Maltodextrin encapsulation improves thermal and pH stability of green tea extract catechins

This study aimed to trap green tea extract (GTE) with maltodextrin (MD) to protect catechins from high temperatures, pH variations, and storage. GTE:MD microparticles (19.35:80.65% wt/wt) were obtained by spray drying, producing microparticles (26 μm) with a trapping efficiency of 63%, containing epigallocatechin gallate (EGCG), gallocatechin gallate, epigallocatechin (EGC), epicatechin, and catechin. The free GTE evaporated at 43℃, loosed 50% of its weight at 100℃, and decomposed at 130℃. The microparticles started to weight loss at 75℃ and decomposed at 290℃. The EGCG and EGC content of the free GTE completely depleted after 30 days at pH 7 and pH 6, respectively. However, the microparticles increased their EGCG content to 121% after 30 days at pH 7 and reduced 3.5% the EGC content after 30 days at pH 6. MD was an effective barrier capable of stabilizing the GTE's polyphenolic content and antioxidant capacity. Practical applications The bioactive compounds of the green tea extracts (GTEs) are catechins with antioxidant activity; however, these compounds and their activity may decrease with the epimerization caused by high temperatures, pH variations, and storage. The immobilization of GTE in maltodextrin (MD) preserved its polyphenols' chemical structures and their antioxidant capacity at different pH and storage times; in addition, the MD immobilization offered thermal protection to the GTE. The results of our study allow us to advance the knowledge in the field, understanding the interactions between GTE components and MD molecules and the possibility of a commercial application of our study.