It is also possible to add thereto one or more co-emulsifying agents which, advantageously, may be selected from the group comprising esters of fatty acids with a branched chain and polyol, in particular esters of fatty acid with a branched chain and glycerol and/or sorbitan and, for example, polyglyceryl isostearate, such as the product marketed under the trademark Isolan GI 34 by Goldschmidt, so