Avaliação da atividade antioxidante e antimicrobiana de produtos naturais e associação com conservantes químicos de alimentos

Abstract

The lipid oxidation and contamination by microorganisms are the main factors that cause great losses in food industries, leading to reduced useful life of products, sensory alterations and destruction of essential components, thereby causing a decrease in the nutritional value and safety. To fight this, industries use chemical additives that tend to prevent or retard such effects. However, there is a great demand from consumers who tend to avoid products containing in its composition synthetic origin additives, aware of the possible effects such as the formation of carcinogenic, mutagenic and teratogenic compounds. In this context, industries seek alternative means that may have results equal or superior to synthetic additives and show no adverse health effects. Hence, we highlight the use of natural additives, as they offer major advantages over their artificial counterparts due to their non-toxic nature along with a wide range of health benefits. Therefore, this study aims to evaluate the antioxidant and antimicrobial activity of extracts of pomegranate peel, surinam cherry leaf and commercial essential oils of lemongrass, anise (erva doce), water mint, field mint and chilli pepper and verify their antimicrobial activity when associated with sodium benzoate and sodium metabisulphite chemical preservatives. The antimicrobial activity of the essential oils, extracts and chemical preservatives has been determined by the Minimum Inhibitory Concentration Test (CIM) with the dilution plate technique with 96 holes to the strains of the Salmonella typhi (ATCC 06539), Escherichia coli (ATCC 10536), Staphylococcus aureus (ATCC 14458) and Bacillus cereus (ATCC 11778) bacteria. And the technique of "checkerboard" has been used for the association test. For the evaluation of antioxidant activity the DPPH method has been used. The best results found by the CIM were the pomegranate peel extract with concentration of 0.625 mg/mL to the B. cereus and S. aureus bacteria; the pomegranate peel extract to Salmonella typhi; and the surinam cherry leaves extract to the Staphylococcus aureus bacteria. Both with results equal to 1.25 mg/ml. When combined with chemical preservatives, there was synergistic combinations containing pomegranate peel extract with sodium benzoate to Salmonella typhi; and with sodium metabisulphite to Salmonella typhi and Staphylococcus aureus bacteria. For the antioxidant activity, the results showed that pomegranate peel extracts and sirinam leaves possess higher antioxidant activity when compared to the oils under study with 50% Inhibitory Concentration (IC50) equal to 0.18 and 0.34 mg/ml, respectively. Thus, it has been concluded that many of the test plants have good results as a favorable alternative for application in foods as a substitute for synthetic additives.