Study On Chemical And Microbiological Compositions And Identification Of Lactic Acid Bacteria From Home-made Kurut In Qinghai

Chemical and microbiological compositions of 32 samples of home-made kurut in Qinghai were determined. The average contents of dry-matter , fat, protein, lactose, ash, calcium and phosphorus were13.25±0.15g/100mL, 5.46±0.10g/100mL, 5.42±0.11g/100mL, 2.28g/100mL, 0.88±0.03g/100mL, 148.11±3.61mg/100mL and 146.72±1.91mg/100mL respectively. On average, titratableacidity was 164.77°T, lactic acid content was 1.139g/L, acetic acid content was 0.255g/L, citric acid content was 0.382g/L and ethanol content was 3.530g/L. On average, vitamin B1 was 0.6278 ug/g, vitamin B2 was 6.2247ug/g, vitamin B6 was 0.2776ug/g and vitamin C was 1.1647mg/100g. The average contents of K, Mg, Na, Zn and S of 20 freeze-dried samples of kurut were 1378.68mg/kg, 153.84mg/kg, 284.83mg/kg, 5.74mg/kg and 453.82mg/kg respectively.Microbiological compositions of the 32 samples were lactic acid bacteria and yeast. The counts of lactic acid bacteria in 1 sample were 5.55×105cfu/mL, 1 sample was 2.14×106cfu/mL, 5 samples were from 2.45×107cfu/mL to 9.45×107cfu/mL,15 samples were from 1.37×108cfu/mL to 9.25×108cfu/mL, 7 samples were from 1.22×109cfu/mL to 4.5×109cfu/mL and the other three samples were from 1.02×1010cfu/mL to 1.96×1010cfu/mL; the counts of yeast in 2 samples were2.07×105cfu/mL and 4.25×105cfu/mL, 1 sample was 5.65×106cfu/mL, 21 samples were from 1.07×107 to 8.60×107cfu/mL, 7 samples were from 1.55×108cfu/mL to 9.30×108cfu/mL and another sample was 2.00×109cfu/mL.According to their morphological, physiological and biochemical properties, including chemical characteristics, among 46 lactobacillus, 40 lactobacillus were identified to 15 homofermentative species or subspecies of lactobacillus, and 6 lactobacillus were identified to 2 heterofermentative species of lactobacillus. Among the homofermentative lactobacillus, L. acidophilus (8 strains),L. casei subsp. pseudoplantaurm (3 strains),L. delbrueckii subsp. bulgaricus (3 strains);L. debrueckii subsp. delbruckii. (4 strains),L. gasserri (3 strains), L. coryniformis subsp. torquens (2 strains),L.