Kamilla Soares de Mendonça

Optimization of osmotic dehydration of yacon slices

ABSTRACT Osmotic dehydration assisted by ultrasound (ODAU) at low temperatures reduces water activity (aw) and maintains nutrients. The influence of solution concentration (SC; 20 to 60° Brix, xylitol and sorbitol) and ultrasound application time (tus, 0 to 40 min) in ODAU of yacon was studied with the aid of a response surface method. The optimum condition with respect to mass transfer parameters, aw, and fructan retention was SC of 60° Brix for both solutions and tus of 2.67 min for xylitol samples and 0 min for sorbitol samples. The application of ultrasound improved dehydration but resulted in depolymerization of fructans.

Influences of convective and vacuum drying on the quality attributes of osmo-dried pequi (Caryocar brasiliense Camb.) slices

Pequi is a fruit from Brazilian Cerrado. Despite its ascorbic acid and carotenoid contents, consumption of pequi is restricted to its region of origin. The goal of this work was to study drying of pequi slices (convective or vacuum drying at 40°C and 60°C) preceded or not preceded by osmotic pretreatment (sucrose solution concentrations of 40% and 60%). It was found that osmotic dehydration pretreatment substantially decreased the moisture content, duration of the drying process, and the volumetric ratio of the dried product. However, it also promoted leaching of bioactive constituents, such as ascorbic acid and carotenoids. Vacuum and low temperature drying without osmotic pretreatment were preferable because the ascorbic acid and carotenoids were retained, rehydration coefficients were higher and there were minimal volume and color changes.

INFLUÊNCIA DAS CONDIÇÕES DO PROCESSO DE SECAGEM NA QUALIDADE DE FATIAS DE PEQUI (CARYOCAR BRASILIENSE CAMB.)

O pequi é uma fruta do cerrado brasileiro que contém altos teores de ácido ascórbico (AA) e carotenóides. No entanto, o consumo de pequi ainda é limitado devido à alta perecibilidade do fruto. O objetivo deste trabalho foi estabelecer as melhores condições para a produção de fatias secas de polpa de pequi, estudando diferentes mecanismos de secagem (convecção ou vácuo, 40 °C e 60 °C) precedidos ou não por pré-tratamento osmótico (40% e 60% de concentração de solução de sacarose). Foi observado que os pré-tratamentos de desidratação osmótica diminuíram a duração do processo de secagem e a variação de volume do produto seco. No entanto, promoveram lixiviação de componentes funcionais, como AA e carotenóides. O emprego de vácuo e baixa temperatura de secagem, sem pré-tratamentos osmóticos, foram superiores a outras condições de secagem, porque produziram fatias de polpa de pequi secas com altos teores de AA e carotenóides e coeficiente de reidratação, moderada duração do processo de secagem e pequenas alterações no volume e na coloração das amostras.

ESTUDO PRELIMINAR DA DESIDRATAÇÃO OSMÓTICA COM PULSO DE VÁCUO DE FIGO (FICUS CARICA L.)

A desidratacao osmotica assistida por pulso de vacuo (PVOD – pulsed vacuum osmotic dehydration) e um processo eficiente para obtencao de alimentos parcialmente desidratados. Devido ao seu elevado teor de umidade os figos precisam ser conservados de alguma maneira. O presente trabalho teve como objetivo avaliar o efeito da concentracao da solucao de sacarose (46,6 a 63,4 °B) e de sua temperatura (31,6 e 48,4 °C) assim como, o tempo de pulso de vacuo aplicado a PVOD (74 mmHg, 0 a 40 min) na incorporacao de materia seca e reducao do teor de agua. A desidratacao osmotica foi realizada por 300 min com proporcao amostra/solucao de 1:10 (m/m). O planejamento experimental utilizado foi um delineamento composto central rotacional 2 3 , incluindo 6 pontos axiais e 4 repeticoes no ponto central, totalizando 18 experimentos. O aumento do tempo de pulso de vacuo apresentou efeitos significativos na reducao do teor de umidade e incorporacao de materia seca.

Caracterização físico-química e reológica de bebidas fermentadas comerciais

The Technical Regulation on Identity and Quality of Whey-based Drinks establish few parameters to dairy beverages, which may impair standardized product providing to the consumer. The ingathering of the physicochemical characteristics provides information that allow the standardization of the product and provide safety to the consumer, whereas the rheological characterization in important for the processing. Samples of five commercial brands of strawberry flavored dairy beverages, with ten to fourteen days of manufacture, from three different batches were analyzed in triplicate in order to study the percentage of protein, fat, pH, titratable acidity, total dry extract, fixed mineral residue and lactose. It was performed a colorimetric determination and verification of the presence of starch .The rheological tests were carried out in a rotational rheometer and the data was adjusted by Herschel-Bulkley’s model. The statistical analysis was executed by an analysis of variance and the Tukey’s test with 5% significance. The analysis showed that the percentages of lipids of three brands were below the required by legislation. Furthermore, the presence of starch in the composition was detected for all analyzed beverages. Both for the physicochemical and rheological parameters the brands of dairy beverage examined differed between themselves in several parameters. These results indicated the need to establish well-defined identity and quality standards aiming at product quality control and consumer safety improvement.