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Killing S. thermophilus & L. delbrueckii spp. bulgaricus in yogurt

yogurt yoghurt shelf stable long life hot filling ambient stable culture

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#1 Anna21


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Posted 05 September 2019 - 10:49 AM

Good morning all!


Do any of you have experience in producing shelf-stable yogurt, with a shelf-life of 6 months, by means of hot filling?


The idea is to kill off all bactera and culture organims, namely Streptococcus thermophilus and Lactobacillus delbrueckii spp bulgaricus, in the heating up process, so as to prevent any further activity during the products shelf-life. 


If I understand correctly a filling temeperature of 75 degrees C will kill off most S.thermophilus organisms, however some LActic acid bacteria could survivi these temperatures. The entire mixture is held at 75 degrees for the duration of the filling period. 


If the Lactic Acid bacteria do survive, what effect will they have on the product over such a shelf life, in terms of flavour and texture?


Which temperatures are known to kill Lactic Acid Bacteria?


Are there any preservatives one can add to prevent Lactic Acid Bacteria from recovering and further multiplying in the product? 


I will appreciate all help, thank you :)

#2 pHruit


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Posted 09 September 2019 - 08:23 AM

Not in the dairy industry, but I did note this white paper from Tetra Pak that broadly lists some of the relevant considerations: http://tpcomprod.blo...ent-yoghurt.pdf


As the paper notes, the time/temperature combination will need to be considered in conjunction with product characteristics - their suggestion of 75°C for 20 seconds is provided with a specific note on pH, as this time/temp will not be sufficient to address bacterial spores.

Also tagged with one or more of these keywords: yogurt, yoghurt, shelf stable, long life, hot filling, ambient stable, culture

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