Laís Ravazzi Amado

O presente trabalho teve como objetivo principal estudar, avaliar, e comparar, a estabilidade térmica das interações entre proteína de soja isolada com três polissacarídeos ajustados em pHs extremos 3 e 11. Resultados sugeriram que a interação de matrizes filmógenas SPI + alginato se mostrou mais termoresistente, com Tonset = 67,7. Tanto a DTG como a DSC foram sensíveis para identificação das temperaturas de maior cinética da desnaturação. A DSC explorou as temperaturas de agregação térmica superiores à 113,0 para as soluções na fase pós-desnaturação, com exceção na mistura SPI + pectina. Após a análise dos resultados termoanáliticos das soluções os filmes preparados foram ajustados em pH 11 e tratados nas temperaturas otimizadas características a partir dos resultados da DTG. Temperaturas de agregação térmica dos filmes foram identificadas nos perfis exotérmicos DSC dos filmes SPI, SPI + pectina, SPI + alginato e SPI + goma alfarroba sugerindo que com o aquecimento pós-desnaturação as ligações covalentes tendem a se formarem. No entanto, devido a pouca variação da entalpia envolvida nestes fenômenos, os resultados sugeriram fragilidade nas ligações químicas após a gelificacão das proteínas e misturas nos filmes. As micrografias obtidas indicam alterações morfológicas com a temperatura de tratamento térmico. Resultados das propriedades mecânicas demonstram atenuação da magnitude das propriedades mecânicas com o aquecimento

The present study aimed to manufacture active biodegradable films from soy protein isolate (SPI), locust bean gum (LBG) and caruru and blackjack leaf extract. The interaction between the compounds was evaluated through the analysis of FTIR. The effect of extract addition on the microstructure, mechanical properties, antioxidant capacity, UV radiation absorption capacity, color and opacity of the film were evaluated. All extracts interacted with the protein, however only two treatments interacted with the LBG present in the film. Addition of extracts in the film provided an increase in antioxidant activity. The addition of the blackjack extract increased the tensile strength of the films, but reduced their elasticity. The addition of caruru extract, however, not favoring the resistance of the films. All the extracts darkened the films and the caruru extract provided more greenish films than all the other made films. The films containing blackjack extract presented a higher intensity of light absorption in the spectral range of ultraviolet A and C.

This study evaluated the influence of heat input change on the drying kinetics, energy consumption, the color, and carotenoid retention during the drying of mangoes. The drying conditions in the first stage were 95°C for 40 min and 80°C for 40 min, so that the surface temperatures of the fruit at the end of this stage were around 60°C. The temperatures of the second stage and corresponding continuous drying (control) were 70 and 60°C. As a result, the thermal intermittence influenced the drying kinetics, causing significant reductions in the overall process time and providing energy savings when compared to continuous drying. The color parameters did not show relevant changes as result of the intermittent drying while good carotenoid retention was obtained in intermittent conditions, when the second stage was 60°C. Therefore, the carotenes were more sensitive to a temperature of 70°C, which highlights the importance of limiting the temperature of the mango to 60°C during the two drying stages to better preserve the quality of the dehydrated fruit. Moreover, the high air temperatures used in the first stage were advantageous for reducing the overall process time and providing energy saving.Practical Applications: Drying is an operation well known for the food industry. However, in so many cases, dryers are not designed with energy consumption in mind. Moreover, simple procedures can bring savings in convective drying, as shown in the present study, where the application of two‐stages in the convective drying of mangoes was advantageous to reduce the overall drying time and provide energy savings in relation to continuous drying. Besides that, good carotenoid retention was obtained using low temperature (60°C) at the second stage. The results can be useful for design of dryers and drying process, considering different temperatures. Intermittent drying of high moisture foods by varying the drying air temperature can be applied both on an industrial scale, in continuous belt dryers or in tunnel dryers, and on a small scale, using two or more dryers with different temperatures.

Composite films in coacervation condition offer an alternative to change properties of protein‐based films, and they present potential applications such as inclusion, stabilization, and release of bioactive compounds in foods. Maximum interactions between soy protein isolate (SPI) (5%) and high methoxyl pectin (PEC) (0.5, 1, 1.5, and 2%), by zeta potential analysis, are found at a pH of 3. The transparency of the SPI films is lost at this pH. When PEC is added to SPI films, the elasticity, solubility, and permeability to water vapor are not significantly altered, but the tensile strength increases. Permeabilities to oxygen are higher for low PEC contents, but as PEC is added, their values are typical of SPI films produced at a pH of 11. A homogeneous structure is found at the higher PEC concentrations. The interactions of PEC–SPI can be useful to tailor films and coatings for applications such as to carry and protect substances of interest. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48732.