Formulation and characterization of food grade water‐in‐oil emulsions encapsulating mixture of essential amino acids

Abstract

The present study was conducted to study the encapsulation properties of a mixture of four amino acids (AAs) in the disperse phase of water-in-oil (W/O) emulsions. Four different AAs (methionine, lysine, threonine, and tryptophan) at 1% (w/w) each AA concentration was used in dispersed phase, while the continuous phase constitutes vegetable oils with 5% (w/w) tetraglycerin monolaurate condensed ricinoleic acid esters as an emulsifier. The optimized conditions include homogenization at 7000 rpm for 5 min using soybean oil as a continuous phase medium. The average droplet diameter of the W/O emulsions ranged between 4 and 5 μm with a coefficient of variation between 20 and 23%. The W/O emulsions were found to be stable over a period of 30 days at 4°C with slight phase separation at 25°C after 30 days of storage. The W/O emulsions retain about 10.5 mg/mL (encapsulation efficiency 79.8%) of amino acids after 30 days of storage at 4 and 25°C. The methionine and lysine have encapsulation efficiency of over 80% in comparison to threonine (79%) and tryptophan (60%) after 30 days of storage at 4 and 25°C.