ALINE KIRIE GOHARA

Título da Dissertação: DESENVOLVIMENTO E CARACTERIZAÇÃO DE BOLO DE CHOCOLATE ISENTO  DE GLÚTEN, CONTENDO AZUKI (VIGNA ANGULARIS) E CHIA (SALVIA HISPANICA, L.)

Orientador: Prof. Dr. Makoto Matsushita

Data da Defesa: 15/02/2013

RESUMO GERAL

 INTRODUCTION. The current changes in the daily of world population reflect in drasticvtransformations of many aspects, especially in food consumption. Nowadays, most of foods do not have the minimum nutrients essential to the maintenance of human health, fact that aroused interest in enriched food developing and with functional appeal, mainly by food industries. The cakes ready for consumption have been acquiring great importance among the bakery products, since they are largely marketed, and hold the second position of the most consumed product ranking in this category, behind only of bread. There are gluten-free versions which can be consumed by celiac patients, however, these are still poor in many nutrients because they are composed primarily of rice flour. Azuki (Vigna angularis) is a legume widely produced and consumed in Asia, used in the various products manufacturing, especially in typical sweets. Chia (Salvia hispanica L.) is an angiosperm plant from the mint family (Lamiaceae) characterized as a grain from tropical and subtropical climate, widely consumed in pre-Columbian America by the Aztecs, in the region that includes Mexico and Guatemala. Both grains, azuki and chia, are considered rich source of many essential nutrients to good health maintenance. One of the most relevant aspects regard to nutrients is the mineral composition. Several minerals are essential for the maintenance of biological systems. Besides, sensorial aspects are very important factors for the development of new products. Factorial design enables evaluating the contribution of a specific ingredient on several characteristics of the final product and multivariate analysis enables extracting additional information when compared to the univariate analysis. This latter chemometric tool allows the pattern recognition, the gathering of information, reduction of data dimensionality and also the organization of data in a simpler structure, easier to understand. The principal component analysis (PCA) is based on perform linear comparisons of the original variables. The principal components (PC) are mutually orthogonal and explained variance decreases with increase in PC number OBJECTIVES. The aim of this study was to apply the Chemometrics to investigate the influence of the factors: percentages of chia and azuki added on gluten-free chocolate cake for the determination of proximal composition, energy, sensory aspects and the of minerals Ca, Cu, Fe, K, Mg, Mn and Zn.
MATERIAL AND METHODS. A 22 full factorial design (two factors at two levels) with duplicates was performed to investigate the influence of two factors on the chocolate cake proximal and mineral composition. A control assay was also prepared for comparison using Principal Components Analysis. The factors were concentrations of chia and azuki flour. All ingredients were previously weighed separately. The rice flour, azuki and chia, at the respective percentage for each formulation, were mixed to obtain a homogeneous fraction (28.80% of the whole formulation) and egg white (8.70%) was mixed to form a solid phase. The egg yolk (5.80%), butter (5.80%) and sugar (16.90%) were homogenized to form a cream on which the mixture of flour, chocolate powder (8.00%), cocoa powder (3.80%), egg whites, water (19.08%), milk powder (2.12%) and baking powder (1.00%) were added slowly to form a homogeneous mass. The cake mass was transferred to a rectangular baking dish and baked in a conventional oven for 30 minutes at 200 ° C, with subsequent cooling to room temperature (25°C). The moisture, ash, crude protein, total lipids, Nifext contents and the energy value were assessed. For mineral analysis, the samples were digested by the dry method and Ca, Cu, Fe, K, Mg, Mn and Zn were quantified in atomic absorption spectrophotometer. A group of 60 nontrained volunteer panelists and potential consumers of the products developed participated in the sensory analysis, which consisted in acceptance testing with the following attributes: smell, color, appearance, flavor, texture and overall acceptance of the cakes using a 9-point hedonic scale. The multivariate analysis was performed by applying Principal Component Analysis (PCA).
RESULTS AND DISCUSSION.
A 22 full factorial design (two factors at two levels) with duplicates was performed to investigate the influence of the factors: the percentage of chia and azuki added on gluten-free chocolate cake on the determination of moisture, ash, crude protein, total lipids, Nifext contents and the energy value, sensory attributes and the contents of minerals Ca, Cu, Fe, K, Mg , Mn and Zn. The formulations were prepared with partially defatted chia flour and azuki wholemeal. Both factors were significant and the increasing of their value contributed positively in the responses of proximal composition, energy and sensory aspects. The percentage of chia was the factor that most contributed to the majority of the responses, except for the nifext. Azuki principal effect was not significant for the responses moisture and energy. The principal components analysis distinguished samples with the highest content of chia mainly for the responses lipids and crude protein, and these formulations had the optimal point in response surfaces. The models for the sensory attributes were not significant and multivariate analysis showed that formulations with the lowest percentage of chia and azuki had characteristics similar to control assay. For the mineral analysis, The factors percentage of chia and azuki were significant and an increase of these values, contributed positively to the responses. The interaction effect was not significant to the responses Ca, Fe, Mg and Zn. The principal components analysis distinguished samples with higher content of chia through PC1, and PC2 separated the formulations with the highest level of azuki from the one with the lowest level. ANOVA and response surfaces analyses showed that the greatest contents of minerals were found in the formulations with the highest concentration of both flours: chia and azuki.
CONCLUSIONS.
The factorial design performed for chocolate cake enable to verify that the models for the proximal composition and energy were significant. The chia flour was the factor that most contributed for most of the responses, except for the nifext. The azuki main effect was not significant for responses moisture and energy. The principal components analysis distinguished samples with higher content of chia mainly due to crude protein and lipids contents, and these samples were the optimal points in the response surfaces of these models. Regarding sensory attributes, the models were not significant and multivariate analysis showed that the lowest percentage of the chia and azuki provided characteristics similar to control assay. The factorial design conducted to incorporate minerals in chocolate cake showed that the factors with the highest percentage of chia and azuki flour were significant, and the increasing of these factors contributes positively to all responses. The interaction effect was not significant only for responses Ca, Fe, Mg and Zn. The principal components analysis distinguished samples with higher content of chia through PC1, and PC2 separated the formulations with the highest level of azuki from the one with the lowest level. ANOVA and response surfaces analyses showed that the greatest contents of minerals were found in the formulations with the highest concentration of both flours: chia and azuki. These grains are good alternatives for common flours substitution in food products, including gluten-free ones. Key words: Salvia hispanica, L., Vigna angularis, response surface methodology, principal components analysis.

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