a b s t r a c tThe major anthocyanin pigments extracted from Hibiscus acetosella flower were investigated by UV-Vis spectroscopy and multivariate curve resolution-alternating least squares (MCR-ALS). Pure spectra and kinetic of the species present at different pH values were recovered for anthocyanins transformation and degradation products, found with and without UV radiation exposure. In the absence of UV radiation, up to seven different species were detected and by UV radiation exposure, this number increased to up to nine. The species detected in the absence of radiation were also detected when pigments samples were exposed to UV radiation, where degradation occurred faster and two new species appear. The kinetic profiles obtained at different pH values allowed the proposal of a reaction mechanism and pathway.

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Honey is a concentrated aqueous solution of sugar, especially glucose and fructose, and minor amounts of dextrin, enzymes, waxes, volatile oils, organic acids, ethers, albuminoidal gum substances and minerals. Commercially available honey samples vary in quality according to various factors such as climate diversity, type of lora of the surrounding region, geographical characteristics, processing, loral supply period, and packaging and storage conditions, which can compromise the standardization and quality of the inal product. The diferent techniques that will be presented in this chapter to assess the quality of honey are tests required by identiication standards and national and international quality control or are important quality tools that can be used in the evaluation of the conditions for obtaining and processing of the honey, fraud identiication and changes to and/or adulteration of the honey, ensuring the physical and chemical composition of the project and guaranteeing quality standards, directly impacting the shelf life and use and presentation of the product.

INTRODUÇÃOA cor é um dos mais importantes atributos de qualidade de um alimento, exercendo uma enorme influência em seu valor estético e servindo de base para a aceitação de uma grande variedade de produtos alimentícios por parte dos consumidores.1 Em produtos naturais, a maioria das substâncias responsáveis pela coloração pertence à classe dos flavonóides. Os flavonóides possuem estrutura marcada pela presença de um esqueleto com 15 átomos de carbono na forma C 6 -C 3 -C 6 , e são divididos em classes dependendo do estado de oxidação do anel central de pirano.2 A Figura 1 apresenta a estrutura química dos principais tipos de flavonóides. 3A classificação do tipo de flavonóide presente em um extrato de planta baseia-se inicialmente no estudo das propriedades de solubilidade e reações de coloração. Este procedimento é seguido por análise cromatográfica do extrato da planta. Os flavonóides podem ser separados por procedimentos cromatográficos e os componentes individuais identificados, quando possível, por comparação com padrões.As duas classes de flavonóides consideradas como mais importantes são os flavonóis e as antocianidinas. 4 As antocianidinas apresentam como estrutura fundamental o cátion flavílico 5 (2-fenilbenzopirilium), representado na Figura 2a. A Figura 2b apresenta um exemplo de estrutura de antocianidina, conhecida como cianidina.Os pigmentos ocorrem geralmente na forma de antocianinas, 6 que são derivadas das antocianidinas. As antocianidinas não possuem grupos glicosídeos e a maioria possui hidroxilas nas posições 3, 5 e 7. Já nas antocianinas, uma ou mais destas hidroxilas estão ligadas a açúcares, sendo os mais comuns glicose, xilose, arabinose, ramnose, galactose ou dissacarídeos constituídos por esses açúca-res, aos quais podem estar ligados ácidos fenólicos, como pcoumárico, cafêico, fenílico e vanílico. O açúcar presente nas molé-culas de antocianinas confere maior solubilidade e estabilidade a estes pigmentos, quando comparados com as antocianidinas.5 A Figura 3 é um exemplo de estrutura de antocianina presente na maioria dos vegetais, a cianidina 3-glucosídeo.O termo antocianina, derivado do grego de flor e azul (anthos = flores; kianos = azul), foi inventado por Marquart em 1853 para se referir aos pigmentos azuis das flores. Percebeu-se mais tarde que não apenas a cor azul, mas também várias outras cores observadas em flores, frutos, folhas, caules e raízes são atribuídas a pigmentos quimicamente similares aos que deram origem ao "flor azul". 7Com a mesma origem biossintética dos outros flavonóides na-

Chemical analyses and sensory evaluation are the most applied methods for quality control of roasted and ground coffee (RG). However, faster alternatives would be highly valuable. Here, we applied infrared-photoacoustic spectroscopy (FTIR-PAS) on RG powder. Mixtures of specific defective beans were blended with healthy (defect-free) Coffea arabica and Coffea canephora bases in specific ratios, forming different classes of blends. Principal Component Analysis allowed predicting the amount/fraction and nature of the defects in blends while partial Least Squares Discriminant Analysis revealed similarities between blends (=samples). A successful predictive model was obtained using six classes of blends. The model could classify 100% of the samples into four classes. The specificities were higher than 0.9. Application of FTIR-PAS on RG coffee to characterize and classify blends has shown to be an accurate, easy, quick and "green" alternative to current methods.

In this work the vitamin C was determined in industrialized nectar juices through ultraviolet (UV) spectroscopy and multiproduct multivariate calibration, based on partial least squares (PLS) regression. Since samples with different flavors, sugar content (light or not) were together in the model construction, it can be considered as a multiproduct and, due to the heterogeneity of the samples, it was necessary to optimize the calibration and validation sets by outliers elimination. The model was developed and validated by the evaluation of the figures of merit such as: accuracy, sensitivity, analytical sensitivity, adjust, linearity, relative prediction deviation, limits of detection and quantification, indicating that the multiproduct model developed from UV spectroscopy and PLS regression can be used in the industrial routine analysis as an alternative to titration or other time and reagent consuming methods. Here, it was evidenced that the UV-PLS multiproduct model provides advantages as being free of sample preparation steps, is suitable to be updated in order to measure other parameters, does not generates residues and is feasible to be implemented for on-line monitoring. Furthermore, the application of multivariate calibration in multiproduct models is extremely attractive from the industrial point of view.