热处理香榧种子油中美拉德产物的生成及其对两种总酚测定方法的影响

Formation of Maillard Reaction Products in Heat-Treated Torreya grandis cv.Merrilli Seed Oil and Their Effects on Two Analytical Methods for the Determination of Total Phenolics

通过测定香榧种子油褐变指数与3-脱氧葡萄糖醛酮、丙酮醛及5-羟甲基糠醛3种美拉德产物的含量验证美拉德反应的发生并进一步考察3种产物对福林-酚法与固蓝BB盐法测定总酚的影响。结果表明:香榧籽在150℃热处理90~120 min时,福林-酚法测得的油脂总酚含量上升,而固蓝BB盐法的测定结果与之相反。低温长时热处理及高温处理皆会引起香榧种子油在294 nm波长处吸光度上升,且在经高温(150℃)处理的油样中检出了3-脱氧葡萄糖醛酮(0.21~0.47μg/g)与5-羟甲基糠醛(0.06~0.40μg/g),在各加热条件的油样中皆检出丙酮醛(0.67~1.73μg/g)。福林-酚法测定中,3-脱氧葡萄糖醛酮、丙酮醛在765 nm波长处的吸光度皆随浓度增大呈线性升高,同浓度3种美拉德产物在此波长处的响应排序为3-脱氧葡萄糖醛酮>丙酮醛>5-羟甲基糠醛;3-脱氧葡萄糖醛酮的存在会造成福林-酚法测定结果偏大且干扰程度与样品总酚含量无关,而与其本身浓度呈正相关。固蓝BB盐法测定中,3种美拉德中间产物在420 nm波长处的吸光度变化皆不显著。因此,针对加工过程中易形成3-脱氧葡萄糖醛酮、丙酮醛的食品基质,选择固蓝BB盐法替代福林-酚法测定总酚含量可降低这两种物质对定量的干扰。

The occurrence of Maillard reaction in heated Torreya grandis cv.Merrilli seed oil was verified by detecting browning index and the contents of the Maillard reaction products(MRPs)3-deoxyglucosone,methylglyoxal and 5-(hydroxymethyl)furfural,and the effects of the MRPs on the quantification of total phenolics using the Folin-Ciocalteu and Fast Blue BB assays were explored.The Folin-Ciocalteu assay showed that the content of total phenolics in the oil increased after treatment at 150℃ for 90 to 120 min,while the Fast Blue BB assay showed the opposite result.It was also observed that the absorbance of the oil at a wavelength of 294 nm increased after long-term low-temperature or high-temperature heat treatment.3-Deoxyglucosone(0.21-0.47μg/g)and 5-(hydroxymethyl)furfural(0.06-0.40μg/g)were detected only in the 150℃ treated oil,while methylglyoxal(0.67-1.73μg/g)existed in both oil samples.In the Folin-Ciocalteu assay,the absorbance at a wavelength of 765 nm of 3-deoxyglucosone and methylglyoxal linearly increased with an increase in their concentrations,and the decreasing order of the absorbance of the MRPs at the same concentration was 3-deoxyglucosone>methylglyoxal>5-(hydroxymethyl)furfural.In the presence of 3-deoxyglucosone,the Folin-Ciocalteu result was greater than the actual value,and the degree of interference was not related to the content of total phenolics in samples,but instead was positively correlated with the concentration of 3-deoxyglucosone.In the Fast Blue BB assay,there was no significant difference in absorbance at 420 nm among the three MRPs.For food matrices prone to the formation of 3-deoxyglucosone and methylglyoxal during processing,the Fast Blue BB assay can be selected instead of the Folin-Ciocalteu assay to mitigate the interferences from the two substances in the quantification of total phenolics.