking for 24 h at 35 ℃ in solutions with three kinds of pectin extractant. The changes in strand separation, firmness, histological structure and the pectin of flesh during soaking in 0.01 N HCI solution （pH 2.0）, 0.035 M ammonium oxalate solution （pH 4.0） or 2% sodium hexametaphosphate solution （pH 4.0） were investigated. When flesh was soaked in the HCI solution, the separation into strands and removal of calcium and magnesium were greater than that soaked in other pectin extractants. High methoxyl pectin was extracted by soaking in HC1 solution （pH 2.0） due to removal of polyvalent cations. This result shows that high methoxyl pectin glues strands together in the flesh of spaghetti squash. The shape of the cells which constituted strands was round; on the other hand, that of cells surrounded strands was elongated. When cooked in boiling water or soaked at pH 2.0, the shape of the former cells was maintained, but the latter cells, which contributed to adhesion between strands, broke down. Thus, the flesh separated into strands. When flesh was boiled for 15-30 min, pectin degraded and dissolved in the cooking solution; consequently, the flesh separated into strands and also the middle lamella of cell walls of strands separated. However, pectin remaining in strands maintained their crispness.展开更多
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. Pec...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. Pectic substances of raw and cooked flesh were fractionated into three reagents. The galacturonic acid compositions of hydrochloric acid （HC1）-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 （DE） ofPA, PB and PC was 67.4%, 61.5% and 55.6%, respectively. The DE of pectin was from the greatest to the least： PA 〉 PB 〉 PC, respectively, and the diethylaminoethyl （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. Highmethoxylpectin was degraded by β-elimination during boiling. Consequently, the flesh was separated into strands. This suggests that highmethoxylpectin glues strands together in the flesh of spaghetti squash.展开更多
文摘The flesh of spaghetti squash separates into strands when cooked. The purpose of this paper is to investigate the cause of strand separation （during cooking） by soaking for 24 h at 35 ℃ in solutions with three kinds of pectin extractant. The changes in strand separation, firmness, histological structure and the pectin of flesh during soaking in 0.01 N HCI solution （pH 2.0）, 0.035 M ammonium oxalate solution （pH 4.0） or 2% sodium hexametaphosphate solution （pH 4.0） were investigated. When flesh was soaked in the HCI solution, the separation into strands and removal of calcium and magnesium were greater than that soaked in other pectin extractants. High methoxyl pectin was extracted by soaking in HC1 solution （pH 2.0） due to removal of polyvalent cations. This result shows that high methoxyl pectin glues strands together in the flesh of spaghetti squash. The shape of the cells which constituted strands was round; on the other hand, that of cells surrounded strands was elongated. When cooked in boiling water or soaked at pH 2.0, the shape of the former cells was maintained, but the latter cells, which contributed to adhesion between strands, broke down. Thus, the flesh separated into strands. When flesh was boiled for 15-30 min, pectin degraded and dissolved in the cooking solution; consequently, the flesh separated into strands and also the middle lamella of cell walls of strands separated. However, pectin remaining in strands maintained their crispness.
文摘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. Pectic substances of raw and cooked flesh were fractionated into three reagents. The galacturonic acid compositions of hydrochloric acid （HC1）-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 （DE） ofPA, PB and PC was 67.4%, 61.5% and 55.6%, respectively. The DE of pectin was from the greatest to the least： PA 〉 PB 〉 PC, respectively, and the diethylaminoethyl （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. Highmethoxylpectin was degraded by β-elimination during boiling. Consequently, the flesh was separated into strands. This suggests that highmethoxylpectin glues strands together in the flesh of spaghetti squash.
