RESEARCH ARTICLE Impact of salted duck egg albumen powder on proteolysis and gelling properties of sardine surimi Tran Hong Quan 1,2 | Soottawat Benjakul 1 1 Department of Food Technology, Faculty of Agro-Industry, Prince of Songkla University, Songkhla, Thailand 2 Faculty of Applied Biological Sciences, Department of Food Technology, Vinh Long University of Technology Education, Vinh Long, Vietnam Correspondence Soottawat Benjakul, Faculty of Agro-Industry, Department of Food Technology, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand. Email: soottawat.b@psu.ac.th Funding information Thailand's Education Hub for Southern Region of ASEAN Countries Project Office of the Higher Education Commission; Higher Education Research Promotion Abstract The influences of salted duck egg albumen powder (SDEAP) as salt replacer at various levels (0.5–2.5%) on autolysis and gelling properties of sardine surimi were investigated. SDEAP had high salt (33.67%) and protein contents (64.52%) with trypsin inhibitory activ- ity of 5,975 kunits/g solid. SDEAP was white in color with L*-value of 96.72. It had low moisture content (3.98%) and water activity (0.38). Autolysis of sardine surimi was drasti- cally inhibited when SDEAP was incorporated with increasing levels as indicated by the more retained myosin heavy chain and the reduced trichloroacetic acid-soluble peptide content. Breaking force and deformation of surimi gel increased, while expressible mois- ture content decreased as the levels of SDEAP added were increased (p < .05). Gummi- ness, hardness, chewiness, springiness, and cohesiveness of surimi gels also increased as SDEAP levels increased (p < .05). Lightness and whiteness were higher in all surimi gels incorporated with SDEAP than the control (p < .05). For microstructure, surimi gels incor- porated with SDEAP at all levels used had finer gel network with smaller voids and more connectivity than the control gel. Thus, SDEAP could be used as a salt replacer for sardine surimi gel preparation and it could improve the properties of resulting gel. KEYWORDS duck egg, gel property, proteolysis, salted albumen, sardine surimi, trypsin inhibitor 1 | INTRODUCTION Salted egg is a popular traditional product in China and some Asian countries. In general, salted egg yolk is higher demand than salted albu- men, which is commonly discarded. Albumen of salted duck egg con- tained 4–7% sodium chloride and had the salty taste (Quan & Benjakul, 2018b). In several traditional Chinese foods, salted duck egg yolk is commonly used as a filling material, for instance glutinous rice dump- lings and mooncakes. With increasing demand in aforementioned foods, an increasing amount of salted duck egg albumen considered as waste is produced inevitably (Tan, Phatthanawiboon, & Mat Easa, 2016). Thus, salted duck albumen needs to be more exploited, espe- cially as the food additive. Salted duck albumen was rich in protein and still contained protease inhibitors (Quan & Benjakul, 2018b). Surimi is a form of wet concentrated fish myofibrillar proteins. First, fish are mechanically deboned and the obtained mince is washed thoroughly to concentrate myofibrillar proteins and simultaneously remove water-soluble proteins (Nopianti, Huda, & Ismail, 2011). Surimi has been known to exhibit the excellent gel forming ability. Gelation includes dissociation and unfolding of myofibrillar proteins. A three-dimensional gel network is sub- sequently developed when unfolded proteins undergo aggregation as induced by heat (Petcharat & Benjakul, 2017). Both dark- and white- fleshed fishes, including fresh water and marine fishes, have commonly been used in surimi production, such as lizardfish (Benjakul, Visessanguan, Tueksuban, & Tanaka, 2004), bigeye snapper (Julavittayanukul, Benjakul, & Visessanguan, 2006), tilapia (Rawdkuen, Sai-Ut, Khamsorn, Chaijan, & Benjakul, 2009), mackerel (Balange & Benjakul, 2009), croaker (Panpipat, Chaijan, & Benjakul, 2010), Alaska pollock (Yin & Park, 2014), silver carp (Majumdar, Deb, Dhar, & Priyadarshini, 2013), and common carp (Ganesh, Dileep, Shamasundar, & Singh, 2006). Sardine (Sardinella albella) is one of This article was published on AA publication on: 20 May 2019 Received: 28 March 2019 Revised: 1 May 2019 Accepted: 12 May 2019 DOI: 10.1111/jtxs.12445 J Texture Stud. 2019;1–9. wileyonlinelibrary.com/journal/jtxs © 2019 Wiley Periodicals, Inc. 1