Abstract This work aims to evaluate the starch/water concentrations (3.6%, 7.1%, 10.7% and 14.3%) effect of different commercial starch sources (namely cassava, maize, high-amylose maize, waxy maize and potato) regarding their pasting properties by using a Rapid Visco Analyser (RVA), gel strength, and intrinsic characteristics (such as morphology, granules size and distribution). The results showed that the 10.7% concentration (standard concentration usually used for evaluating starch properties) is not always predictive for the starches rheological behaviour. Meanwhile, the characteristics of the formed gels were not only related to RVA properties. For instance, decisions based on the results using the concentration of 10.7% can be far different from those used in industrial applications. The data reported can be useful to demonstrate how conditions, properties and starches characteristics are correlated, also to facilitate the selection of the best conditions that are closer to the desired application.

Enzymes are protein complexes compounds widely studied and used due to their ability to catalyze reactions. The food processing mainly aims the inactivation of enzymes due to various undesirable effects. However, there are many processes that can be optimized by its catalytic activity. In this context, different technologies have been applied both to inactivate or to improve the enzymes efficiency. The Ultrasound technology emerges as an alternative mainly applied to achieve the enzyme inactivation. On the contrary, very few investigations show the ability of this technology under certain conditions to achieve the opposite effect (i.e. increase the catalytic activity of enzymes). The objective of this study was to correlate the ultrasonic energy delivered to the sample (J/mL) with the residual enzymatic activity and explain the possible mechanisms which results in the enzymatic activation/inactivation complex behavior. The activity of POD in coconut water was evaluated as a model. The enzymatic activity initially increased, followed by reduction with a trend to enzyme inactivation. This complex behavior is directly related to the applied ultrasonic energy and their direct mechanical effects on the product, as well as the effect in the enzymatic infinite intermediate states and its structural conformation changes. The obtained results are useful for both academic and industrial perspectives.

In the present study, the efficacy of ozone inactivation of B. subtilis spores and E. coli in cassava starch was evaluated. Cassava starch with 18 and 30% moisture content was processed with ozone at concentrations of 40-118 ppm and exposure times of 15-120 minutes. The processing at 113 ppm/120 minutes (maximum exposure level to ozone evaluated) at 18% of moisture content did not cause significant reduction of B. subtilis spores and caused the reduction of only 2 decimal of E. coli. On the other hand, when the ozonation process was carried out for 120 minutes at 30% of moisture content, 3.6 decimal reduction of B. subtilis was achieved at 40 ppm of ozone and total B. subtilis load reduction (>5 log cycles) was observed at 118 ppm of ozone. Similarly, total E. coli load reduction (>7 log cycles) was achieved at 40 ppm of ozone exposure for 60 minutes. Therefore, the results indicate that the ozone efficacy against microorganisms in cassava starch was mainly dependent on the sample moisture content and to ozone concentration and exposure time. Moreover, it was observed that ozone is a promising technology to reduce microbial counts in dried food.

O processamento de alimentos deve garantir segurança e qualidade a um consumidor cada vez mais exigente, criando a necessidade de melhor entendimento das operações unitárias envolvidas nessa produção. A fluidodinâmica computacional (CFD) tem sido bastante usada para entendimento de processos térmicos de alimentos, ainda o método mais seguro e utilizado para conservação de alimentos. Mesmo assim, nenhum estudo da literatura descreve o processo térmico de alimentos líquidos em embalagens com geometria prismático retangular. O presente trabalho avaliou tal processo, assim como a influência da orientação da embalagem na eficiência do processo, demonstrando o potencial da utilização da CFD na avaliação de processos térmicos de alimentos líquidos, assim como a importância das propriedades reológicas e da convecção natural na eficiência deles. Além disso, mostrou que a orientação da embalagem não resulta em diferenças na eficiência do processo avaliado.

