The effect of ultrasound-assisted enzymatic hydrolysis (UAEH) on the physicochemical properties and bioactivity of edible swiftlet’s nest hydrolysates
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Keywords:
Ultrasound-assisted enzymatic hydrolysis, edible swiftlet nest co-product hydrolysates, bromelain, freeze-drying, bioactivity
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Abstract
This study investigates the effect of ultrasound-assisted enzymatic hydrolysis (UAEH) compared with non-hydrolyzed samples on the physicochemical properties and bioactivity of edible swiftlet’s nest (ESN) co-product hydrolysates using bromelain under optimized processing conditions. ESN was subjected to UAEH treatment (40 °C, pH 7.0, 40 kHz) followed by freeze-drying. The results showed that hESN-C achieved the highest yield (62.13%) and degree of hydrolysis (37.95%), while hESN-CP gave the lowest (28% yield, 9.57% degree of hydrolysis). FTIR spectroscopy confirmed the retention of key glycoprotein functional groups across all hydrolysate fractions: characteristic O–H/N–H stretching vibrations at 3270-3272 cm-1, Amide I at 1630-1631 cm-1, and Amide II at 1526-1537 cm-1, together with glycan-associated C–O/C–N stretching vibrations, indicating selective peptide bond cleavage by bromelain without disruption of glycosidic linkages and preservation of the carbohydrate architecture in the resulting bioactive glycopeptides. HPLC qualitatively confirmed sialic acid retention in all fractions (retention time 6-7 min). Amino acid profiling revealed complete essential amino acid profiles in all samples, with the highest concentrations in hESN-C dominated by L-valine (36,507.33 mg/kg), L-proline (37,083.32 mg/kg), and L-serine (37,635.48 mg/kg). Fatty acid analysis identified oleic acid (0.1491%) and linoleic acid (0.0428%) as the predominant unsaturated fatty acids, particularly in hESN-CP. Particle size analysis demonstrated that UAEH produced smaller, more uniformly distributed nanoparticles (14.17-27.03 nm) with low polydispersity indices (<0.3). Scanning electron microscopy revealed distinct morphological differences: hESN-C and hESN-D exhibited homogeneous laminar structures, whereas hESN-CP displayed heterogeneous porous morphology attributed to keratin from feather residues. UAEH treatment significantly increased soluble protein content (hESN-C: 1.246 μg/μL; hESN-CP: 0.844 μg/μL) and DPPH radical scavenging activity (up to 10.70% for hESN-CP) relative to non-hydrolyzed controls. Heavy metal concentrations (Hg: 0.0172–0.0236 mg/L; Cd: 0.1194–0.1444 mg/L; Pb: 0.11–1.4 mg/L) remained within Chinese safety thresholds, and water activity was reduced to safe levels (<0.60). Collectively, these results demonstrate that UAEH is an effective and sustainable strategy for valorizing ESN co-products into physicochemically improved, bioactive glycopeptide hydrolysates with potential as functional food ingredients. Future studies employing quantitative in vitro bioactivity assays and in vivo validation are warranted to substantiate broader health-benefit claims.
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Kusumawati, N., Setiarso, P., Kuntjoro, S., Romadhoni, I. F., Djalilah, G. N., Rahmawati, K., … Fachriansyah, M. Z. (2026). The effect of ultrasound-assisted enzymatic hydrolysis (UAEH) on the physicochemical properties and bioactivity of edible swiftlet’s nest hydrolysates. Communications in Science and Technology, 11(1), 215–233. https://doi.org/10.21924/cst.11.1.2026.1974
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References
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39. C. Wen, J. Zhang, J. Zhou, M. Cai, Y. Duan, H. Zhang, H. Ma. Antioxidant Activity of Arrowhead Protein Hydrolysatees Produces by a a Novel Multi-Frequency S-Type Ultrasound-Assisted Enzymolysis. Natural Product Research. 34 (2020) 3000-3003.
40. B. H. Yeo, T. K. Tang, S. F. Wong, L. Z. Cheong, and O. M. Lai. Potential Residual Contaminants in Edible Bird’s Nest. Front. Pharmacol. 12 (2021) 1-15.
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42. S. S. P. Perdana, N. Kusumawati, M. M. S. Basukiwardojo, P. Setiarso, G. N. Djalilah, and K. Rahmawati. The effect of ultrasonication on the quality of keratin extraction based on ionic liquid from duck feather. Commun. Sci. Technol. (2025) 1–8.
