Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem Characterization and emulsifying properties of aquatic lecithins isolated from processing discard of rainbow trout fsh and its eggs Osman Kadir Topuz a, ⁎ , Tuğçe Aygün a , Ali Can Alp a , Hanife Aydan Yatmaz b , Mehmet Torun c , Pınar Yerlikaya a a Department of Aquatic Food Processing Technology, Fisheries Faculty, Akdeniz University, 07054 Antalya, Turkey b Food Safety and Agricultural Research & Development Center Antalya, Akdeniz University, Antalya, Turkey c Department of Food Engineering, Engineering Faculty, Akdeniz University, 07054 Antalya, Turkey ARTICLE INFO Keywords: Aquatic lecithin Rainbow trout egg Fish processing discard Emulsifying properties ABSTRACT This study investigates the characterization and emulsifying properties of diferent type lecithins. Emulsifying properties of lecithins isolated from rainbow trout egg (RL) and trout processing discard (WL) were compared with the soybean (SL) and hen egg yolk (HL) lecithin in sunfower-fsh oil O/W emulsion systems. The phos- pholipid contents of RL and WL were signifcantly higher than those of HL and SL. The higher phospholipid contents in RL and WL resulted in lower droplet size (18.3–20.5 μm), higher viscosity (2.37–2.51 mPa.s) and higher physical stability (78.11–75.33) of emulsions. The linoleic acid (C18:2) was the most abundant PUFA in terrestrial origin lecithins (HL and SL), whereas DHA and EPA, a valuable omega-3 fatty acid, were the major PUFAs in aquatic origin lecithins (RL and WL). RL and WL formed more stable emulsions than HL and SL. This study provides valuable information for utilization of RL and HL as emulsifer in emulsion systems. 1. Introduction Lecithin, a by-product of edible oil industry, is produced from gum generated during the degumming step of oil refning process. Lecithin is a mixture of phospholipids, lysophospholipids, glycolipids triglycerides, carbohydrates and other minor components that has extensive appli- cations in the food, cosmetic and pharmaceutical industries as an emulsifer, solubizer, antti-spattering agent, cooking spray, crystal- lization controller and fller, among other functions (Nguyen et al., 2014; Xie & Dunford, 2016; Belayneh, Wehling, Cahoon, Ciftci, 2018). Lecithin can be obtained from diferent oilseeds such as soybean, ca- nola, sunfower seed, rapeseed, camelina, kernels, peanut (Xie & Dunford, 2017; Belayneh, Wehling, Zhang, Ciftci, 2018). Apart from oilseed, lecithin can be isolated from the dairy products, egg yolk and marine sources (Belhaj et al., 2010; Asaduzzaman & Chun, 2015; Imran et al., 2015; Asomaning & Curtis, 2017). Lecithins from diferent sources exhibit diferent properties because they have diferent fatty acid and phospholipid components. Marine phospholipids are diferent from other phospholipids derived from oilseeds and egg yolk (Lu et al., 2017). Marine lecithin contains a high percantage of polyunsaturated fatty acids (PUFAs), mainly eicosa- pentaenoic acid (EPA) and docosahexaenoic acid (Belhaj et al., 2010) in phospholipid form. PUFAs have been reported to protect the immune system against the many diseases, such as coronary heart diseases, hypertension and infammatory disorders (Belhaj et al., 2010). Phos- pholipid form PUFAs have advantages such as better bioavailability and better oxidation resistance compared the triglyceride form of PUFAs (Lu et al., 2017). Phosphatidylcholine is a main phospholipid of marine lecithin decreases the cell proliferation and increases the apoptosis of tumor cells under carcinogen treatment (Fukunaga et al., 2008; Belhaj et al., 2010). Phospholipids are abundant in fsh ofal such as viscera, head and egg of fsh (Mahmoud et al., 2008) compared to muscle. There is a growing interest of using marine origin lecithin as in- gredient for food fortifcation and emulsifcation, since it contains high level of PUFAs (mainly EPA and DHA) in phospholipid forms. In ad- dition, marine lecithin is used as natural surfactants for emulsion pre- paration and as efective carriers of omega-3 rich oil as they could be incorporated easily into aqueous and emulsifed foods. Rainbow trout fsh is a popular aquatic food in all over the world. Rainbow trout fsh (Oncorhynchus mykiss) consumption has been increasing year by year because of its delicious taste and aroma. In parallel with the increase in trout fsh consumption, by-product and processing discard have been also increased for last decade. About 25% of the total fsh production is considered inedible. This biomass would https://doi.org/10.1016/j.foodchem.2020.128103 Received 14 February 2020; Received in revised form 7 September 2020; Accepted 12 September 2020 ⁎ Corresponding author at: Department of Aquatic Food Processing Technology, Fisheries Faculty, Akdeniz University, 07054, Konyaaltı, Antalya, Turkey. E-mail address: oktopuz@akdeniz.edu.tr (O.K. Topuz). Food Chemistry 339 (2021) 128103 Available online 17 September 2020 0308-8146/ © 2020 Elsevier Ltd. All rights reserved. T