CHARACTERIZATION AND UTILIZATION OF MICROENCAPSULATED SCENT LEAF (ocimum gratissimum) ESSENTIAL OIL FOR THE PRODUCTION OF FUNCTIONAL SOY BASED YOGHURT

Abstract

Ocimum gratissimum (Scent leaf) is an aromatic plant that has been used in traditional medicine for the treatment of many diseases. Essential oil from the leaves have been proven to possess antioxidants, antiseptics, antibacterial and antifungal activities. This study looked into microencapsulation of Ocimum gratissimum essential oil (OGEO) using cassava starch and gum arabic as cell walls and hydrocolloids. The Fourier Transmittance Infrared, Scanning electron microscope and antioxidant activities of the microcapsules were evaluated. The microcapsules were used in the production of soy-based yoghurt and stored for a period of 5 days at room temperature. The best encapsulation efficiency and highest antioxidant activity were obtained for the sample ratio 94:6 cassava: gum arabic and 5ml of ocinum gratissimum essential oil. The microcapsule efficiency was 91.12%. The major functional group in the microcapsules were Alkyne (C≡C), Nitrogen multiple and cumulated double bond (-NCS), Alkane (C-H) and Alcohol (O-H). The antioxidant activity of the soy -based yoghurt increased with incorporation of the microcapsules. However, microcapsule incorporation had no significant (p>0.05) effect on the proximate composition of the yoghurt except on the ash content which increased from 0.63 g/100g to 0.78 g/100g. In addition, the microcapsules reduced the syneresis of the soy based yoghurt by above 15%. The shelf life study indicated that the syneresis of the yoghurt incorporated with the microcapsules is still about 15% less than freshly prepared soy- based yoghurt without the microcapsule. All the yoghurts with OGEO microcapsules are at safe microbial level even after 5 days. The sensory quality of the samples incorporated with OGEO microcapsules was not affected by OGEO but by quantity of the cassava starch in the yoghurt. A lower cassava starch resulted in lower sensory quality. However, yoghurt samples with 98.5% cassava starch and 1.5% gum arabic had sensory quality of above 70%. Conclusively, inclusion of Ocimum gratissimum essential oil enhanced the bioactive properties of the yoghurt and as well enhanced the shelf life. The OGEO microcapsule do not have serious adverse effect on the quality attribute. The microcapsules had about 21.7 to 96.36% antioxidant activities retention, while the yoghurt had about 14.1 to 91% antioxidant activities retention.