Influência da refrigeração e do uso de biofilme de fécula de mandioca sobre escurecimento enzimático em frutos de mangaba

The aim of this study was to assess the influence of heat treatment on physicochemical and rheological characteristics of natural yogurts, as well as the influence of lyophilization process on natural yogurts after reconstitution. In the first experiment, three yogurt treatments were processed, as follows: Treatment 1, yogurt produced with raw refrigerated milk; Treatment 2, yogurt produced with refrigerated pasteurized milk; and Treatment 3, yogurt produced with UHT (ultra-high temperature) milk, in addition to analyses of fat, protein, moisture, titratable acidity, and pH. The shelf life of yogurts at 1, 8, 15, 22, and 29 days of storage, as well as pH, acidity, syneresis, viscosity, viable lactic bacteria, and total coliforms were also assessed. In the second experiment, yogurts were submitted to lyophilization process, performed by scanning electron microscopy analysis and subsequently in those reconstituted, in addition to being assessed the physicochemical, rheological, and viable lactic bacteria characteristics. The results found in the first experiment showed that heat treatment was positive for viscosity, syneresis, and lactic bacteria, being viable until the 15th day of storage only for yogurts submitted to heat treatment. In the second experiment, lyophilization preserved the physicochemical characteristics of yogurts, but the number of initial lactic bacteria was different, also negatively affecting yogurt viscosity. Key words: Acidity. Viable lactic cells. Lyophilization. pH. Shelf life. ResumoObjetivou-se avaliar a influência do tratamento térmico nas características físico-químicas e reológicas de iogurtes naturais e a influência do processo de liofilização em iogurtes naturais após sua reconstituição. No primeiro experimento, foram processados três tratamentos de iogurtes Tratamento 1 -iogurte produzido com leite cru refrigerado; Tratamento 2 -iogurte produzido com leite pasteurizado refrigerado; Tratamento 3 -iogurte produzido com leite UAT (Ultra Alta Temperatura) e feitas as análises de gordura, proteína, umidade, acidez titulável e pH. Avaliou-se também a vida de prateleira dos iogurtes nos tempos 1, 8, 15, 22 e 29 dias de armazenamento, tendo sido feitas as análises de pH, acidez, sinérese, viscosidade, bactérias lácticas viáveis e coliformes totais. No experimento II, os iogurtes foram submetidos ao processo de liofilização realizado analise de microscopia eletrônica de varredura

The objective was to produce flour from sorghum grains, to determine the physicochemical and microbiological characteristics, and to develop different formulations of cookies, with total and partial replacement of rice flour, evaluating the moisture content, color, expansion factor and texture profile -TPA. Five formulations were processed, as follows: control -0%; F1 -25%; F2 -50%; F3 -75% and F4 -100% sorghum flour. The sorghum flour showed physical, chemical and microbiological characteristics in accordance with current legislation, and can be inserted into human food. The different cookie formulations after baking had a moisture content below 7%. With the addition of sorghum flour, the cookies showed lower light F4 -32.35 L*. The addition of sorghum flour did not affect the expansion factor of the cookies, with average value of 2.13. The different concentrations of sorghum flour, showed interference in analysis of the Texture-TPA profile, the F3 formulation, presented higher values of hardness 25594.44 N, fracturability 251 N, cohesiveness 0.27. Elasticity has not been compromised. The highest values of gumminess 53.08 N, chewability 1471.15 mJ were found in the formulation F4 -100% FS. These results may help improve the quality of sorghum-based gluten-free foods for celiac consumers.

The aim of this study is to evaluate the effect of whey storage period (0, 24, 48 and 72 h) on the physicochemical parameters, color, texture and microstructure of fresh ricotta during storage. Sweet whey and acid whey were evaluated based on titratable acidity, pH, fat, cryoscopy, and density, while ricotta was based on yield, fat, protein, ash, acidity, pH, moisture, total solids, color, texture, and microstructure. This was done with analysis of variance in a completely randomized design using Tukey test at 5% probability. Whey pH values increased with storage time. Ricotta made with stored whey had average yield of 5.33%, with decreased fat content and pH, and increased acidity. There were subtle differences in color and texture of ricotta during storage; its hardness and gumminess decreased, resulting in microstructure compression. It is concluded that the production of ricotta with whey stored for up to 72 h makes the product appropriate for consumption.

