Natural Hydrocolloids as Wall Materials for Microencapsulation of Bioactive Compounds in Food Systems: A Critical Review

Abstract

Abstract

Bioactive food ingredients rarely survive intact the journey from formulation to absorption. Polyphenol oxidase degrades phenols, vitamins photodegrade, probiotic cells lose viability in the stomach and mineral salts react with matrix components long before they reach the small intestine. Microencapsulation in natural hydrocolloids is the food industry's principal answer to this problem, and the literature on it has grown quickly. That growth has not been matched by consistency. This review examines six established wall materials (Sodium Alginate, Pectin, Chitosan, Gum Arabic, Carrageenan, and Guar gum) together with five that remain underused (Xanthan gum, Locust Bean gum, Gellan gum, Konjac Glucomannan, and Tamarind seed polysaccharide), and evaluates the five techniques most commonly paired with them. Rather than treating materials and processes as separate subjects, a single causal chain was followed: how wall chemistry sets gel mesh size, how mesh size and core charge together determine what can actually be retained, and how the same structural features govern release in the gut. Two challenges recur throughout. Encapsulation efficiency is reported by at least two incompatible calculations, making cross-study comparisons unreliable and pooled estimates meaningless. Moreover, small cationic species, iron and zinc above all, are systematically poorly retained in anionic gels; some of the low values reported for them are analytical artifacts rather than real losses, because an intact alginate matrix shields the ions from colorimetric reagents.