Food processes must ensure safety and high-quality products for a growing demand consumer creating the need for better knowledge of its unit operations. The Computational Fluid Dynamics (CFD) has been widely used for better understanding the food thermal processes, and it is one of the safest and most frequently used methods for food preservation. However, there is no single study in the literature describing thermal process of liquid foods in a brick shaped package. The present study evaluated such process and the influence of its orientation on the process lethality. It demonstrated the potential of using CFD to evaluate thermal processes of liquid foods and the importance of rheological characterization and convection in thermal processing of liquid foods. It also showed that packaging orientation does not result in different sterilization values during thermal process of the evaluated fluids in the brick shaped package.

A tecnologia de homogeneização a alta pressão (HAP) tem sido estudada por diversos autores como metodologia não térmica para a conservação de alimentos líquidos. Entretanto, o perfil do fluido durante o processo, assim como os mecanismos de inativação e rompimento celular, ainda não estão totalmente elucidados. O presente trabalho avaliou o escoamento de leite desnatado durante HAP por meio de fluidodinâmica computacional (CFD). Consideraram-se pressões de homogeneização de até 300 MPa, sendo avaliados os perfis de pressão e velocidade do fluido durante o processo. Os resultados obtidos demonstram que as tensões de cisalhamento resultantes do escoamento do fluido dentro do gap e a cavitação na saída do mesmo são os mecanismos mais prováveis para inativação microbiana no homogeneizador avaliado.

High pressure homogenization (HPH) technology has been studied by various authors as a non-thermal process for liquid food preservation. However, the fluid characteristics during processing, as also the cell inactivation and disruption mechanisms have still not been totally elucidated. The present work evaluated the flow of skimmed milk during HPH using computational fluid dynamics (CFD). The homogenization pressure was varied up to 300 MPa and the pressure and velocity profiles evaluated during the process. The results obtained showed that the shear stress due to the flow of the liquid inside the gap and the cavitation on exiting, are the most probable mechanisms of microbial inactivation in the homogenizer evaluated.

A pasteurização dentro da embalagem é o método mais usado para a estabilização microbiológica de cervejas. A crescente busca por alimentos mais seguros e de melhor qualidade cria a necessidade de melhor entendimento dos processos envolvidos na sua produção. Entretanto, pouco se conhece sobre os perfis de temperatura e velocidade durante o tratamento térmico de alimentos líquidos em embalagens comerciais, muitas vezes resultando em processos superdimensionados como garantia de segurança, porém comprometendo características sensoriais e nutricionais do produto e custos do processo. Simulações por fluidodinâmica computacional (CFD) têm sido usadas por vários autores na avaliação desses processos. O presente trabalho teve como objetivo avaliar o efeito da orientação da embalagem na pasteurização de cerveja em uma lata comercial de alumínio por meio de CFD. Simulou-se aquecimento a 60 ºC até 15 UPs (processo convencional de pasteurização em cervejas, em que 1 unidade de pasteurização (UP) equivale a 1 minuto a 60 ºC). Avaliou-se o perfil de temperatura e velocidade das correntes de convecção ao longo do processo e a variação das UPs em relação ao tempo, considerando as latas na posição convencional, invertida e horizontal. Os perfis de temperatura e velocidade mostraram-se adequados ao esperado segundo dados da literatura. Ao contrário da esterilização de alimentos líquidos consistentes em latas cônicas, a orientação da embalagem não resultou em melhoria no processo.

In-package pasteurization is the most used method for beer microbiological stabilization. The search for safer and better quality food has created a need to better understand the processes involved in producing it. However, little is known about the temperature and velocity profiles during the thermal processes of liquid foods in commercial packaging, which results in over-dimensioned processes to guarantee safety, decreasing the sensorial and nutritional characteristics of the product and increasing process costs. Simulations using Computational Fluid-Dynamics (CFD) have been used by various authors to evaluate those processes. The objective of the present paper was to evaluate the effect of packaging orientation in the pasteurization of beer in a commercial aluminum can using CFD. A heating process was simulated at 60 ºC up to 15 PUs (a conventional beer process, in which 1 Pasteurization Unit (PU) is equivalent to 1minute at 60 ºC). The temperature profile and convection current velocity along the process and the variation of the PUs were evaluated in relation to time considering the cans in the conventional, inverted, and horizontal positions. The temperature and velocity profiles were similar to those presented in the literature. The package position did not result in process improvement.