Lactic Acid Production in Milk Containing Cleaning or Sanitizing Compounds

1984 ◽  
Vol 47 (3) ◽  
pp. 197-199 ◽  
Author(s):  
MICHAEL B. LIEWEN ◽  
ELMER H. MARTH
Keyword(s):  
Lactic Acid ◽  
Ammonium Chloride ◽  
Acid Production ◽  
Lactic Acid Production ◽  
Streptococcus Thermophilus ◽  
Lactobacillus Bulgaricus ◽  
Titratable Acid ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Dry Milk

Sterile reconstituted nonfat dry milk containing 0.1% (v/v) each of 19 cleaning or sanitizing compounds intended for use on dairy farms or in milk factories was inoculated with Streptococcus lactis 4175, Streptococcus cremoris C-13, Streptococcus thermophilus ST4 or Lactobacillus bulgaricus. Milk then was incubated at 32°C for 12 h and pH and titratable acid were determined. Five products (alkaline inflation cleaner, hypochlorite sanitizer-farm use, isopropanol udder wash, ammonium chloride detergent-factory use, alkaline cleaner A-factory use) were inhibitory to at least three of the four lactic acid bacteria at the 0.1% concentration. These were then tested at 0.050, 0.025, 0.012 and 0.006% concentrations. Of the five products, only the isopropanol udder wash (at all four concentrations) inhibited S. lactis and S. cremoris. The isopropanol udder wash at all four concentrations and the ammonium chloride cleaner at 0.050% inhibited L. bulgaricus. S. thermophilus was inhibited by the isopropanol udder wash at 0.050%, whereas the alkaline cleaner A-factory use, at 0.050 and 0.025%, may have been mildly stimulatory to acid production by this bacterium.

EFFECT OF MALATHION AND TRICHLORFON ON GROWTH1 AND MORPHOLOGY OF LACTIC CULTURE ORGANISMS

1971 ◽  
Vol 34 (1) ◽  
pp. 16-22 ◽  
Author(s):  
D. D. Deane ◽  
M. M. Van Patten
Keyword(s):  
Lactic Acid ◽  
Cell Size ◽  
Acid Production ◽  
Cell Structure ◽  
Lactic Acid Production ◽  
Lactobacillus Bulgaricus ◽  
Chain Formation ◽  
Streptococcus Lactis ◽  
Litmus Milk ◽  
Dry Milk

Addition of 100 ppm of malathion or trichlorfon had little effect on lactic acid production in reconstituted non-fat dry milk by Streptococus diacetilactis or Streptococus thermophilus. Variation in cell size of Streptococus cremoris 3, Streptococcus lactis W 8 and several strains of S. thermophilus occurred following repeated transfers in litmus milk to which 100 ppm of malathion or 500 ppm trichlorfon had been added. The Lactobacillus bulgaricus A culture, after 15 serial transfers in litmus milk containing 500 ppm of trichlorfon, exhibited increased frequency of chain formation and cell structure 30 to 50 μ long with few visible cross walls. A similar effect was observed with L. bulgaricus A and L. bulgaricus GA after repeated transfers in litmus milk which contained 100 ppm malathion. One of five strains of L. casei studied showed similar changes in morphology after repeated transfers in litmus milk which contained 100 ppm malathion. Adding 500 ppm trichlorfon produced a lesser effect. Changes in morphology of this strain of L. casei were not permanent since cells resumed their usual appearance following three to five transfers in plain litmus milk.

Lactic Acid Production by Streptococcus lactis and Streptococcus cremoris in Milk Precultured with Psychrotrophic Bacteria

1977 ◽  
Vol 40 (6) ◽  
pp. 406-410 ◽  
Author(s):  
M. A. COUSIN ◽  
E. H. MARTH
Keyword(s):  
Lactic Acid ◽  
Acid Production ◽  
Lactic Acid Production ◽  
Raw Milk ◽  
Psychrotrophic Bacteria ◽  
Titratable Acid ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Control Milk ◽  
Cell Free Filtrate

Psychrotrophic organisms isolated from raw milk were inoculated into fresh raw milk and incubated at 7 C for 5 days. Half of each sample was autoclaved, the other half, pasteurized. Streptococcus lactis and Streptococcus cremoris were individually inoculated into the milks and incubated at 21 C for 20 h. Acid production was measured at 2-h intervals. Lactic acid production was greater in milks precultured with added psychrotrophs or the normal flora than in pasteurized control milks. In most instances, pasteurized precultured milks had more acid than did autoclaved precultured milk. More titratable acid was produced in autoclaved rather than pasteurized control milks. Milks with the psychrotroph and lactic streptococci added simultaneously had more titratable acid than did control milk. When cell-free filtrates of psychrotrophic cultures were used instead of cells of psychrotrophs, results resembled those obtained with the bacteria. Simultaneous inoculation of milk with lactic acid bacteria and cell-free filtrate gave results comparable to those from milks precultured for 5 days with the cell-free filtrate.

