Novel medium-and long-chain triacylglycerols rich structured lipids enriched in n-3 polysaturated fatty acids encapsulated by spray drying: Characterization and stability

Abstract

Novel MLCTs-rich SLs, enriched with n-3 PUFAs, were synthesized to combine the benefits of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and medium-chain FAs (MCFAs). However, these SLs were susceptible to oxidative degradation. To solve this issue, the MLCT-rich SLs were microencapsulated using different wall materials through spray drying technique. Initially, in this study three formulations of different wall materials were designed: modified starch/maltodextrin [MS/MD (2:1)], gum Arabic/maltodextrin [GA/MD (2:1)], and mixed [MIX (MS:GA:MD, 1:1:1)]. Subsequently, all the three formulations were analysed. The analysis included encapsulation yield, encapsulation efficiency, moisture content, hygroscopicity, water activity, density properties, Carr's index, cohesiveness, flowability, porosity, wettability, solubility, color, and relative crystallinity. Fourier transform infrared spectroscopy (FTIR) was employed to identify the chemical structure of the microcapsule powder. The moisture content ranged from 1.71% to 3.45%, while water activity ranged from 0.17 to 0.31 of all formulations, indicating suitability for long-term storage. Additionally, the highest microencapsulation yield (93.23%) and microencapsulation efficiency (93.74%) were achieved with GA/MD formulation. GA/MD also exhibited the highest relative crystallinity (32.50%). Moreover, FTIR analysis confirmed the successful encapsulation of the oil in the microcapsules. Furthermore, scanning electron microscopy (SEM) images revealed spherical shapes without any visible cracking on the surfaces of the microcapsules. Besides, GA/MD formulation demonstrated better results in density properties, flowability, porosity, and wettability. During the oxidative stability, GA/MD microencapsulation provided the best protection against lipid oxidation. These findings highlight the effectiveness of using GA/MD formulation for the production of microcapsule powders containing MLCTs-rich SLs.