Benefits of superfine grinding method on antioxidant and antifungal characteristic of Brazilian green propolis extract

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.(AU)

Benefits of superfine grinding method on antioxidant and antifungal characteristic of Brazilian green propolis extract

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.

Atmosfera modificada e refrigeração para conservação pós-colheita de camu-camu / Modified atmosphere and refrigeration for postharvest camu-camu

O presente trabalho tem por objetivo avaliar a conservação pós-colheita de camu-camu, utilizando a refrigeração e a atmosfera modificada propiciada pelos filmes de policloreto de vinila (PVC) e polipropileno biaxialmente orientado de 50µm espessura (BOPP50) e assim avaliar a durabilidade em relação ao controle (sem embalagem). Os frutos foram mantidos a 5±1°C e 90±2% de umidade relativa, durante 25 dias e avaliados a cada quatro dias de armazenamento quanto à firmeza, pH, sólidos solúveis, acidez titulável, ácido ascórbico, antocianinas, perda de massa e concentração de CO2 da atmosfera no interior da embalagem. O filme de BOPP50 mostrou não ser a melhor alternativa para a conservação de camu-camu, pois a sua baixa permeabilidade aos gases ocasionou o acúmulo de CO2 no interior da embalagem, propiciando o processo fermentativo dos frutos após 13 dias de armazenamento. Os atributos pH, sólidos solúveis, acidez titulável, ácido ascórbico e antocianinas não foram afetados pelos tipos de filmes utilizados, mas sim pelos dias de armazenamento. Os resultados mostraram que a utilização do filme de PVC, juntamente com refrigeração, para conservação pós-colheita de camu-camu, foi eficaz na manutenção da firmeza do fruto e na redução de perda de massa, mantendo os frutos comercialmente viáveis por 21 dias, enquanto o controle e os revestidos por BOPP50 se apresentaram inviáveis após 13 dias de armazenamento.(AU)

This study aimed to evaluate the postharvest camu-camu by using cooling and modified atmosphere propitiated by the films of polyvinyl chloride (PVC) biaxially oriented polypropylene of 50µm thickness (BOPP50) to evaluate the durability the control (without packaging). The fruits were kept at 5±1°C and 90±2% relative humidity for 25 days and evaluated every four days of storage regarding firmness, pH, soluble solids, titratable acidity, vitamin C, anthocyanins, weight loss and CO2 concentration of the atmosphere inside the package. The BOPP50 film showed not be the best alternative for the conservation of camu-camu, because its low permeability to gases caused the accumulation of CO2 inside the package, allowing the fermentation of fruits after 13 days of refrigerated storage. Characteristics of pH, soluble solids, titrable acidity, vitamin C and anthocyanins were not affected by the types of films used, but through the days of storage. The results showed that the use of PVC film with cooling to postharvest camu-camu, was effective to maintain the firmness and reduction in weight loss by keeping the fruit commercially viable for 21 days, while control coated BOPP50 was unviable with 13 days of storage.(AU)