Resumo Os ovos são usados como ingredientes da indústria alimentícia devido às suas propriedades funcionais. Ovos de diferentes espécies de aves podem ser usados no processamento industrial. Foram realizados experimentos reológicos em estado estacionário para obtenção das curvas de fluxo e também em estado dinâmico para estudar as propriedades reológicas dos ovos de emas Rhea americana. O comportamento viscoelástico dos fluidos em função das temperaturas de coagulação para albúmen e gema e da frequência oscilatória foi estudado. Foram analisados 15 ovos de rhea armazenados por até 28 dias a 10 °C em 1, 7, 14, 21 e 28 dias. As frações de albumina e gema mostraram comportamento reológico pseudoplástico com pequeno cisalhamento de fluxo inicial e dependência do tempo de cisalhamento, com albúmen demonstrando tixotropia e a gema mostrando reopexia. Em testes reológicos de cisalhamento baixo, observou-se gelificação térmica de albúmen, apresentando uma primeira mudança no módulo elástico em torno de 56 °C, e um segundo de 78 °C. Na gema, observou-se uma mudança a partir de 66 °C, com variações mais estruturais no desenvolvimento do gel a temperaturas mais elevadas. Para os ovos de rhea, a temperatura estruturante de gel (gelificação) de albumen (80 °C) e gema de ovo (69 °C) não sofreu variações durante os períodos de armazenamento. Em comparação com os ovos comerciais, as maiores temperaturas de viscosidade e gelificação apresentadas pelos ovos rhea podem ajudar a determinar o tamanho do sistema de processamento industrial, pois podem ser submetidos a temperaturas mais altas sem modificar estruturas proteicas e dificultar o processo.

Abstract Eggs are used as food industry ingredients due to their functional properties. Eggs from different bird species are used in industrial processing; therefore, rheological experiments were carried out at steady state to obtain the flow curves and also at a dynamic state to study the rheological properties of greater rhea eggs. The viscoelastic behavior of the fluids as a function of the coagulation temperatures for albumen and yolk and of the oscillatory shear frequency was studied. Fifteen rhea eggs stored for up to 28 days at 10 °C were analyzed at 1, 7, 14, 21, and 28 days. The albumen and yolk fractions showed pseudoplastic rheological behavior with small initial flow shear and dependence on shear time, with albumen demonstrating thixotropy and the yolk showing rheopexy. In low shear rheological tests, thermal gelation of albumen was observed, presenting a first change in the elastic modulus around 56 °C, and a second from 78 °C. In the yolk, a change was observed from 66 °C, with more structural variations in the development of the gel at higher temperatures. For rhea eggs, the gel structuring (gelation) temperature of albumen (80 °C) and egg yolk (69 °C) did not undergo variations during the storage periods. Compared to commercial eggs, the higher viscosity and gelation temperatures presented by the rhea eggs can help determine the size of the industrial processing system as they can be submitted to higher temperatures without modifying protein structures and hindering the process.

Resumo As embalagens ativas podem liberar substâncias para inibir a microbiota e as reações na superfície dos alimentos. Dentre essas substâncias a curcumina pode ser usada pois apresenta atividade antimicrobiana e antioxidante. A difusão de compostos ativos em filmes de acetato de celulose pode ser estendida por longos períodos a taxa controlada. Sua adição pode afetar as propriedades mecânicas e de barreira dos filmes, tornando-se necessário mensurar estas alterações. Assim, objetivou-se preparar filmes ativos de acetato de celulose e tween 80 incorporados com mistura simples de curcumina e nanosuspensão de curcumina e avaliar cor, propriedades mecânicas, permeabilidade ao CO2 e migração do componente ativo. A curcumina influenciou as características mecânicas, ópticas e não afetou a permeabilidade dos filmes. O tween 80 favoreceu a migração da curcumina e a redução do tamanho das partículas não aumentou a migração de curcumina.

Abstract Active packaging can release substances to inhibit microbiota and reactions on the surface of foods; among these substances, curcumin can be applied for its antimicrobial and antioxidant activity. The diffusion of active compounds in cellulose acetate films can be extended for long periods at controlled rate. The addition may affect the mechanical and barrier properties of films, requiring the measurement of the alterations. The purpose of this study was to prepare active films of cellulose acetate and tween 80 incorporated with a simple mixture of curcumin and curcumin nanosuspension as well as assess color, mechanical properties, permeability to CO2 and migration of the active component. Curcumin influenced the mechanical and optical characteristics of the films but had no effect on the permeability to CO2. Tween 80 favored the migration, and the reduction in particles size did not increase the migration of curcumin.

