title: In vitro digestibility of beta-casein and beta-lactoglobulin under simulated human gastric and duodenal conditions: a multi-laboratory evaluation.
abstract: Initially the resistance to digestion of two cow's milk allergens, beta-casein, and beta-lactoglobulin (beta-Lg), was compared using a "high-protease assay" and a "low-protease assay" in a single laboratory. The low-protease assay represents an alternative standardised protocol mimicking conditions found in the gastrointestinal tract. For the high-protease assay, both proteins were incubated with either pepsin or pancreatin and digestion monitored by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and reverse phase-high performance liquid chromatography. The low-protease assay involved gastroduodenal digestion in the presence or absence of phosphatidylcholine (PC). Both beta-casein and beta-Lg were susceptible to hydrolysis by pepsin and pancreatin in the high-protease assay. In contrast, the kinetics of beta-casein digestion in the low-protease assay were slower, beta-Lg being pepsin resistant. During duodenal digestion, beta-Lg was gradually degraded and addition of PC slowed digestion. Subsequently, the reproducibility of the low-protease assay was assessed in 12 independent laboratories by visual assessment of the gels and densitometric analysis: the inter- and intra-laboratory variability was affected by sampling and electrophoresis method employed. The low-protease assay was shown to be reproducible. Future studies will extend these findings using a broader panel of proteins.
authors.affiliation: Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4 7UA, UK. giusy.mandalari@bbsrc.ac.uk
authors.forename: G
authors.initials: G
authors.lastname: Mandalari
authors.forename: K
authors.initials: K
authors.lastname: Adel-Patient
authors.forename: V
authors.initials: V
authors.lastname: Barkholt
authors.forename: C
authors.initials: C
authors.lastname: Baro
authors.forename: L
authors.initials: L
authors.lastname: Bennett
authors.forename: M
authors.initials: M
authors.lastname: Bublin
authors.forename: S
authors.initials: S
authors.lastname: Gaier
authors.forename: G
authors.initials: G
authors.lastname: Graser
authors.forename: G S
authors.initials: GS
authors.lastname: Ladics
authors.forename: D
authors.initials: D
authors.lastname: Mierzejewska
authors.forename: E
authors.initials: E
authors.lastname: Vassilopoulou
authors.forename: Y M
authors.initials: YM
authors.lastname: Vissers
authors.forename: L
authors.initials: L
authors.lastname: Zuidmeer
authors.forename: N M
authors.initials: NM
authors.lastname: Rigby
authors.forename: L J
authors.initials: LJ
authors.lastname: Salt
authors.forename: M
authors.initials: M
authors.lastname: Defernez
authors.forename: F
authors.initials: F
authors.lastname: Mulholland
authors.forename: A R
authors.initials: AR
authors.lastname: Mackie
authors.forename: M S J
authors.initials: MS
authors.lastname: Wickham
authors.forename: E N C
authors.initials: EN
authors.lastname: Mills
mesh_terms: D000485:Allergens / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D002364:Caseins / Q000276:immunology / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004063:Digestion; D004386:Duodenum / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D005753:Gastric Mucosa / Q000378:metabolism; D006801:Humans; D007782:Lactoglobulins / Q000276:immunology / Q000378:metabolism*; D008892:Milk / Q000737:chemistry / Q000276:immunology; D010194:Pancreatin / Q000378:metabolism; D010434:Pepsin A / Q000378:metabolism; D015203:Reproducibility of Results; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry
chemical_list: D000485:Allergens; D002364:Caseins; D007782:Lactoglobulins; D012967:Sodium Dodecyl Sulfate; D010194:Pancreatin; D010434:Pepsin A