Quality of pomegranate peel cultivar Valenciana as determined by different drying methods

Abstract The pomegranate fruit exhibits medicinal properties due to the nutraceutical characteristics, especially of its peel. The objective of this study was to analyze the influence of different drying methods on the physicochemical and biochemical characteristics of the pomegranate peel. The experiment was conducted in a completely randomized design in subdivided plots: 4 (full sun [SUN], drying chamber [DC] at 60 ± 2 °C, cold chamber at 10 °C and 60% relative humidity (RH) [CC], solar dryer [SD]) × 2 (presence or absence of 1% ascorbic acid [AA]). The analyzed variables were mass loss, index of drying heterogeneity (IHD), Hue internal (LI, CI, HI) and external (LE, CE, HE) angles, as well as Chroma, of the peel, and finally, total phenolic compound (TCFT) and flavonoid (TFLA) content. DC treatment led to the shortest drying time, followed by SUN and SD treatments. A reduction in IHD was observed with respect to time, which was more pronounced in DC treatment. CC treatment produced a more positive response both for LI and LE. TCFT and TFLA content produced from DC treatment presented an interaction effect, which was reduced by the application of AA. On the other hand, dehydration without the application of AA in the drying chamber or in full sun resulted in the best responses in TCFT and TFLA content.摘要 石榴果实因具备营养保健特性，尤其其石榴皮，具有药用价值。本研究旨在分析不同干燥方式对石榴皮理化特性与生化特性的影响。实验采用完全随机裂区设计，设置4种干燥方式：全日光晾晒(SUN)、60±2℃干燥箱(DC)、10℃且相对湿度(RH)60%的冷藏箱(CC)、太阳能干燥器(SD)，以及2种预处理方式：添加或不添加1%抗坏血酸(AA)。本次分析的指标包括：质量损失率、干燥异质性指数(IHD)、果皮内部色相角（亮度LI、色度CI、色调HI）与外部色相角（亮度LE、色度CE、色调HE）、彩度，以及总酚类化合物(TCFT)和总黄酮(TFLA)含量。结果表明，干燥箱处理的干燥时长最短，其次为全日光晾晒与太阳能干燥器处理。随干燥进程推进，干燥异质性指数呈下降趋势，且该趋势在干燥箱处理组中最为显著。冷藏箱处理对内部亮度LI与外部亮度LE均展现出更优的正向调控效果。干燥箱处理所得的总酚类化合物与总黄酮含量存在交互效应，而添加抗坏血酸会削弱该效应。另一方面，在干燥箱或全日光晾晒且未添加抗坏血酸的脱水处理，可使总酚类化合物与总黄酮含量达到最佳水平。