Original article Potential of bagasse obtained using hydrothermal liquefaction pre-treatment as a natural emulsifier Sekove Vodo, 1 Noamane Taarji, 1 Meryem Bouhoute, 1 Lorena de Oliveira Felipe, 1 Marcos A. Neves, 1,2,3 * Isao Kobayashi, 1,3 Kunihiko Uemura 3 & Mitsutoshi Nakajima 1,2,3 1 Tsukuba Life Science Innovation Program (T-LSI), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan 2 Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan 3 Food Research Institute, NARO, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan (Received 13 September 2019; Accepted in revised form 29 January 2020) Summary Bagasse, a by-product from raw sugar factories, is conventionally burned for energy production. In this study, bagasse extracts from hydrothermal liquefaction (HTL) treatment (160 °C, 1 MPa and 30 min) with a carbohydrate content of 510.3 mg g À1 and 0.5 mg g À1 of total phenols were applied as emulsifiers in oil-in-water (O/W) emulsions. Bagasse extracts from HTL (0.5–4 wt%) lowered the interfacial tension between oil–water interphase from 19.8 to 14.0 mN m À1 , owing possibly to the surface-active hydrophilic carbohydrate-hydrophobic lignin complexes in the extracts (lignin content: 7.1% w/w). Emulsions sta- bilised by bagasse extracts from HTL with average droplet size, d av of 0.79 lm were comparable with gum arabic (GA), d av of 2.24 lm after 11 days at 25 °C. Bagasse extracts containing biopolymers have the potential for industrial applications involving emulsion systems; therefore, HTL treatment of bagasse without any solvents can be regarded as an effective tool for producing natural emulsifiers. Keywords Bagasse, hydrothermal liquefaction, interfacial tension, lignin, natural emulsifiers, oil-in-water emulsion. Introduction Hydrothermal liquefaction, also known as autohydrol- ysis, and hot water extraction follow the working prin- ciple of subcritical water condition with a temperature range from 150 to 350 °C and pressures from 0.4 to 20 MPa. At these conditions, water has a lower den- sity and dielectric constant allowing it to act as a reac- tant and hydrolyse biomass that is not easily soluble at room temperature. Conventionally, biomass pre- treatment employs a combination of chemicals and biological enzymes to fractionate the structural com- plexity of bagasse; however, these methods are costly and time-consuming and produce by-products that are harmful to the environment. HTL has recently been gaining interest with its use as a pre-treatment method for biomass as in lignin pre-treatment (Cheng et al., 2016; Watanabe et al., 2018), sorghum (Yu et al., 2016), water hyacinth (Singh et al., 2015), switchgrass (Yu et al., 2016) and Chinese quince fruit (Liu et al., 2018). It is not only limited to biomass as Enteshari & Mart  ınez-Monteagudo (2018) treated the protein frac- tion of ice-cream wastewater with subcritical treatment and Tao et al. (2019) used pressurised heating on okara protein. HTL treatment as a green technology very much appeals as a promising route for conversion technology with focus on alternate, clean and cheap technologies being a global challenge. Bagasse, as a potential source of hemicellulose and cellulose for conversion in biorefinery concepts, has been thoroughly studied. It is a fibrous by-product from raw sugarcane processing and usually weighs up to 280 kg for every one tonne of sugarcane being crushed (Rabelo et al., 2011). With the global produc- tion of 279 million metric tonnes, it is abundant and 50% is usually left unutilised after burning in high- pressure boilers to produce electrical energy (Pandey et al., 2000; Chandel et al., 2012). It contains poly- meric cellulose of 40–50%, hemicellulose at 25–35% and lignin from 7 to 24%. Minerals, waxes and other compounds exist but to a lesser content. Research on HTL as a pre-treatment method is concentrated towards woody biomass and algae valorisation for biorefineries (Caporgno et al., 2016; D~ ar~ aban et al., 2015; Jin et al., 2014; Karag€ oz et al., 2005; Sipponen et al., 2016;), while application on food is largely unex- plored considering the bagasse extract from HTL, has *Correspondent: E-mail: marcos.neves.ga@u.tsukuba.ac.jp International Journal of Food Science and Technology 2020, 55, 1485–1496 doi:10.1111/ijfs.14543 © 2020 Institute of Food Science and Technology The peer review history for this article is available at https://publons.com/publon/10.1111/ijfs.14543. 1485