Production of fruit yoghurt with incorporated Annona (Annona muricata L.) and evaluation of its physicochemical, microbiological and sensory properties

Abstract

Fruit yoghurts can have many health benefits on humans compared to normal yoghurts because fruits have high therapeutic and nutritional properties. Therefore, fruit yoghurts are becoming popular among a health conscious population in Sri Lanka. There are many underutilized fruit species in Sri Lanka and their uses are yet to be explored. Moreover, these underutilized fruits can play a vital role in human nutrition because of their therapeutic and nutritional properties. Therefore, the objective of the present study was to develop a fruit yoghurt with incorporated Annona (Annona muricata L.), an underutilized fruit species growing well in Sri Lanka. Plain yoghurts as well as Annona incorporated yoghurts were prepared with cow milk and other ingredients such as sugar and gelatin. Annona fruit pieces were prepared by blanching and dehydration methods. Plain type Annona jelly fruit yoghurts, stirred type honey incorporated Annona fruit yoghurts and stirred type Annona fresh fruit yoghurts were prepared in the laboratory. Physicochemical properties of yoghurts such as Total Solid (TS) %, Fat %, Solid Non Fat (SNF) %, titratable acidity and pH during their shelf-li/e were determined. Furthermore, microbiological and sensory properties of Annona incorporated yoghurts were also determined and compared with those of a commercial brand of fruit yoghurt. Sensory properties of yoghurts such as appearance, taste, aroma, texture and overall acceptability were determined on a five-point hedonic scale with 3G^sensory^panelists. Sensory results were analyzed using Kruskal Wallis non-parametric ANOVA test with the use of STAT1STIX computer software (Ver 2.0) for windows. Annona jelly fruit yoghurt was selected as the best yoghurt because of its significantly (P<0.05) higher sensory properties. Total solid, SNF and fat percentages of Annona jelly fruit yoghurts were 21.8%, 8.8% and 3.4%, respectively. Shelf-life of the Annona jelly fruit yoghurt was 21days. In addition to above properties, Annona fruit is reported to have high therapeutic properties especially for diabetic and constipated patients. In can be concluded that Annona fruit can successfully be incorporated into yoghurts to produce a value-added fruit yoghurt with higher nutritional and sensory properties.