Resistance of beta-lactoglobulin-bound lactose to the hydrolysis by beta-galactosidase

François Morgan (1) , Gwenaele Henry (1) , Yvon Le Graet (1) , Daniel Mollé (1) , Joelle Léonil (1) , Said Bouhallab (1)

1 STLO - Science et Technologie du Lait et de l'Oeuf

An in vitro study was conducted to investigate the sensitivity of lactose-b-lactoglobulin conjugates to b-galactosidase from Kluyveromyces lactis. The hydrolysis was monitored by ion exchange chromatography. Compared to free lactose or lactulose, which were rapidly hydrolysed, protein-bound lactose was not hydrolysed by b-galactosidase even after an extended hydrolysis time. Tryptic digestion of the conjugates before addition of b-galactosidase improved the substrate accessibility and led to the release of about 50% of the linked lactose. The results strongly suggest that the resistance of protein bound lactose is linked to the globular and compact structure of lactose-b-lactoglobulin conjugates.

Mots clés: ²-lactoglobulin; milk sugar; saccharification

Mots clés: beta lactoglobuline; lactose; beta galactosidase; hydrolyse

Domaines: Alimentation et Nutrition; Ingénierie des aliments

François Morgan, Gwenaele Henry, Yvon Le Graet, Daniel Mollé, Joelle Léonil, et al.. Resistance of beta-lactoglobulin-bound lactose to the hydrolysis by beta-galactosidase. International Dairy Journal, 1999, 9 (11), pp.813-816. ⟨hal-01568877⟩