The aim of this study was to evaluate near-infrared reflectance spectroscopy (NIR), and multivariate calibration potential as a rapid method to determinate anthocyanin content in intact fruit (açaí and palmitero-juçara). Several multivariate calibration techniques, including partial least squares (PLS), interval partial least squares, genetic algorithm, successive projections algorithm, and net analyte signal were compared and validated by establishing figures of merit. Suitable results were obtained with the PLS model (four latent variables and 5-point smoothing) with a detection limit of 6.2 g kg(-1), limit of quantification of 20.7 g kg(-1), accuracy estimated as root mean square error of prediction of 4.8 g kg(-1), mean selectivity of 0.79 g kg(-1), sensitivity of 5.04×10(-3) g kg(-1), precision of 27.8 g kg(-1), and signal-to-noise ratio of 1.04×10(-3) g kg(-1). These results suggest NIR spectroscopy and multivariate calibration can be effectively used to determine anthocyanin content in intact açaí and palmitero-juçara fruit.

RESUMO-A agroindústria do açaí gera uma grande quantidade de resíduos, constituída de caroços e fi bras, o que é um grave problema ambiental e de saúde pública. O objetivo deste estudo foi estudar as fi bras do mesocarpo e o caroço do fruto do açaí para sua utilização em materiais compósitos. As amostras foram caracterizadas usando análise por termogravimetria (TG/DTG) em atmosferas inerte e oxidativa, microscopia eletrônica de varredura e microscopia óptica. As fi bras apresentaram boa estabilidade térmica até 230 o C e um processo de degradação em atmosfera inerte em três etapas. Em atmosfera oxidativa, as fi bras apresentaram menor estabilidade térmica e uma mudança no processo de degradação de três para quatro etapas. Os resultados da análise térmica do caroço mostraram um comportamento térmico similar ao da fi bra. A microscopia mostrou que as fi bras presentes no fruto do açaí recobrem o caroço e possuem morfologia irregular com a presença de células do parênquima na sua superfície. O comportamento térmico das fi bras do açaí é semelhante ao de outras fi bras vegetais já utilizadas industrialmente na área de compósitos poliméricos, o que abre novas e promissoras áreas para sua utilização. Termos para indexação: fi bra natural, análise térmica, morfologia. THERMOGRAVIMETRIC EVALUATION OF AÇAÍ FRUIT (Euterpe oleracea Mart.) AGRO INDUSTRY WASTEABSTRACT -The açaí fruit agro industry produces a large amount of waste, mainly seeds and fi bers, which is a serious environmental and public health problem. The aim of this work is to study the mesocarp fi bers and the açaí fruit seed to use in composite materials. The samples have been characterized by using thermogravimetric analysis (TGA/DTG) in inert and thermo-oxidative atmospheres, scanning electron and optical microscopy. The fi bers have shown good stability until 230 o C and a three-degradation step process in inert atmosphere. In oxidative atmosphere, the fi bers presented a decrease in thermal stability and a change in the decomposition process from three to four steps. For the seeds, a similar behavior was observed, although a lower thermal stability was observed when compared to the fi ber. Longitudinal morphology of the fi bers that cover the açaí seed is rough, and parenchyma cells can be seen on the surface. The açaí fi bers exhibited a thermal behavior comparable to other natural fi bers used in composites, which is promising for new applications. Index terms: natural fi bers, thermal analysis, morphology. INTRODUÇÃONas últimas décadas, a importância das fi bras naturais como aditivos ou reforços para produtos poliméricos vem aumentado signifi cativamente, devido a fatores como o alto preço das fi bras sintéticas e à busca crescente por materiais de baixo custo e que sejam provenientes de fontes renováveis, possuam boas propriedades mecânicas e térmicas, e não causem danos ambientais. Devido a esta nova tendência mundial, muitos estudos têm sido realizados para a utilização destas fi bras em indústrias como a de materiais, construção civil, automobilí...

The aim of this work was to study the source of the açaí residue for its possible commercial applications by characterizing the fruit (fresh and dry mass), and performing an anatomic study of the pericarp from which were identified the origin of the anthocyanins, and fatty acids, and fibers; also the vascular system, its fibers constituents and fibrils were characterized. It was concluded that anthocyanins were located on the epiderm and external parenchyma, and that solids retained on the sieve come from the sclerenchyma, and that the fatty acids come from the storage parenchyma. The vascular tissue was formed by the fibers around 20 mm length. The length distribution of the fibrils had a mean length of 580µm.

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This study assesses the storage temperature effect on the anthocyanins of pasteurized and unpasteurized açaí pulp. The data was obtained using a pasteurized and lyophilized pulp (PLP) to evaluate the temperature effect (0, 25, and 40 °C). Part of non-pasteurized frozen pulp (NPP) was pasteurized (NPP-P) at 90 °C for 30 seconds; both pulps were stored at 40 °C. The anthocyanin content reduction in the drink was evaluated from the half-life time (t1/2), activation energy (Ea), temperature quotient (Q10), and the reaction rate constant (k). The t1/2 of the PLP anthocyanins stored at 40 °C was 1.8 times less than that stored at 25 °C and 15 times less than that stored at 0 °C; therefore, the higher temperatures decreased the stability of anthocyanins. The pasteurization increased the t1/2 by 6.6 times (10.14 hours for NPP and 67.28 hours for NPP-P). The anthocyanin degradation on NPP-P followed a first order kinetic, while NPP followed a second order kinetic; thus it can be said that the pasteurization process can improve the preservation of anthocyanins in the pulp.