Abstract:
Soursop (Annona muricate L.) is an underutilized tropical fruit grown in Sri Lanka with the
promising nutritional and therapeutic value. The study was conducted to develop soursop
incorporated frozen yoghurt (SFY) and to determine its physicochemical properties. Two different
wiped cream levels (5% and 10% w/w) and three levels (10%,20% and 30% w/v) of pasteurized
soursop pulp was tested. The best product accepted from sensory evaluation, was tested against the
control (without added fruit) for physicochemical, microbial, shelf life and therapeutic value. Results
showed that 80% fresh milk, 20% soursop fruit pulp were the best combinations for SFY (p≤ 0.05).
According to the proximate analysis moisture, protein, fat, fiber, ash and carbohydrate content of
SFY were 71.82±0.4%, 4.36±0.2%, 6.29±0.2%, 0.91±0.1%, 0.93±0.1% and 15.84±0.2%,
respectively. During storage, pH and titratable acidity of developed SFY were varied from 4.54±0.01
to 4.47±0.02, and 0.93±0.05 to 4.53±0.01 accordingly. Total soluble solid content, water holding
capacity and syneresis of SFY contain 26.83±0.2%, 14.33±1.5% and 13±0.1 respectively. Yeast and
mold count did not exceed the Sri Lankan Standard Institute (SLSI) recommended values during the
8 weeks of storage. By measuring probiotic count the therapeutic value was measured in SFY.
Probiotic count of SFY was exceeded the minimum therapeutic value during the storage period.
Incorporation of 20% (w/v) of soursop into frozen yoghurt is possible and the product can be safely
stored for 8 weeks.
Keywords: Fermentation; Frozen yoghurt; Milk; Probiotics; Soursop
