乳品中活性益生菌选择性检测方法的研究

研究了含活性益生菌乳品中嗜热乳链球菌、保加利亚乳杆菌、嗜酸乳杆菌、双歧杆菌和干酪乳杆菌的选择性计数方法。结果表明：ST—琼脂培养基适合嗜热乳链球菌的计数；LC—琼脂培养基适合干酪乳杆菌的计数；MRS—NNLP琼脂培养基适合双歧杆菌的计数；MRS—pH5．2琼脂培养基适合保加利亚乳杆菌的计数；MRS—柳醇琼脂或MRS—山梨醇琼脂可用于嗜酸乳杆菌和干酪乳杆菌的计数；若产品中只含有嗜酸乳杆菌和干酪乳杆菌时，可先测其总数，再用LC—琼脂培养基选择计数干酪乳杆菌数，两者之差即为嗜酸乳杆菌数。

SELECTIVE ENUMERATION METHOD OF PROBIOTIC BACTERIA IN DAIRY FOODS

Among the various media developed for selective enumeration of yogurt and dairy foods,ST agar could be used for selective enumeration of S. thermophilus ,MRS agar(pH5.2) is suitable for L. delbrueckii ssp. bulgaricus , MRS-salicin agar or MRS-sorbitol agar for L.acidophilus, and MRS-NNLP agar could be used for selective enumeration of Bifidobacteria,LC agar could be used for selective enumeration of L. casei. However, MRS-salicin agar or MRS-sorbitol agar could not be used for selective enumeration L.acidophilus and L. casei in products containing both. If L. casei is added, then MRS-salicin agar or MRS-sorbitol agar could be used to obtain a total population of L.acidophilus and L. casei and the population of L. casei could be subtracted from the total populations of L.acidophilus and L. casei enumerated using MRS-salicin agar or MRS-sorbitol agar.