43. Q. Fan, P. Wang, X. Zheng, S. S. Hamzah, H. Zeng, Y. Zhang, and J. Hu. Effect of dynamic high pressure microfluidization on the solubility properties and structure profiles of proteins in water-insoluble fraction of edible bird’s nests. LWT Food Sci. Technol. 132 (2020) 1–8.
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47. L. S. Chang, R. Karim, A. Sabo Mohammed and H. Mohd Ghazali. Production and characterization of enzyme-treated spray-dried soursop (Annona muricata L.) powder. J. Food Process Eng. 41 (2018).
2. R. Waskito, K. Rahmawati, N. Hidayah, F. F. Fachrirakarsie, N. H. Putri, K. Z. R. Maulida, and P. Setiarso. The effect of ascorbic acid on nitrite and peroxide levels and nutritional content of edible swiftlet’s nest. Rasayan J. Chem. 16(4) (2023) 2340–2344.
3. J. Y. Gan, L. S. Chang, N. A. M. Nasir, A. S. Babji, and S. J. Lim. Evaluation of physicochemical properties, amino acid profile and bioactivities of edible bird's nest hydrolysate as affected by drying methods. LWT Food Sci. Technol. (2020) 1–25.
4. N. N. Zulkefle, M. A. Ibrahim, N. F. Azuan, S. E. Ch’ng, N. Ismail, M. Z. A. Bakar, and K. W. Chan. A review on the edible bird’s nest quality and manufacturing standards of the three largest exporting countries in the world. J. Food Qual. (2024) 1–23.
5. A. F. E. Sheikha. Why the importance of geo-origin tracing of edible bird nests is arising?. Food Research International. 150 (2021).
6. S. P. Loh, S. H. Cheng, and W. Mohamed. Edible bird’s nest as a potential cognitive enhancer. Front. Neurol. 13 (2022) 1–12.
7. K. Chantakun & S. Benjakul. Effect of ultrasound-assisted pretreatment in combination with heating on characteristics and antioxidant activities of protein hydrolysate from edible bird’s nest co-product. J. Food Sci. Technol. 59(10) (2022) 3908–3917.
8. S. J. Lim, L. S. Chang, S. Fazry, W. A. W. Mustapha, and A. S. Babji.. Functional food and ingredients from seaweed, edible bird’s nest and tropical fruits: a translational research. Food Res. Technol. 151 (2021).
9. C. H. Ng, P. L. Tang, and Y. Y. Ong. Enzymatic hydrolysis improves digestibility of edible bird’s nest (EBN): combined effect of pretreatment and enzyme. J. Food Meas. Charact. 17 (2023) 549–563.
10. J. Qian, D. Chen, Y. Zhang, X. Gao, L. Xu, G. Guan, and F. Wang. Ultrasound-assisted enzymatic protein hydrolysis in food processing: mechanism and parameters. Foods. 12 (2023) 1–27.
11. B. H. Yeo, S. F. Wong, C. P. Tan, Y. Rukayadi, and O. M. Lai. Characterization of freeze- and spray-dried edible bird’s nest hydrolysates. Int. J. Chem. Biochem. Sci. 24(7) (2023) 199–203.
12. P. L. Tang and X. J. Koh. Ultrasound-assisted enzymatic hydrolysis enhances anti-inflammatory and hypoglycemic activities of edible bird’s nest. Food Biosci. 56 (2023) 1–10.
13. W. Y. Tham, M. K. Ong, & C. Y. Teoh. Sialic acid, nutritional and fatty acid compositions of three species of freshwater fish eggs. BIO Web of Conferences. 182 (2025).
14. J. W. A. Ling, L. S. Chang, A. S. Babji and S. J. Lim. Recovery of value-added glycopeptides from edible bird's nest (EBN) co-products: enzymatic hydrolysis, physicochemical characteristics and bioactivity. J. Sci. Food Agric. 100 (2020) 4714–4722.
15. P. K. Chong, S. L. Mun, L. S. Chang, A. S. Babji, and S. J. Lim. Fractionation of edible bird’s nest glycoprotein hydrolysates: characterisation and antioxidative activities of the fractions. Food Sci. Hum. Wellness. 11 (2022) 886–894.
16. A. Damayanti, A. R. Hakim, and R. Saputri. GC-MS analysis of metabolite composition in edible bird’s nest from Jenamas, Central Kalimantan. Int. J. Pharm. Appl. Health Sci. 1(1) (2023) 6–9.
