Water biopolymer systems

The current interpretation of NMR data from water biopolymer systems has been summarised in reviews and books It is not intended to re-review the subject here, merely to sununarise the conclusions. 

Hills, B.P., Manning, C.E., and Godward, J. 1999. A multistate theory of water relations in biopolymer systems. In Advances in Magnetic Resonance in Food Science (P.S. Belton, B.P. Hill, and G.A. Webb, eds), pp. 45-62. Royal Society of Chemistry, Cambridge, UK. 

Nowadays it is established that confocal microscopy observation can be a more sensitive method to assess die phase state of mixed biopolymer systems than the traditional centrifugation or viscometric methods (Alves et al., 1999, 2001 Vega et al., 2005). Indeed, microscopy can demonstrate that a system may be already phase-separated at compositions well below the apparent binodal line (as determined by these other methods). The report of Alves et al. (2001) demonstrates the relationship between specific compositional points in the phase diagram (Figure 7.1) and the observed microstructure (Figures 7.2 and 7.3) for water + gelatin + locust bean gum (LBG). The white areas in Figures 7.2 and 7.3 corre-... 

In another set of studies, it has been reported that the in vitro digestibility of lipid droplets by pancreatic lipase is significantly affected by emulsifier type (Mun et al, 2006, 2007 Park et al., 2007). Intuitively, one might expect that a thick dense layer of strongly bound protein-polysaccharide complex at the oil-water interface would reduce considerably the in vivo accessibility of lipases, and hence would reduce the rate of human metabolism of fats. Establishment of the validity of this hypothesis must still await consolidation of a substantial body of detailed results from independent systematic studies on a broad range of mixed biopolymer systems. 

R286 P. S. Belton, NMR Studies of Hydration in Low Water Content Biopolymer Systems , Magn. Reson. Chem., 2011, 49(S1), S127. 

In a multi-component biopolymer system (like starch-cellulose films), each biopolymer engages in biopolymer-biopolymer interactions contributing each one and both to the system properties. Occasionally, these interactions are more important than individual actions. A neat starch film will always display high water absorbency properties, this fact impeding the its application for most water resistance applications. 

Biodegradable films made from edible biopolymers from renewable sources could become an important factor in reducing the environmental impact of plastic waste. Proteins, lipids, and polysaccharides are the main biopolymers employed to make edible films and coatings. Which of these components are present in different proportions and determine the properties of the material, as a barrier to water vapor, oxygen, carbon dioxide, and lipid transfer in food systems (Gomez-Guillen et al. 2002 and 2009). 

The amount of water boimd to the proteins and polysaccharides depends primarily on the ratio of water to the biopolymer in the investigated system The two extreme cases are the dry biopolymer (water content tend to zero) and highly diluted aqueous solutions of the biopolymers. The dry biopolymer undergoes hydration if is exposed to the water vapor of increased vapor pressure. The extent of hydration can be determined y measuring the... 

The amount of hydrated biopolymer and of free water in the biopolymer-water system, the thermodynamic notion of partial specific volume has been introduced and is frequently determined. The relation to Vsp, the specific volume, is shown by the equation ... 

An increase in temperature causes the gelatin/water system to show that the biopolymer tends to compaction (decreasing in Rh and [ /]), which requires an increase of energy consumption due to a difficulty in flowing (increase in D and high This phenomenon... 

For many solubilized enzymes the greatest catalytic activity and/or changes in conformation are found at R < 12, namely, when the competition for the water in the system between surfactant head groups and biopolymers is strong. This emphasizes the importance of the hydration water surrounding the biopolymer on its reactivity and conformation [13], It has been reported that enzymes incorporated in the aqueous polar core of the reversed micelles are protected against denaturation and that the distribution of some proteins, such as chymotrypsine, ribonuclease, and cytochrome c, is well described by a Poisson distribution. The protein state and reactivity were found markedly different from those observed in bulk aqueous solution [178,179],... 

The hydration of propylene with sulfuric acid catalyst in high-temperature water was investigated using a flow reaction system.31 The major product is isopropanol. A biopolymer-metal complex, wool-supported palladium-iron complex (wool-Pd-Fe), has been found to be a highly active catalyst for the hydration of some alkenes to the corresponding alcohols. The yield is greatly affected by the Pd/Fe molar ratio in the wool-Pd-Fe complex catalyst and the catalyst can be reused several times without remarkable change in the catalytic activity.32... 

FIGURE 5.9 DSC profiles of potato starch at different water contents (volume fraction of water indicated next to each profile). Heating rate=10 °C/min. Donovan (1979), Phase transitions of starch-water system. Biopolymers, 18, 263-275. Copyright Wiley-VCH Verlag GmbH Co. KGaA. Reproduced with permission. 

Donovan, J. W. (1979). Phase transitions of the starch-water system. Biopolymers 18,263-275. 

Complex pyrolysis chemistry takes place in the conversion system of any conventional solid-fuel combustion system. The pyrolytic properties of biomass are controlled by the chemical composition of its major components, namely cellulose, hemicellulose, and lignin. Pyrolysis of these biopolymers proceeds through a series of complex, concurrent and consecutive reactions and provides a variety of products which can be divided into char, volatile (non-condensible) organic compounds (VOC), condensible organic compounds (tar), and permanent gases (water vapour, nitrogen oxides, carbon dioxide). The pyrolysis products should finally be completely oxidised in the combustion system (Figure 14). Emission problems arise as a consequence of bad control over the combustion system. 

Undegraded biopolymer slurry material remaining after trench construction may initially interfere with operations. Possible siltation interferences can prevent collection of samples from piezometers. A rise in upgradient water levels can result in potential blockage of groundwater flow, suggesting that airflow should be pulsed to allow for contaminated water to flow through the system. 

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