Kinetic and thermodynamic studies on the degradation of carotene in carrot powder beads

This study examined the characteristic, kinetic, and thermodynamic properties of encapsulated carrot powder beads. Membrane solutions required for encapsulation of the carrot powders were prepared from soy protein isolates, cassava starch and their combinations. The solutions were categorized into plasticized and non-plasticized using glycerol in combination with sorbitol as plasticizers. 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 membrane solutions as a result of the blend compositions as well as the addition of plasticizers substantially influenced quality criteria of the encapsulated carrot powder beads such as encapsulation efficiency, encapsulation yield, and particle size. Membrane compositions and pH affected release rate of the encapsulated beads. A higher release rate of carotene was observed at pH 6.8 and 7.4. The carrot powder beads were more stable at pH 1.2. The release mechanism of the beads was Fickian (diffusion-controlled). Degradation of the carotene content was investigated by accelerated stability test under regulated temperatures at 40, 50 and 60 °C, and constant water activity of 0.75, for 49 days. The degradation data were fitted into first-order kinetics. The rate constant of degradation was in the range of 0.021–0.363 week−1. The beads with a mix of soy protein isolate (50%) and cassava starch (50%) composite based membrane was the most secured having the longest half-lives of 225, 116 and 106 days at 40, 50 and 60 °C respectively. All the samples showed comparable thermodynamic features, indicating a similar mechanism of degradation of the carotene. Addition of plasticizers into the membrane solutions affected protection of carotene content of the encapsulated carrot powders. •Synergistic effect of matrix compositions improved the beads' characteristics.•The release mechanism of carotene content was diffusion-controlled.•Composite of protein and starch based matrix secured carotene better.•Plasticized matrices were more conductive to heat and moisture.•All the samples exhibited similar thermodynamic features.