BEHAVIOR OF SALMONELLA TYPHIMURIUM IN SKIMMILK DURING FERMENTATION BY LACTIC ACID BACTERIA1

1972 ◽  
Vol 35 (8) ◽  
pp. 482-488 ◽  
Author(s):  
H. S. Park ◽  
E. H. Marth
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Salmonella Typhimurium ◽  
Streptococcus Thermophilus ◽  
Mixed Cultures ◽  
Lactobacillus Bulgaricus ◽  
Complete Inactivation ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Incubation Temperatures

Skimmilk was inoculated with Salmonella typltimurium (approximately 103/ml) and with Streptococcus cremoris, Streptococcus lactis, mixtures of S. cremoris and S. lactis, Streptococcus diacetilactis, Streptococcus thermophilus, Lactobacillus bulgaricus, mixtures of S. thermophilus and L. bulgaricus, a mixture of L. helveticus and S. thermophilus, and Leuconostoc citrovorum. Inocula of lactic acid bacteria ranged from 0.25 to 5.0% and incubation temperatures from 21 to 42 C. Streptococcus cremoris, S. lactis, and mixtures of the two repressed growth but did not inactivate S. typhimurium during 18 hr of incubation at 21 or 30 C when the lactic inoculum was 0.25%. An increase in inoculum to 1% resulted in inactivation of S. typhimurium at 30 C by some of the mixed cultures. Both S. diacetilactis and L. citrovorum were less inhibitory to S. typhimurium than were S. cremoris or S. lactis. When added at the 1% level, Streptococcus thermophilus was more detrimental to S. typhimurium at 42 C than was L. bulgaricus. Mixtures of these two lactic acid bacteria, when added at levels of 1.0 and 5.0%, caused virtually complete inactivation of S. typhimurium during the interval between 8 and 18 hr of incubation at 42 C.

Preservation of Lactic Acid Bacteria on Anhydrous Silica Gel for Three Years

1983 ◽  
Vol 46 (8) ◽  
pp. 699-701 ◽  
Author(s):  
MARIA C. T. DE SILVA ◽  
MARIA A. TESSI ◽  
MARIA A. MOGUILEVSKY
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Silica Gel ◽  
Streptococcus Thermophilus ◽  
Lactobacillus Helveticus ◽  
Lactobacillus Bulgaricus ◽  
Preservation Methods ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Negative Effect

This study, which covers three years of storage. analyzes the application of silica gel preservation methods to lactic acid bacteria widely used in yogurt and cheese fermentation. Strains of Streptococcus lactis, Streptococcus lactis subsp. diacetylactis, Streptococcus cremoris, Streptococcus thermophilus. Lactobacillus bulgaricus, Lactobacillus helveticus and a yogurt culture were adsorbed on anhydrous silica gel in screw-cap tubes or in ordinary test tubes which were subsequently flame-sealed under vacuum. During 3 years. the bacteria were tested for viability by incubation in sterile milk. All of the bacteria retained their acidifying activity, with the exception of the yogurt culture. Extending preservation for more than 2 years had a negative effect on the activity of the yogurt culture. Results obtained support the use of screw-cap tubes which, in general, were suitable to preserve suspensions of lactic acid bacteria adsorbed on anhydrous silica gel.

Lactic Acid Production by Streptococcus thermophilus and Lactobacillus bulgaricus in Milk Precultured with Psychrotrophic Bacteria

1977 ◽  
Vol 40 (7) ◽  
pp. 475-479 ◽  
Author(s):  
M. A. COUSIN ◽  
E. B. MARTH
Keyword(s):  
Lactic Acid ◽  
Acid Production ◽  
Lactic Acid Production ◽  
Titratable Acidity ◽  
Streptococcus Thermophilus ◽  
Raw Milk ◽  
Starter Cultures ◽  
Lactobacillus Bulgaricus ◽  
Psychrotrophic Bacteria ◽  
Cell Free Filtrate

Raw milk was incubated at 7 C for 5 days after it was inoculated with psychrotophic bacteria previously isolated from other raw milks. Then a portion of each sample of milk was pasteurized; the remainder was autoclaved. Streptococcus thermophilus and Lactobacillus bulgaricus were individually inoculated into all pasteurized and autoclaved milks which were then incubated at 37 C and titratable acidity was measured at 2-h intervals. Pasteurized milks precultured with psychrotrophic bacteria supported more acid production than did pasteurized control milks. S. thermophilus and especially L. bulgaricus produced more acid in autoclaved than in pasteurized milks. Cell-free filtrates from cultures of psychrotrophic bacteria were added to raw, pasteurized, and autoclaved milks before they were inoculated with the lactic acid bacteria. Results were similar to those obtained when psychrotrophic bacteria were added to milk. When the cell-free filtrate was added to milks simultaneously with starter cultures, less than 10 h were required to produce conditions in milk favorable for enhanced lactic acid production.

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