| 摘要 |
In the production of a stabilized, mixed bacterial concentrate, three types of bacteria are separately incubated in separate culture media viz. (1) Streptococcus lactis, S. cremoris, Lactobacillus bulgaricus and/or Streptococcus thermophilus; (2) Streptococcus citrovorus and/or S. paracitrovorus; and (3) Streptococcus diacetylactis, the respective media are concentrated, as by centrifuging, to obtain separate concentrates of the three bacteria, the three concentrates are mixed together in predetermined proportions to produce a mixed concentrate without permitting further growth of the bacteria, and the mixed concentrate is frozen. The concentrate contains at least 10 x 109 cells per ml, and includes 2-25% by weight of glycerol (stabilizing agent), and nutrient medium. Use of 20% or more of glycerol provides a concentrate which remains liquid below 32 DEG F. and is especially suited for making yoghurt. The culture medium for the above-designated type (1) bacteria is neutralized during the culturing to maintain the pH between 5.2 and 6.6. It is stated to be usually unnecessary to neutralize during the culturing of type (2) bacteria, except when corn steep liquor is used as the culture medium. Where cottage cheese or hard cheeses are to be made, 98% by weight of the total bacteria in the concentrate should be of type (1) and 2% of type (2). For making buttermilk, 1-4% by weight of the total bacteria should be type (3), 8% of type (2) and the balance of type (1).ALSO:In the production of a stabilized, mixed bacterial concentrate, three types of bacteria are separately incubated in separate culture media viz. (1) Streptococcus lactis, S. cremoris, Lactobacillus bulgaricus and/or Streptococcus thermophilus; (2) Streptococcus citrovorus and/or S. paracitrovorus; and (3) Streptococcus diacetylactis, the respective media are concentrated, as by centrifuging, to obtain separate concentrates of the three bacteria, the three concentrates are mixed together in predetermined proportions to produce a mixed concentrate without permitting further growth of the bacteria, and the mixed concentrate is frozen. The concentrate contains at least 10 x 109 cells per ml, and includes 2-25% by weight of glycerol (stabilizing agent), and nutrient medium. Use of 20% or more of glycerol provides a concentrate which remains liquid below 32 DEG F. and is especially suited for making yoghurt. The culture medium for the above-designated type (1) bacteria is neutralized during the culturing to maintain the pH between 5.2 and 6.6 It is stated to be usually unnecessary to neutralize during the culturing of type (2) bacteria, except when corn steep liquor is used as the culture medium. Where cottage cheese or hard cheeses are to be made, 98% by weight of the total bacteria in the concentrate should be of type (1) and 2% of type (2). For making buttermilk, 1-4% by weight of the total bacteria should be type (3), 8% of type (2) and the balance of type (1).
|
