Conservação de queijo ralado através da aplicação de ozônio durante a etapa de desidratação

Abstract

Most of the grated cheeses found on the market are dry, salty, acidic, with little taste and low in fat. These factors that impair the sensory quality of the product on the other hand help to inhibit the development of molds and yeasts over the shelf life. Another factor that inhibits the growth of molds and yeasts is the conservative sorbic acid, however, according to the count of molds and yeasts present in grated cheese and product water activity the preservative may not be effective enough to maintain the quality standards shelf life. The action of ozone on molds and yeasts is quite effective as they are easily achieved in a shorter period of time than bacteria, so using ozone in food processing may be an alternative for industries. The objective of this work was to develop a process using ozone for the conservation of grated Grana-type cheese and grated Parmesan cheese, seeking to reduce the addition of the chemical preservative in the product. This work was carried out on an industrial scale and was divided into three stages. In the first stage, the sorbic acid concentration was evaluated for the conservation of the grated cheeses. In the second stage the ozone action on the conservation of the grated cheeses was evaluated. third and last stage the conservation of grated cheeses with the use of ozone and sorbic acid was carried out and affective and descriptive sensorial tests were also carried out. In the first stage the conservative sorbic acid was added in the concentrations 0, 0.05, 0.1, 0.15 and 0.20%, but the microbiological stability of the grated cheeses was reached at a mean final moisture of 19% only with the addition of the conservative sorbic acid in concentration above of the limit allowed by the legislation. Ozone was applied to the grated cheeses during 10 minutes of heating at the concentrations 0, 9, 23, 31, 38 mg ozone / kg dehydrated grated cheese and during the 3 minutes of cooling at concentrations 0, 3, 7, 9 and 11 mg of ozone / kg of grated cheese dehydrated both in the process of dehydration. It was determined that the concentration of 9 mg ozone / kg dehydrated grated cheese showed the best results with a reduction of molds and yeasts of 98% and in a shorter time. Grated cheese was produced with the combination of the preservative sorbic acid and ozone to evaluate t he possibility of producing grated cheeses at 19% moisture with microbiological stability over the shelf life. To evaluate the effects of ozone on the experiments, the products were submitted to analysis of fatty acid composition, oxidative rancidity and also the sensorial analysis with affective and descriptive tests. When analyzing the composition of fatty acids and sensorial analysis, significant differences were found between the standard samples and the samples treated with ozone, although these differences were small. It was found that the action of ozone on grated cheeses caused minimal damages to the product, both chemical and sensorial.