Abstract
In this study, chitosan nanoparticles (CNPs) were prepared by the ionic gelation technique with tripolyphosphate (TPP), and the effect of CNP composition and physicochemical characteristics were evaluated. After the synthesis optimization, CNPs were used as carriers for a fish protein hydrolysate (FPH) with bioactive properties (CNPH). The physicochemical characteristics, antioxidant capacity and antimicrobial, antihypertensive and emulsifier properties of unloaded and loaded CNPs in a food system model were studied. CNPH showed a uniform particle distribution, size ~200 nm, high stability (zeta potential around 30 mV), radical scavenging activity and increased antimicrobial activity against Staphylococcus aureus, Shigella sonnei and Aeromonas hydrophila. Additionally, CNPH showed an angiotensin I-converting enzyme (ACE)-inhibitory activity of 63.6% and, when added to a food emulsion model, this system containing CNPs, with or without FHP, exhibited improved food emulsion stability. Thus, CNPs were able to carry the FPH while maintaining their bioactive properties and can be an alternative to the delivery of bioactive peptides with potential as an emulsion stabilizer for food applications.
Highlights
Chitosan (C) is a natural linear polycationic heteropolysaccharide composed of β-1,4linked d-glucosamine and N-acetyl-d-glucosamine obtained by the deacetylation of its parent polymer chitin, the second most abundant natural polymer in nature after cellulose [1]
The reagents and materials used were as follows: chitosan was purchased from Guinama (Valencia, Spain); the molecular weight (220 kDa) determined by a glass capillary viscometer and degree of deacetylation (78.6%) by Ftir determined from the ratio of absorbance: (A1655 cm−1/A3450 cm−1) × 100/1.33 were conducted according to FernándezMartín et al [22]
Chitosan is positively charged due to the protonation of amino groups, which can interact with anions such as TPP by the ionotropic gelation technique, leading to the formation of chitosan nanoparticles (CNPs) [24,31]
Summary
Chitosan (C) is a natural linear polycationic heteropolysaccharide composed of β-1,4linked d-glucosamine and N-acetyl-d-glucosamine obtained by the deacetylation of its parent polymer chitin, the second most abundant natural polymer in nature after cellulose [1]. Chitosan exhibits exceptional biological characteristics for food applications, such as biocompatibility, biodegradability, and nontoxicity [2]. It possesses mucoadhesive properties and exerts antimicrobial activity against a broad spectrum of microorganisms including Gram-positive and Gram-negative bacteria, filamentous fungi and yeast [3] and can be used as blends with other polymers and natural compounds to obtain bioactive edible films for foods [4]. Several studies describe the stabilization of O/W (oil/water) emulsions by CNPs, in which the CNPs are adsorbed onto the oil surface through interactions with an added anionic surfactant or protein [8,9]. CNPs act as an emulsion stabilizer by forming an interfacial complex with absorbed surfaceactive agents (i.e., anionic surfactants or proteins), acting mainly by a steric stabilization mechanism [11,12]
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