Preparation and Formation Mechanism of Spherical Particles with High Quality: A Case Study of l-Isoleucine

Abstract

As one of the eight essential amino acids in the human body, l-isoleucine plays an important role in human life metabolism and can be applied as a nutritional supplement and food additive in the food field. However, the crystallization of l-isoleucine is generally flaky with poor powder properties, such as bulk density and flowability, which is not conducive to a wide range of industrial applications. In this study, we successfully prepared large spherical particle crystals via two different ways of crystallization. l-Isoleucine undergoes the evolution from initial round flakes to three-dimensional petal-like structures and finally to spherical particles by evaporation crystallization in the presence of hydroxypropylmethylcellulose (HPMC). l-Isoleucine also aggregates into spherical particles in the acid–base reaction crystallization process by adding a small amount of suitable and volatile bridging liquids, such as cyclohexane and ethyl acetate. In conclusion, both approaches improved the crystal properties of l-isoleucine and produced spherical particles with a larger particle size, higher bulk density, and higher compression resistance, thereby providing new insight into the preparation of high-quality l-isoleucine.