气质联用结合电子鼻表征不同温度热风干燥苹果脆片关键香气化合物

李嘉欣; 吴昕烨; 毕金峰; 苟敏

doi:10.13386/j.issn1002-0306.2021120071

气质联用结合电子鼻表征不同温度热风干燥苹果脆片关键香气化合物

Characterization of Key Aroma Compounds of Apple Slices Dried by Hot-air at Different Temperatures by GC-MS and Electronic Nose

摘要

摘要: 为明确富士苹果的关键香气化合物以及干燥温度对富士苹果关键香气化合物的影响，采用顶空固相微萃取气质联用（headspace solid-phase micro-extraction gas chromatography-mass spectrometer，HS-SPME-GC-MS）技术结合电子鼻对富士苹果鲜样、50、60、70和80 ℃热风干燥苹果脆片的挥发性化合物进行表征。结果表明，苹果鲜样和4种干燥样品共鉴定出64种挥发性化合物，包括酯类23种、醇类18种、醛类8种、烯烃类2种、酮类2种、内酯类3种、酸类1种、含硫化合物3种和杂环化合物4种。不同样品各类挥发性化合物的种类及含量均存在较大差异，鲜样香气化合物含量为397.059 mg/kg，不同温度热风干燥样品挥发性化合物含量由高到低分别为64.189 mg/kg（50 ℃处理）、57.703 mg/kg（80 ℃处理）、32.124 mg/kg（70 ℃处理）、32.020 mg/kg（60 ℃处理）。气味活性值（odor-active value，OAV）分析表明，苹果鲜样与热风干燥样品共有关键香气化合物8种，分别为α-法尼烯（12746.11~1597.75）、2-甲基丁酸己酯（755.62~6.90）、己醇（2988.00~168.54）、1-辛烯-3-醇（53.12~12.08）、壬醛（1534.99~47.36）、反式-2-壬烯醛（1202.98~189.38）、芳樟醇（1264.30~212.75）和6-甲基-5-庚烯-2-酮（11.27~3.90）。除此以外，热风干燥样品独有的关键香气化合物包括2-甲基-1-丁醇（32.26~7.16）、3-甲基-4-庚醇（14.39~6.90）、苯乙醇（11.11~4.67）、辛醛（211.25~84.36）、3-羟基-2-丁酮（64.57~21.86）、3-甲硫基丙醇（13.52~5.88）和2-戊基呋喃（26.44~14.88）。电子鼻分析表明鲜样与热风处理苹果脆片香气轮廓存在差异，通过主成分分析（principle component analysis，PCA）可以对鲜样和脱水苹果脆片进行有效区分。综合考虑香气、能耗，相比于50 ℃热风处理，80 ℃可以在短时间内使苹果片呈现热风脱水制品的特征性风味。因此，80 ℃热风干燥条件最佳。

Abstract: To clarify the key aroma compounds of Fuji apples and the influence of drying temperatures, the volatile compounds of Fuji apple slices dried by hot-air at 50, 60, 70 and 80 ℃ were characterized by head space solid-phase micro-extraction gas chromatography-mass spectrometer (HS-SPME-GC-MS) combined with electronic nose. The results showed that 64 volatile compounds were identified in fresh and four kinds of dried apple samples, including 23 esters, 18 alcohols, 8 aldehydes, 2 alkenes, 2 ketones, 3 lactones, 1 acid, 3 sulfur-containing compounds and 4 heterocyclic compounds. The differences between types and contents of volatile compounds in different samples were great. The content of aroma compounds in fresh samples was 397.059 mg/kg. Total volatile compounds contents in four hot-air dried samples from high to low were 64.189 mg/kg at 50 ℃, 57.703 mg/kg at 80 ℃, 32.124 mg/kg at 70 ℃ and 32.020 mg/kg at 60 ℃, respectively. Odor-active value (OAV) analysis showed that there were 8 key aroma compounds both in fresh apple sample and hot-air dried apple samples. They were α-farnesene (12746.11~1597.75), hexyl 2-methylbutyrate (755.62~6.90), hexanol (2988.00~168.54), 1-octene-3-ol (53.12~12.08), nonanal (1534.99~47.36), trans-2-nonenal (1202.98~189.38), linalool (1264.30~212.75) and 6-methy-5-hepten-2-one (11.27~3.90). The key aroma compounds identified in hot-air dried samples included 2-methyl-1-butanol (32.26~7.16), 3-methyl-4-heptanol (14.39~6.90), phenylethanol (11.11~4.67), octanal (211.25~84.36), 3-hydroxy-2-butanone (64.57~21.86), 3-methylthiopropanol (13.52~5.88) and 2-pentylfuran (26.44~14.88). Electronic nose analysis showed that there were differences in aroma profiles between fresh apple and apple slices dried by hot-air at different temperatures. The fresh samples and dried apple slices could be effectively distinguished by principle component analysis (PCA). Considering aroma and energy consumption, 80 ℃ hot air dehydration apple slices had better characteristic aroma than 50 ℃ hot air treatments. Therefore, 80 ℃ hot air drying was the optimal drying condition.