From By-Product to Value-Added Ingredient: Incorporation of Bilberry Pomace in Wheat Bread
Arnoldas Keibas, Laura Jūrienė, Petras Rimantas Venskutonis
Department of Food Science and Technology, Kaunas University of Technology, Lithuania
Keywords: bilberry pomace, Vaccinium myrtillus, bread, nutritional improvement, quality improvement
Abstract:
Bilberries are recognised for their high dietary fibre and bioactive compound content, which contribute to human health. However, their limited shelf life leads to processing into juices, jams, and beverages, which generate substantial by-products such as skins, seeds, and pulp. These residues, often discarded, are rich in valuable constituents. Bilberry pomace, in particular, contains anthocyanins, flavonols, phenolic acids, fibre, vitamins, and polyunsaturated fatty acids, which enhance antioxidant activity and nutritional value. Instead of being treated as waste, bilberry pomace is seen as a promising resource for developing functional foods, dietary supplements, and pharmaceutical applications.
This study explores the potential of bilberry (Vaccinium myrtillus L.) pomace as a functional ingredient of bread, aiming to enhance its nutritional, biological, and quality attributes. Both defatted pomace from juice pressing (M2) and purée production (M4) and non-defatted pomace from purée production (M3) were incorporated into French-style wheat bread formulations by substituting 5%, 7.5%, and 10% of the flour accordingly. Bread quality was evaluated through measurements of volume, weight, crumb porosity, and moisture content, while antioxidant activity was determined using the QUENCHER method (TPC, ABTS+ ﮲).
Incorporation of bilberry pomace, rich in dietary fibre, sugars, and bioactive compounds, significantly influenced bread quality. Optimal supplementation with 5–7.5% (M3) improved loaf volume from an average of 1,731.67 cm3 to 2,151.67 cm3, crumb porosity from 76.58% to 84.02%, moisture from 41.13% to 45.4%, and sensory attributes, imparting a darker colour, enhanced texture, and a mild berry flavour. Higher levels negatively affected the structure by reducing loaf volume and crumb porosity, and increasing moisture. Antioxidant activity, however, increased proportionally with pomace addition (5–10%), with total phenolic content in different types of pomace ranging from 17.30 to 23.30 mg GAE/g. The average total phenolic content in bread products was 4 to 14 times higher than in the control sample, with the highest levels observed in the M3 and M4 pomace types. These findings highlight bilberry pomace as a promising functional ingredient for bread fortification, contributing to both product quality and health-promoting value.
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