超高压与热处理对火龙果汁流变特性的影响

Comparison of Ultra-High Pressure and Heat Treatment on Rheological Property of Pitaya Juice

采用不同温度和不同压力处理鲜榨火龙果汁,以果汁流体类型、触变性为评价指标,探讨热处理和超高压处理对火龙果汁流变特性影响。结果表明:原果汁、热处理和超高静压处理后果汁都属于假塑性流体。在1～30s-1低剪切速率下,果汁的表观黏度随处理温度提升而降低;在大于30 s-1剪切速率下,表观黏度基本与空白保持一致。超高静压处理中,经过400 MPa处理的果汁表观黏度比其他压力条件处理的都要大,而300 MPa和450 MPa处理的结果略高于空白,350 MPa处理结果基本与空白吻合。触变性方面,空白与经过超高压处理果汁没有表现出明显的触变性,而经过热处理的果汁却表现出明显触变性质,而且随着处理温度升高,触变环面积逐渐变少。

The rheological properties and thixotropy properties of the pitaya juice treated at different heating temprature and different ultra-high pressure were investigated. The result showed that all the processed pitaya juice behaved as pseudoplastic fluid. At the low shear stress of 1 -30 s^-1, colloidal viscosity was decreased with the increase of treatment temperature. When the shear stress was more than 30 s^-1, the sample viscosity were essentially the same with the control one. At the different high pressure, the highest colloidal viscosity was found at 400MPa; the colloidal viscosity at 300 MPa and 450 MPa were slightly higher than the blank sample. The colloidal viscosity was almost the same with blank samples at 350 MPa. For the thixotropy properties, the blank sample and high pressure treated sampies all showed no thixotropy properties. But the samples of heat treatment behaved the thixotropy properties and the thixotropie loop area was decreased with the increase of treatment temperature.