Avaliação da atividade antimicrobiana e antioxidante de extratos de caqui (Diospyros kaky l.) para proteção de produtos cárneos

Abstract

Microbial and oxidative changes occurring in meat and meat products cause loss of quality and consequent commercial devaluation. The consumption of meat products has caused concern among consumers by the presence of chemical preservatives, which are often questioned because of the risk of harmful side effects to health. In an attempt to control microbial and oxidative changes, researches have been performed with the purpose of isolating natural phytochemicals obtained from various plant substrates, which besides having the preference of the consumers, also have the ability to act helping in the prevention of diseases. Antioxidant and antimicrobial activities have been attributed to the phenolic compounds; persimmon (Diospyros kaky L.) was used in this study since it is rich in polyphenols. Initially, we compared the antioxidant activity of hydroethanolic extracts of Diospyros kaki, L. of the cultivars Quioto and Rama Forte in chicken meat. The effect of these cultivars on the color and sensory characteristics of the samples was also verified. The crude hydroethanolic extract of persimmon cv. Rama Forte was used in subsequent tests since it showed a higher content of phenolic compounds, higher antioxidant activity, and it did not affect the sensory characteristics of chicken meat. The hydroethanolic extract of persimmon cv. Rama Forte was fractionated using solvents with different polarities (n-hexane, chloroform, and ethyl acetate) and subjected along with the hexane, chloroform, and ethyl acetate fractions and the residual fraction to the determination of total phenolic compounds as well as antimicrobial and antioxidant activity in vitro. The antioxidant activity in beef was verified and compared with the activity of the oily extract of rosemary (Chr. Hansen ®). The extract and/or the most efficient fractions were evaluated for antioxidant and antimicrobial activity as well as for the influence on the sensory characteristics and color of meat products (beef burgers and salami). Based on the results obtained, the crude hydroethanolic extract of persimmon cv. Rama Forte and the residual and ethyl acetate fractions showed antioxidant activity in beef during the storage period, however, no antimicrobial activity was observed. In the salami samples, the crude hydroethanolic extract of persimmon cv. Rama Forte also showed antioxidant activity and did not alter the sensory characteristics or microbial counts performed after the manufacturing period of the salami. In the frozen beef burgers, crude hydroethanolic extract of persimmon cv. Rama Forte and residual and ethyl acetate fractions, when used in the concentrations of 0.5 and 0.7%, did not show antioxidant potential or antimicrobial characteristics. Moreover, they did not interfere in the sensory samples. However, the ethyl acetate fraction (0.5 and 0.7%) contributed to the retention and stability of the red color of the samples of beef burgers during the storage of the frozen product. Thus, based on the results obtained, it seems appropriate to assume that the crude hydroethanolic extract of persimmon cv. Rama Forte as well as residual and ethyl acetate fractions have antioxidant potential. Further studies should be performed mainly in relation to the antioxidant activity in frozen meat products.