RESUMO
In this study, maqui berries were subjected to vacuum drying at 40-80 °C to assess and compare the effect on proximate composition, dietary fiber, phenolic and flavonoid compounds, antioxidant capacity and sugar content. The Weibull model was used for describing the vacuum drying process. The results indicated that the highest retention of total phenolic content (TPC) and total flavonoid content (TFC) was obtained after drying at 80 °C. Six phenolic compounds were identified and quantified by liquid chromatography. These were gallic acid, protocatechuic acid, ellagic acid, ferulic acid, myricetin and quercetin. In general, every phenolic compound showed a higher retention at temperatures above 60 °C. The antioxidant capacity of dried samples (ORAC assay) showed significant differences compared to the fresh fruit. Fructose and glucose were the two sugars present in the fruit. These results show that vacuum drying of maqui berries at 80 °C is an appropriate temperature for maintaining TPC, TFC, anthocyanins, sugars and dietary fiber with a shorter drying time compared to the other temperatures.
RESUMO
In an attempt to obtain shelf-stable litchi fruit with preserved nutritional quality and good sensory features, quarters of peeled and pitted fruits were vacuum dried at 50, 60 and 70 °C at a constant pressure of 8.0 kPa. The product was assessed for its vitamin C, total phenolics and texture (hardness). In addition, the product with the best texture was assessed for its shelf-life by means of accelerated testing. Results suggest that vacuum dried litchi retained almost 70% of the vitamin C and total phenolics when compared to frozen fruits (control). Vitamin C and phenolic compounds content significantly decreased with drying, while no difference was found between different drying temperatures. Hardness increased with drying temperature. The sample dried at 70 °C presented crispness, which is a desired quality feature in dried fruit products. This sample was subjected to shelf-life evaluation, whose result suggests a shelf-life of eight months at 23 °C. Total color change (CIE ΔE00) was the expiry criterion. Vacuum drying was a suitable technique for producing shelf-stable litchi fruit with good texture while preserving its desirable original nutrients. Consumption of vacuum dried litchi may be beneficial to health due to its remarkable content of phenolic compounds and vitamin C.
Assuntos
Ácido Ascórbico/análise , Manipulação de Alimentos/métodos , Conservação de Alimentos/métodos , Litchi/química , Fenóis/análise , Dessecação , Frutas/química , Valor Nutritivo , Pressão , Temperatura , VácuoRESUMO
The purpose of this study was to investigate the effect of temperature in the vacuum drying process of Mentha piperita L. (50 to 90 °C). Generally, drying processes affect the quality of product, however, vacuum drying works under sub-atmospheric pressures. In order to investigate how temperature affects this herb, as to color, chlorophyll, total phenolic (TPC), total flavonoid (TFC) contents, antioxidant activity by DPPH and ORAC methods. Mineral, vitamin C and sugar contents were also evaluated. A slight change in color and chlorophyll content was observed in the samples. The highest values for TPC, TFC and antioxidant activity methods were obtained at 50 and 70 °C however, a decrease in the vitamin C content was observed. Minerals such as K, Ca, Mg and Na were found. Sucrose showed the highest sugar content. This work suggests that M. piperita L. can be used as a natural antioxidant, whether fresh or dried.