Navegando por Assunto "Vitamina C"

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Acesso aberto (Open Access)
Efeito dos diferentes tratamentos e embalagens nas características da polpa de acerola e na determinação dos teores de ácido ascórbico e das antocianinas durante o armazenamento
(Universidade Estadual de Campinas, 1999-12-21) SILVA, Maria de Fatima Vilhena da; MENEZES, Hilary Castle de; http://lattes.cnpq.br/6478475854489070
West Indian cherry is a rich source of ascorbic acid and a relative source of anthocyanins. The fruit and its products have been objects of great demand to serve individually as a nutritional source, or as a supplementary source of this vitamin for other foods. Ascorbic acid and the anthocyanins present antioxidant and preventative properties of various diseases which affect man, such as cancer, cardiovascular problems and others. One of the problems in the industrialization of this fruit and its products is related to the losses of ascorbic acid and the color of the product. Thus, this research was conducted with the objective of investigating the degradation of ascorbic acid and of the anthocyanins in West Indian cherry pulps submitted to different treatments: pulp without heat treatment, thermal inactivation or blanching, pasteurization (HTST) with and without aeration. The pulps were tested in glass and tin packages, and stored for six months for a better evaluation of their vitamin potential and lhe level of color maintenance of the products. All the experiments were developed at the pilot plant level. The second chapter considers the tests conducted with different methods for the determination of ascorbic acid in West Indian cherry pulp for the selection of those which offered good results as compared to CLAE, and which are fast, precise and economic. The method which fitted these characteristics, was that of titration with 2,6-dichloroindophenol. However, due to the intense color of the pulp, it was necessary to study a way to facilitate the titration and make the results more precise. The modifications made to this method to reach these objectives are presented in the second chapter. The new modifications showed result in excellent performance and the data were statistically similar to those obtained by CLAE. In the third chapter, an investigation of the physicochemical characteristics of the West Indian cherry pulps was made, emphasizing the effect of processing and types of package at zero time and during the storage period of six months. In this chapter, the individual results, the correlation amongst the analyses for ascorbic acid, total anthocyanins, pH, total titrable acidity expressed as malic acid and as citric acid, total solids and °Brix were shown. The results showed high correlation between ascorbic acid and anthocyanins. In the fourth chapter, a detailed study of the color of the pulps was made using the L a b system, that is, a study of the "hue", difference in color and saturation of color during storage. It was possible to verify from the results, that the product color was directly related to the type of processing and storage conditions. In the fifth and last chapter, the anthocyanins in the pulp without heat treatment were identified, and also the effects of processing on these pigments. The anthocyanin encountered in highest amounts was cyanidine, malvidine and pelargonidine also being present. The latter was shown to be more sensitive to heat treatments. Deaeration of the pasteurized pulp, and type of package showed no significant difference.
Acesso aberto (Open Access)
Principais compostos bioativos e capacidade antioxidante da polpa do camu-camu (Myrciaria dubia) em diferentes estádios de maturação
(Universidade Federal do Pará, 2014-06-25) OLIVEIRA, Thaise Cristine de Souza; MATTIETTO, Rafaella de Andrade; http://lattes.cnpq.br/7832266671782588; LOPES, Alessandra Santos; http://lattes.cnpq.br/8156697119235191
This study aimed to determine physical and physico-chemical characteristics, bioactive compounds and antioxidant capacity from camu-camu pulp of three different progenies, came from Active Germplasm Bank of camucamuzeiro, at Embrapa Amazônia Oriental, in three ripening stages. Over the ripening, the mass and the diameters varied (p ≤ 0.05) just for progeny 44 and the pulp yield increased for all the progenies, with results over 50% in the ripe stage. The ripening stage didn’t show effects in the moisture and ashes content and also pH for progeny 38; ashes for progeny 44 and fat and insoluble fibers for progeny 17. The others results varied with the ripening, but, with different behaviors to each progeny, except for the total sugar, soluble solids contents and the SS/TTA ratio, which showed a tendency to increase, and the total titratable acidity decreased in all the progenies. Overall, a higher level of vitamins C were obtained in the green stage, with a first step of degradation, as it reached the semi-ripe stage, followed by a synthesis step until the end of the ripening stage, except for the progeny 38, which showed a reduction. As for the phenolic compounds, during the ripening stage, the three progenies were characterized for synthesis and degradation processes of the total phenolic compounds; the total flavanols decreased; the flavonols content had a distinct behavior in each progeny, with an increasing in the progenies 17 and 38, and a decreasing in the progeny 44; due to a limitation of the method used to determine small quantities, It was possible to quantify anthocyanins only for progenies 17 and 44 in the ripening stage. The antioxidant capacity, determinated through the methods TEAC and DPPH, decreased in all the progenies. Besides the significant effects of the ripening stage, the results showed that the genetic variability of camu-camu influenced significantly the physical characteristics of the fruits and the continents of all compounds studied, and still the antioxidant capacity obtained through the methods mentioned.