Table_1_Comparison of the volatile organic compounds in Citrus reticulata ‘Chachi’ peel with different drying methods using E-nose, GC-IMS and HS-SPME-GC-MS.xlsx

IntroductionCitrus reticulata ‘Chachi’ peel (CRCP), which is named “Guangchenpi” in China, is a geographical indication product with unique flavor properties. CRCP has been used for centuries as a traditional genuine herb because of its excellent therapeutic effects. In addition, owing to its unique odor and high nutrition, it is widely used in various food preparations. Volatile organic compounds (VOCs) are regarded as an important quality marker for CRCP and are highly susceptible to effects in the drying process due to their thermal instability.
MethodsIn the current study, the main VOCs in CRCP were processed using different drying methods, including sun-drying, hot air drying, and vacuum-freeze drying. The VOCs were identified by the electronic nose (E-nose), gas chromatography-ion mobility spectrometry (GC-IMS), and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS).
ResultsThe results showed that the CRCP dried by vacuum-freeze exhibited the highest VOCs contents and retained the richest compounds compared to those dried by other methods, which indicated that vacuum-freeze drying is the most suitable for CRCP production. Furthermore, the chemometrics analysis revealed that the primary differential metabolites of the samples generated using different drying methods were terpenes and esters.
DiscussionOverall, our study would help better understand the VOCs present in CRCP with different drying methods. The outcomes of the current study would guide the drying and processing of CRCP, which is beneficial for large-scale storage and industrial production of CRCP.

引言
茶枝柑果皮（Citrus reticulata ‘Chachi’，简称CRCP）在我国又名“广陈皮”，是兼具独特风味特质的地理标志产品。CRCP凭借优异的药用功效，已作为传统道地药材使用数百年之久。此外，因其独特的气味与丰富的营养成分，它被广泛应用于各类食品制备场景。挥发性有机化合物（Volatile Organic Compounds，简称VOCs）被视为CRCP的重要品质标志物，且因其热不稳定性，在干燥过程中极易受到外界因素影响。

方法
本研究针对CRCP，采用晒干、热风干燥与真空冷冻干燥三种不同干燥方式进行处理，并通过电子鼻（electronic nose，简称E-nose）、气相色谱-离子迁移谱（gas chromatography-ion mobility spectrometry，简称GC-IMS）以及顶空固相微萃取-气相色谱-质谱联用法（headspace solid-phase microextraction-gas chromatography-mass spectrometry，简称HS-SPME-GC-MS）对样品中的VOCs进行鉴定分析。

结果
结果显示，与其他干燥方式处理的样品相比，真空冷冻干燥的CRCP中VOCs含量最高，且保留的化合物种类最为丰富，这表明真空冷冻干燥是最适用于CRCP生产的干燥方式。此外，化学计量学分析表明，不同干燥方式处理的样品间主要差异代谢物为萜类与酯类化合物。

讨论
综上，本研究有助于深入理解不同干燥方式下CRCP中VOCs的组成与变化情况。本研究结果可为CRCP的干燥与加工提供科学指导，有利于CRCP的规模化贮藏与工业化生产。