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Abstract(s)
A inovação no mercado alimentar tem sido associada à procura de alimentos seguros e nutritivos que previnam ou controlem doenças, promovendo a saúde e a qualidade de vida. Portanto, é imperativo que as empresas alimentares criem novos produtos baseados em ingredientes e formulações inovadoras. Revestimentos e filmes comestíveis elaborados a partir de proteínas do soro surgem como uma alternativa às embalagens convencionais, sendo uma valorização sustentável de subprodutos da indústria alimentar.
Neste sentido, o principal objetivo deste programa de doutoramento foi o desenvolvimento e caracterização de revestimentos e filmes bioativos comestíveis, feitos a partir de proteína de isolada de soro (PIS) ou alginato (ALG), incorporados com bactérias probióticas e prebióticos para melhorar o valor funcional, qualidade e segurança dos alimentos.
Assim, na primeira secção, foi realizada a incorporação e avaliada a estabilidade de Bifidobacterium animalis subsp. lactis BB-12 e Lactobacillus casei 01 em filmes comestíveis de PIS. Os filmes foram avaliados ao longo de 60 dias a 23 e 4 °C, e os resultados mostraram que as células viáveis permaneceram elevadas, atingindo 106 unidades formadoras de colonias (UFC)/g. A B. animalis subsp. lactis BB-12 permitiu maiores contagens viáveis durante o período de armazenamento. Além disso, as propriedades físicas cor, atividade da água, espessura, textura e estrutura molecular foram avaliadas e permaneceram estáveis durante todo o período de armazenamento em ambas as temperaturas. Para corroborar esta afirmação, os filmes foram usados para revestir fatias de fiambre, para entender se estes eram capazes de manter a viabilidade probiótica e conferir eficiência antimicrobiana, promover a preservação de fiambre e, eventualmente, aumentar o seu prazo de validade. Estes revestimentos comestíveis inibiram o crescimento detetável de Staphylococcus spp., Pseudomonas spp., Enterobacteriaceae e leveduras/bolores durante 45 dias de armazenamento, a 4 °C. As fatias de fiambre revestidas perderam menos água e não mostraram alteração de cor em comparação com fatias não revestidas. Uma avaliação sensorial revelou uma preferência pelo fiambre revestido em comparação com o fiambre tradicional. No final do
Resumo
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armazenamento, o número de células viáveis foi mantido a 108 UFC/g sugerindo que o fiambre fatiado é um transportador adequado para as estirpes probióticas até após 45 dias de armazenamento.
Na segunda secção, foi avaliada a viabilidade de B. animalis subsp. lactis BB-12 em filmes de PIS e ALG incorporando prebióticos (inulina e fructooligosacarídeos (FOS)), a 23 ºC durante 60 dias. A incorporação do prebiótico melhorou a sobrevivência de B. animalis subsp. lactis BB-12, mantendo-o a ca. 106 UFC/g até ao final do armazenamento, com a inulina a apresentar os melhores resultados. A análise estrutural não demonstrou diferenças entre os filmes sem e com prebióticos e probióticos. Além disso, o teor de humidade e a solubilidade em água diminuíram com a incorporação de prebióticos.
Como prova de conceito, uma barra de cereais foi desenvolvida com os revestimentos comestíveis com B. animalis subsp. lactis BB-12 e inulina, e a aceitabilidade do consumidor, as propriedades físico-químicas e microbiológicas foram avaliadas durante 90 dias de armazenamento. A PIS foi a melhor solução de revestimento mantendo a viabilidade celular em barras de cereais durante o armazenamento e após a digestão in vitro. Durante todo o período de armazenamento, as propriedades físico-químicas de todos os tipos de barras não mudaram. No entanto, as barras revestidas apresentaram valores mais altos de atividade da água e teor de humidade comparativamente às barras não revestidas. Cor e textura não foram afetadas após o revestimento das barras. Os parâmetros sensoriais mostraram que as barras revestidas foram tão bem aceites como as barras controlo. Além disso, os consumidores apreciaram mais o odor e o sabor das barras revestidas com PIS do que as barras revestidas com ALG.
No geral, com base neste projeto, conseguimos obter revestimentos comestíveis e filmes à base de proteínas de soro com probióticos, que também podem conter prebióticos na sua composição, para garantir a estabilidade dos probióticos, a segurança dos alimentos e o aumento do nível nutricional e funcional dos mesmos. Além disso, a indústria de embalagens pode rever estratégias para vender embalagens comestíveis e biodegradáveis, assim como a indústria alimentar pode aumentar a vida útil dos seus alimentos, mantendo-os seguros e tornando-os funcionais.
