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Estudos de bioatividade de genótipos de framboesa e produtos derivados
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As framboesas (Rubus idaeus L.) são frutos altamente perecíveis, sujeitos a perdas pós-colheita significativas devido a danos mecânicos e ao rápidodesenvolvimento fúngico. Nesse contexto, a transformação de frutos in natura não comercializáveis em produtos funcionais revela-se como estratégia sustentável para minimizar o desperdício alimentar e fomentar a economia circular. Por outro lado, as framboesas destacam-se pela riqueza em compostos fitoquímicos, cuja estabilidade ebioacessibilidade após a ingestão podem ser comprometidas pela interação com a matriz alimentar e pelas condições do trato gastrointestinal. Este trabalho propõe o desenvolvimento de um doce hipocalórico de framboesa,utilizando pectina de baixo metoxilo (LMP) como agente gelificante, com o duplo objetivo de proteger e preservar a bioacessibilidade dos fitoquímicos relevantes e reduzir significativamente o teor de açúcar, sem adição de iões de cálcio – uma vez que a framboesa apresenta teores adequados deste ião – ou outros aditivos gelificantes, obtendo-se assim uma formulação “clean label”, mais natural e alinhada com as tendências atuais de consumo saudável. Para a formulação do doce optou-se pelo genótipo ‘id. A’ por se tratar de uma cultivar já comercializada, em contraste à ‘id. B’ que, embora promissor, ainda se encontra em fase de desenvolvimento no programa de melhoramento genético. Para tal, delinearam-se dois ensaios experimentais complementares: (i) caracterização e bioatividade de um novo genótipo de framboesa resultante de melhoramento genético face a uma cultivar comercial, e (ii) desenvolvimento de um doce hipocalórico (2,5% de LMP e 12,7% de açúcar) face a um doce tradicional (relação fruta-açúcar, 1:1), caracterizando-os com base nos parâmetros avaliados para a matéria-prima, bem como, avaliação reológica, avaliação da estabilidade microbiológica e apreciação sensorial. Os resultados indicaram que a incorporação de pectina de baixo metoxilo conferiu ao doce hipocalórico uma textura agradável, assegurando simultaneamente a libertação controlada dos polifenóis durante a digestão simulada. Além disso, a redução do teor de açúcar não comprometeu as propriedades sensoriais, demonstrando o potencial de valorização de excedentes de produção com o desenvolvimento de formulações saudáveis e inovadoras.
Raspberries (Rubus idaeus L.) are highly perishable fruits, prone to significant post-harvest losses due to mechanical damage and rapid fungal development. In this context, the transformation of unmarketable fresh fruit into functional products emerges as a sustainable strategy to minimize food waste and promote a circular economy. Moreover, raspberries are notable for their richness in phytochemical compounds, whose stability and bioaccessibility after ingestion may be affected by interactions with the food matrix and the conditions of the gastrointestinal tract. This study aims to develop a low-calorie raspberry jam, using low-methoxyl pectin (LMP) as a gelling agent, with the dual objective of protecting and preserving the bioaccessibility of relevant phytochemicals while significantly reducing sugar content – without the addition of calcium ions – since raspberries naturally contain adequate levels of this ion – or other gelling additives, thus achieving a more natural “clean label” formulation in line with current healthy consumption trends. For the formulation of the jam, the ‘id. A’ genotype was selected due to its current commercial use, in contrast with ‘id. B’, which, although promising, is still under development within a genetic improvement program. Two complementary experimental trials were conducted: (i) characterization and bioactivity assessment of a new raspberry genotype developed through genetic improvement, compared with a commercial cultivar, and (ii) development of a low-calorie jam (2.5% LMP and 12.7% sugar) in comparison with a traditional jam (fruit-to-sugar ratio 1:1), characterizing both based on the parameters evaluated for the raw material, as well as rheological assessment, microbiological stability analysis, and sensory evaluation. Results showed that the incorporation of low-methoxyl pectin resulted in a lowcalorie jam with a pleasant texture, while enabling controlled release of polyphenols during simulated digestion. Furthermore, the reduction in sugar content did not compromise sensory properties, demonstrating the potential for valorising surplus production through healthy and innovative formulations.
Raspberries (Rubus idaeus L.) are highly perishable fruits, prone to significant post-harvest losses due to mechanical damage and rapid fungal development. In this context, the transformation of unmarketable fresh fruit into functional products emerges as a sustainable strategy to minimize food waste and promote a circular economy. Moreover, raspberries are notable for their richness in phytochemical compounds, whose stability and bioaccessibility after ingestion may be affected by interactions with the food matrix and the conditions of the gastrointestinal tract. This study aims to develop a low-calorie raspberry jam, using low-methoxyl pectin (LMP) as a gelling agent, with the dual objective of protecting and preserving the bioaccessibility of relevant phytochemicals while significantly reducing sugar content – without the addition of calcium ions – since raspberries naturally contain adequate levels of this ion – or other gelling additives, thus achieving a more natural “clean label” formulation in line with current healthy consumption trends. For the formulation of the jam, the ‘id. A’ genotype was selected due to its current commercial use, in contrast with ‘id. B’, which, although promising, is still under development within a genetic improvement program. Two complementary experimental trials were conducted: (i) characterization and bioactivity assessment of a new raspberry genotype developed through genetic improvement, compared with a commercial cultivar, and (ii) development of a low-calorie jam (2.5% LMP and 12.7% sugar) in comparison with a traditional jam (fruit-to-sugar ratio 1:1), characterizing both based on the parameters evaluated for the raw material, as well as rheological assessment, microbiological stability analysis, and sensory evaluation. Results showed that the incorporation of low-methoxyl pectin resulted in a lowcalorie jam with a pleasant texture, while enabling controlled release of polyphenols during simulated digestion. Furthermore, the reduction in sugar content did not compromise sensory properties, demonstrating the potential for valorising surplus production through healthy and innovative formulations.
Descrição
Dissertação de Mestrado, Engenharia Alimentar, 2025, Universidade de Lisboa, Instituto Superior de Agronomia.
Palavras-chave
pequenos frutos bioacessibilidade fitoquímicos pectina de baixo metoxilo desenvolvimento de novos produtos small fruits bioaccessibility phytochemicals low-methoxyl pectin new product development