Alginate modification using n-butanol for red fruit (Pandanus conoideus) oil encapsulation

Red fruit oil, rich in fatty acids, is prone to oxidation, reducing its shelf life. Encapsulation using modified alginate can enhance its stability. Alginate, a natural emulsifier, requires hydrophobic modification due to its hydrophilic nature for oil encapsulation. This research aims to modify alginate through esterification with n-butanol to enhance its hydrophobicity, thereby improving the binding of red fruit oil. The study examines the effects of the mole ratio of n-butanol to alginate, esterification time, and pH of alginate on the modification of alginate, emulsification, and the beads produced. Results showed that the highest degree of substitution (DS), that is 0.283, was obtained by 15 h esterification of 40:1 mole ratio of n-butanol:alginate in pH = 4 conditions. The attachment of butyl chain to alginate backbone was identified from their IR spectra. Increasing DS led to the molecular weight reduction (Mv = 22–27 kDa). The thermal stability of alginate is maintained after modification with n-butanol. Ability of modified alginate by attaching the C4 chain increased stability of red fruit oil emulsion up to 40 min without any separation. The emulsion was stabilized using modified alginate produced red fruit oil beads with ±30% encapsulation efficiency. The formed beads prevented the oxidation of red oil (oxidation degree < 3%) after 5 days of storage. This research emphasizes better handling and storage of the red fruit oil.