ROLE OF TEMPERATURE, ACIDIC PH AND LACTIC BACTERIA ON THE STABILITY OF ROTAVIRUS AND CORONAVIRUS IN MILK

Rotavirus and Coronavirus infectivity persists in contaminated milk, s tored at +4-degrees-C for 6 days or -30-degrees-C for 6 months. The vi ruses can also be recovered after 3 or 6 hours at +42-degrees-C and 30 minutes at +53-degrees-C ; Rotaviruses are still detected after paste urisation (15 seconds at +80-degrees-C). In acid medium (pH 3,8 or pH 4,4) Rotavirus persists for 6 days at +4-degrees-C and +20-degrees-C, and 3 to 6 hours at +42-degrees-C. However, Coronavirus is more sensit ive to those pH values, its infectivity is still detected after 6 days at +4-degrees-C, but disappears after 24 hours at +20-degrees-C and 2 hours at +42-degrees-C. Otherwise, lactic bacterias effect on both vi ruses is only due to medium acidification and depends on pH values. Ro tavirus stability to physicochemical processing, found in milk technol ogy, is suggestive of a possible viral transmission to man through mil k and dairy products (pasteurised or not), stored at less-than-or-equa l-to +20-degrees-C. Coronavirus contamined milk can remain infectious when stored several days at room temperature, on the contrary fermente d products allow viral persistence to occur only if they are stored at +4-degrees-C.