Encapsulation of bioactive compounds and its application in the development of healthier meat products
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This study was designed to establish encapsulation systems to protect liposoluble bioactive compounds, lutein (LU), curcumin (CUR), and fish oil (FO: omega-3 fatty acids). A suitable encapsulation method was designed for each compound. The physical and chemical characteristics of the encapsulated compound were investigated. LU and FO were co-encapsulated for healthier meat product development by fortifying lutein and modifying the lipid fatty acids profile in the final product. Curcumin was encapsulated with ovalbumin (OVA), a protein separated from egg white. The chemical stability and antioxidant activity of curcumin were increased by binding it with protein, especially at pH 7.0. Curcumin added at 1.0% OVA, showed the highest encapsulation efficiency (> 97%). Three commonly used anionic polysaccharides, alginate (AL), carboxymethyl cellulose (CMC), and gum arabic (GA), were tested to determine their effects on curcumin in the CUR-OVA complex. The CUR-loaded complexes showed a sponge-like structure, and the confocal laser scanning microscope (CLSM) image showed that the CUR and OVA were co-localized. The Fourier-transform infrared (FT-IR) results indicated that hydrogen bonds and hydrophobic interactions were the main force in binding CUR onto OVA. Attaching the polysaccharides to OVA did not affect CUR's encapsulation properties and stability. LU was encapsulated through a polysaccharide-based complex: alginate-chitosan. LU was located and stabilized in the hydrophobic environments caused by the neutralization of net charge on the alginate (AL) and chitosan (CS) and the intermolecular hydrogen bonds between the LU, AL, and CS. The LU-loaded polysaccharides complex showed a flake-like structure, and lutein was inserted into the AL/CS complexes as amorphous forms. The lutein-loaded complexes had greater than 98% entrapment efficiency and 35% loading capacity. Lutein within AL/CS complex showed significantly increased stability under UV light and high temperatures. In FO encapsulation, the OVA/AL complex was used as the wall, and the wall-to-oil ratio was fixed at 1:1 based on yield, oil recovery, and internalization efficiency (IE). The scanning electron microscopy (SEM) results indicated that the freeze-dried fish oil powders had irregular shapes with visible pores on the surface. A garlic essential oil (GEO)-added sample showed the strongest oxidative stability throughout the storage period (30 days). In co-encapsulating FO-LU-GO for healthier processed meat development, antioxidants were investigated to protect fish oil from oxidation and lutein from degradation. Curcumin showed the highest inhibitory effects on lipid oxidation. To investigate the effectiveness of encapsulation, two fish oils (FOs), FO1, a commercialized fish oil without antioxidants, and FO2, the one with antioxidant present, were used. A chicken-pork sausage research model showed that encapsulation significantly prevented lipid oxidation in cooked meat even when the antioxidants were present in the original fish oil (FO2). The fatty acids profiles of cooked meat showed that encapsulation effectively prevented the destruction of EPA/DHA. The lutein retention rates were increased from 82.23% and 63.59% to 97.50% and 84.50% for FO1 and FO2, respectively, upon encapsulation. The results of our study showed that both protein-polysaccharides and polysaccharides-based complexes are effective in encapsulating and protecting liposoluble bioactive compounds during processing and storage. Co-encapsulation effectively delivered hydrophilic bioactive compounds and fish oil into meat products. These results offer good scientific support for encapsulating various compounds that can promote the development of healthier meats.