LAUSR

BACKGROUND Great efforts have been made to improve oral bioaccessibility of lipophilic ingredients with multi-functionalities. Achieving intestinal delivery of lipophilic ingredients and their encapsulation in micelles composed of bile salts and lipid hydrolysates (i.e., fatty acids) are critical factors in improving oral bioaccessibility. Therefore, oil-core microcapsules are considered ideal carriers of lipophilic ingredients. Previous studies have reported oil-core/zein-shell microcapsules constructed by a one-step anti-solvent process. Still, its efficacy as an intestinal delivery system was limited due to the porous shell structure. RESULTS Zein solution was pretreated with ultrasound and tannic acid (TA) crosslinking. Composite oil-core microcapsule (COM) with compact shell structure was successfully prepared by using modified zein solution in the anti-solvent process. FTIR and CD analyses indicated that ultrasound and TA synergistically promote the conformational transition of zein from α-helix to β-sheet and enhance the hydrophobic interactions among protein chains. The above changes contribute to the strengthen of shell zein network. Correspondingly, COM presents superior encapsulation efficiency and environmental stability over the simple oil-core microcapsule (SOM) prepared without the usage of ultrasound and TA. Furthermore, antioxidant activity of β-carotene was well retained during the encapsulation process. In vitro studies indicated that COM was more resistant to digestibility and acid-induced swelling. More than 87% of β-carotene could be released in the intestine in a sustainable way. The controllable release behavior thus promoted a significant increase in bioaccessibility of β-carotene encapsulated in COM compared with SOM (85.9% vs. 48.5%). CONCLUSION COM generated here was potential for bioaccessibility improvement of lipophilic ingredients. This article is protected by copyright. All rights reserved.