17. S. K. Tai, Z. Hamzah, Q. H. Ng, and C. S. Tan. Surface morphology study on unclean, commercial and bromelain treated edible bird nest (EBN) using scanning electron microscope. IOP Conf. Ser. Mater. Sci. Eng. 932 (2020).
18. Badan Pusat Statistik. Exports of bird’s nest by major countries of destination, 2012–2024. (2025). [Online]. Available: https://www.bps.go.id/en/statistics-table/1/MjAyMiMx/exports-of-bird-nest-by-major-countries-of-destination---2012-2024.html
19. M. M. S. Basukiwardojo, N. Kusumawati, M. T. Asri, S. A. Dzulkarnain, A. N. A. Hafidl, A. Kahfi, M. A. Nabila, F. Setiawan, L. Isyrak, and K. Rahmawati. Ionic liquid ultrasound-assisted extraction (IL-UAE) for duck feather keratin and in silico evaluation as a potential procollagen n-endopeptidase inhibitor. Commun. Sci. Technol. 10(1) (2025) 75–86.
20. G. Bermudez, C. Terenzi, F. Medri, V. Andrisano, and S. Montanari. Comprehensive amino acids profiling of microalgae by gas chromatography-mass spectrometry analysis after pre-column derivatization. J. of Food Composition and Analysis. 140 (2025) 1-11.
21. A. K. Hemker, A. Abdullah, S. Pimentel-Moral, V. M. Gómez-López and F. J. Barba. Effects of high-pressure-assisted enzymatic hydrolysis on physicochemical and antioxidant properties of fish protein hydrolysates. J. Food Eng. 278 (2020).
22. M. Olszwy-Tomczyk. How to Express The Antioxidant Properties of Substances Properly? Chemical Paper. 75 (2021) 6157-6167.
23. S. Rahayu, W. Suryapratama, F. M. Suhartati, M. Bata, E. A. Rimbawanto, and B. Hartoyo. Quality of edible bird’s nest treated by keratinolytic enzymes-based cleaning solution. Food Res. 8(2) (2024) 299–307.
24. H. S. M. Noor, R. M. Ariff, L. S. Chang, X. Y. Chai, H. Y. Tan, N. A. Daud, A. S. Babji, and S. J. Lim. Enzymatic recovery of glycopeptides from different industrial grades edible bird’s nest and its by-products: nutrient, probiotic and antioxidant activities, and physicochemical characteristics. Food Sci. Hum. Wellness. 11 (2022) 1555–1564.
25. R. M. Ibrahim, N. N. M. Nasir, M. Z. A, Bakar, R. Mahmud, N. A. A. Razak. The Authentication and Grading of Edible Bird’s Nest by Metabolite, Nutritional, and Mineral Profiling. Foods. 10 (2021) 1-14.
26. C. H. Lee, N. Hamdan, B. B. Nyakuma, S. L. Wong, K. Y. Wong, H. Tan, and T. H. Lee. Purification, identification and molecular docking studies of antioxidant and anti-inflammatory peptides from edible bird's nest. Food Chem. 454 (2024).
27. C. H. Tung, J. Q. Pan, H. M. Chang, & S. S. Chou. Authentic determination of bird’s nests by saccharides profile. Journal of Food and Drug Analysis. 16(4) (2008) 86–91.
28. A. Ujuldah, A. R. Hakim, and R. Saputri. FTIR spectroscopic characterization of edible bird’s nest from Jenamas, Central Kalimantan. Int. J. Pharm. Appl. Health Sci. 1(1) (2023) 1–5.
29. M. H. Wang, Z. F. Wang, C. G. Yang, D. L. Wang, & S. Q. Wang. Changes in the Serum and Tissue Levels of Free and Conjugated Sialic Acids, Neu5Ac, Neu5Gc, and KDN in Mice after the Oral Administration of Edible Bird’s Nests: An LC–MS/MS Quantitative Analysis. Separations. 107 (2024).
30. T. Dighriri, M. Aljofan, and A. S. Alshammari. Omega-3 polyunsaturated fatty acids and their role in brain functions: A systematic review. J. Food Biochem. 46(4) (2022) e14123.
31. S. Shaninfar, M. R. Goli, and M. Rezaei. Bioactive compounds and fatty acid profile of edible bird’s nest: Functional and nutritional perspectives. J. Ethn. Foods 12 (2025) 15.
