Fortification of set-type yoghurts with Elaeagnus angustifolia L. flours: Effects on physicochemical, textural, and microstructural characteristics

The effect of peeled oleaster (Elaeagnus angustifolia L.) flour (PO) and unpeeled oleaster flour (UPO) in different levels (1% and 2%) on the quality parameters of set type yoghurt was investigated throughout 28 days of storage. Acidification kinetics, water holding capacity, syneresis level, textural characteristics and microstructure were firstly measured. Additionally, influence of oleaster flours on DPPH and ABTS(+) radical scavenging activity and total phenolic content of yoghurt samples was also assessed. Besides, all the products were subjected to sensorial preference test. Enrichment with 2% PO and UPO reduced fermentation time by 31 and 37 min, respectively. Addition of PO and UPO increased cohesiveness and the viscosity index, furthermore, syneresis decreased. Oleaster supplementation to yoghurt significantly increased scavenging activities of DPPH and ABTS radicals and the highest activities were determined in yoghurts fortified with 2% UPO. The results demonstrated that yoghurt with reduced syneresis, improved functional properties, and enhanced some textural characteristics can be achieved by a 2% UPO addition. Also, surprisingly yoghurts containing 2% UPO had similar consumer overall preference scores comparing to plain yoghurt.