基于热诱导的绿咖啡油氧化过程解析及活性成分变化规律研究

绿咖啡油是一种富含生物活性成分的功能性油脂,贮藏过程中极易氧化酸败影响产品品质。本文以海南地区兴隆咖啡为原料提取绿咖啡油,系统研究在60 ℃加速贮藏36 d内氧化指标、生物活性成分及表征氧化的光谱特征峰变化。结果表明：过氧化值、茴香胺值、硫代巴比妥酸、总氧化值初始值分别为0.97±0.04 meq/kg、4.19±0.14、55.08± 1.98 nmol/mL、8.05±0.06,经过36 d的氧化分别显著升高到28.56±0.15 meq/kg、19.19±0.13、102.38±2.18 nmol/mL、133.43± 0.45。本研究中共鉴定出11种脂肪酸,在绿咖啡油氧化过程中,饱和脂肪酸与不饱和脂肪酸比值由1.14上升至1.49。利用高效液相色谱测定绿咖啡油中的二萜类物质和生育酚,咖啡豆醇、咖啡醇的初始含量分别为21.01±0.31 mg/g、23.44±0.52 mg/g,在氧化24 d后升高至8.21±0.10 mg/g、8.99±0.02 mg/g,随后含量趋于稳定。共定性出α、δ和γ-生育酚,总生育酚含量由初始的49.75±0.88 mg/100 g在氧化18 d达到最大值53.70±1.72 mg/100 g,在氧化结束时降至34.58± 0.05 mg/100 g。利用傅里叶变换红外光谱（FTIR）从特征官能团的角度分析绿咖啡油的氧化过程,油脂在3008、2927、2854、1745、1461、1375、1238、1164、721 cm^-1处有特征吸收峰。采用拉曼光谱技术表征绿咖啡油加速贮藏中的氧化变质,在1000~1800 cm^-1波段的峰强度有明显减弱趋势。本研究表明绿咖啡油在热诱导下的贮藏过程中发生了明显的氧化反应,可为提升绿咖啡油贮藏稳定性提供理论参考。

Exploration of the Accelerated Oxidation Process and Change Rule of Bioactive Components from Green Coffee Oil Based on Thermal Induction

Green coffee oil is a kind of functional oil rich in biologically active ingredients, which is easily oxidized and rancid during storage and affects product quality. In this paper, green coffee oil was extracted from Xinglong coffee in Hainan area, and the changes in the oxidation index, biologically active components and spectral characteristic peaks that characterize oxidation were systematically studied within 36 days of accelerated storage at 60 ℃. The results showed that the initial values of peroxide value, anisidine value, thiobarbituric acid and total oxidation value was 0.97±0.04 meq/kg, 4.19±0.14, 55.08±1.98 nmol/mL, 8.05±0.06, respectively. After 36 days of oxidation, it significantly increased to 28.56±0.15 meq/kg, 19.19±0.13, 102.38±2.18 nmol/mL, and 133.43±0.45. A total of 11 fatty acids were identified in this study. During the oxidation of green coffee oil, the ratio of saturated fatty acids to unsaturated fatty acids rose from 1.14 to 1.49. High performance liquid chromatography was used to determine diterpenoids and tocopherol in green coffee oil. The initial content of cafestol and kahweol was 21.01±0.31 mg/g and 23.44±0.52 mg/g, respectively, which increased to 8.21±0.10 mg/g and 8.99±0.02 mg/g after 24 days of oxidation, and then the content tended to be stable. This experiment qualified α, δ and γ-tocopherols. The content of total tocopherols increased from the initial 49.75±0.88 mg/100 g to a maximum value of 53.70±1.72 mg/100 g after 18 days of oxidation, and dropped to 34.58±0.05 mg/100 g at the end of oxidation. Fourier transform infrared spectroscopy (FTIR) was used to analyze the oxidation process of green coffee oil from the perspective of characteristic functional groups. The oil had characteristic absorption peaks at 3008, 2927, 2854, 1745, 1461, 1375, 1238, 1164 and 721 cm^-1. Raman spectroscopy was used to characterize the oxidative deterioration of green coffee oil during accelerated storage, and the peak intensity in the 1000-1800 cm^-1 band had a significant weakening trend. This study showed that the green coffee oil undergone a significant oxidation reaction during the thermally induced storage process, which can provide a theoretical reference for improving the storage stability of green coffee oil.