The Case Of Psychrotrohic Bacteria
By Leon Van Der Westhuizen Psychrotrophic bacteria seem to be becoming the newest thorn inthe side of the dairy industry. Scary bit is that we are helpingthem along. “How?” do you ask? Because of economic factors the pre-processing time of raw milkhas been extended to an average of 4 days. This allows ampletime for psychrotrophic, proteolytic bacteria to grow, and formheat stable enzymes. Although the psychrotrophic bacteria areeasily killed off by normal pasteurization temperatures, theformed enzymes can survive UHT processes. This causes multiple problems and we here at Elsenburg Dairy Labhave especially seen those problems on products like cottagecheese and UHT milk, more so over the past few years. This is agroup of bacteria that actually loves the cold chain, as ithelps them outwit, outlast and outperform their competition.Nowadays psychotropic bacteria predominate in raw milk in thecold chain, especially Pseudomonas spp. So much so that when the same milk is plated out and incubatedat 7 C and at 30 C(as in Total Plate Count), the psychotropicgrowth will overtake the mesophilic growth, causingpsychrotrophic counts to be higher than total plate counts. I don’t think the methods of analysis are of much importance inthis article, because there are many, ranging frommicrobial(determining the bacteria) and biochemical(determiningthe formed enzyme). Qualitative tests are of no use as we wantto be able to enumerate the psychrotrophic bacteria. The main concern I have is to raise awareness of a fast growingproblem, that will only become more so in the future. Possible solutions are the following: 1) Ask your lab to do a monthly psychrotrophic count on allfarmers. This will identify your high risk milk supply. 2) Thermising the milk to 68 C before cooling on the farm. Thiswould have to be done with a plate heat exchanger, but would beeconomical at this stage, because the milk is already at bodytemperature(37 C) and the treated milk can run against theincoming milk to heat it and to be cooled down itself. An icebank would also be needed to finish the cooling process. Thethermising process would obviously increase the overall qualityof the milk as well, without influencing heat stability to alarge degree. 3) Very rapid cooling on the farm to 2 C, instead of the usual4 C and keeping it there until processing. 4) Using a pre-cooler at the factory to cool the milk downquickly from the 5-7 C that it arrives at, to 2 C. About the author: Leon the Milkman is the owner of http://www.LeontheMilkman.com and http://www.dairy-info.org from where he gives a dairy dictionary and cheese tasting terms guide to new members. Article Source: http://EzineArticles.com/?expert=Leon_Van_Der_Westhuizen http://EzineArticles.com/?The-Case-Of-Psychrotrohic-Bacteria&id=236486 bad credit no employment required cash loan bad credit corporate checking what does a credit score of 655 mean debt consolidation california
