Efeito do aquecimento ôhmico nas características físico-químicas, microbiológicas e sensoriais do soro de leite

Abstract

The ohmic heating (OH) consists of the passage of electric current in the food, promoting its heating due to the conversion of electric energy into thermal. The amount of heat generated is proportional to the induced electric current. Due to the rapid heating rate, the ohmic process presents some advantages over conventional processes (pasteurization and sterilization), such as: the maintenance of nutritional compounds and the reduction of fouling, important factors in the processing of dairy products. In addition, another advantage of OH is the presence of an additional non-thermal effect on the microbial cells causing electroporation (pore formation in the cell membrane), thus promoting a reduction in the thermal resistance of the microorganisms. This important phenomenon allows the reduction of the thermal intensity of the process, guaranteeing the same microbiological lethality and, consequently, lower nutritional degradation. Due to the presence of several thermosensitive compounds and the formation of undesirable products caused by the action of heat, the ohmic processing presents as a promising technology in the production of foods, especially in dairy products. Thus, the objective of this work was to evaluate the effect of the ohmic processing on the physical-chemical, microbiological and sensorial characteristics of the product, in order to characterize and compare the whey treated by conventional and ohmic processing. In Chapter I of this work a literature review was carried out aiming at evaluating the sensorial and technological aspects of the use of the thermal heating of dairy products. In Chapter II the physical-chemical, rheological and sensorial properties of pasteurized whey were analyzed by means of ohmic heating. It can be concluded that the effects of OH on whey are dependent on the intensity of the voltage applied in the treatment. Low electrical fields provided greater color variation, while providing better preservation of the bioactive compounds of antioxidant and antihypertensive capacity. Its physical and sensorial characteristics, however, remained similar to whey pasteurized by the conventional method. These results suggest that the ohmic heating technology is an interesting alternative for the processing of whey.