Encapsulation of cumin seed oil in chickpea protein- maltodextrin matrix

Abstract

This study aimed to investigate developing a plant-based protein matrix for microencapsulation of cumin oil, by determining optimum pH for solubility, emulsion stability of chickpea protein isolate (CPI) and investigating the effect of the matrix composition on encapsulation effiency and aromatic composition of cumin oil. Solubility, net surface charge, and emulsifying properties (emulsion activity/stability indices, and creaming stability) of CPI at ranging pH 3.0-9.0 were investigated. The highest protein solubility (94.4%) and emulsion activity index (61.8 m2/g), and the highest creaming stability (9.8% separation) was obtained at pH 9.0. CPI stabilized emulsions were optimized based on pH due to the higher emulsion stability index, which is 123.8 min at pH 7.0. CPI concentration of 0.5-2.31% (w/w) and oil concentration of 5-23.11% were adjusted in order to investigate the emulsion stabilization capacity of CPI using response surface methodology. It was observed that obtained CPI has the lowest effect on emulsion formation. Optimum conditions for minimum creaming were identified as: 0.19% CPI concentration and 6.83% oil concentration. CPI was found to be thermally stable with high denaturation temperature (161.4°C) and required 142.2 J/g enthalpy for denaturation. Cumin (Cuminum cyminum L.) seed essential oil was microencapsulated employing the complex matrix formation of CPI and maltodextrin DE 12-16 using spray drying. Effects of cumin oil concentration (10-20%), CPI concentration (1-3%) and maltodextrin (MD) concentration (25-35%) on the physicochemical characteristics and aromatic composition of the microcapsuled cumin oil were investigated. It was observed that, CPI-MD complex matrices had positive effects on microencapsule properties such as relatively lower surface oil, and higher encapsulation efficiency and oil retention, when they were formulated properly. Oil retention of 86.6–96.4%, encapsulation efficiency of 90.9–98.4%, and surface oil of 1.4–7.9% were obtained in samples. Correspondingly, it was observed that MD–CPI interaction was an effective parameter for emulsion stability. Optimum conditions for maximized oil retention (92.9%) and encapsulation efficiency (98.60%) were identified as: CPI concentration of 2.1%, cumin oil concentration of 14.8% and MD concentration of 35%. Moreover, GC-MS analysis of obtained microencapsulates was also carried out to determine the changes in essential oil composition during spray drying. It was observed that cymene, α-pinene, β-pinene, sabinene, terpinene, terpineol, phellandrene, and cumin aldehyde were the major volatile components in cumin oil. It was observed that optimized design not only had the highest encapsulation yield, but also provided better protection against the degradation of volatile composition of cumin oil.