Effect of Whey Protein Purity on the Characteristics of Algae Oil-Loaded Encapsulates Obtained by Electrospraying Assisted by Pressurized Gas.

In this paper, the effect of protein purity in three different whey protein grades on the characteristics of algae oil encapsulates obtained via room-temperature electrospraying assisted by pressurized gas (EAPG) encapsulation process was studied. Three different commercial grades of whey protein purity were evaluated, namely 35, 80, and 90 wt.%. Oil nanodroplets with an average size of 600 nm were homogeneously entrapped into whey protein microparticles 3 µm in size. However, the sphericity and the surface smoothness of the microparticles increased by increasing the protein purity in the grades of whey protein studied. The porosity of the microparticles was also dependent on protein purity as determined by nitrogen adsorption-desorption isotherms, being smaller for larger contents of protein. Interestingly, the lowest extractable oil was obtained with WP35, probably due to the high content of lactose. The peroxide values confirmed the superior protective effect of the protein, obtaining the smallest peroxide value for WP90, a result that is consistent with its reduced porosity and with its lower permeability to oxygen, as confirmed by the fluorescence decay-oxygen consumption method. The accelerated stability assay against oxidation confirmed the higher protection of the WP80 and WP90. In addition, the increased content in protein implied a higher thermal stability according to the thermogravimetric analysis. These results further confirm the importance of the adequate selection of the composition of wall materials together with the encapsulation method.

Effect of Blanching on Enzyme Activity and Bioactive Compounds of Blackberry

ABSTRACT The inactivation of peroxidase and polyphenol oxidase and the degradation of phenolic compounds, anthocyanins, and antioxidant activity in blackberry were investigated during blanching in water at 80-90 °C, and in steam, from 0 to 10 minutes. The enzyme kinetics indicated the presence of two isoenzymes with different thermal stability, following two-phase model, in which the reaction rate constant increased with increasing temperature for both the heat labile and heat resistant component. The phenolic compounds also followed a biphasic pattern, indicating a more heat resistant fraction, and the rate constants increased with increasing temperature. For the antioxidant activity and anthocyanins, the first order kinetic model (R2>0.982) indicated an increase in degradation rate constants with temperature, from 0.050 to 0.137min-1 for DPPH, 0.085 to 0.285min-1 for ABTS, and 0.017 to 0.052 min-1 for anthocyanins.

Viabilidade de células de levedura em massas congeladas de pão francês / Leavening cells viability in frozen French bread dough

A elaboração e o armazenamento de pães crus congelados têm se mostrado vantajosos para os pontos de venda e para o consumidor final. O primeiro, pela redução da perda e menor exigência de espaço físico e mão-de-obra especializada, e o segundo, por disponibilizar pães sempre frescos. O presente trabalho objetivou verificar a influência do armazenamento sobre a viabilidade das células de levedura em massas congeladas de pão francês. Para tanto, as massas foram elaboradas seguindo a metodologia de massa direta: os ingredientes (pré-mistura para pão francês, fermento fresco e água) foram misturados até o desenvolvimento completo do glúten; então foi dividida em porções de 60g e modelada. O congelamento foi realizado em ultracongelador a -32°C, e o armazenamento foi feito em câmaras com temperaturas de -18°C e -40°C. Para a estimativa de vida de prateleira, analisou-se a cinética da redução da viabilidade das leveduras. Esse teste foi realizado em placas de Petri contendo meio Sabouraud acrescido de cloranfenicol 0,2 por cento a 28°C durante cinco dias. A cinética de redução das células de levedura seguiu uma reação de primeira ordem, cujas constantes de velocidades foram 0,027 dias-1 (R²=0,931) e 0,026 dias-¹ (R²=0,938) para as temperaturas de -18°C e -40°C, respectivamente. Para ambas as temperaturas, a redução em 50 por cento da população de leveduras se deu em aproximadamente 25 dias.

The preparation and storage of frozen bread has proved to be advantageous for the market and to the final consumer. First because of loss reduction and need for smaller physical storage space and workforce, second because it provides always fresh bread. This study aimed to investigate the influence of storage on the viability of yeast cells in frozen French bread. In order to that, frozen French breads were prepared by the direct-dough method: the ingredients (premix for French bread, fresh yeast and water) were mixed until the dough was fully developed and then divided into portions of 60g and moulded. Freezing was held in ultra freezer at -32°C and the storage was made in chambers at temperatures of -18oC and -40°C. To estimate the shelf life, the study of reduction of leavening cells viability in frozen French bread dough was analyzed. This test was performed in Petri dishes containing Sabouraud agar with chloramphenicol 0.2 percent at 28°C during 5 days. The kinetics of reduction of leavening cells viability followed a first-order reaction, which rate constants were 0.027 days-1 (R²=0.931) and 0.026 day-¹ (R²=0.938) for -18°C and -40°C temperatures, respectively. For both temperatures, the 50 percent reduction in the number of leaven occurred in approximately 25 days.