[关键词]
[摘要]
为研究紫外(Ultraviolet,UV)光降解5-羟甲基糠醛(5-Hydroxymethylfurfural,5-HMF)的特性及机理,该研究构建5-HMF水模拟体系,分析紫外光辐射时间、强度、5-HMF初始质量浓度和光敏剂(FeSO4、TiO2 和VB2)对5-HMF降解的影响;通过密度泛函理论(Density Functional Theory,DFT)分析5-HMF紫外光降解反应性,并采用超高压液相色谱/四级杆串联飞行时间质谱联用仪鉴定其紫外光降解产物。结果表明:紫外光辐射时间越长,强度越大,5-HMF的初始质量浓度越小,降解率越高;当强度为400 μW/cm2、辐射时间为240 min、初始质量浓度为31.5 mg/L时,5-HMF的降解率最大,达83.64%;FeSO4 和TiO2 对5-HMF的紫外光降解有促进作用,而VB2对其有抑制作用;当FeSO4 和TiO2 的添加浓度和质量分数分别是1.0 mmol/L和0.025%时,5-HMF的降解率最大,分别为100.00%和76.68%(辐射时间分别为40、80 min,强度400 μW/cm2);DFT分析结果表明,5-HMF的C=O键更易受到攻击而降解,C4-C11和C1-C8间的化学键易断裂;在UV、UV/FeSO4、UV/TiO2体系中分别鉴定出1、2和5种5-HMF的降解产物;DFT分析结果与质谱鉴定结果相吻合。该研究为降低食品中的5-HMF提供了理论和应用研究基础。
[Key word]
[Abstract]
To explore the characteristics and mechanism of ultraviolet (UV) irradiation-induced photodegradation of 5-hydroxymethylfurfural (5-HMF), an aqueous simulation system of 5-HMF was constructed, and the effects of UV irradiation time, light intensity, initial mass concentration of 5-HMF and photosensitizers (FeSO4, TiO2 and VB2) on the degradation of 5-HMF were analyzed. The UV photodegradation reactivity of 5-HMF was analyzed by the density functional theory (DFT), and its UV degradation products were identified by an ultra-high performance liquid chromatography quadrupole time-of-flight tandem mass spectrometer. The results showed that the longer the UV irradiation time, the higher light intensity, the smaller the initial mass concentration of 5-HMF, and the higher the degradation rate. The degradation rate was the highest (83.64%) when the UV irradiation intensity was 400 μW/cm2, the radiation time was 240 min and the initial mass concentration was 31.5 mg/L. Both FeSO4 and TiO2 promoted the UV-induced degradation of 5-HMF, whilst VB2 inhibited the degradation of 5-HMF. The degradation rates of 5-HMF were the highest when the added concentrations and mass fractions of FeSO4 and TiO2 were 1.0 mmol/L and 0.025%: 100.00% (irradiation time 40 min, light intensity 400 μW/cm2) and 76.68% (irradiation time 80 min, light intensity 400 μW/cm2), respectively. The results of DFT analysis showed that the C=O bond of 5-HMF was more susceptible to attack and degradation, and the chemical bonds between C4-C11 and C1-C8 were easily broken. One, two and five degradation products of 5-HMF were identified in the UV, UV/FeSO4 and UV/TiO2 systems, respectively. The results of DFT analysis were consistent with the results of mass spectrometry identification. This study provides a theoretical and applied research basis for the reduction of 5-HMF in foods.
[中图分类号]
[基金项目]
农业农村部农业科技创新条件提升建设工程项目(2020-440100-012846);“十四五”广东省农业科技创新十大主攻方向“揭榜挂帅”项目(2023SDZG04)