WPI has shown that the combined effects of ultrasound and heat
mediate great effects on thermal properties and gelling behavior.
We examined the effects of ultrasonication and heat treatment
alone and combined on the thermal behavior of whey proteins in
solution. Different WPIs were applied to study whether the
b-Lg:a-La ratio would affect the outcome of the experiments.
Analysis of denaturation enthalpies revealed that ultrasonication
and heat combined (NTC treatment) lead to significant reductions
in enthalpy, whereas neither ultrasonication nor heat alone
was sufficient to confer this effect (Fig. 1B).
The greater effect conferred by the NTC treatment is concurrent
with the observations done for WP samples from a whey production
line by Martini et al. (2010). Furthermore, Chandrapala et al.
(2011) show that ultrasonication of WPC for 30 min. does not alter
the enthalpy of denaturation if performed at cold temperatures
(6 ± 4 C), indicating that the heat generated during ultrasonication
indeed plays an important role in the observed effects. It is possible
that the heat generated as a consequence of ultrasonication initiates
unfolding of the protein to some degree, thereby making the
protein more susceptible for the impact of ultrasonication.
If this is the case, inducing an even looser, thus even more susceptible
protein structure, would in theory enhance this effect.
Inducing a looser structure was accomplished by shifting pH away
from the protein pIs, which lead to stronger effects of the NTC
treatment (Fig. 1B). This indicates that it is indeed likely that the
way the NTC treatment works is by means of generated heat causing
some degree of denaturation of the proteins that will then be
susceptible to the shear forces and high pressure produced by
ultrasonication
WPI has shown that the combined effects of ultrasound and heatmediate great effects on thermal properties and gelling behavior.We examined the effects of ultrasonication and heat treatmentalone and combined on the thermal behavior of whey proteins insolution. Different WPIs were applied to study whether theb-Lg:a-La ratio would affect the outcome of the experiments.Analysis of denaturation enthalpies revealed that ultrasonicationand heat combined (NTC treatment) lead to significant reductionsin enthalpy, whereas neither ultrasonication nor heat alonewas sufficient to confer this effect (Fig. 1B).The greater effect conferred by the NTC treatment is concurrentwith the observations done for WP samples from a whey productionline by Martini et al. (2010). Furthermore, Chandrapala et al.(2011) show that ultrasonication of WPC for 30 min. does not alterthe enthalpy of denaturation if performed at cold temperatures(6 ± 4 C), indicating that the heat generated during ultrasonicationindeed plays an important role in the observed effects. It is possiblethat the heat generated as a consequence of ultrasonication initiatesunfolding of the protein to some degree, thereby making theprotein more susceptible for the impact of ultrasonication.If this is the case, inducing an even looser, thus even more susceptibleprotein structure, would in theory enhance this effect.Inducing a looser structure was accomplished by shifting pH awayfrom the protein pIs, which lead to stronger effects of the NTCtreatment (Fig. 1B). This indicates that it is indeed likely that theway the NTC treatment works is by means of generated heat causingsome degree of denaturation of the proteins that will then besusceptible to the shear forces and high pressure produced byultrasonication
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