Department of Postharvest Science of Fresh Produce, ARO, the Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel.
J Agric Food Chem. 2011 Nov 9;59(21):11779-85. doi: 10.1021/jf203037v. Epub 2011 Oct 18.
To elucidate the roles of ethanol fermentation metabolism in causing off-flavors, 'Mor' mandarins were exposed to anaerobic atmospheres for 0, 2, 4, 7, and 10 days to gradually increase juice ethanol and acetaldehyde levels through enhanced fermentation. Exposure to anaerobic atmosphere caused progressive decline in fruit sensory quality, from nearly "good" to "very bad", because of decreased typical mandarin flavor and increased sensation of 'musty' and 'ethanol' off-flavors. GC-MS analysis revealed significant (p ≤ 0.05) increases in the contents of 12 aroma volatiles, including the ethanol fermentation metabolites ethanol and acetaldehyde, and several fatty acid and amino acid catabolism derivates, 7 of which were ethyl esters, which suggests that they were esterification products of ethanol and acyl-CoA's derived from fatty acid and amino acid catabolism. These de novo synthesized anaerobiosis-regulated ethyl esters impart 'pungent', 'ethereal', 'waxy', 'musty', and 'fruity' notes. Overall, these results suggest that besides the direct effects of ethanol and acetaldehyde, downstream ethanol esterification products may also be involved in causing off-flavor sensation in mandarins.
为了阐明乙醇发酵代谢在产生异味中的作用，将‘椪柑’暴露于无氧环境中 0、2、4、7 和 10 天，通过增强发酵逐渐增加果汁中的乙醇和乙醛水平。无氧环境的暴露导致果实感官品质逐渐下降，从近乎“良好”到“非常差”，因为典型的柑橘风味减少，而“霉味”和“乙醇味”等异味增加。GC-MS 分析显示，包括乙醇发酵代谢物乙醇和乙醛在内的 12 种香气挥发物的含量显著增加（p≤0.05），以及几种脂肪酸和氨基酸分解代谢产物，其中 7 种为乙酯，这表明它们是乙醇和酰基辅酶 A 的酯化产物，酰基辅酶 A 来源于脂肪酸和氨基酸的分解代谢。这些新合成的厌氧调节乙酯赋予了“刺鼻”、“醚状”、“蜡质”、“霉味”和“水果味”的特征。总的来说，这些结果表明，除了乙醇和乙醛的直接作用外，乙醇酯化产物的下游产物也可能参与了柑橘异味的产生。
