Physicochemical and functional properties of lentil protein isolates prepared by different drying methods
- Authors: Joshi, Matina , Adhikari, Benu , Aldred, Peter , Panozzo, Joe , Kasapis, Stefan
- Date: 2011
- Type: Text , Journal article
- Relation: Food Chemistry Vol. 129, no. 4 (2011), p. 1513-1522
- Full Text: false
- Reviewed:
- Description: Lentil protein isolate (LPI) extract was converted into powder by freeze drying, spray drying and vacuum drying. Differences in particle size distribution, protein subunit composition and colour and surface morphology were observed amongst the three drying methods. Spray and freeze-dried LPI powders exhibited higher solubility (81% and 78%, respectively) compared to vacuum dried powders (50%). The spray dried powders showed a low water absorption capacity (0.43 ± 0.02 g/g) compared to freeze (0.48 ± 0.02 g/g) and vacuum-dried (0.47 ± 0.01 g/g) LPI powders. Spray and freeze-dried powders displayed better gelation ability and higher gel strength, compared to vacuum-dried powder. Both spray and freeze-dried gels showed typical viscoelastic gel characteristics, with G′ dominating over G″ and very low loss tangent. The holding time required for gelation of vacuum dried powder at 90 °C was significantly longer, compared to spray and freeze dried powders. Hence, drying methods used for preparation of lentil protein isolate powders can affect physicochemical and associated functional properties. © 2011 Elsevier Ltd. All rights reserved.
The rheological behavior of native and high-pressure homogenized waxy maize starch pastes
- Authors: Wang, Bao , Wang, Lijun , Li, Dong , Wei, Qing , Adhikari, Benu
- Date: 2012
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 88, no. 2 (2012), p. 481-489
- Full Text: false
- Reviewed:
- Description: Both steady and large amplitude dynamic rheological testes were carried out in hydrothermally gelatinized waxy maize starch (WMS) pastes. The concentration of WMS was maintained at 6.0% (w/w) throughout these tests. The WMS pastes exhibited shear thickening behavior during the first up curve in steady shear tests. The shear thickening behavior was found to be irreversible and could not be retained after equilibrating the pastes beyond 6 h. The change in the shape of Lissajous curves was insignificant during strain sweeps at higher angular frequencies. This arose because of slow response of WMS pastes to oscillatory strain within a period of oscillatory shear, which can be attributed to the domination of rheological properties by amylopectin in continuous phase. High-pressure homogenization (HPH) was found to significantly reduce the apparent viscosity of the WMS pastes. After HPH, the WMS pastes behaved like typical Newtonian fluids. © 2011 Elsevier Ltd. All rights reserved.
Hydrostatic pressure effects on the structural properties of condensed whey protein/lactose systems
- Authors: Dissanayake, Muditha , Kasapis, Stefan , George, Paul , Adhikari, Benu , Palmer, Martin , Meurer, Barbara
- Date: 2013
- Type: Text , Journal article
- Relation: Food Hydrocolloids Vol. 30, no. 2 (March 2013), p. 632-640
- Full Text: false
- Reviewed:
- Description: Hydrostatic pressure effects on whey protein/lactose mixtures were recorded with subsequent analysis of their structural, molecular and glass transition properties in comparison to thermal effects at atmospheric pressure. Experimental techniques used were small deformation dynamic oscillation in shear, modulated differential scanning calorimetry, Fourier transform infrared spectroscopy, and theoretical modelling of glass transition phenomena. Levels of solids ranged from 30 to 80% (w/w) in formulations with a protein/co-solute ratio of four-to-one. Addition of lactose protects the secondary conformation of the protein under application of high hydrostatic pressure. Nevertheless, pressurized protein systems are able to form three-dimensional structures due to the reduction in polymeric free volume and the development of an efficient friction coefficient amongst tightly packed particles. Systems can be seen as developing a "molten globular state", where the structural knots of pressure-treated networks remain in the native conformation but achieve intermolecular cross-linking owing to frictional contact. Furthermore, pressure treated assemblies of condensed whey protein preparations could match the viscoelasticity of the thermally treated counterparts upon cooling below ambient temperatures. That allowed examination of the physical state and morphology of a condensed preparation at 80% solids by the combined framework of reduced variables and free volume theory thus affording derivation of glass transition temperatures for pressurized and atmospheric samples. (C) 2012 Published by Elsevier Ltd.