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.

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.