Dipartimento di Scienze Veterinarie, Università di Torino, 10095 Grugliasco (TO), Italy.
Veneto Agricoltura, Istituto per la Qualità e le Tecnologie Agroalimentari, 36016 Thiene (VI), Italy.
J Dairy Sci. 2020 May;103(5):4056-4067. doi: 10.3168/jds.2019-17451. Epub 2020 Mar 12.
Robiola di Roccaverano, from the Piedmont region of Italy, is a Protected Designation of Origin soft cheese made with raw goat milk. The peculiarity of this cheese is that during the manufacturing process, a natural starter culture (NC) is added to raw milk. This study examined the viable microorganisms of technological interest, including lactic acid bacteria and fungal populations, in samples of raw milk, NC, and fresh and ripened cheese collected from one dairy using culture-dependent techniques. First, the isolated colonies were analyzed using random amplification of polymorphic DNA (RAPD) PCR, and strains with similar fingerprints were clustered together. Further, representative isolates of each group were subjected to 16S or 26S ribosomal DNA sequencing. Finally, species-specific PCR was conducted to distinguish the Lactococcus lactis ssp. lactis and Lc. lactis ssp. cremoris. Among the studied lactic acid bacteria, 13 RAPD profiles were obtained, corresponding to 9 different bacterial species or subspecies. Concerning mold and yeast isolates, 5 species were found that coincided with 5 RAPD types. Observing the strains isolated in the study, Lc. lactis was the most prevalent species in raw milk and NC samples, and Leuconostoc mesenteroides was the predominant species identified in 5- and 15-d cheese isolates. Furthermore, whereas only these 2 species were detected in NC, Enterococcus and Lactobacillus genera were found in raw milk and cheese, respectively. Concerning the mold and yeast isolates, in NC Kluyveromyces spp. was mainly found, and in cheese samples the representative species were Geotrichum candidum and Yarrowia lipolytica. Finally, raw milk and cheese safety were evaluated, and the samples complied with the standard required by European Commission regulation number 2073/2005.
罗比奥拉·迪·罗卡瓦拉诺，来自意大利皮埃蒙特地区，是一种用生羊奶制成的受保护的原产地软奶酪。这种奶酪的特点是在生产过程中，向生牛奶中添加天然起始培养物（NC）。本研究使用基于培养的技术，检查了来自一个乳品厂的生牛奶、NC 以及新鲜和成熟奶酪样本中具有技术意义的活菌，包括乳酸菌和真菌种群。首先，使用随机扩增多态性 DNA（RAPD）PCR 分析分离的菌落，将指纹相似的菌株聚类在一起。然后，对每个组的代表性分离株进行 16S 或 26S 核糖体 DNA 测序。最后，进行物种特异性 PCR 以区分乳球菌乳亚种和乳球菌乳亚种。在所研究的乳酸菌中，获得了 13 种 RAPD 图谱，对应于 9 种不同的细菌种或亚种。关于霉菌和酵母分离株，发现了 5 种与 5 种 RAPD 类型一致的物种。观察研究中分离的菌株，乳球菌是生牛奶和 NC 样品中最常见的物种，明串珠菌是 5 天和 15 天奶酪分离株中占优势的物种。此外，虽然仅在 NC 中检测到这 2 个物种，但肠球菌属和乳杆菌属分别在生牛奶和奶酪中被发现。关于霉菌和酵母分离株，在 NC 中主要发现了克鲁维酵母属，而在奶酪样品中代表性物种是球拟酵母和产脂耶氏酵母。最后，评估了生牛奶和奶酪的安全性，样品符合欧盟委员会第 2073/2005 号条例要求的标准。
