Spray-dried Capsicum oleoresin microparticles: A comprehensive study on stability, cytotoxicity, and digestibility

Capsicum oleoresin, an active ingredient in hot peppers of the genus Capsicum, is abundant in capsaicinoids. It offers significant health benefits, however due to its high pungency, this makes its pure form very challenging to consume orally. The main aim of this study is to prepare Capsicum oleoresin microparticles for oral delivery and to characterize and evaluate their cytotoxicity, in vitro stability and controlled release in gastrointestinal conditions. Gum Arabic (GA), OSA-modified corn starch (EMCAP), modified malt (MALT), and their ratio 1:1 combination (GA: EMCAP; EMCAP: MALT; MALT: GA) were employed as wall materials resulting in six different oil-in-water emulsions containing 15 % solids (5 % Capsicum oleoresin and 95 % wall material). These formulations were homogenized and spray dried. The encapsulation efficiency of each formulation was determined by Ultra Performance Liquid Chromatography (UPLC). The formulated microparticles, individual microparticle components, and Capsicum oleoresin were tested for cytotoxicity on human intestinal monolayers Caco-2 and HepG2 liver cells. Furthermore, the INFOGEST static in vitro simulation assessed the digestion of microparticles using UPLC to obtain % capsaicin release. The highest encapsulation efficiency was obtained for EMCAP: MALT (90.4 %), MALT: GA (90.2 %), and GA (90.5 %). LC-QToF analysis identified capsinoids, capsaicinoids, and organic compounds in Capsicum oleoresin and microparticles. Identification of these components was also confirmed by Raman spectroscopy. All particles exhibited irregular surfaces, teeth concavities, and different sizes typical of spray-dried particles using carbohydrates as wall material. In vitro, cytotoxicity studies of all formulations with five concentrations ranging from 5 to 100 μg/ml showed no significant cytotoxicity after exposure times of 4 h on Caco-2 and 72 h on HepG2 cells. Microparticles resulted in higher degradation of color and capsaicin during storage at 45 °C compared to at 25 °C. In vitro digestion showed MALT: GA microparticles started with a 7.4 % release in the oral phase after 2 min of digestion. A further 2 h incubation in simulated gastric fluid resulted in a cumulative release of 25 %, followed by 78.6 % of capsaicin after 4 h in the intestinal fluid. This data reassures us about MALT: GA's effective capsaicin delivery potential, which presents a better profile of delivering capsaicin in high amounts into the intestine. These findings contribute to developing more efficient delivery systems, providing new insights into bioactive compounds' stability, released profiles, and safety, thus paving the way for improved applications in functional foods.