ABSTRACT: Green propolis is found only in Brazil and due to its important biological characteristics, the food industry views it as a rich source of bioactive compounds. However, an extract must be produced for its application, which is difficult considering the rigid characteristics of raw propolis. Superfine grinding, a process capable of reducing particle size, enables the extraction of most bioactive compounds in propolis. This study evaluated the influence of grinding on size characteristics, antioxidant and antifungal properties of Brazilian green propolis for food preservation. The propolis powder was produced through six different types of grinding (different sieves and rpm), and its quality was evaluated by scanning electron microscopy-energy dispersive X-ray spectroscopy. After grinding, extracts and bioactive assays were produced and the total phenolic content, antioxidant and antifungal capacity were determined. The data showed that the grinding process affected all the results of bioactive assays used. Treatment B (sieve 0.08 mm, 12,000 rpm) presented statistically significant values for the bioactivity assays and thus antifungal activity against Rhizopus stolonifer (doses 0-5 %) was tested only for the control (standardized size without superfine grinding) and treatment B. Both treatments showed antifungal activity, but the control provided more effective mycelial growth inhibition (lower dose 1 %). Superfine grinding increased the antioxidant activity, although this behavior was not observed in the antifungal assay. Despite these results, green propolis extracts present important biological effects that indicate their use as food preservatives to extend shelf life of food products.

Abstract Coffee is one of the most consumed beverages in the world. Its chemical composition may have varied according to the planting site, degree of roasting, and method of preparation. This work aimed to evaluate the antioxidant activity of coffee from the region of Cerrado in the State of Minas Gerais, Brazil. The evaluation was performed with samples roasted at two different levels (traditional and extra dark) and using two different preparation methods (decoction and infusion) that reflect the conditions of preparing coffee. In vitro antioxidant activity by ABTS and DPPH radical methods and the concentration of total phenolic compounds and caffeine were determined. Samples made by decoction showed a higher content of phenolic compounds and no significant difference was observed between the degrees of roasting. However, the antioxidant activity and caffeine concentration of the extra dark samples were higher than those of the traditional samples for both preparation methods. The decoction preparation method was better for extracting phenolic compounds and the extra dark roast showed a higher concentration of caffeine and antioxidant activity. The samples showed a high antioxidant activity, indicating the coffee from Cerrado is an important source of antioxidants.

Over the last decade a considerable increase in the number of studies addressing the use of antioxidants from natural sources has led to the identification and understanding of the potential mechanisms of biologically active components. This results from the fact that they can be used to replace synthetic antioxidants commonly used in food. Murtilla (Ugni molinae Turcz) is a native berry grown in Chile, and in the present study, the phenolic composition and antioxidant activity of its fruits were studied. Hydroalcoholic extracts of dehydrated fruits from two genotypes of murtilla (Ugni molinae Turcz.) were produced. Extracts of wild murtilla and 14-4 genotype fruits had 19.35 and 40.28mg GAE/g for Total Phenolic Compounds, 76.48, and 134.35μmol TEAC/g for DPPH, and 157.04 and 293.99 μmol TEAC/g for ABTS, respectively. Components such as quercetin, epicatechin, and gallic, benzoic and hydrocaffeic acids were identified by CG/MS analysis. All of them showed antioxidant activity. Therefore, it is possible to say that the hydroalcoholic extracts of murtilla have antioxidant potential to be used in lipidic food.