Microencapsulated ascorbic acid: Development, characterization, and release profile in simulated gastrointestinal fluids

Abstract

The aim of this study was to produce ascorbic acid (AA) microcapsules by complex coacervation, characterize them, and evaluate the release profile in simulated gastrointestinal fluids. The microcapsules were made of gelatin and pectin at concentrations of 1.0, 2.0, and 3.0%. The coacervated microcapsules were assessed for morphology (by optical microscopy and scanning electron microscopy), water activity (Aw), hygroscopicity, solubility, encapsulation efficiency (EE), thermal behavior, and AA release profile. The AA microcapsules were characterized by low solubility, low hygroscopicity, high thermal stability, and low diameter (<10 μm), with EE ranging from 23.7 to 94.3%. The release profile was faster in gastric fluid (pH 1.8) than in intestinal fluid (pH 6.8). The sample containing 2.0% of wall material and 50% (w/w) of the simple emulsion (core) had the highest EE and the best in vitro release profile, with release of only 68% of AA in 120 min in the gastric fluid. Practical applications Ascorbic acid (AA) is widely used in the food industry as an antioxidant, but practical use becomes limited due to its high instability. Microencapsulation was proposed as an alternative to increase the stability of this compound. Gelatin and pectin were used as wall materials in the production of ascorbic acid microcapsules by complex coacervation. Both solubility and hygroscopicity were low while the thermal stability of the active material improved with the microencapsulation process. Ascorbic acid release was more pronounced in gastric fluid (pH 1.8) and slower in intestinal fluid (pH 6.8). The results of this study demonstrate that the microcapsules produced represent a feasible method of increasing AA availability in food products, especially for those samples that presented high encapsulation efficiency.

Chemical Stability of Ascorbic Acid Integrated into Commercial Products: A Review on Bioactivity and Delivery Technology

“…Antiradical capability commonly reflects the antioxidant ability, and ascorbic acid in foodstuff and bio-systems acts as antioxidant. As the most effective and natural antioxidant with the least side effects, ascorbic acid can inhibit various diseases caused by oxidative stress in the body, such as cancer, cardiovascular disease, aging and cataracts [ 15 ]. Studies have shown that the mortality from these diseases is inversely related to plasma concentration of ascorbic acid [ 19 ].…”

“…However, the high viscosity of high-concentration polymers limits the granulation by spray-drying. To a certain extent, the loading capacity is related to the wall-to-core ratio and increases with the increase in the coating of wall materials [ 15 ]. Complex coacervation is the phase separation of at least two hydrocolloids from the initial solution, and then the coacervate phase is deposited around the suspended or emulsified bioactive compounds.…”

“…Compared with spray drying, this method does not involve a heat treatment process and is more suitable for encapsulating thermally unstable ascorbic acid [ 94 ]. The microcapsules prepared with gelatin and pectin as wall materials improve the thermal stability of ascorbic acid, although the solubility of the microcapsules is relatively low [ 15 ]. The encapsulation efficiency of ascorbic acid using gelatin and acacia as wall materials is about 97% [ 93 ].…”

“…The release process of encapsulated ascorbic acid is as follows: absorption of solvent by the carrier, dissolution of the wall-coating, and the diffusion of inner core. The release of bioactive compounds in carriers depends on many factors, such as the selection of the wall material, the ratio of wall/core, the size of the carrier, the solubility of the bioactive compound, and the release conditions [ 15 , 97 ]. Ascorbic acid releases kinetics from ascorbate gummies, which were investigated using an in vitro simulated digestion model.…”

“…There is a hypothesis that the molecular weight of the used polymers is negatively related to the release of the encapsulated compounds [ 14 ]. The encapsulation efficiency of ascorbic acid in gelatin-coated microcapsules reached up to about 94%, but the release of ascorbic acid in the stomach was faster than that in the intestine [ 15 ]. However, only 30% of ascorbic acid in chitosan nanoparticles was released in a simulated gastric solution, while the release in simulated intestinal condition exceeded 75% [ 16 ].…”