Development of vacuum-dried powder and drinking yoghurt from soursop fruit (Annona muricata L.) and evaluation of their physicochemical and functional properties

Abstract Soursop (Annona muricata) is an underutilized seasonal climacteric fruit which exhibits many therapeutic and nutritive values. The objective of present study was to develop soursop fruit powder and soursop incorporated drinking yoghurt and to evaluate their physico-chemical and antioxidant properties. Soursop fruit powder was developed by inactivating enzymes of matured fresh cuts followed by vacuum drying at 60oC for 6 h. Soursop drinking yoghurt was developed by incorporating soursop pulp (15%, 20% and 25% w/v) followed by selecting the best fruit content (i.e 20% w/v) based on the sensory evaluation trials. Titratable acidity, pH, Total Soluble Solids, Syneresis and Milk Solid Non Fat of selected soursop drinking yoghurt were 0.85%, 4.5, 16.3 Brix, 29.3% and 13.8% respectively. The soursop drinking yoghurt (20% w/v) with added sucralose and sugar were separately compared with normal drinking yoghurt as a control. The drinking yoghurt with added sucralose was selected as the most preferable product based on the sensory attributes of odour, appearance, texture, taste, aftertaste, and overall acceptability. A significantly (p<0.05) higher antioxidants potential in terms of total polyphenolic content, total flavonoids content, ferric reducing antioxidant power, radical scavenging activities of 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic) and 2,2-diphenyl-1-picrylhydrazyl were shown in the soursop drinking yoghurt (14.13±0.63 mgGAE/g; 3.39±0.36 mgQE /g; 1.32±0.30 mgTE/g; 30.1±3.24 mgTE/g and 25.67±3.38 mgTE/g respectively) than vacuum-dried powder. Vacuum dried powder had high content of protein (8.71%), fibre (4.28%) and ash (3.97%). Further study showed the soursop drinking yoghurt as a potential source of functional food while soursop fruit powder as a good supplementary food.