Innovation in food industry has been linked to the search for safe and nutritional foods that prevent or control disease, promoting health and quality of life. So, it is imperative that the food industry creates novel products based on innovative ingredients and formulations. Edible coatings and films made from whey proteins appear as an alternative answer to the consumer’s demand and represent a sustainable valorization of the food industry by-products. In this sense, the main objective of this doctoral program was the development and characterization of bioactive edible coatings and films, made from whey protein isolate (WPI) or alginate (ALG), incorporated with functional bacteria and prebiotics to improve the functional value, quality and safety of food products. In the first section, the incorporation and stability of Bifidobacterium animalis subsp. lactis BB-12 and Lactobacillus casei 01 in WPI edible films was evaluated. Films were evaluated throughout 60 days at 23 and 4 °C, showing that the viable cells remained high, reaching 106 colony forming units (CFU)/g. B. animalis subsp. lactis BB-12 was found in higher viable counts during the storage period. In addition, the films physical properties like color, water activity, thickness, texture and molecular structure were evaluated and remained stable throughout the storage period, at both temperatures. To corroborate this assertion, the films were used to coat slices of ham to understand if they were able to maintain probiotic viability and confer antimicrobial efficiency, promote sliced ham preservation and eventually increase its shelf-life. These edible coatings inhibited the detectable growth of Staphylococcus spp., Pseudomonas spp., Enterobacteriaceae and yeast/molds during 45 days of storage at 4 °C. Coated sliced ham lost less water and exhibited no color change compared to uncoated slices. A sensory evaluation revealed a preference for the coated ham compared to the traditional, uncoated one. By the end of storage, viable cell numbers were maintained at 108 CFU/g suggesting that the sliced ham is a suitable carrier for probiotic strains even after 45 days of storage. Abstract X In the second section, the viability of B. animalis subsp. lactis BB-12 in WPI and ALG films incorporated with prebiotics (inulin and fructooligosaccharides (FOS), at 23 ºC for 60 days was assessed. The incorporation of prebiotic compounds improved the survival of B. animalis subsp. lactis BB-12 viability, with inulin showing the best performance, as it maintained the viability at 107 CFU/g. The structural analyzes demonstrated no differences between films without and with prebiotics and probiotics. Furthermore, moisture content and water solubility decreased with prebiotics incorporation. As proof of concept, a cereal bar was developed with an edible coating which included B. animalis subsp. lactis BB-12 and inulin, and the consumer's acceptability and physicochemical and microbiological properties were evaluated during 90 days of storage. WPI was the best coating solution maintaining cell viability in cereal bars during storage and after in vitro digestion. Throughout the storage period, physicochemical properties of uncoated, WPI and ALG bars did not change. However, coated bars showed higher values of water activity and moisture content comparatively to uncoated bars. Color and texture were not affected after coating the bars. The sensory parameters showed that the coated bars were as well accepted as the control ones. In addition, consumers appreciated more the odor and flavor of WPI coated bars than ALG coated bars. Overall, based on this project, we were able to obtain whey proteins based edible coatings and films with probiotics, which may also contain prebiotics in their composition that assure the stability of probiotics, the safety of food, and increasing nutritional and functional capacity of the food. Additionally, the packaging industry can review their strategies for selling edible and biodegradable packaging, as well as the food industry can increase food shelf-life of their food, keeping safety and turning them functional. Acknowledgements
Innovation in food industry has been linked to the search for safe and nutritional foods that prevent or control disease, promoting health and quality of life. So, it is imperative that the food industry creates novel products based on innovative ingredients and formulations. Edible coatings and films made from whey proteins appear as an alternative answer to the consumer’s demand and represent a sustainable valorization of the food industry by-products. In this sense, the main objective of this doctoral program was the development and characterization of bioactive edible coatings and films, made from whey protein isolate (WPI) or alginate (ALG), incorporated with functional bacteria and prebiotics to improve the functional value, quality and safety of food products. In the first section, the incorporation and stability of Bifidobacterium animalis subsp. lactis BB-12 and Lactobacillus casei 01 in WPI edible films was evaluated. Films were evaluated throughout 60 days at 23 and 4 °C, showing that the viable cells remained high, reaching 106 colony forming units (CFU)/g. B. animalis subsp. lactis BB-12 was found in higher viable counts during the storage period. In addition, the films physical properties like color, water activity, thickness, texture and molecular structure were evaluated and remained stable throughout the storage period, at both temperatures. To corroborate this assertion, the films were used to coat slices of ham to understand if they were able to maintain probiotic viability and confer antimicrobial efficiency, promote sliced ham preservation and eventually increase its shelf-life. These edible coatings inhibited the detectable growth of Staphylococcus spp., Pseudomonas spp., Enterobacteriaceae and yeast/molds during 45 days of storage at 4 °C. Coated sliced ham lost less water and exhibited no color change compared to uncoated slices. A sensory evaluation revealed a preference for the coated ham compared to the traditional, uncoated one. By the end of storage, viable cell numbers were maintained at 108 CFU/g suggesting that the sliced ham is a suitable carrier for probiotic strains even after 45 days of storage. Abstract X In the second section, the viability of B. animalis subsp. lactis BB-12 in WPI and ALG films incorporated with prebiotics (inulin and fructooligosaccharides (FOS), at 23 ºC for 60 days was assessed. The incorporation of prebiotic compounds improved the survival of B. animalis subsp. lactis BB-12 viability, with inulin showing the best performance, as it maintained the viability at 107 CFU/g. The structural analyzes demonstrated no differences between films without and with prebiotics and probiotics. Furthermore, moisture content and water solubility decreased with prebiotics incorporation. As proof of concept, a cereal bar was developed with an edible coating which included B. animalis subsp. lactis BB-12 and inulin, and the consumer's acceptability and physicochemical and microbiological properties were evaluated during 90 days of storage. WPI was the best coating solution maintaining cell viability in cereal bars during storage and after in vitro digestion. Throughout the storage period, physicochemical properties of uncoated, WPI and ALG bars did not change. However, coated bars showed higher values of water activity and moisture content comparatively to uncoated bars. Color and texture were not affected after coating the bars. The sensory parameters showed that the coated bars were as well accepted as the control ones. In addition, consumers appreciated more the odor and flavor of WPI coated bars than ALG coated bars. Overall, based on this project, we were able to obtain whey proteins based edible coatings and films with probiotics, which may also contain prebiotics in their composition that assure the stability of probiotics, the safety of food, and increasing nutritional and functional capacity of the food. Additionally, the packaging industry can review their strategies for selling edible and biodegradable packaging, as well as the food industry can increase food shelf-life of their food, keeping safety and turning them functional. Acknowledgements