甘薯淀粉RVA测定程序初探

应用快速粘度仪(Rapid Visco-Analyser,RVA)研究了甘薯淀粉和全粉的糊化在不同测定条件下的表现。发现甘薯样品的RVA谱在很大大程度上受测定条件的影响,主要影响因素为:加热速率、95℃时的保持时间、结束温度保持时间以及剪切效应。另外起始温度保持0或1min时,样品最高粘度表现较高。加热时间一般在4min或6min时,样品最高粘度能获得最高值。冷却时间和结束温度主要影响最终粘度。冷却时间延长,样品最终粘度先升高后降低;而且随着结束温度降低,最终粘度表现递增。建议甘薯样品的RVA分析程序为:50℃保持1min,4min内加热至95℃,95℃保温5.5min,同样4min内冷却至50℃,并最终在50℃保持4min。

Study on Testing Procedure of Rapid Visco Analyser for Sweet Potato Starch

Three sweet potato starches and three sweet potato flours were assayed to a number of different RVA profiles.Significant difference in viscosities was observed with different RVA operating conditions. The most important factors causingthese variations were the heating rate, the holding time at 95℃, the final holding time and the shear thinning. In addition, the peakviscosities were kept at high level when initial holding time was zero or one minute. Otherwise the maximum peak viscosity wasshown with heating for 4min or 6min. The cooling time and the final temperature were important factors affecting the finalviscosity, but the desired conditions for them were dependent on attributes of instrument. A proposal for RVA procedure ofsweet potato samples is: to hold at least 1min at 50℃, to heat to 95℃ for 4min, to hold at 95℃ for 5.5min, to cool to 50℃ for4min, and to hold at 50℃ for 4min.