title: Foam fractionation as a tool to study the air-water interface structure-function relationship of wheat gluten hydrolysates.
abstract: Enzymatic hydrolysis of wheat gluten protein improves its solubility and produces hydrolysates with foaming properties which may find applications in food products. First, we here investigated whether foam-liquid fractionation can concentrate wheat gluten peptides with foaming properties. Foam and liquid fractions had high and very low foam stability (FS), respectively. In addition, foam fractions were able to decrease surface tension more pronouncedly than un-fractionated samples and liquid fractions, suggesting they are able to arrange themselves more efficiently at an interface. As a second objective, foam fractionation served as a tool to study the structural properties of the peptides, causing these differences in air-water interfacial behavior. Zeta potential and surface hydrophobicity measurements did not fully explain these differences but suggested that hydrophobic interactions at the air-water interface are more important than electrostatic interactions. RP-HPLC showed a large overlap between foam and liquid fractions. However, a small fraction of very hydrophobic peptides with relatively high average molecular mass was clearly enriched in the foam fraction. These peptides were also more concentrated in un-fractionated DH 2 hydrolysates, which had high FS, than in DH 6 hydrolysates, which had low FS. These peptides most likely play a key role in stabilizing the air-water interface.
authors.affiliation: Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Center (LFoRCe), KU Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium. Electronic address: arno.wouters@kuleuven.be.
authors.forename: Arno G B
authors.initials: AGB
authors.lastname: Wouters
authors.affiliation: Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Center (LFoRCe), KU Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium.
authors.forename: Ine
authors.initials: I
authors.lastname: Rombouts
authors.affiliation: Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Center (LFoRCe), KU Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium.
authors.forename: Nele
authors.initials: N
authors.lastname: Schoebrechts
authors.affiliation: Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Center (LFoRCe), KU Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium.
authors.forename: Ellen
authors.initials: E
authors.lastname: Fierens
authors.affiliation: Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Center (LFoRCe), KU Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium.
authors.forename: Kristof
authors.initials: K
authors.lastname: Brijs
authors.affiliation: Department of Food Sciences and Formulation, Gembloux Agro-Bio Tech, University of Liège, 5030 Gembloux, Belgium.
authors.forename: Christophe
authors.initials: C
authors.lastname: Blecker
authors.affiliation: Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Center (LFoRCe), KU Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium.
authors.forename: Jan A
authors.initials: JA
authors.lastname: Delcour
mesh_terms: D000388:Air; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004798:Enzymes / Q000737:chemistry; D005753:Gastric Mucosa / Q000378:metabolism; D005983:Glutens / Q000737:chemistry*; D006868:Hydrolysis; D057927:Hydrophobic and Hydrophilic Interactions; D009991:Oscillometry; D010434:Pepsin A / Q000737:chemistry; D011312:Pressure; D011492:Protein Hydrolysates / Q000737:chemistry*; D055672:Static Electricity; D013329:Structure-Activity Relationship; D013499:Surface Properties; D013552:Swine; D014908:Triticum / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D004798:Enzymes; D011492:Protein Hydrolysates; D014867:Water; D005983:Glutens; D010434:Pepsin A
keywords: Air-water interfacial properties; Foam fractionation; Hydrolysate; Hydrophobicity; Wheat gluten