Studies on the physical and chemical properties of buckwheat starch from different areas and their effects on the characteristics of soba

• Main Authors: Jin-Ki Kim, 金秦基
• Other Authors: Min-hsiung Lee
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/07223615668898451717

博士 === 國立臺灣大學 === 農業化學研究所 === 87 === The purpose of this thesis was to investigate the physical and chemical properties of buckwheat starches produced from different areas. The experiments included two major parts. The first part was to analyze the physical and chemical properties of buckwheat starches that were isolated and purified from four kinds of buckwheat (TC1, SW2, CHI and USA). The starches were then fractionated into amylose and amylopectin by the method of Hizukuri (1986). The measurements including water binding capacity, swelling power，differential scanning calorimetry and rapid viscosity analysis were performed . The X-ray diffraction and scanning electron microscopy were also used to investigate the crystalline and exterior microstructure of starches. The second part was to study the physical and chemical properties of buckwheat noodle prepared with the buckwheat flours. We hope that the results of this research might provide useful information for the development of buckwheat products. The results of the first part of this study showed that high yields of four buckwheat starches (TC1, SW2, CHI and USA ) isolated and purified with dilute alkali solution (0.1% NaOH ) were 62.8% 61.6% 64.8% and 63.2%. The purified starches were then fractionated into amylopectin and amylose fractions according to Hizukuri method. It was found that the blue value andβ-amylolysis limit(%)of four buckwheat starch and their amylopectin and amylose were in the order of amylose ＞starch＞ amylopectin. Two major peaks were shown amylose and amylopectin fractions in the gel filtration elution curves of buckwheat starch. The amylopectin fraction from buckwheat starch appeared only in a single peak in the elution curve. The M.W. of the four amylopectins ranged between 5,000 and 40,000 kD. The DP of amylopectin was around 7,000 and the CL was about 22. The isoamylase-treated buckwheat amylopections all showed three peaks in the gel filtration elution curve and the DPn of there three peaks were 40, 20 and 7. The DSC analysis of four different buckwheat starches showed that there was positive correlation between the completion temperature of first and second peaks. The △H1 of DSC was correlated with the peak viscosity, holding strength, cold pasty viscosity and final viscosity measured by RVA ,The solubility of buckwheat starch also had positive correlation with breakdown and total set back of RVA. The second part of this study showed that there were no significant difference in swelling power, water binding capacity, and RVA among starches. There was no difference in weight loss after cooking the noodle among the whole buckwheat noodle and the buckwheat noodle made with the addition of starch or wheat flour with the addition of other starches or wheat flour , had more weight loss after cooking. The results of texture profile analysis (TPA) showed that there were significant differences in the hardness, chewiness, and gumminess among buckwheat noodles made of whole buckwheat flour from four different areas. The hardness, springiness and chewiness of six kinds of buckwheat noodles made of buckwheat with different starches added were also significantly different. The noodles made of four different buckwheat flour were compared by sensory evaluation. The results showed significant differences in their texture and acceptance. The RVA analysis of buckwheat flour showed that the viscosity and hydration properties were correlated with cooking properties of buckwheat noodle. The temperature of peak viscosity had positive correlation with swelling power of buckwheat flour at 85℃ .It implied that the largest swelling power and the highest viscosity of buckwheat flour were both occurred at 85℃ . The results of TPA determination and sensory evaluation of buckwheat starch showed that the chewiness had significant positive correlation with hardness and adhesiveness. The acceptance and quality of while buckwheat noodle evaluated by sensory were also positively correlated with adhesiveness analyzed by TPA it proposed that the acceptance of buckwheat was influenced mainly by the texture of buckwheat.