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The composition and fine structure of pectins found in plant cell walls are heterogeneous, with striking differences, depending on their source, and this eventually determines their functional and technological properties. The aim of this study was to extract and determine the chemical composition and physicochemical properties of pectins from different sources: passion fruit peel, orange pomace, and soy hull. Pectin extraction was performed with heated hydrochloric acid solution, followed by precipitation with 96% ethanol. Extraction yield, chemical composition, molar mass, physicochemical properties (fat absorption capacity, cation exchange capacity, water holding capacity, and antioxidant activity) of pectin were measured. Pectin extraction efficiency was higher for passion fruit peel and orange pomace (15.71 and 17.96%, respectively). Soy hull had low pectin extraction (5.66%). Galacturonic acid content was 23.21% for passion fruit peel pectin and 16.01% for orange pomace pectin. Water holding capacity, fat absorption capacity, and cation-binding capacity present in pectin extracted from passion fruit peel were higher, suggesting this poorly investigated product could be used as thickening and emulsifying agents in food preparations. Phenolic compounds with antioxidant capacity provide pectins with additional properties and expand their industrial use.

Orange firmness, peel thickness, and total pectin content are associated with fruit quality and denote important parameters for the food industry. These attributes are usually determined through destructive methods that can be time-consuming and also unable to monitor fruit quality over time. Therefore, non-invasive methods such time-domain nuclear magnetic resonance (TD-NMR), near-infrared (NIR), and mid-infrared (MIR) spectroscopies may represent efficient alternatives to evaluate these quality attributes. In this work, partial least square regression (PLSR) models of TD-NMR relaxometry as well as NIR and MIR spectroscopic data were used to predict firmness, peel thickness, and total pectin content of fresh Valencia oranges. Principal component analyses (PCA) were applied to explain the correlations of orange ripening stage, flowering, and crop season with its physicochemical parameters. Data obtained through standard destructive methods were used to calibrate and validate the PLSR models. NIR and MIR showed the best PLSR models for orange firmness, with Pearson correlation coefficients (r) of 0.92 and 0.84 and squared errors of prediction (SEP) equal to 6.22 and 9.05 N, respectively. Orange peel thickness PLSR model was validated only by TD-NMR (r = 0.72; SEP = 0.49 mm). TD-NMR and NIR also presented potential to predict total pectin orange in orange (r = 0.76 and 0.70; SEP = 5.76% and 5.04%, respectively). Therefore, NIR presented a higher potential to predict orange firmness than MIR and TD-NMR. On the other hand, TD-NMR showed a higher prediction power concerning peel thickness than NIR and MIR. Both NIR and TD-NMR methods showed similar prediction powers for total pectin content.

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O objetivo deste trabalho foi avaliar a qualidade nutricional e sensorial de pães de mel enriquecidos com farinhas de bagaço de maçã, de bagaço de laranja e de casca de maracujá. Com o intuito de viabilizar o uso desses ingredientes alternativos e de baixo custo como fontes de fi bra alimentar testou-se a substituição de 15 % da farinha de trigo da formulação padrão pelas farinhas dos respectivos subprodutos de frutas. As formulações teste apresentaram alto teor de fi bra alimentar, especialmente da fração solúvel, maior umidade e reduzido valor calórico. A formulação adicionada de bagaço de maçã destacou-se entre as demais pelo aporte signifi cativamente superior de fi bra (9,61 %). Os resultados obtidos na análise sensorial dos pães indicaram boa aceitabilidade desses produtos para todos os parâmetros sensoriais avaliados (cor, aroma, sabor e textura), perfazendo índice médio de aceitação global entre 77,4 % e 80,3 %. Além disso, verifi cou-se intenção de compra positiva, com 39,3 % a 44,6 % das respostas concentradas no termo hedônico "possivelmente compraria", sem diferença signifi cativa entre as formulações teste. Os resultados indicaram a possibilidade de uso desses subprodutos de frutas como ingredientes fi brosos para serem usados na formulação de produtos alimentícios diferenciados, como o pão de mel, por melhorarem signifi cativamente o aporte de fi bras (principalmente em relação à fração solúvel), o que contribuirá para o combate do desperdício de nutrientes potenciais e para a promoção da saúde do consumidor.