Lethality of various F0 values on spores of putrefactive anaerobe 3679 and thermophils in chocolate milk drink

Some small processors of "sterilized" chocolate milk drink in crown capped soft drink bottles are experiencing difficulties with spoilage of this product. Most processors are using a process time of 18-20 minutes at 240° F. The spoilage is thought to be due to under processing, inadequate equipment, contaminated ingredients, questionable sanitary practices, slow cooling, holding and filling at ambient temperatures, and high storage temperatures. Although “sterilized" chocolate milk drink has been processed for over 40 years, very little research is published concerning the product. This was thought to be due in part, to the fact that production of the product is rather low. With modern day refrigeration, "sterilized" chocolate milk drink seems to have been overshadowed by its counterpart, pasteurized chocolate milk drink. However, there is still some demand for the bottled product in certain localities. Clostridium botulinum has a heat resistance at 250° F of 2.8 minutes for 10,000 spores per ml. in neutral phosphate buffer solution. If heating is adequate to kill the spores of Putrefactive Anaerobe No. 3679, the process insures the destruction also, of Clostridium botulinum (15). All foods capable of sustaining the growth of this organism must be processed on the assumption that the organism is present and must be destroyed. From a public health standpoint, foods with pH values greater than 4.5 must be processed such that the sterilization value is equal to that of 2.8 minutes at 250° F. However, other organisms with greater heat resistance must be destroyed if the food is kept above ordinary storage temperatures (more than 100° F.). In certain localities storage temperatures would be much higher than 100° F., especially during summer months, therefore, underprocessed foods could spoil at these elevated storage temperatures. The purpose of this experiment was to determine the effect of various inoculated spore populations, processed at various times and incubated at 110 and 130° F. upon chocolate milk drink. It was felt that experimental data of this nature might be of value to processors, public health officials, and all parties concerned in alleviating the causes of spoilage of this product.