Condiments and culinary supplements are subjected to long-term storage and may undergo physical, chemical, and biological changes that can influence their quality. Thus, the objective of the present study was to analyze the drying kinetics of rose pepper (Schinus terebinthifolius Raddi) fruits in an oven with forced air circulation at different temperatures, namely, 45, 55, 65, and 75°C, and determine the effective diffusion coefficient and activation energy using different mathematical models. Furthermore, the effects of the different drying temperatures were analyzed for external color parameters and yield of essential oil contents by gas chromatography coupled to a mass spectrometer. Of the ten models used for fitting, Thompson’s model was one with the best fitting to represent the drying of rose pepper fruits. The diffusion coefficient increases with the elevation of drying air temperature, described by the Arrhenius equation, with activation energy of 53.579 kJ·mol−1. The color of the fruits decreased in lightness (L ∗ ) with the increase in temperature. Of the thirty-eight terpenes identified, α-pinene and cis-ocimene were the most abundant, with the overall highest yield being found at a drying temperature of 45°C.

Evaluate texture in relation to the hardness, fracturability, cohesiveness, elasticity and chewiness parameters of Brazil nut kernels stored in different packagings over time of 240 days. The experimental compression tests were conducted in 15 kernels for each treatment using a texturometer equipped with a load cell of 25 kg. The following parameters were used: pre-test speed: 2.0 mm s -1 ; test speed: 0.50 mm s -1 and post-test speed: 0.50 mm s -1 ; 10% compression and rest period of 2 s between the two cycles; initial load of 7 g; and data acquisition rate of 10 points per second. The data were subjected to analysis of variance (ANOVA), followed by the Scott-Knott test at 5% significance level, using R software. Storage time interfered in the moisture content, leading to the highest value initially, 4.03% w.b., and lowest value at 120 days, with an average of 2.705% w.b. The hardness values of the kernels stored in the polypropylene packaging remained the same throughout storage. The different packagings and storage times had no influence on the fracturability parameter. Polypropylene and vacuum packaging did not influence the elasticity of kernels throughout storage. Cohesiveness and chewiness showed differences between the packagings and between the storage periods.

The aim of this study was to assess the influence of heat treatment on physicochemical and rheological characteristics of natural yogurts, as well as the influence of lyophilization process on natural yogurts after reconstitution. In the first experiment, three yogurt treatments were processed, as follows: Treatment 1, yogurt produced with raw refrigerated milk; Treatment 2, yogurt produced with refrigerated pasteurized milk; and Treatment 3, yogurt produced with UHT (ultra-high temperature) milk, in addition to analyses of fat, protein, moisture, titratable acidity, and pH. The shelf life of yogurts at 1, 8, 15, 22, and 29 days of storage, as well as pH, acidity, syneresis, viscosity, viable lactic bacteria, and total coliforms were also assessed. In the second experiment, yogurts were submitted to lyophilization process, performed by scanning electron microscopy analysis and subsequently in those reconstituted, in addition to being assessed the physicochemical, rheological, and viable lactic bacteria characteristics. The results found in the first experiment showed that heat treatment was positive for viscosity, syneresis, and lactic bacteria, being viable until the 15th day of storage only for yogurts submitted to heat treatment. In the second experiment, lyophilization preserved the physicochemical characteristics of yogurts, but the number of initial lactic bacteria was different, also negatively affecting yogurt viscosity.

Jambu is a vegetable originally from the northern region of Brazil, has bioactive properties, being little explored by other regions, due to its high peresivity. And one of the methods to increase the shelf life of plant products is the removal of water. The objective of this work was to evaluate the drying kinetics of jambu leaf mass. Two treatments were carried out: The mass of fresh jambu leaves and the mass of fresh jambu leaves with the addition of drying foam, both submitted in an oven with forced air circulation at temperatures (50, 60 and 70 °C and thickness of 1.0 cm). The proximate composition of the materials was performed before and after drying. Twelve mathematical models were tested on drying kinetics data and thermodynamic properties were calculated. The parameters of the proximate composition for the mass of leaves and foam after drying were: Moisture content of (2 to 7%), ash content of (13 to 17%), protein content of (22 to 30%), lipids of (0.6 to 4%) and total titratable acidity (0.20 to 0.28%) of tartaric acid. The models that best fit the experimental data to describe the drying kinetics of jambu masses were: Wang & Singh. The use of foam mat presented higher values of effective diffusion coefficient and activation energy and lower values of enthalpy and entropy, reducing the drying time.