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# How to calculate spoilage rate in canning

 Author Message    Topic Search   Topic Options scotty Guest Group Post Options    Thanks(0)    Quote  Reply Topic: How to calculate spoilage rate in canning    Posted: 22 Mar 2010 at 10:56pm Good to see the Fo calculator. Tnks! How do you work out how many canns should fail micro test. Pet food for cats. Tnks Scot Sponsored Links michael Guest Group Post Options    Thanks(0)    Quote  Reply Posted: 22 Mar 2010 at 10:56pm Scotty It is fairly easy to calculate the number of surviving micro-organisms in a canning process. I say fairly easy since a knowledge of both the effects of heat on microorganisms and maths, probability and logarithms in particular, is required! The critical equation has been described by Stumbo* in his well known book on 'Thermobacteriology in food processing':- t = D(log a - log b) D= decimal reduction time (minutes) at a reference temperature for target organism-time to reduce the population by 90% t= total equivalent time in minutes at reference temperature a= initial microbial load b= number of surviving micro-organisms. Using this equation one can predict the probability of one or more cans spoiling, this can be adjusted for 100, 1000, or whatever number you want. I have developed a simple model which shows how to do this and enables D and other values to be varied. The URL is at www.dairyscience.info/newCalculators/probability.aspYou dont say what your problem is. If the spoilage rate is in excess of the predicted one then you have a problem. This might be caused by ingress of contaminated cooling water, check residual chlorine levels; defective seams; inadequate processing; high spore loads. *Stumbo, C. R. (1973) Thermobacteriology in food processing. Second edition. Academic Press, New York and London.