Physicochemical,crystallinity, pasting and thermal properties of heat‐moisture‐treated pinhão starch

The effect of heat‐moisture treatment (HMT) on the properties of pinhão starches under different moisture and heat conditions was investigated. The starches were adjusted to 15, 20 and 25% moisture levels and heated to 100, 110 and 120°C for 1 h. The X‐ray diffractograms, swelling power, solubility, gel hardness, pasting properties and thermal properties of the native and HMT pinhão starches were evaluated. Compared to native starch, there was an increase in the X‐ray intensity and gel hardness of HMT starches, with the exception of the 25% moisture‐treated and 120°C heat‐treated starch. HMT reduced the swelling power and solubility of the pinhão starches when compared to native starch. There was an increase in the pasting temperature, final viscosity and setback and a decrease in the peak viscosity and breakdown of HMT pinhão starches compared to native starch. HMT increases the gelatinisation temperature of native pinhão starch and reduces gelatinisation enthalpy.     

茶叶挥发性成分及其生物活性的研究

用水蒸气蒸馏法分别从新鲜的茶叶和加工后的新茶中提取挥发油,利用气相色谱-质谱联用技术对挥发油中的化学成分进行分离和结构鉴定,运用气相色谱面积归一化法确定各个成分的相对百分含量。从新鲜茶叶挥发油中鉴别出51种成分,从加工后的新茶挥发油中鉴别出45种成分,两者挥发油成分存在着一定的差异。对新鲜茶叶挥发油和加工后的新茶挥发油做了抗氧化试验和抗菌试验,结果表明,两者挥发油对·OH均有清除作用,新鲜茶叶挥发油对·OH有较强的清除作用,两者挥发油对试验菌株均有明显的抑制和灭活作用。