温度对绿色葡萄干色泽及干燥特性的影响

Effects of temperature on color and drying characteristics of green raisins

  • 摘要: 【目的】 研究不同温度条件下热风干燥对葡萄干色泽相关指标、水分扩散系数的影响,为绿色葡萄干的工业化生产加工提供理论和技术支撑。 【方法】 采用不同温度(30、32.5、35、37.5和40℃)对无核白葡萄进行干燥,分析温度对葡萄色泽、水分扩散系数及制干品质的影响,拟合干燥动力学模型。 【结果】 干燥温度为35℃时绿色葡萄干比率最高达到64%,色泽与原料的差异最小,色差ΔE仅为6.99,Ch0Lab等色泽指标分别为18.23、1.4、14.57、2.99、17.95。叶绿素、叶绿素a、叶绿素b、类胡萝卜素、总酚含量分别为0.56、0.19、0.36、0.32、0.18 mg/g。35℃更适宜绿色葡萄干加工。最符合葡萄干燥的模型,决定系数 R2值最大,误差平方和、SSE和均方根误差RMSE均值最小,分别为 0.998 1、0.005 4和 0.007 7。绿色葡萄干最适宜的有效水分扩散系数为5.334 8×10-9【结论】 热风干燥温度为35℃时最有利于无核白绿色葡萄制干,35℃时有效水分扩散系数分别为30、32.5、37.5和40℃的114.13%、110.58%、95.17%和76.58%,Logarithmic 模型可以有效的描述热风干燥工艺条件下葡萄果实水分的变化规律。

     

    Abstract: 【Objective】 The effects of hot air drying on the color and luster indexes and moisture diffusion coefficient of raisins under different temperature conditions were studied, which provided theoretical and technical support for the industrial production and processing of green raisins. 【Methods】 Different temperatures(30, 32.5, 35, 37.5 and 40℃)were used to dry seedless white grapes, and the effects of temperature on grape color change, moisture diffusion coefficient and raisin quality were analyzed, and the drying kinetic model was fitted. 【Results】 When the drying temperature was 35°C, the ratio of green raisins reached 64%, the difference between color and raw materials was the smallest, the color difference ΔE was only 6.99, and the color indexes of C, h0, L, a, b and so on were 18.23, 1.4, 14.57, 2.99 and 17.95, respectively.Chlorophyll, chlorophyll a, chlorophyll b, carotenoids and total phenols were 0.56, 0.19, 0.36, 0.32 and 0.18 mg/g, respectively.35℃ is more suitable for green raisin processing.The most consistent model for grape drying, with the largest coefficient of determination R2, the sum of squared errors and the mean of SSE and root mean square error Rmse the smallest, respectively, 0.998,1, 0.005,4, and 0.007,7.The most suitable effective water diffusion coefficient of green raisins is 5.334,8×10-9. 【Conclusion】 The effective water diffusion coefficients of 30, 32.5, 37.5 and 40℃ were 114.13%, 110.58%, 95.17% and 76.58%, respectively, and the Logarithmic model could effectively illustrate the variation of grape fruit moisture under the hot air drying process.

     

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