Answer added in Food Microbiology and Safety9 Juice spoiling microbesBy Sushil Purbey · National Bureau of Soil Survey and Land Use PlanningAll of the above are great observations. It has been my experience that the juices that spoil are post-processing contaminants. They are being recon... [more]All of the above are great observations. It has been my experience that the juices that spoil are post-processing contaminants. They are being recontaminated from pumps, filling machines, lines, gaskets that are not dismantled complely for cleaning and sanitizing. What is spoiling the product? Yeasts? Lactobacilli? If these are the spoilage agents, then it is most likely the scenario suggested above. Once established what the spoilage organism is that spoils the product, look for it in the places listed above.Following
Article: Microbiological safety of mayonnaise, salad dressings, and sauces produced in the United States: a review.R B Smittle[show abstract] [hide abstract]
ABSTRACT: The literature on the death and survival of foodborne pathogens in commercial mayonnaise, dressing, and sauces was reviewed and statistically analyzed with emphasis on Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes. The absence of reports of foodborne illness associated directly with the consumption of commercially prepared acidic dressings and sauces is evidence of their safety. Salmonella, E. coli O157:H7, E. coli, L. monocytogenes, Staphylococcus aureus, and Yersinia enterocolitica die when inoculated into mayonnaise and dressings. Historically, mayonnaise and dressings have been exempt from the acidified food regulations and have justly deserved this status due primarily to the toxic effect of acetic and to a lesser extent lactic and citric acids. These organic acids are inimical to pathogenic bacteria and are effective natural preservatives with acetic being the most effective in killing pathogenic bacteria at the pH values encountered in these products. Statistical analysis on data reported in the literature shows that the most important and significant factor in destroying pathogenic bacteria is pH as adjusted with acetic acid followed by the concentration of acetic acid in the water phase. The reported highest manufacturing target pH for dressings and sauces is 4.4, which is below the 4.75 pKa of acetic acid and below the reported inhibitory pH of 4.5 for foodborne pathogens in the presence of acetic acid. The overall conclusion is that these products are very safe. They should remain exempt from the acidified food regulations providing adequate research has been done to validate their safety, and the predominant acid is acetic and reasonable manufacturing precautions are taken.Journal of food protection 09/2000; 63(8):1144-53. · 1.94 Impact Factor
Article: Relationship of cellular fatty acid composition to survival of Lactobacillus bulgaricus in liquid nitrogen.[show abstract] [hide abstract]
ABSTRACT: Concentrated cultures of Lactobacillus bulgaricus were prepared by resuspending cells grown in semisynthetic media in sterile 10% non-fat milk solids. The concentrated cultures were frozen in liquid nitrogen for 24 h. The cell suspensions exhibited decreased viability after storage, and the amount of death varied among the different strains tested. Storage stability of all strains examined was improved by supplementing the growth medium with sodium oleate. Radioisotopes were used to study the fate of sodium oleate with L. bulgaricus NCS1. [1-(14)C]sodium oleate was incorporated solely into the lipid portion of the cells, including both neutral and polar lipids. The fatty acid composition of L. bulgaricus NCS1, NCS2, NCS3, and NCS4 grown with and without sodium oleate was studied. The major fatty acids of strains NCS1, NCS2, and NCS3 grown without sodium oleate were dodecanoic, tetradecanoic, hexadecanoic, hexadecenoic, and octadecenoic acids. In addition to these, strain NCS4 contained C(19) cyclopropane fatty acid. The major fatty acids of all strains grown with sodium oleate were tetradecanoic, hexadecanoic, hexadecenoic, octadecenoic, and C(19) cyclopropane fatty acids. All strains grown in broth containing sodium oleate contained larger amounts of octadecenoic and C(19) cyclopropane fatty acid, and less saturated fatty acids than when grown without sodium oleate. Statistical analyses indicated that C(19) cyclopropane fatty acid was most closely related to stability of the lactobacilli in liquid nitrogen. A negative regression line that was significant at P < 0.001 was obtained when the cellular content of this fatty acid was plotted against death.Applied microbiology 05/1974; 27(4):738-43.
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ABSTRACT: Concentrated cell suspensions of Lactobacillus bulgaricus prepared from cells grown in semisynthetic media were frozen in liquid nitrogen. After storage for 24 hr, the cell suspensions were found to have decreased colony counts and acid-producing capacity in milk. The amount of loss varied among the different strains tested. The addition of known cryoprotective agents to cell suspensions of the most labile strain before freezing provided little or no protection to the cells. However, storage stability of all strains investigated was improved by supplementing the growth medium with Tween 80 (polyoxyethylene sorbitan monooleate). The concentration of Tween 80 necessary for maximal storage stability varied among strains.Applied microbiology 11/1972; 24(4):551-4.