Water Dynamics in Whey-Protein-Based Composite Hydrogels by Means of NMR Relaxometry

Abstract

Whey-protein-isolate-based composite hydrogels with encapsulated black carrot (Daucus carota) extract were prepared by heat-induced gelation. The hydrogels were blended with gum tragacanth, pectin and xanthan gum polysaccharides for modulating their properties. 1H spin-lattice relaxation experiments were performed in a broad frequency range, from 4 kHz to 30 MHz, to obtain insight into the influence of the different polysaccharides and of the presence of black carrot on dynamical properties of water molecules in the hydrogel network. The 1H spin-lattice relaxation data were decomposed into relaxation contributions associated with confined and free water fractions. The population of the confined water fraction and the value of the translation diffusion coefficient of water molecules in the vicinity of the macromolecular network were quantitatively determined on the basis of the relaxation data. Moreover, it was demonstrated that the translation diffusion is highly anisotropic (two-dimensional, 2D).

Water Dynamics in Starch Based Confectionery Products including Different Types of Sugar

“…As the relaxation experiments have been carried out in the frequency range encompassing five decades, the relaxation rates are associated with dynamical processes occurring on considerably different time scales—at low frequencies, one observes slow dynamics, while with increasing frequency a progressively faster dynamics is probed. In the simplest case of a single dynamical process contributing to the relaxation, the relaxation rate, ( ) denotes the resonance frequency in angular frequency units), can be expressed as [ 27 ]; where denotes a characteristic time constant of the dynamical process, referred to as a correlation time, while is the corresponding dipolar relaxation constant. Anticipating the results, it has turned out that the relaxation data of Figure 1 can be reproduced in terms of two dynamical processes and a frequency independent relaxation contribution: …”

“…NMR relaxometry has been applied to enquire into the dynamical properties of several kinds of food, including eggs [ 26 ], where differences in water dynamics in different kinds of eggs and the influence of storage on dynamical properties of water were investigated. Whey-protein-based composite hydrogels [ 27 ], with different formulations, were examined to understand the dynamics of water molecules enclosed in the systems. One should also mention the works devoted to the aging of banana and spoilage of milk [ 28 ], the determination of the dynamics of virgin rape oil molecules [ 29 ], the characterization of balsamic vinegars of different aging processes [ 30 ], and the establishment of a relationship between translational diffusion coefficients and the viscosity of different kinds of oil for controlling the authenticity of oil products [ 31 ].…”

New Composite Hydrogel Based on Whey and Gelatin Crosslinked with Copper Sulphate

“…Porous media are largely characterized using a non-destructive method, such as nuclear magnetic resonance (NMR) relaxometry [ 34 , 35 , 36 ], a method that analyzes the molecular motions of water molecules inside the polymer matrix, in the millisecond range. Water plays an important role in hydrogels production, since it influences the mechanical and rheological characteristics of hydrogels, because of interactions between a fraction of water with the polymer chains; therefore, this method can describe the structural formation of hydrogels.…”

“…Ozel et al [ 36 ] have applied 1 H spin-lattice relaxation data for quantitative determinations of water molecules in the polymer network of whey composite hydrogels with black carrot extract and to demonstrate the highly anisotropic translation diffusion also. NMR relaxometry by T 2 measurements provides information about the effect of polysaccharides (xanthan, pectin, alginate, and sunflower) on the swelling degree of whey-based composite hydrogel blended with xanthan, pectin, alginate, and sunflower [ 37 ].…”

Effect of microwave‐vacuum drying on the physicochemical properties of a functional tomato snack bar

“…Conventional heating (for the samples with 1% LMP and 8% TP) resulted in longer relaxation times and higher contributions for the first component and shorter relaxation times and contributions for medium and long components. The longer T 21 (2.06 ms) and higher peak area (71.4%) of conventionally heated samples suggested that the initial hydration layers around the solid particles were larger than those dried in a microwave‐vacuum oven 38 . On the other hand, conventionally heated samples showed shorter T 23 times and area values: 81.02 ms and 12.5%, respectively.…”