Abstract The objective of this study was to develop simple mathematical models for the prediction of the total anthocyanin content of fruits and vegetables, using colorimetry. Phenolic extracts of 13 species of fruits and vegetables were produced using 70% acidified ethanol and 70% ethanol. The quantification of the total anthocyanins of the extracts was performed by the spectrophotometric method, and the color characterization was done through the tristimulus colorimeter. The correlation between the L* value and the anthocyanin content was high (r = - 0.95) for extracts produced with 70% ethanol and diluted 20 times. Linear equations based on colorimetric coordinates, with R2 from 0.80 to 0.99, were obtained using 70% ethanol and 70% acidified ethanol as extraction solvent, with or without dilutions. Therefore, colorimetry, as a rapid method that does not involve the use of specific solvents, can be used to predict the total anthocyanin content of fruits and vegetables.

Abstract Synthetic colourants are widely used for colouring foods. However, their safety has been questioned. Due to this limitation and the global trend of consuming healthy foods, the industry is faced with the need to replace artificial colourings, which has given rise to a growing interest in colourants from natural sources. Thus, this work obtained the moisture adsorption isotherms of the natural food dyes of anthocyanins, betalains and curcumin and evaluated the humidity, water activity (aw), hygroscopicity, colour and antioxidant capacity in vitro. Isotherms were determined by the static gravimetric method with saturated salt solutions (LiCl. H2O, MgCl2.6H 2O, Mg(NO3)2.6H2O, NaCl, KCl and K2 SO4) at 25 °C. Experimental data were adjusted by GAB, BET, Halsey, Oswin and Henderson models. All models, except Henderson's for Curcumin, fitted the data and BET was used to represent the moisture adsorption isotherm. All the isotherms were type sigmoidal, characteristic of most foods. The observed water content (<0.3%) and a w (<0.03) can be considered favourable to stability. Colour analysis indicated a high colouring strength and the antioxidant capacity suggested that, in addition to representing a source of colour in food products, natural dyes may have an additional function, with possible health benefits.

Abstract The objective of this study was to develop, characterize and evaluate the stability of whey protein beverages containing anthocyanins from jabuticaba skins. Beverage formulations containing 0.5% (F1), 2.0% (F2), 4.0% (F3) and 6.0% (F4) of whey proteins and 2.0 mL of the concentrated phenolic extract from jabuticaba skins were developed. Physicochemical parameters (pH, acidity, total soluble solids, protein content, viscosity, color), antioxidant capacity, total anthocyanins and total phenols of the beverages were determined. In addition, a sensory acceptance test and a stability study were performed. The physicochemical analyses indicated that the protein concentration significantly (p < 0.05) affected the values of acidity, total soluble solids, total phenols and antioxidant capacity. The protein content also influenced the total color difference (ΔE) between formulations. The greater differences were observed in the formulation pairs containing low and high protein contents. The formulations F1, F2 and F3 were equally accepted on overall impression and color attributes. The stability study demonstrated that there was no significant change (p > 0.05) in the total anthocyanins and in the physicochemical properties of F3 over storage time, which indicated a good stability and a great market potential of the whey protein beverages containing anthocyanins from jabuticaba skins.

Abstract This study was aimed at optimizing the ultrasound-assisted extraction (UAE) of phenolic compounds from jussara and blueberry fruits using the response surface methodology (RSM). UAE was found to be more efficient to extract phenolic compounds from both fruits than the conventional extraction. The optimum extraction conditions for the jussara fruits were: extraction time between 30 and 62 min for total anthocyanins and total phenolics, fruit:solvent ratio of 10% and 6% (w/v) for total anthocyanins and total phenolics, respectively. The ethanol concentration was non-significant (p> 0.05). Acidified water was found to be an extracting solvent as efficient as ethanol in the extraction of phenolic compounds from jussara fruits. The optimum extraction conditions for blueberry anthocyanins were: ethanol concentration between 20-70% vol, and fruit: solvent ratio greater than 20% (w/v) within the range studied. The extraction time was not significant (p> 0.05). For total phenolic content: the concentration of ethanol was between 40-80%, and fruit: solvent ratio greater than 20% (w/v) and extraction time over 50 minutes. It was possible to adjust the mathematical model for the coordinates a* (verde vs vermelho) and C* (color saturation) of the jussara extracts.