32. T. H. Lee, W. A. Wani, C. H. Lee, N. A. Azmi, S. Kavita, M. Znati, and H. B. Jannet. Characterization of polar and non-polar compounds and bioactivity of edible bird’s nest from Johor, Malaysia. Chem. Biodiversity (2020).
33. O. Mahaq, H. A. Hassim, M. H. M. Noor, N. Titisari, & H. Ahmad. Effects of dietary edible bird’s nest supplementation on hippocampal neurons of multigenerational mice. International Journal of Biosciences. 3(3) (2024) 33-46..
34. R. Mohamad Ibrahim, N. N. Mohamad Nasir, M. Z. Abu Bakar, R. Mahmud, and N. A. Ab Razak. The authentication and grading of edible bird’s nest by metabolite, nutritional, and mineral profiling. Foods. 10 (2021) 1574.
35. N. N. Mohamad Nasir, R. Mohamad Ibrahim, M. Z. Abu Bakar, R. Mahmud, and N. A. Ab Razak. Characterization and extraction influence protein profiling of edible bird’s nest. Foods. 10 (2021) 2248.
36. D. D. Murugan, Z. M. Zain. K. W. Choy, N. H. Zamakshshari, M. J. Choong, Y. M. Lim, & M. R. Mustafa. Edible Bird’s Nest Protects Against Hyperglycemia-Induced Oxidative Stress and Endothelial Dysfunction. Frontiers in Pharmacology. 10 (2020).
37. T. T. Nguyen, H. Q. Pham, N. T. L. Tran, and D. V. Nguyen. Fatty acid composition and bioactive properties of edible bird’s nest hydrolysates. Food Chem. 402 (2024) 134215.
38. P. L. Tang, H. S. Goh, and S. S. Sia. Combined enzymatic hydrolysis and herbal extracts fortification to boost in vitro antioxidant activity of edible bird’s nest solution. Chinese Herbal Medicines 13 (2021) 549–555.
39. C. Wen, J. Zhang, J. Zhou, M. Cai, Y. Duan, H. Zhang, H. Ma. Antioxidant Activity of Arrowhead Protein Hydrolysatees Produces by a a Novel Multi-Frequency S-Type Ultrasound-Assisted Enzymolysis. Natural Product Research. 34 (2020) 3000-3003.
40. B. H. Yeo, T. K. Tang, S. F. Wong, L. Z. Cheong, and O. M. Lai. Potential Residual Contaminants in Edible Bird’s Nest. Front. Pharmacol. 12 (2021) 1-15.
41. M. C. Quek, N. L. Chin, Y. A. Yusof, C. L. Law, S. W. Tan. Characterization of edible bird’s nest of different production, species and geographical origins using nutritional composition, physicochemical properties and antioxidant activities. Food Res. Int. (2018) 1-42.
42. S. S. P. Perdana, N. Kusumawati, M. M. S. Basukiwardojo, P. Setiarso, G. N. Djalilah, and K. Rahmawati. The effect of ultrasonication on the quality of keratin extraction based on ionic liquid from duck feather. Commun. Sci. Technol. (2025) 1–8.
43. Q. Fan, P. Wang, X. Zheng, S. S. Hamzah, H. Zeng, Y. Zhang, and J. Hu. Effect of dynamic high pressure microfluidization on the solubility properties and structure profiles of proteins in water-insoluble fraction of edible bird’s nests. LWT Food Sci. Technol. 132 (2020) 1–8.
44. M. N. G. Amin, G. Soegiarto, and L. Wulandari. The physicochemical and antioxidant activity of Realfood’ hydrolysed bird nest (RHBN). Appl. Food Res. 5 (2025) 1–7.
45. A. S. Babji, M. H. Nurfatin, I. K. E. Syarmila, & M. Masitah. Secrets of edible bird nest. UTAR Agriculture Science Journal. 1 (2015) 32–37.
46. Y. Dong, W. Yan, and Y. Q. Zhang. Effects of Spray Drying and Freeze Drying on Physicochemical Properties, Antioxidant and ACE Inhibitory Activities of Bighead Carp (Aristichthys nobilis) Skin Hydrolysates. Foods. 11(14) (2022) 1-13.
47. L. S. Chang, R. Karim, A. Sabo Mohammed and H. Mohd Ghazali. Production and characterization of enzyme-treated spray-dried soursop (Annona muricata L.) powder. J. Food Process Eng. 41 (2018).