RESUMO Filmes biodegradáveis à base de proteínas de soro de leite apresentam grande potencial para aplicação como embalagens, devido às suas excelentes propriedades mecânicas e ópticas. Contudo, alguns processos, como a aplicação de radiação gama, podem afetar as propriedades físicas, mecânicas e cor dos filmes produzidos a partir dessas proteínas. Objetivou-se, com este estudo, produzir filmes biodegradáveis a partir de concentrado proteico de soro de leite irradiado (50 kGy) e avaliar a sua eficiência como embalagem para maçã. A aplicação de filmes elaborados com proteínas de soro de leite irradiadas não se apresentou como uma boa barreira à perda de umidade, quando submetidos à temperatura de 25 ºC e umidade relativa de 55 %, porém, é uma ótima alternativa para a preservação da cor, retardando o escurecimento da maçã após o corte.

ABSTRACT Biodegradable films from whey proteins have a great potential for application on packaging, due to their excellent mechanical and optical properties. However, some processes, such as the use of gamma radiation, can affect the physical, mechanical and color properties of films produced from these proteins. This study aimed to produce biodegradable films from irradiated whey protein concentrate (50 kGy) and evaluate their efficiency for packaging apple. The use of films prepared with irradiated whey proteins was not a good barrier to moisture loss, when subjected to a temperature of 25 ºC and relative humidity of 55 %, but it is a great alternative for color preservation, slowing the browning of apples after cutting.

Curcumin is a powerful bioactive agent and natural antioxidant, but it is practically water-insoluble and has low bioavailability; a possible solution to this obstacle would be formulations of curcumin nanoparticles. Surfactants such as tween 80 can be used to stabilize low-solubility molecules preventing particle aggregation. The objectives of this study were the preparation of a suspension with curcumin nanoparticles in tween 80, the testing of pure curcumin solubility and of a simple mixture of curcumin with tween 80 and nanosuspension in water and ethanol as solvents, and finally the assessment of the antioxidant activity. We prepared the nanosuspension by injecting a curcumin solution in dichloromethane at low flow in water with tween 80 under heating and ultrasound. The analysis of particles size was conducted through dynamic light scattering; the non-degradation of curcumin was verified through thin-layer chromatography. The analyses of antioxidant activity were carried out according to the DPPH method. The method applied to reduce the particles size was efficient. Both the curcumin suspension and nanosuspension in tween 80 increased its solubility. Curcumin and the formulations presented antioxidant activity.

The development of mold of environmental origin in honey affects its quality and leads to its deterioration, so yeasts and molds counts have been used as an important indicator of hygiene levels during its processing, transportation and storage. The aim of this study was to evaluate the levels of yeasts and molds contamination and their correlation with moisture and acidity levels in Apis mellifera L. honey from central Brazil. In 20% of the samples, the yeasts and molds counts exceeded the limit established by legislation for the marketing of honey in the MERCOSUR, while 42.8% and 5.7% presented above-standard acidity and moisture levels, respectively. Although samples showed yeasts and molds counts over 1.0 x 10² UFC.g-1, there was no correlation between moisture content and the number of microorganisms, since, in part of the samples with above-standard counts, the moisture level was below 20%. In some samples the acidity level was higher than that established by legislation, but only one sample presented a yeasts and molds count above the limit established by MERCOSUR, which would suggest the influence of the floral source on this parameter. In general, of the 35 samples analyzed, the quality was considered inadequate in 45.7% of cases.

O azeite de pequi possui coloração vermelho-alaranjada devido à presença de carotenoides. Possíveis alterações químicas nesses compostos durante o processamento podem influenciar em modificações físicas do produto que ocorrem quando este é submetido ao aquecimento. Este estudo teve como objetivo utilizar parâmetros cinéticos para avaliar a degradação de carotenoides e a alteração de cor do azeite de pequi submetido ao aquecimento em temperatura de fritura. Para avaliar o efeito do aquecimento, o azeite de pequi foi tratado termicamente a 180°C em intervalo crescente de 10 minutos até uma hora de aquecimento. Realizaram-se as análises de carotenoides totais e cor e com esses resultados determinaram-se os parâmetros cinéticos. Ao longo do aquecimento, o teor de carotenoides foi praticamente todo degradado e consequentemente a cor foi bastante alterada. A cinética de degradação dos carotenoides foi de primeira ordem e da alteração de cor foi de ordem zero. Essas cinéticas refletiram as observações visuais das amostras do azeite de pequi obtidas depois de cada tratamento.

The pequi oil has red-orange color due to carotenoids content. Possible chemical modifications on these compounds during processing may influence physical modifications to the product when this oil is submitted to heating. This study aimed to use kinetic parameters to evaluate carotenoids degradation and color change of the pequi oil submitted to heating at frying temperature. To evaluate the effect of heating, pequi oil was heated at 180°C in 10 minutes increasing intervals until one hour. Analyses were performed for total carotenoids and color and these results were used to determine kinetic parameters. Along the heating the carotenoids content was almost completed degraded and consequently, the color changed significantly. Kinetics of carotenoids degradation was of first order and the color change was of zero order. These kinetics reflected the visual observations of pequi oil samples obtained after each treatment.