| Summary: | Edible bird’s nest (EBN) which is made of the saliva of swiftlets is one of the main functional foods. It rich in glycoprotein and contains sialic acid, natural antioxidants, probiotics, and bioactive compounds. During the processing of EBN, by-products such as bird’s feathers were separated to ensure the quality and safety of EBN. However, these by-products still contain valuable glycoproteins that can be recovered through enzymatic hydrolysis. Although these compounds can be recovered, it can be unstable and susceptible to thermal exposure as well as high-pressure degradation that lead to poor palatability and absorption. In this regard, this study emphasised on the encapsulation of EBN by-product hydrolysates (EBNBH) by using three different formulations of encapsulating agents to determine the most suitable wall material to encapsulate EBNBH. They were maltodextrin (MD), maltodextrin-carboxymethyl cellulose (MD-CMC) and maltodextrin-xanthan gum (MD-XG). The screening process of encapsulating agents showed MD-XG is the most suitable wall material compared to MD and MD-CMC as it has the lowest moisture content (8.22 %), highest encapsulation efficiency (70.95 %), highest antioxidant activity (71.80 g AAE/kg) and highest sialic acid content (32.41 g kg-1) in accordance with its surface morphology which has smoother and more uniform surface due to the protective shell around each particle. Three encapsulation parameters (EBNBH concentration, MD-XG concentration and inlet temperature of spray dryer) were optimised using response surface methodology with Box-Behnken design to get the optimal parameters for encapsulation which were found to be 2.725 % w/v EBNBH, 3.051 % w/v MD-XG and 181 ℃ of spray dryer’s inlet temperature that yielded optimal encapsulation efficiency (90.49 %) and antioxidant activity (88.28 g AAE/kg). The free EBNBH (F-EBNBH) and optimal encapsulated EBNBH (OE-EBNBH) were physicochemically characterised and underwent stability test and kinetic degradation study. From the physicochemical characterisation, OE-EBNBH was found to have significantly higher recovery yield (24.76 %) and sialic acid retention after spray drying (94.92 %), better solubility (94.11 %), lower moisture content (7.65 %), water activity (0.286) and hygroscopicity (5.36 %) and smaller particle size (6.14 μm) compared to F-EBNBH (20.30 %, 55.48 %, 85.73 %, 11.76 %, 0.394, 13.65 % and 7.09 μm, respectively). The sialic acid content and antioxidant activity in OE-EBNBH were also significantly higher after 10 weeks of storage at 4 ℃ and 30 ℃ indicating lower kinetic degradation rate and longer half-life compared to F-EBNBH. In conclusion, this study demonstrates that optimised encapsulation of EBNBH using maltodextrin with xanthan gum as encapsulating agent could improve the physicochemical characteristics and properties of EBNBH. OE-EBNBH is functionally stable and has good storage stability properties.
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