title: Structural markers of the evolution of whey protein isolate powder during aging and effects on foaming properties.
abstract: The market for dairy powders, including high added-value products (e.g., infant formulas, protein isolates) has increased continuously over the past decade. However, the processing and storage of whey protein isolate (WPI) powders can result in changes in their structural and functional properties. It is therefore of great importance to understand the mechanisms and to identify the structural markers involved in the aging of WPI powders to control their end use properties. This study was performed to determine the effects of different storage conditions on protein lactosylations, protein denaturation in WPI, and in parallel on their foaming and interfacial properties. Six storage conditions involving different temperatures (θ) and water activities (aw) were studied for periods of up to 12mo. The results showed that for θ≤20°C, foaming properties of powders did not significantly differ from nonaged whey protein isolates (reference), regardless of the aw. On the other hand, powders presented significant levels of denaturation/aggregation and protein modification involving first protein lactosylation and then degradation of Maillard reaction products, resulting in a higher browning index compared with the reference, starting from the early stage of storage at 60°C. These changes resulted in a higher foam density and a slightly better foam stability (whisking) at 6mo. At 40°C, powders showed transitional evolution. The findings of this study will make it possible to define maximum storage durations and to recommend optimal storage conditions in accordance with WPI powder end-use properties.
authors.affiliation: Centre National Interprofessionnel de l'Economie Laitière (CNIEL), 42, rue de Châteaudun 75314 Paris, France; Science et Technologie du Lait et de l'Oeuf (STLO), Agrocampus Ouest, INRA, 35000, Rennes, France.
authors.forename: E-A
authors.initials: EA
authors.lastname: Norwood
authors.affiliation: Science et Technologie du Lait et de l'Oeuf (STLO), Agrocampus Ouest, INRA, 35000, Rennes, France. Electronic address: cecile.lefloch-fouere@agrocampus-ouest.fr.
authors.forename: C
authors.initials: C
authors.lastname: Le Floch-Fouéré
authors.affiliation: Science et Technologie du Lait et de l'Oeuf (STLO), Agrocampus Ouest, INRA, 35000, Rennes, France.
authors.forename: V
authors.initials: V
authors.lastname: Briard-Bion
authors.affiliation: Science et Technologie du Lait et de l'Oeuf (STLO), Agrocampus Ouest, INRA, 35000, Rennes, France.
authors.forename: P
authors.initials: P
authors.lastname: Schuck
authors.affiliation: Science et Technologie du Lait et de l'Oeuf (STLO), Agrocampus Ouest, INRA, 35000, Rennes, France.
authors.forename: T
authors.initials: T
authors.lastname: Croguennec
authors.affiliation: Science et Technologie du Lait et de l'Oeuf (STLO), Agrocampus Ouest, INRA, 35000, Rennes, France.
authors.forename: R
authors.initials: R
authors.lastname: Jeantet
mesh_terms: D000818:Animals; D015416:Maillard Reaction; D008894:Milk Proteins / Q000737:chemistry*; D011208:Powders; D011489:Protein Denaturation; D000067816:Whey Proteins
chemical_list: D008894:Milk Proteins; D011208:Powders; D000067816:Whey Proteins
keywords: denaturation; foam; lactosylation; storage; whey protein