Sodium Alginate Microencapsulation of an Umami Peptide Fraction (F2) from Goose Bone Paste: Preparation and Reduced Apparent Gastric-Phase Release

Abstract

Goose bone paste is an underutilised poultry-processing by-product and a potential source of taste-active peptides. A nominal 1–3 kDa peptide fraction (F2), operationally designated an umami peptide fraction by analogy with comparable bone-hydrolysate fractions reported in the literature, was isolated from a neutral-protease hydrolysate by sequential ultrafiltration and encapsulated in sodium alginate (SA) microcapsules using extrusion–dripping ionic gelation. Single-factor screening identified the following formulation conditions: 2.0% (w/v) SA, 2.5% (w/v) CaCl2, 0.3% (w/v) SE-15, a core-to-wall mass ratio of 0.3, and a preparation temperature of 50 °C. A verification batch prepared under these conditions gave an encapsulation efficiency of 75.44%, with the ±1.07% denoting the SD of three technical determinations from that batch. The dried microcapsules had a moisture content of 2.98 ± 0.21% and passable flowability. The mean particle diameter was 856 ± 52 μm, with a within-batch coefficient of variation of 5.56 ± 0.28%; a complete particle-size distribution was not recorded. In pepsin-free simplified simulated gastric fluid, the apparent release from the microcapsules rose from about 6% at 1 h to about 13% at 5 h, whereas the apparent detection ratio of free F2 rose from about 56% to about 99%. The calculated concentrations fell at or below the validated limit of quantification, the microcapsule-group absorbances lay near the photometric floor of the instrument, and only three sampling times were used. These percentages and the kinetic fits are therefore qualitative to semi-quantitative. The data support only the relative statement that alginate encapsulation lowered the apparent release of F2 under the tested acidic conditions. They do not establish an exact release rate, an error estimate for the microcapsule group, or a specific release mechanism.