Area de Tecnología de los Alimentos, Facultad de Ciencias de Ourense, Universidad de Vigo, 32004 Ourense, Spain.
Food Microbiol. 2010 Apr;27(2):229-35. doi: 10.1016/j.fm.2009.10.003. Epub 2009 Oct 9.
Total aerobic mesophilic microflora (on SPC agar), lactic acid bacteria (on MRS agar) and lactobacilli (on Rogosa agar) were enumerated in samples from the surface and the interior of the pieces throughout the manufacture of six batches of lacón. Three of the batches were made without additives and three with additives (glucose (2 g/kg), sodium nitrite (E(250)) (125 mg/kg), sodium nitrate (E(251)) (175 mg/kg), sodium ascorbate (E(301)) (500 mg/kg), and sodium citrate (E(331)) (100 mg/kg)). The counts decreased throughout the manufacturing process, particularly after the salting stage. The use of additives did not affect the counts or the evolution of the microbial groups, except for the lactobacilli, which were present in higher numbers in the batches with additives. In four batches (two without and two with additives), from MRS agar and from Rogosa agar plates, 10 colonies were randomly taken from each sampling point of each batch (five from the surface sample and five from the interior sample) and from each culture medium; a total of 224 strains from MRS agar, and 176 strains from Rogosa agar that were identified by classical methods. The MRS agar displayed moderate selectivity for the isolation of lactic acid bacteria, and only 59% of the isolated strains belonged to this microbial group. Homofermentative and facultative heterofermentative lactobacilli (particularly Lactobacillus curvatus and Lactobacillus sakei) were the most abundant species isolated on this medium. The selectivity of the Rogosa agar for lactobacilli was extremely high. The species of lactobacilli isolated on this medium at different stages of manufacture of the four batches of lacón were consistent with those isolated from MRS agar. The use of additives in the lacón did not appreciably affect the kinds and proportions of species isolated on either MRS agar or Rogosa agar.
在制作 6 批拉科恩的过程中，对样品表面和内部的总需氧嗜温微生物（在 SPC 琼脂上）、乳酸菌（在 MRS 琼脂上）和乳杆菌（在罗哥萨琼脂上）进行了计数。其中 3 批不添加添加剂，3 批添加了添加剂（葡萄糖（2g/kg）、亚硝酸钠（E(250))(125mg/kg）、硝酸钠（E(251))(175mg/kg）、抗坏血酸钠（E(301))(500mg/kg）和柠檬酸钠（E(331))(100mg/kg））。在整个生产过程中，特别是在腌制阶段后，计数会减少。添加剂的使用并没有影响计数或微生物群的演变，除了乳杆菌，在添加添加剂的批次中数量更多。在 4 批（2 批无添加剂和 2 批有添加剂）中，从 MRS 琼脂和罗哥萨琼脂板上，从每个批次的每个采样点（表面样品和内部样品各 5 个）和每个培养基中随机取出 10 个菌落；从 MRS 琼脂共分离出 224 株，从罗哥萨琼脂共分离出 176 株，通过经典方法进行鉴定。MRS 琼脂对乳酸菌的分离具有中等选择性，只有 59%的分离株属于该微生物群。同型发酵和兼性异型发酵乳杆菌（特别是弯曲乳杆菌和清酒乳杆菌）是该培养基上分离出的最丰富的物种。罗哥萨琼脂对乳杆菌的选择性极高。在这 4 批拉科恩生产的不同阶段，从罗哥萨琼脂分离出的乳杆菌与从 MRS 琼脂分离出的乳杆菌的种类和比例一致。添加剂的使用对 MRS 琼脂和罗哥萨琼脂上分离出的物种的种类和比例没有明显影响。
