TY - JOUR

T1 - Water mobility and microstructure of acidified milk model gels with added whey protein ingredients

AU - Li, Ruifen

AU - Czaja, Tomasz Pawel

AU - Glover, Zachary J.

AU - Ipsen, Richard

AU - Jæger, Tanja Christine

AU - Rovers, Tijs A.M.

AU - Simonsen, Adam Cohen

AU - Svensson, Birte

AU - van den Berg, Frans

AU - Hougaard, Anni Bygvrå

N1 - Funding Information: This research was jointly supported by the Danish Dairy Research Foundation and Chinese Scholarship Council, CSC . Arla Foods Ingredient (Nr. Vium, Denmark) is thanked for providing nano-particulated whey protein, micro-particulated whey protein and whey protein concentrate powders. Publisher Copyright: © 2022 The Author(s)

PY - 2022

Y1 - 2022

N2 - Water mobility was assessed in acidified milk model systems made from casein and whey protein ingredients using low-field nuclear magnetic resonance (LF-NMR). Two water pools, less mobile and mobile water, were detected during acidification, while three water pools were observed in the resultant stirred acidified milk systems during storage, including a free water fraction of expelled serum (i.e., spontaneous syneresis). The system with highest content of micro-particulated whey protein (MWP) contained a smaller amount of less mobile water at the end of acidification, whereas its stirred acidified gel showed a higher proportion of less mobile water. In addition, it also displayed a higher spontaneous syneresis, induced syneresis and instability index, and lower water-holding capacity (WHC) with a more open and coarse gel structure compared to other systems. The system with highest content of nano-particulated whey protein (NWP) showed a gel structure with larger aggregates, and its water mobility was only slightly affected by structural rearrangements after stirring, resulting in more mobile water in the stirred acidified gel. Compared to NWP, systems with whey protein concentrate (WPC) showed similar spontaneous syneresis and WHC, but lower induced syneresis with a more homogeneous and denser gel structure. Quantitative image analysis of confocal laser scanning microscopy (CLSM) micrographs showed that values of gel particle size (ξ), inter-pore distance (λ), fractal dimension (Df), normalized variation (σ2) and pore ratio (Pa) can be correlated to water mobility.

AB - Water mobility was assessed in acidified milk model systems made from casein and whey protein ingredients using low-field nuclear magnetic resonance (LF-NMR). Two water pools, less mobile and mobile water, were detected during acidification, while three water pools were observed in the resultant stirred acidified milk systems during storage, including a free water fraction of expelled serum (i.e., spontaneous syneresis). The system with highest content of micro-particulated whey protein (MWP) contained a smaller amount of less mobile water at the end of acidification, whereas its stirred acidified gel showed a higher proportion of less mobile water. In addition, it also displayed a higher spontaneous syneresis, induced syneresis and instability index, and lower water-holding capacity (WHC) with a more open and coarse gel structure compared to other systems. The system with highest content of nano-particulated whey protein (NWP) showed a gel structure with larger aggregates, and its water mobility was only slightly affected by structural rearrangements after stirring, resulting in more mobile water in the stirred acidified gel. Compared to NWP, systems with whey protein concentrate (WPC) showed similar spontaneous syneresis and WHC, but lower induced syneresis with a more homogeneous and denser gel structure. Quantitative image analysis of confocal laser scanning microscopy (CLSM) micrographs showed that values of gel particle size (ξ), inter-pore distance (λ), fractal dimension (Df), normalized variation (σ2) and pore ratio (Pa) can be correlated to water mobility.

KW - Acidified milk

KW - Free water

KW - Gel microstructure

KW - Image analysis

KW - Mobile water

KW - Syneresis

U2 - 10.1016/j.foodhyd.2022.107548

DO - 10.1016/j.foodhyd.2022.107548

M3 - Review

AN - SCOPUS:85123762926

VL - 127

JO - Food Hydrocolloids

JF - Food Hydrocolloids

SN - 0268-005X

M1 - 107548

ER -