Preparation, Structural Analysis and Properties of Naringin/Limonin Microcapsules

This study aimed to improve the bioavailability of naringin and limonin, reduce their bitter taste, and extend its application for the development of food. Microencapsulated naringin/limonin was prepared by orifice granulation method with sodium alginate-chitosan-calcium chloride as wall material, respectively. The technology process was further optimized by single factor experiment and response surface methodology using the embedding rate of naringin/limonin as response value. The micro morphology, molecular structure, relative bitterness intensity, thermal stability, and in vitro digestibility of products were characterized by scanning electron microscope (SEM), Fourier transform infrared spectrum (FTIR), electronic tongue, thermal stability analysis and simulating digestion experiments, respectively. The results showed that the optimal conditions were the ratio of wall to core material was 2.67, the mass fraction of chitosan was 0.9%, and the mass fraction of calcium chloride was 3%, the embedding rate could reach 88.2%, which was less than 5% compared with 88.68%, indicating that the process was accurate and reliable. SEM confirmed that naringin/limonin was effectively and tightly wrapped with sodium alginate-chitosan-calcium chloride system, and there were no cracks, holes or dents on the surface of the microcapsule. The thermal stability and electronic tongue test confirmed that the microencapsulation of naringin/limonin could significantly improve the stability of naringin/limonin, and effectively reduce their bitter intensity. The sustained release test of simulated gastrointestinal digestion in vitro showed that the overall release rate of microcapsules was only about 31% after digestion in simulated gastric juice for 6 h, and the cumulative release rate was over 75% after digestion in simulated intestinal juice for 45 min. These results indicated that microencapsulation could effectively promote the biotransformation and absorption of naringin/limonin in the intestinal tract, and improve its utilization rate. The results of this study could provide a basis for expanding the high-value utilization of naringin/limonin in food and pharmaceutical fields.