Spray-Dried Microencapsulation of Oregano (Lippia graveolens) Polyphenols with Maltodextrin Enhances Their Stability during In Vitro Digestion

The effect of in vitro gastrointestinal digestion on the release of microencapsulated phenolic compounds was evaluated through an optimized spray drying process. A stock extract of oregano phenolic compounds was developed and microencapsulated in a spray dryer following a central composite rotatable design, controlling the variables, inlet temperature (111.7-168.2°C), and percentage of wall material (5.8-34.1%). Optimum drying conditions for spray drying were decided based on different yield percentages ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" id="M1"> <a:mi>Y</a:mi> </a:math> %) and encapsulated phenolic compounds (EPC). The analyzed physical properties were morphology measured by electron microscopy and humidity; other properties evaluated were the content of total phenolic compounds, antioxidant capacity determined by DPPH and ABTS assays, and phenolic profile by ultraperformance liquid chromatography coupled to mass spectrometry (UPLC-MS). During the gastrointestinal simulation, a stability of 85% was determined in the intestinal stage. Microencapsulation technology by spray drying is an excellent selection to stabilize and protect bioactive compounds of oregano and promote its use as a functional ingredient.