Green and sustainable technology in the production of emulsifiers: monoesters

Food emulsifiers are indispensable ingredients in most processed food containing fats and oils. Synthetic surfactants and emulsifiers are widely used in many of our foods, but, it becomes very important to replace them by natural molecules with good health records. Natural surface active agents such as monoglycerides, polyglycerol esters of fatty acids and sorbitan esters of fatty acids are still key emulsifiers because of their high surface activity, low critical micelle concentration (CMC) and low toxicity. The commercial large scale production of these chemicals relies on traditional homogeneouscatalysis process making use of strong mineral acids and alkalis. This technology possesses severe drawbacks, related to the generation of large amounts of by-products, high energy demand, and heterogeneity of the ester mixtures obtained. The innovativeand proprietary technology from COMBICAT allows production of polyols via esterification (fatty acids and alcohols) or transesterification (triglycerides and alcohols) of vegetable oil and animal fats as well as fatty acids methyl esters with monohydric or polyhydric alcohols in the presence of heterogeneous solid catalyst. The feedstocks used are polyhydric alcohols, fatty acids and a fat/oil from vegetable and animal alcohols such as glycerols, sorbitol, manitol, dusitol, xyletol as methyl esters, preferably esters of saturated or unsaturated fatty acids with a number of carbon atoms between 10-32. The temperature of the process is in the range of 50-250°C and the amount of catalyst is 2-10%wt. The preparation of monoesters of polyhydric alcohols, particularly sorbitol comprises of two steps: 1) the protection of the alcohol groups of sorbitol by acetylization with a lower carbonyl compound and, 2) reacting such protected polyhydric alcohol with a fatty acid. The catalysts are solid acid of the family of zeolites, meoporous oxides and heteropolyacids. As zeolite, large and medium pores are preferred amongst them faujasites, omega, offretite, ZSM5, Beta, SSZ24, MCM22, SSZ26 are more preferred, which are commercially available. The carbonyl compound use in the acetylation of thealcohol is an aldehyde or ketone preferably a low aliphatic ketone, formaldehyde, acetaldehyde or propanal. In the case festerification, the reaction is carried out in one reactor in where the acetylation is followed by esterification with a unique acid catalyst, or on two different reactors.