Ciafardini G, Cioccia G, Zullo B A
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. 2017 Apr;62:58-61. doi: 10.1016/j.fm.2016.09.014. Epub 2016 Sep 22.
The opalescent appearance of the newly produced olive oil is due to the presence of solid particles and microdrops of vegetation water in which the microorganisms from the olives' carposphere are trapped. Present research has demonstrated that the microbiota of the fresh extracted olive oil, produced in the mills, is mainly composed of yeasts and to a lesser extent of molds. The close link between the composition of the microbiota of the olives' carposphere undergoing to processing, and that of the microbiota of the newly produced olive oil, concerns only the yeasts and molds, given that the bacterial component is by and large destroyed mainly in the kneaded paste during the malaxation process. Six physiologically homogenous yeast groups were highlighted in the wash water, kneaded paste and newly produced olive oil from the Taggiasca variety which had been collected in mills located in the Liguria region. The more predominant yeasts of each group belonged to a single species called respectively: Kluyveromyces marxianus, Candida oleophila, Candida diddensiae, Candida norvegica, Wickerhamomyces anomalus and Debaryomyces hansenii. Apart from K. marxianus, which was found only in the wash water, all the other species were found in the wash water and in the kneaded paste as well as in the newly produced olive oil, while in the six-month stored olive oil, was found only one physiologically homogeneous group of yeast represented by the W. anomalus specie. These findings in according to our previous studies carried out on other types of mono varietal olive oils, confirms that the habitat of the Taggiascas' extra virgin olive oil, had a strong selective pressure on the yeast biota, allowing only to a few member of yeast species, contaminating the fresh product, to survive and reproduce in it during storage.
新生产的橄榄油呈现乳白外观是由于存在固体颗粒和植物水分微滴，橄榄果际微生物被困于其中。目前的研究表明，在工厂中新鲜提取的橄榄油中的微生物群主要由酵母组成，霉菌的占比相对较小。正在加工的橄榄果际微生物群组成与新生产的橄榄油微生物群组成之间的紧密联系，仅涉及酵母和霉菌，因为细菌成分在搅拌过程中主要在揉捏糊状物中被大量破坏。在利古里亚地区工厂收集的塔吉亚斯卡品种的冲洗水、揉捏糊状物和新生产的橄榄油中，突出显示了六个生理同质的酵母组。每组中更占优势的酵母分别属于单一物种，分别为：马克斯克鲁维酵母、嗜油酸假丝酵母、迪氏假丝酵母、挪威假丝酵母、异常威克汉姆酵母和汉逊德巴利酵母。除了仅在冲洗水中发现的马克斯克鲁维酵母外，所有其他物种在冲洗水、揉捏糊状物以及新生产的橄榄油中均有发现，而在储存六个月的橄榄油中，仅发现一个以异常威克汉姆酵母物种为代表的生理同质酵母组。根据我们之前对其他类型单一品种橄榄油进行的研究，这些发现证实，塔吉亚斯卡特级初榨橄榄油的生境对酵母生物群具有强大的选择压力，在储存期间，仅允许少数污染新鲜产品的酵母物种成员在其中存活和繁殖。
