TY - JOUR
T1 - Discriminating between different proteins in the microstructure of acidified milk gels by super-resolution microscopy
AU - Li, Ruifen
AU - Ebbesen, Morten Frendø
AU - Glover, Zachary J.
AU - Jæger, Tanja Christine
AU - Rovers, Tijs A.M.
AU - Svensson, Birte
AU - Brewer, Jonathan R.
AU - Simonsen, Adam Cohen
AU - Ipsen, Richard
AU - Hougaard, Anni Bygvrå
N1 - Publisher Copyright:
© 2023 The Authors
PY - 2023
Y1 - 2023
N2 - Super-resolution microscopy (Stimulated Emission Depletion, STED) combined with quantitative image analysis and rheology was used to study acidified milk gels with the addition of both endogenous milk proteins (i.e., liquid casein and whey protein concentrate, LCC and LWPC) and different types of whey protein ingredients. Casein and whey protein were stained separately using two different dyes prior to mixing. STED micrographs showed that added whey protein concentrate (WPC) and nano-particulated whey protein (NWP) were able to self-aggregate and attach to casein assemblies by inter-chain crosslinking. The behavior of NWP was shown to be similar to the behavior of LWPC, except that NWP formed larger aggregates with increased connectivity to the gel network. Micro-particulated whey protein (MWP) did not appear to interact with any other proteins and scattered MWP particles were visible in the mixed gels. The spatial colocalization of the fluorescence emission stemming from casein and whey protein, respectively, was highest for the system that contained only endogenous proteins. The lowest colocalization level was found for the systems with added MWP which also showed the highest image coarseness in accordance with the lowest observed G’. The systems with added LWPC or NWP exhibited thicker aggregate strands, which correlated to higher G’ compared to the other systems with WPC.
AB - Super-resolution microscopy (Stimulated Emission Depletion, STED) combined with quantitative image analysis and rheology was used to study acidified milk gels with the addition of both endogenous milk proteins (i.e., liquid casein and whey protein concentrate, LCC and LWPC) and different types of whey protein ingredients. Casein and whey protein were stained separately using two different dyes prior to mixing. STED micrographs showed that added whey protein concentrate (WPC) and nano-particulated whey protein (NWP) were able to self-aggregate and attach to casein assemblies by inter-chain crosslinking. The behavior of NWP was shown to be similar to the behavior of LWPC, except that NWP formed larger aggregates with increased connectivity to the gel network. Micro-particulated whey protein (MWP) did not appear to interact with any other proteins and scattered MWP particles were visible in the mixed gels. The spatial colocalization of the fluorescence emission stemming from casein and whey protein, respectively, was highest for the system that contained only endogenous proteins. The lowest colocalization level was found for the systems with added MWP which also showed the highest image coarseness in accordance with the lowest observed G’. The systems with added LWPC or NWP exhibited thicker aggregate strands, which correlated to higher G’ compared to the other systems with WPC.
KW - Casein
KW - Image analysis
KW - Mixed gels
KW - Rheological properties
KW - Stimulated emission depletion (STED)
KW - Whey protein ingredients
U2 - 10.1016/j.foodhyd.2023.108468
DO - 10.1016/j.foodhyd.2023.108468
M3 - Journal article
AN - SCOPUS:85146158605
VL - 138
JO - Food Hydrocolloids
JF - Food Hydrocolloids
SN - 0268-005X
M1 - 108468
ER -