Free Access
Volume 28, Number 3, April 2000
Page(s) 245 - 252
Section Original articles
Analusis 28, 245-252 (2000)
DOI: 10.1051/analusis:2000116

The use of synthetic foods to optimise microwave-assisted digestion procedures

W. Zorgati, D.N. Rutledge and M.H. Feinberg

Institut National de la Recherche Agronomique, Laboratoire de Chimie Analytique 16, rue Claude Bernard, 75231 Paris Cedex 05, France

(Received December 29, 1999; Revised April 18, 2000; accepted April 27, 2000.)

Major food constituents such as proteins, fats and carbohydrates are generally recognised as having a strong influence on the performance of acid sample digestion. Various Scheffé mixture experimental designs were used to detect the influence and the interactions between these constituents during the Kjeldahl nitrogen digestion using focused microwaves. Pure ingredients were mixed in different proportions in order to prepare 7 synthetic food samples covering a wide range of foods types. 3 heating powers were applied and nitrogen recovery yields were recorded at different times. Two types of models were proposed to describe the data: one that explains the shape of the recovery profiles, the other that gives the response surfaces of the recovery yield as a function of digestion time. From these models precise guidelines to optimise the digestion program of a given food can be deduce.

Key words: Microwave -- Kjeldahl -- digestion -- mixture design.

© EDP Sciences, Wiley-VCH 2000