USE OF FOURIER-TRANSFORM INFRARED-SPECTROSCOPY AND PARTIAL LEAST-SQUARES REGRESSION FOR THE DETECTION OF ADULTERATION OF STRAWBERRY PUREES

Fourier transform infrared (FT-IR) spectroscopy and chemometrics have been combined to detect adulteration in strawberry purees. The mid-IR spectra of 983 fruit purees were used as the data for a partial least squares regression on to a binary dummy variable, that represents two sample types, strawberry or non-strawberry. Three hundred and seventy of the spectra were used as an independent test set, of which 94.3% we re correctly assigned by the model. Strawberry purees mixed with certa in adulterants were included in the database to demonstrate that the d etection of these adulterants was possible using this technique. The p otential long-term stability of the model, developed with 1993 and 199 4 fruit, was illustrated by analysing the spectra of fruit harvested i n 1995, of which 96.6% were correctly assigned. A 'blind test' of the model was carried out with a set of 23 fruit puree samples prepared by an industrial collaborator. Twenty two of these samples were classifi ed in accordance with the description of the samples provided by the c ompany. (C) 1998 SCI.