Department of Agricultural, Environmental and Food Sciences, University of Molise, Via De Sanctis, I-86100, Campobasso, Italy.
Department of Agricultural, Environmental and Food Sciences, University of Molise, Via De Sanctis, I-86100, Campobasso, Italy.
Food Microbiol. 2015 May;47:12-20. doi: 10.1016/j.fm.2014.10.010. Epub 2014 Nov 11.
Previous microbiological research demonstrated the presence of a rich micro-flora composed mainly of yeasts in the suspended fraction of freshly produced olive oil. Some of the yeasts are considered harmful as they can damage the quality of the olive oil through the hydrolysis of the triacylglycerols. Present research has demonstrated that the lipolytic activity of some lipase-producer strains belonging to a yeast species called Candida adriatica, Candida diddensiae and Yamadazyma terventina can be modulated by the water and the polyphenol content of olive oil. Laboratory tests highlighted a substantial increase in free fatty acid in the inoculated olive oil characterized by high water content and low polyphenol concentration. The acidity of the olive oil samples containing 0.06% and 0.31% of water increased significantly by 33% in the lipase-producer yeast strains tested during a period of 2 weeks of incubation at 30 °C. All other yeasts showed strong lipolytic activity in the presence of 1.31% of water - the only exception to this was the C. adriatica 1985 strain. The phenolic compounds typical of olive oil represent another important factor able to condition the viability and the lipolytic activity of the lipase-producer yeasts. From the tests performed on the olive oil characterized by an increasing content of total polyphenols equal to 84, 150 and 510 mg per kg of oil, the percentage of the lipase-producer yeasts able to hydrolyse the triacylglycerols was respectively 100%, 67% and 11%.
先前的微生物学研究表明，在新鲜橄榄油的悬浮部分存在着一种由酵母组成的丰富微生物菌群。其中一些酵母被认为是有害的，因为它们可以通过水解三酰基甘油来破坏橄榄油的质量。目前的研究表明，一些属于被称为 Candida adriatica、Candida diddensiae 和 Yamadazyma terventina 的酵母物种的脂肪酶产生菌的脂解活性可以通过橄榄油的水和多酚含量来调节。实验室测试突出表明，在接种的橄榄油中，游离脂肪酸含量显著增加，其特征是水含量高而多酚浓度低。在 30°C 孵育 2 周期间，用测试的脂肪酶产生酵母菌株接种的橄榄油样品中，水含量为 0.06%和 0.31%时，酸度显著增加了 33%。所有其他酵母在 1.31%的水存在下都表现出很强的脂解活性-唯一的例外是 C. adriatica 1985 菌株。橄榄油中特有的酚类化合物是另一个能够影响脂肪酶产生酵母的生存能力和脂解活性的重要因素。在对橄榄油进行的测试中，总多酚含量分别增加到 84、150 和 510mg/kg 油，能够水解三酰基甘油的脂肪酶产生酵母的百分比分别为 100%、67%和 11%。
