Effect of concentration and temperature on the thermal conductivity of frozen acerola pulp

A finalidade deste trabalho foi a determinação experimental da condutividade térmica da polpa de acerola nas concentrações de 5.5, 7.5, 9.5, 11.5 e 13.5 °Brix e nas temperaturas de 0, –5, –10, –15, –20, –25 e –30 °C. A metodologia utilizada foi a da sonda linear de aquecimento e os resultados experimentais obtidos foram comparados com valores estimados pelos modelos teóricos em série, paralelo e Maxwell-Eucken, avaliando o erro envolvido. Observou-se uma influência tanto da concentração quanto da temperatura na condutividade térmica da polpa. Houve aumento da condutividade com a redução da temperatura e da concentração de sólidos, observando-se os maiores aumentos na faixa de 0 a –10 °C. Equações polinomiais e lineares foram ajustadas para a determinação direta da condutividade térmica da polpa de acerola na faixa de temperatura e concentração estudada.The purpose of this work was the experimental determination of the thermal conductivity of acerola pulp at concentrations of 5.5, 7.5, 9.5, 11.5 and 13.5 °Brix and temperatures of 0, –5, –10, –15, –20, –25 and –30 °C. The methodology used involved a hot wire probe, and the experimental results were compared with values estimated by several theoretical models (series, parallel and Maxwell-Eucken models) to evaluate the error involved. We observed an influence both of the concentration and the temperature on the thermal conductivity of the pulp. An increase of the conductivity with a decrease in temperature and in the solids concentration was detected. We observed the greatest increases in the range of 0 to –10 °C. Linear and polynomial equations were adjusted for the direct determination of the thermal conductivity of the pulp in the range of temperature and concentration studied

Physical-chemical and biochemical characterization of Buchenavia tomentosa Eichler fruits

Abstract The wild native species of the Brazilian savannah have attractive flavors and nutritive compounds. Among the Combretaceaes genus, the Buchenavia tomentosa Eichler plays an important role in popular medicine, however, little is known about its chemical composition. Thus, in order to a chemical-biological prospection in fruits of the Tocantins savannah, the aim of this work was to characterize the B. tomentosa fruits collected in the central and southern regions of Tocantins State, about some of its physical, physical-chemical and biochemical properties. The fruits, for this study, were collected in two regions (Palmas and Gurupi) in Tocantins State and analyzed in the parameters: coloration, centesimal composition, pectin, soluble solids, pH and acidity, vitamin C content and phenolic compounds. The study obtained results demonstrate that the fruits are of a light yellow color, are acidic, have high values of °Brix and glycidic fraction (carbohydrates). However, the high levels of vitamin C (1.26 to 3.57 g ascorbic acid per 100 g of pulp) and phenolic compounds (2.93 to 4.20 g GAE 100 g-1) are noteworthy. This study evidences a great nutritional potential for the fruits of B. tomentosa

ANTIOXIDANT ACTIVITY DURING STORAGE OF APPLES SUBJECTED TO IRRADIATION

Nowadays, the number of studies about fruit conservation as well as the benefits of consumption of foods rich in antioxidant compounds was increased. This study aimed to quantify antioxidant compounds and their activity and to evaluate the physical and chemical changes during the post-harvest storage of Eva's apple cultivars that were subjected to gamma irradiation at doses of 0; 0.5; 1.0 and 1.5 kGy. The antioxidant activity was measured by the 2.2-diphenyl-1-picrylhydrazyl (DPPH) and the β-carotene/linolenic acid methods. Levels of total phenolics, ascorbic acid, color, and soluble solids were evaluated. The results showed that, regardless of the irradiation dose, there was an increase in % SRL during post-harvest storage of Eva's apples. Low irradiation doses were able to preserve the phenolic compounds, maintain the ascorbic acid levels and avoid an increase in the soluble solids content