Effect of Polysaccharides on the in vitro ß-lactoglobulin digestibility

PESCUMA, M.; HEBERT, E.M.; MOZZI, F.; FONT DE VALDEZ, G.

San Miguel de Tucumán

Simposio; II SIMPOSIO INTERNACIONAL DE BACTERIAS LACTICAS; 2006

CERELA-CONICET

In general, processed foods contain mixtures of polysaccharides and proteins. Interactions between these biopolymers can affect reological properties and digestibility of food products. Whey proteins are added to many processed foods to enhance its nutritional value, while polysaccharides are included in order to increase viscosity. Certain lactic acid bacteria, used in the formulation of fermented products, are able to synthesize polysaccharides and degrade dairy proteins. Hydrolysis of b-lactglobulin (BLG), the major whey protein, may release peptides of low molecular weight (3-8 kDa), which in certain conditions diffuse the intestinal barrier causing allergenic problems. The aim of this work was to evaluate the ability of Lactobacillus delbrueckii subsp. bulgaricus CRL 454 to degrade BLG, focusing on the release of allergenic peptides (3 - 8 kDa) by means of an in vitro model simulating the digestive process. The effect of different polysaccharides (microbial: EPS1190, EPS804 and vegetal: pectin) on BLG digestibility was also evaluated. BLG was incubated with non proliferating cells of L. delbrueckii subsp. bulgaricus CRL 454 at 37°C during 6 h. The obtained hydrolyzate was blended with the polysaccharides, subjected to gastric digestion with pepsin (2 h, 37°C) and further hydrolyzed (37°C, 6 h) by trypsin and chymotrypsin in dialysis bags of different molecular weight cut-offs (3 – 8 kDa). Degradation was assessed by the o-PA method and Tricine – SDS gels. BLG was significatively (p < 0.05) degraded (48%) by L. delbrueckii subsp. bulgaricus CRL 454. BLG gastric digestion increased (15%) when pectin was added, while release of allergenic peptides, produced by trypsin and chymotrypsin digestion, was diminished (2%). Similar results were observed for EPS1190. On the contrary when EPS804 was included in the mixture, the release of these peptides (3-8 kDa) increased (4%). These results demonstrated the importance of a rational selection of the polysaccharides to be included in food products, taken into account the interactions between these biopolymers and the proteins occurring in the food matrix.