Hydrolysis of b-lactoglobulin by LAB in an in vitro gastric/pancreatic system. Effect of exopolysaccharides.

PESCUMA, M.; HEBERT, E.M.; DALGALARRONDO, M.; GAUDIN, J-C; HAERTLÉ, T.; MOZZI, F.; FONT DE VALDEZ, G.; CHOBERT, J.M.

St. Malo, Francia

Simposio; Second International Symposium on Antimicrobial Peptides.; 2009

Peptides generated by hydrolysis of BLG by non-proliferating cells of the strain Lactobacillus acidophilus CRL 636 were analyzed.  Polysaccharides are commonly used in the dairy industry to improve food texture. They may interact with proteins in the form of hydrocolloids , affecting their digestibility. The effect of polysaccharides (pectin, and two EPS synthesized by two Streptococcus thermophilus strains, EPS1190 and EPS804) on BLG digestibility using an in vitro gastric/pancreatic system was determined. Non-proliferating cells of Lb. acidophilus CRL 636 were able to hydrolyze 52% of BLG. Twenty-six resulting peptides with molecular masses in the range 544 - 4119 Da were identified by LC-MS/MS. These peptides resulted mostly from the hydrolysis of the more accessible N-terminal part of BLG. Degradation of BLG by pepsin was poor (8%). When BLG was previously hydrolyzed by Lb. acidophilus CRL 636, peptic hydrolysis reached 54.8%. After addition of pectin and EPS1190 hydrolysis increased till 58.2 and 57.2%, respectively. Peptides crossing 8 kDa dialysis membranes after trypsin/chymotrypsin hydrolysis were analyzed by HPSEC. The produced peptides were smaller when BLG was hydrolyzed previously by the Lb. acidophilus strain. Moreover, in the presence of pectin, the amount of larger peptide (3.5 kDa) observed in the size exclusion chromatograms was reduced considerably. Our studies showed that pre-hydrolysis of BLG by Lb. acidophilus CRL 636 had a positive influence on BLG digestibility and that polysaccharides may change the peptide profile yielded by tryptic/chymotryptic hydrolysis, releasing smaller size peptides, which are known to be less immuno-reactive. Additionally, Lb. acidophilus CRL 636 was able to hydrolyze the main epitopes (41-60, 102-124, 149-162) of BLG, reducing its allergenic potency.