不同热泵干燥温度对柑橘果皮品质的比较分析

Quality of Citrus Peels Dried at Different Temperatures using Heat Pump

为了探究热泵干燥温度对柑橘果皮品质的影响,以新鲜的柑橘果皮为原料,分别对日晒(对照)和不同热泵温度(40℃、50℃、60℃、70℃、80℃)条件干燥获得的柑橘果皮的色泽、复水比、精油含量、总黄酮含量和抗氧化活性进行了测定。结果表明:L值随着温度的升高先增大后降低,a值在40℃、50℃、60℃热泵干燥和热晒干燥无显著差异(p>0.05),在温度高于60℃时呈下降趋势,b值随着温度的升高而增大,60℃热泵干燥ΔE值最小;当复水达到平衡时,日晒干燥、40℃、50℃、60℃热泵干燥柑橘果皮的复水比没有显著的差别(p>0.05),且显著高于70℃和80℃干燥的柑橘果皮(p<0.05);精油和总黄酮的含量随着温度的升高先增大后降低,其中在60℃时,精油和总黄酮含量最高,分别为2.04%和13.46%;DPPH和ABTS+的清除能力也是60℃最高,分别为54.16%和37.13%。综合各项指标,热泵干燥温度为60℃时,可以较大的保持柑橘果皮的色泽、黄酮和抗氧化性等品质指标,为柑橘果皮热泵干燥的实际应用提供技术指导。

To understand the effect of drying temperature on the quality of citrus peels dried using a heat pump,the colors,rehydration ratios,essential oil contents,total flavonoid contents,and antioxidant activities of the sun-dried,fresh citrus peels(control)and those dried at different temperatures(40,50,60,70,and 80℃)using a heat pump are compared.The L value first increases and then decreases with an increase in the drying temperature.The a values of the citrus peels dried using a heat pump at 40,50,and 60℃ and those of the sun-dried peels show no significant differences(p>0.05).However,the a value decreases with an increase in temperature to >60℃.In contrast,the b value increases with an increase in the drying temperature.The lowest ΔE value is obtained when the citrus peels are dried using heat pump at 60℃.At equilibrium,the rehydration ratios of sun-dried citrus peels and the peels dried using a heat pump at 40,50,and 60℃exhibit insignificant differences(p>0.05),but these are significantly higher than those of the peels dried using a heat pump at 70 and 80℃(p<0.05).The essential oil and total flavonoid contents of the peels first increase and then decrease as the drying temperature increases.At 60℃,the highest essential oil and total flavonoid contents of 2.04% and 13.46%,respectively,are obtained.The highest DPPH and ABTS+scavenging capacities of 54.16% and 37.13%,respectively,are also observed at 60℃.Therefore,drying using a heat pump at 60℃ can allow the preservation of the quality of citrus peels,including the color,total flavonoid content,and antioxidant activity of the peels.This finding can facilitate the practical application of heat pumps in drying citrus peels.