Abstract The food industry should have methods that allow identifying bioactive compounds quickly, efficiently and at low cost. The objective of this research was to obtain mathematical models for predicting the amount of total phenolics, anthocyanins and antioxidant capacity of blackberry, blueberry and jaboticaba skin, based on colorimetric parameters (L*, a*, b*, C* and h*). All analyses were done in the phenolic extracts obtained from these fruits. The mathematical models were obtained through multiple linear regression using the stepwise method. The significant correlation between the colorimetric parameters and chemical analyses resulted in models with a high predictive ability (high r2), such as in the determination of the contents of anthocyanins (r2 = 0.99), total phenolics (r2 = 0.86) and for the antioxidant capacity (r2 = 0.99). Thus, the prediction of levels of these bioactives compound, using colorimetric parameters, is very promising for cost and time savings.

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: O mercado de polpa de açaí ( Euterpe oleracea Mart.) congelada tem tido crescimento aceitável e apresenta grande potencial mercadológico em função da sazonalidade e do elevado nível nutricional do fruto. Porém, devido à inexistência de padrões para todos os tipos de frutas, encontram-se no mercado produtos sem uniformidade. O objetivo do presente estudo foi avaliar polpas de açaí congeladas de diferentes marcas comerciais, quanto às características químicas, físico-químicas e microbiológicas. Para ATT e pH, duas marcas do Pará e duas de Minas Gerais foram reprovadas, quando comparadas com a legislação vigente. Observou-se que K (1253,6mg 100g-1), Ca (312mg 100g-1), Mg (178mg 100g-1), e P (145mg 100g-1) foram os principais minerais encontrados nas amostras avaliadas. O Fe apresentou conteúdo médio entre 9,65mg 100g-1 e 22,66mg 100g-1. Quanto às características microbiológicas, as contagens para E.coli atenderam à legislação. As contagens de mesófilos aeróbios, fungos filamentosos e leveduras apresentaram variações nos resultados. A contagem de S. aureus coagulase positiva apresentou-se dentro dos padrões (102UFC g-1) e foi detectada a presença de Salmonella sp. em uma marca, dentre as seis avaliadas. As polpas de açaí analisadas apresentaram valores de fenólicos totais variando de 240,14mg AGE 100g-1 a 372,43mg AGE 100g-1 e os níveis de antocianinas totais variando de 12,05 a 24,98mg 100g-1. Os resultados físico-químicos e microbiológicos obtidos indicaram a necessidade de implementação imediata das Boas Práticas de Fabricação; em contrapartida, as polpas congeladas de açaí apresentaram considerável potencial antioxidante.

ABSTRACT: The frozen açaí ( Euterpe oleracea Mart.) pulp market has had acceptable development and presents great market potential due to its high nutritional level and fruit's seasonality. However, due to the lack of standards for all types of fruit, products without uniformity are in the market. This study aimed to evaluate frozen açaí pulp belonging to different trademarks related to chemical, physicochemical, and microbiological characteristics. Regarding the total titratable acidity (TTA) and pH, two trademarks from Pará and two from Minas Gerais were rejected compared with the current legislation. It was observed that K (1,253.6mg 100 g-1), Ca (312mg 100g-1), Mg (178mg 100g-1), and P (145mg 100g-1) were the main minerals reported in the analyzed samples. Fe showed an average content from 9.65mg 100g-1 to 22.66mg 100g-1. As for microbiological characteristics, the counts for E. coli were in compliance with legislation. Counts of mesophilic aerobic, filamentous fungi, and yeasts showed variations in the results. The count of coagulase-positive S. aureus met the standards [102 Colony Forming Units (CFU) g-1]; and presence of Salmonella sp. in a trademark was detected among the six evaluated trademarks. The analyzed pulp of açaí showed total phenolics values ranging from 240.14mg AGE 100g-1 to 372.43mg AGE 100g-1, and anthocyanin total levels ranging from 12.05 to 24.98mg 100g-1. The obtained physicochemical and microbiological results indicated the need for immediate implementation of Good Manufacturing Practices; conversely, the frozen pulp of açaí showed considerable antioxidant potential.