TY - JOUR

T1 - In situ SAXS study of non-fat milk model systems during heat treatment and acidification

AU - Li, Ruifen

AU - Jæger, Tanja Christine

AU - Rovers, Tijs A.M.

AU - Svensson, Birte

AU - Ipsen, Richard

AU - Kirkensgaard, Jacob J.K.

AU - Hougaard, Anni Bygvrå

N1 - Publisher Copyright: © 2022 The Authors

PY - 2022

Y1 - 2022

N2 - Small-angle X-ray scattering (SAXS) was used to monitor structural changes induced by heat treatment and acid gelation in milk matrices with added whey protein concentrates (WPCs) and nano-particulated whey protein (NWP). In general, heat treatment was found to mainly affect whey protein components while pure casein micelles remained largely unaffected. Conversely, acidification mainly affected caseins while leaving pure whey protein components intact. In mixed systems, the overall behaviour could be understood as a combination of the above effects, however, the type of the added whey protein components influenced the resulting structure formation and dynamics. NWP led to formation of larger structures compared to WPC components during heat treatment, although the latter showed faster aggregation dynamics. During acidification the NWP containing samples exhibited structural changes at slightly higher pH values than the WPC samples. The modeling of pure liquid whey protein (LWPC) samples showed that the heat induced denaturation and resulting aggregation of individual whey proteins is mainly a surface effect leaving the overall protein shape and dimensions unaffected. Schematic diagrams based on the current SAXS data and previous studies were constructed to illustrate the suggested interaction mechanisms between casein and whey proteins during both heating and acidification.

AB - Small-angle X-ray scattering (SAXS) was used to monitor structural changes induced by heat treatment and acid gelation in milk matrices with added whey protein concentrates (WPCs) and nano-particulated whey protein (NWP). In general, heat treatment was found to mainly affect whey protein components while pure casein micelles remained largely unaffected. Conversely, acidification mainly affected caseins while leaving pure whey protein components intact. In mixed systems, the overall behaviour could be understood as a combination of the above effects, however, the type of the added whey protein components influenced the resulting structure formation and dynamics. NWP led to formation of larger structures compared to WPC components during heat treatment, although the latter showed faster aggregation dynamics. During acidification the NWP containing samples exhibited structural changes at slightly higher pH values than the WPC samples. The modeling of pure liquid whey protein (LWPC) samples showed that the heat induced denaturation and resulting aggregation of individual whey proteins is mainly a surface effect leaving the overall protein shape and dimensions unaffected. Schematic diagrams based on the current SAXS data and previous studies were constructed to illustrate the suggested interaction mechanisms between casein and whey proteins during both heating and acidification.

KW - Acidified gel

KW - Casein micelle

KW - Interactions of milk proteins

KW - Nano-particulated whey protein

KW - Small-angle X-ray scattering

KW - Whey protein concentrate

U2 - 10.1016/j.foodres.2022.111292

DO - 10.1016/j.foodres.2022.111292

M3 - Journal article

C2 - 35761598

AN - SCOPUS:85129477077

VL - 157

JO - Food Research International

JF - Food Research International

SN - 0963-9969

M1 - 111292

ER -