Determination of polydextrose as a fat replacer in butter

Polydextrose is used in several countries as a low caloric sugar and fat substitute (bulking agent). It is prepared by condensation of glucose, D-glucitol, and citric acid (89:10:1). The resulting condensation product has no chemically defined structure but it represents a mixture of polymerisation products. The determination of polydextrose in butter is complicated owing to a large excess of fats and to the presence of other compounds, mainly proteins. FT-IR spectroscopy seems to be a satisfying method for the detection of polydextrose in samples derived from food products. The presence of polydextrose in butter was verified after the removal of fats by extraction with petroleum ether and deproteinisation with Sevag reagent, CHCl3/n-butanol (v/v = 4:1) mixture, or trichlorocetic acid. The solid fraction of butter and butter containing a known amount of polydextrose were prepared and analysed by FT-IR spectroscopy. IR marker bands of polydextrose centred at 1150, 1076 and 1040 cm(-1) were found only in the case of the sample of butter with polydextrose.