Application of soy protein isolate and cassava starch based film solutions as matrix for ionic encapsulation of...

Research into characterization and storage stability of carrot powders encapsulated in soy protein isolate and cassava starch based film solutions via ionic gelation method was performed. Carotene a major antioxidant presents in carrot powders plays a beneficial role in preventing some health problems such as cancer, and cardiovascular/coronary heart diseases. Consequently, the carotene contains a hydrocarbon with an unsaturated double bond or its oxygen derivatives, which makes it unstable and sensitive to moisture, heat, oxygen, light, and acid. There is therefore the need for encapsulation of this nutritive and healthy component of carrot powders to extend its stability. Film solutions required for encapsulation of the carrot powders were prepared from soy protein isolate, cassava starch and their combinations, and were as well categorized into plasticized and non-plasticized using glycerol in combination with sorbitol as plasticizer. Ionic encapsulation was achieved using sodium alginate for gelation of carrot powder beads in 5% calcium chloride solution for curing. Distinction in gelation features of the film solutions as a result of blend compositions as well as the addition of plasticizers substantially influenced the quality criteria of encapsulated carrot powder beads such as encapsulation efficiency, encapsulation yield, moisture content, hygroscopicity, particle size, and also their sensory qualities. Their values varied between 70.93-82.59%, 70.35-75.35%, 9.88-13.04%, 40.00-49.00 g/100 g, and 2.18-2.64 mm respectively. 100% soy protein isolate based film solution performed much better than 100% cassava starch based film solutions in preventing degradation of carotene content of the encapsulated carrot powder beads. Plasticization of the membrane solutions caused greater carotene degradation. Combination of soy-protein isolate (50%) and cassava starch (50%) composite based film solutions gave the best protection for carotene degradation having shelf life of 106 days while plasticized cassava starch based was the least with the shelf life of 13 days which is closed to that of the control (carrot powders).