With the aim to answer society’s current concerns on the environmental impact of fossil resources centered industrialization, researchers have been focused in developing novel intensified processes to obtain commercial biobased consumer chemicals. Among the wide range of such chemical, surfactants are of special interest because of its high consumption volume and the wide variety of applications. Biobased surfactants currently available in the market are mainly produced from fatty acids from natural oils and saccharides from natural resources (Hayes, 2012). For example, fatty acid sucrose esters which are declared as emulsifier E473 (food ingredient number), are produced from sucrose (from sugar cane) and fatty acids derivatives (such as fatty acid methyl esters), and their current market is estimated in over 10,000 t/year (Carnero-Ruiz, 2000).
Sucrose esters are generally produced by direct transesterification of sucrose with fatty acid methyl ester (FAME). In this chemical route, reactants are not miscible and they are present in two different phases. Different processing alternatives have been developed to overcome this problem, and so three different processes can be identified: solvent process, emulsion process, and melt process (or solvent-free process) (Nelen & Cooper, 2004). However, some technical problems related to these processes can make sucrose ester production inefficient and economically non-viable. Difficulty and high cost of solvent removal in solvent and emulsion processes, and caramelization of sucrose in melt process, are major drawbacks.
Considering that proper contact between sucrose and FAME is a key issue in the production of sucrose esters, this work focused on the reaction system where emulsifiers are added to promote contact between reactants. Emulsifiers used include the product itself (sucrose esters) and some compounds that are found as impurities during FAME production, such as monoacylglycerols and soaps (See Figure 1). Such emulsifiers are of similar nature of the desired product and could contribute and improve its specific functional properties. Since further product separation might not be necessary, the use of these compounds in the reaction system follows process intensification principles.
In this work, enhancement of sucrose solubility in FAME is experimentally evaluated at different conditions. A box-behnken experimental design was used to study the influence of temperature and emulsifier concentration in sucrose solubility, in order to obtain appropriate operation parameters. Binary and ternary data of emulsifier-reactants system were collected for further modeling of the multicomponent reaction system. Comparison between emulsifiers allows to study the influence of emulsifier type (ionic, non-ionic) and chemical structure (hydrophilic-lipophilic balance) in the reaction system. For quantification of dissolved sucrose and esters, high performance liquid chromatography (HPLC) is used. Data generated in this work contributes as the basis for the computer simulation of the reacting system