RESUMO: Este estudo teve como objetivo desenvolver e caracterizar bebidas formuladas com proteínas de soro de leite adicionadas de luteína. Bebidas formuladas com 0,5 (F1), 2,0 (F2), 4,0 (F3) e 6,0% m/v (F4) de proteínas de soro caracterizadas fisico-quimicamente e microbiologicamente e, avaliadas sensorialmente. As análises físico-químicas indicaram que o teor de proteína alterou significativamente (P<0,05) os valores de acidez, sólidos solúveis e as coordenadas colorimétricas, foi possível ajustar modelos matemáticos para todas essas variáveis. As análises microbiológicas mostraram contaminação não significativa (P<0,05) durante o processamento que poderia comprometer a qualidade das bebidas. Os teores de carotenoides e a atividade antioxidante não variaram significativamente (P>0,05) com o aumento do teor de proteína. A formulação F2 apresentou a maior aceitação sensorial. As bebidas são uma alternativa promissora para o uso do soro de leite e aumentam o valor agregado do produto pela adição de luteína.

ABSTRACT: This study aimed to develop and characterize beverages formulated with whey protein and added lutein. Beverages formulated with 0.5 (F1), 2.0 (F2), 4.0 (F3) and 6.0% w/v (F4) whey protein were physicochemically and microbiologically characterized, and sensory evaluated. The physicochemical analyses indicated that the protein content significantly changed (P<0.05) the acidity values, soluble solids and the colorimetric coordinates, making possible to adjust mathematical models for all these variables. Microbiological analyses showed no significant contamination (P<0.05) during processing that would compromise drinks quality of the drinks. Carotenoid content and the antioxidant activity did not change significantly (p>0.05) with increased protein content. The F2 formulation showed the highest sensory acceptance. Beverages offer a promising alternative to whey use and enhance the value of the product by the addition of lutein.

A indústria de leite e derivados no Brasil lança todos os anos diversos novos produtos no mercado, incluindo produtos de alto valor nutricional e tecnologia de fabricação de baixo custo. Focando neste tema, foi avaliado o efeito do envase a quente de uma bebida a base de soro de leite tratada termicamente após fermentação, e sua conservação à temperatura ambiente, por 84 dias. Durante o processamento, utilizou-se um tratamento térmico brando, aliado ao baixo pH, para que a bebida pudesse ser armazenada a temperatura ambiente. Garrafas PET de 250 mL foram utilizadas para o envase a quente do produto. Para avaliar sua estabilidade durante o armazenamento, foram realizadas periodicamente análises físico-químicas, microbiológicas e análise sensorial. Os resultados obtidos foram analisados por análise de variância e teste de Tukey para comparação de médias. Análises físico-químicas e microbiológicas indicaram que a bebida manteve-se estável; entretanto, o sabor foi alterado ao longo do armazenamento. O baixo custo do processamento e embalagem são benefícios do produto avaliado, podendo-se concluir que a bebida é uma boa forma para a utilização do soro de leite. Uma grande vantagem deste produto é o seu armazenamento à temperatura ambiente, dispensando o uso da refrigeração durante o transporte e acondicionamento em supermercados.

The Brazilian dairy industry launches several new products on the market every year, including products with high nutritional value and low-cost manufacturing technology. Focusing on this issue, a cheese whey beverage thermally treated after fermentation was hot-filled and evaluated for 84 days. During the beverage manufacturing, we applied a mild heat treatment in combination with low pH aiming to store the beverage at room temperature. PET bottles were used to hot filling of the product. To assess the product stability during the storage period, we performed, periodically, physico-chemical, microbiological and sensory analysis. The obtained results were analyzed by the Analysis of Variance and Tukey's test. Physical-chemical and microbiological analysis indicated that the beverage remained stable; however, the flavor was altered during the storage period. Since hot-filling of dairy beverages in PET bottles is a low cost-effective procedure easily deployed in dairy plants, this process allows the productive use of cheese whey. A remarkable advantage of such product is its possible storage at room temperature, reducing distribution and sales expenditures with cooling.