热泵干燥对生咖啡豆活性物质和挥发性成分的影响研究

Effect of Heat Pump Drying on the Bioactive Components and Volatile Compounds in Green Coffee Beans

摘要:

本文以日晒干燥为对比，研究了热泵干燥对生咖啡豆活性物质和挥发性成分的影响，探索不同干燥温度（40 ℃、45 ℃、50 ℃、55 ℃和60 ℃）下生咖啡豆色泽、脂肪、主要活性成分咖啡因、葫芦巴碱及挥发性成分的变化规律，并采用一元方差分析（ANOVA）对不同处理下生咖啡豆的风味成分进行统计学分析。结果表明：色泽明亮度随温度升高逐渐增大；温度为55 ℃时样品脂肪含量最高为9.21 g/100g DW；咖啡因含量随温度的升高略有增大，而葫芦巴碱含量基本保持不变（0.81~0.89 g/100 g DW）；采用顶空固相微萃取-气相色谱质谱联用（HS-SPME/GC-MS）共定性出61种挥发性化合物，酸类、醛类和醇类为生咖啡豆中三类主要的挥发性化合物，其它类别化合物含量相对较低；其中在40 ℃处理下样品中酸类化合物含量最高为41.85%，醛类化合物在日晒干燥处理下含量最高为35.21%，而醇类化合物在60 ℃时样品含量最高为34.52%。

Abstract:

Using sun-dried samples as the control, the effects of heat pump drying on the bioactive components and volatile compounds in green coffee beans were investigated. The patterns of color variations, and the content of fat, caffeine (main active ingredient), trigonelline, and volatiles of green coffee beans treated at different drying temperatures (40 ℃, 45 ℃, 50 ℃, 55 ℃, and 60 ℃) were explored. One-way analysis of variance (ANOVA)was used to conduct statistical analysis of the data on the flavor components of green coffee beans from different treatments. The results indicated that the color brightness increased with increasing temperature; the highest fat content (9.21 g/100 g dry weight (DW)) was obtained at 55 ℃; and the caffeine content increased slightly with increasing temperature, whereas the trigonelline content remained constant. Headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME/GC-MS) was used to detect the volatile compounds of green coffee beans, and 61 types of compounds were identified. The acids, aldehydes, and alcohols were the predominant compounds, whereas other types of compounds accounted for only a small proportion. The highest content of acids (41.85%), alcohols (34.52%), and aldehydes (35.21%) were found in the samples treated at 40 ℃, 60 ℃, and sun drying conditions, respectively.