Caracterização microbiológica de matérias primas e validação do binómio: tempo x temperatura de esterilização de preparados alimentares

The contamination of raw materials and food products is an important issue to the food industry that needs to be controlled, in order to reach acceptable food safety standards. Dried fruits, chocolate and cocoa are potentially dangerous raw materials due to eventual contamination with bacteria, fungi and yeasts. Fruits such as raspberries also have a high microbiological load. In order to be able to utilize these ingredients in food preparations, the food industry must apply microbiological inactivation methods, such as heat treatment, to the food preparation. Within the heat treatments used, pasteurization and thermal sterilization are included. Time-temperature binomials vary according to the food preparation and microorganisms that may be present. The thermal sterilization allows the inactivation of spore forming bacteria (being the most dangerous Clostridium botulinum and Bacillus cereus). The aim of this thesis was to quantify the total microbiological and spore load of raw materials from different sources, used by Frulact and optimize time/temperature binomials used in the sterilization of food preparations. Two different food preparations were used, one of chocolate and another of raspberry, to which three different binomials were applied (109ºC/10 minutes, 111°C/10 minutes, 116°C/10 minutes to the chocolate preparation; 104ºC/10 minutes, 106ºC/8 minutes at 109ºC/10 minutes to the raspberry preparation). It was possible to conclude that the binomial used by Frulact for the sterilization of the chocolate preparation (116ºC/10 minutes) is efficient and thus appropriate for the destruction of microorganisms (Clostridium, Bacillus cereus) present in this raw material. On the other side, it was found that the binomial normally applied to the raspberry preparation (104°C/10 min) is not adequate for the sterilization of this product. The results obtained suggest that the 106ºC/8 minutes binomial is effective in this case. It was also determined the microbiological heat resistant load in raw materials or preparations with interest to the company.