Avaliação da composição química e nutricional da folha de mandioca e azeitona em conserva empregando técnicas espectroanalíticas e quimiométricas

Abstract

In chapter I, studied the cassava leaf grown in the State of Bahia, Brazil, after undergoing thermal and fermentation processes in order to eliminate the hydrocyanic acid present in its structure. In this sense, the physicochemical characteristics and the proximate composition were evaluated by means of the methods described by the Adolfo Lutz Institute. The determination of the mineral composition took place through the use of the microwave-assisted acid decomposition procedure, followed by the measurement of the analytical signal through the ICP OES. The accuracy of the method was confirmed by analysis of certified reference materials from spinach and apple leaves (NIST 1570a and NIST 1515) from the Institute of Standards and Technology (NIST). The residual carbon content was evaluated using the ICP OES. When comparing raw samples with fermented and cooked samples, nutrient losses can be observed. The results were evaluated by means of multivariate analysis (PCA and HCA), in which it was observed a tendency for the samples to be separated into groups, according to the type of treatment to which the samples were submitted. For the bioactive substances and antinutrients, the optimization of the extraction method was used as an initial step, using the following designs: Centroid-Simplex Mixture, Full Factorial and Doehlert. The results presented showed that there were losses of analytes by leaching when comparing the raw samples with those that underwent some type of processing. In Chapter II, bioactive substances and antinutrients were evaluated in samples of preserved olives collected in different markets in the city of Salvador, Bahia, Brazil. This fruit to be consumed underwent chemical processes in order to reduce the content of oleuropein responsible for the bitter taste of olives in natura. Thus, the extraction method of bioactive substances and antinutrients was optimized by applying chemometric tools. From the results of the optimal conditions, we have; stirring time 7 minutes; acidified methanol 0.05 molL-1 and water bath temperature 62ºC. The total phenolics, total flavonoids, tannins and sodium oxalate were also determined, and it was possible to observe that when comparing the different stages of fruit maturation, black olives had a higher content than green olives.