Thermal-mechanical treatment of blackcurrant pomace for enrichment in yoghurt

Abstract

Blackcurrant pomace (BP) is currently rarely used in human nutrition, although it contains a high amount of dietary fibre (∼60%). A proper enrichment of foods could provide a good opportunity to improve the recommended daily fibre intake. Yoghurt, as a dispersed system, with high consumer acceptance, is a suitable candidate for pomace enrichment. Due to its strong tendency towards sedimentation, direct enrichment is not possible. The aim of the study was to thermal-mechanically functionalise BP, to enrich cow milk yoghurt to an amount of 5%. Chemical composition, particle size and techno-functional properties of BP and functionalised BP, as well as functional and rheological properties and physical microstructure of the resulting yoghurts, were characterised. Fermentation of enriched yoghurt with functionalised pomace containing a high amount of soluble dietary fibre (SDF) and in consequence exhibiting a high water retention capacity (WRC) and good swelling behaviour led to improved product texture. The study shows that pomace, as a by-product of juice production, is suitable for enriching dispersed systems such as yoghurt without negatively affecting rheological properties. The results confirm that a thermal-mechanical functionalisation of the pomace is necessary to reach this goal.