British Journal of Nutrition

Research Article

Physical and chemical transformations of cereal food during oral digestion in human subjects

C. Hoeblera1 c1, A. Karinthia1, M.-F. Devauxa1, F. Guillona1, D. J. G. Gallanta1, B. Boucheta1, C. Melegaria2 and J.-L. Barrya1

a1 INRA, Laboratory of Applied Technology and Nutrition, BP 71627, 44316, Nantes Cedex 03, France

a2 Barilla, Via Mantova 166, 43100, Parma, Italy

Abstract

Chemical and physical transformations of solid food begin in the mouth, but the oral phase of digestion has rarely been studied. In the present study, twelve healthy volunteers masticated mouthfuls of either bread or spaghetti for a physiologically-determined time, and the levels of particle degradation and starch digestion before swallowing were compared for each food. The amounts of saliva moistening bread and spaghetti before swallowing were, respectively, 220 (SEM 12) v. 39 (SEM 6) g/kg fresh matter. Particle size reduction also differed since bread particles were highly degraded, showing a loss of structure, whereas spaghetti retained its physical structure, with rough and incomplete reduction of particle size. Starch hydrolysis was twice as high for bread as for spaghetti, mainly because of the release of high-molecular-mass α-glucans. The production of oligosaccharides was similar after mastication of the two foods, respectively 125 (SEM 8) and 92 (SEM 7) g/kg total starch. Starch hydrolysis, which clearly began in the mouth, depended on the initial structure of the food, as in the breakdown of solid food. These significant physical and chemical degradations of solid foods during oral digestion may influence the entire digestive process.

(Received January 07 1998)

(Revised April 23 1998)

(Accepted May 27 1998)

Correspondence:

c1 *Corresponding author: Dr Christine Hoebler, fax +33 2 40675012, email hoebler@nantes.inra.fr