Effect of addition of thermally modified cowpea protein on sensory acceptability and textural properties of wheat bread and sponge cake.
This paper investigates the sensory acceptability and textural properties of leavened wheat bread and sponge cake fortified with cow protein isolates that had been denatured and glycated by thermal treatment. Defatted cowpea flour was prepared from cow pea beans and the protein isolate was prepared (CPI) and thermally denatured (DCPI). To prepare glycated cowpea protein isolate (GCPI) the cowpea flour slurry was heat treated before isolation of the protein. CPI was more susceptible to thermal denaturation than GCPI as determined by turbidity and sulphydryl groups resulting in greater loss of solubility. This is attributed to the higher glycation degree and higher carbohydrate content of GCPI as demonstrated by glycoprotein staining of SDS PAGE gels. Water absorption of bread dough was significantly enhanced by DCPI and to a larger extent GCPI compared to the control, resulting in softer texture. CPI resulted in significantly increased crumb hardness in baked bread than the control whereas DCPI or GCPI resulted in significantly softer crumb. Bread fortified with 4% DCPI or GCPI was similar to control as regards sensory and textural properties whereas 4% CPI was significantly different, limiting its inclusion level to 2%. There was a trend for higher sensory acceptability scores for GCPI containing bread compared DCPI. Whole egg was replaced by 20% by GCPI (3.5%) in sponge cake without affecting the sensory acceptability, whereas CPI and DCPI supplemented cakes were significantly different than the control.
Production and characterisation of potato patatin-galactose, galactooligosaccharides, and galactan conjugates of great potential as functional ingredients.
Potato proteins are of high interest because of their high nutritional quality and multiple health benefits, but they are currently undervalued due to their limited solubility and stability. Glycated patatin (PTT) with galactose, galactooligosaccharides (GOSs) and galactan were produced through the Maillard reaction and characterised structurally and functionally. Fourier-transform infrared and fluorescence spectroscopy data revealed important changes in total secondary structures through glycation with GOSs (61.2%) and galactan (36.7%) and also significant tertiary structural changes leading to an exposure of tryptophan residues. These structural changes led to more heat stable forms of PTT with a higher unfolding temperature (70-90 °C) than the unmodified protein (50-70 °C) and with higher antioxidant activity. PTT:galactose conjugates exhibited similar thermal stability and pH-structural behaviour to native PTT. However, the high level of galactose conjugation to PTT and increased exposure of hydrophobic residues led to a significant increase in its emulsifying stability at pH 3.
Rapid determination of the effectiveness of insect resistant packaging
A technique was developed to evaluate the usefulness of odour barriers and to determine the effect of package content in consumer size packages on resistance to infestation by insects. Female Plodia interpunctella (Hubner) could distinguish sealed packets containing food from non-food items as a suitable site for oviposition. Utilization ofthis technique will reduce the time needed to evaluate new materials for use in insect resistant packaging.