Estratégias analíticas para a determinação da composição química da polpa de oiti e pinhão empregando ferramentas quimiométricas.

Abstract

This work investigated the chemical composition of oiti pulp and pine nuts using chemometric tools. Chapter 1 deals with the oiti approach oiti (Licania tomentosa (Benth.) Fritsch.), native fruit from Brazil, which is not vastly utilized in human diet due to the scarcity of information about its nutritional characterization. In this paper, the proximate composition, physical-chemical characterization, mineral content, bioactive compounds and antinutrients of oiti pulp were investigated. Multivariate analysis techniques (Kohonen Neural Network, PCA and HCA) were used to evaluate whether there were significant differences among the samples collected in the city of Salvador, Bahia, Brazil, regarding to nutritional composition. RNA-AG hybrid algorithm was applied to optimize the method used for total phenolic compounds determination. The samples were digested in microwave ovens using HNO3 and H2O2 oxidative mixture for multi-element determination of Ca, Cu, K, Mg, Mn, P and Zn by means of inductively coupled plasma optical emission spectrometry (ICP OES). Residual carbon content was determined to evaluate the efficiency of acid digestion procedure. The method accuracy was confirmed by spinach leaves certified reference material analysis (1570a) and apple leaves (1515) from the National Institute of Standards and Technology (NIST). The results indicate that oiti pulp can contribute to human health due to its nutritional value and its natural antioxidant properties, enabling applications in the pharmaceutical industry and new food products development. In chapter 2, the focus of the study was the pine seed (Araucaria angustifolia (Bertol.) Kuntze) rich in nutrients and the neutral flavor can be very versatile in South American cuisine. Thus, the study aimed to determine and chemiometrically evaluate minerals, proximate composition and toxic element in pine nuts (raw and cooked), marketed in five Brazilian states, such as: Minas Gerais, São Paulo, Paraná, Santa Catarina and Rio Grande do Sul. The methodology used consisted of pine nuts acid digestion (fresh and cooked) from five Brazilian states in HNO3 / H2O2 mixture in a digestor block. The exploratory analysis was carried out by usage of chemometric tools generating Boxplot, PCA and HCA graphs in R software, thus allowing to get relevant information regarding the cooking effect on the minerals present in the pine nuts. Therefore, it was possible to discriminate the samples regarding the preparation methods (raw and cooked), in which the raw samples indicated the highest concentrations of the analyzed analytes, although the cooked samples showed leaching of nutrients into the cooking water during cooking process. Therefore, this information is necessary for a better understanding of Brazilian pine nuts nutritional value, which can be used in the development of new culinary dishes and for therapeutical diets.