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The potential of blackcurrant pomace as a raw material for the extraction of dietary fibre was evaluated using two pomaces one sourced from the UK and one from Poland.A fractionation protocol was designed to isolate and subsequently quantify the soluble and insoluble dietary fibre fractions. Blackcurrant pomace and isolated pectins, hemicelluloses and celluloses were assessed by means of sugar compositional analysis, spectroscopy, size exclusion chromatography and dilute solution viscometry. The blackcurrant pomaces presented considerable amounts of dietary fibre with soluble fibre ranging from 25-30% w/w and insoluble dietary fibre accounting for about 47% w/w for both pomaces. Blackcurrant pomaces differed in the amount of extracted pectins with an almost two times higher pectin yield obtained from blackcurrant pomace sourced from Poland. The hemicellulosic polysaccharide content was 15% w/w whereas the amount of cellulosic fraction varied from 14-17% w/w. Pectins isolated from both blackcurrant pomaces were LM pectins with a degree of esterification in the range of 11-38%. The work has identified that dietary fibres obtained from blackcurrant pomace had desirable ratio of insoluble to soluble fibre and are a potential new source of dietary fibre.

The aim of this study was to investigate the role of the plant food matrix in influencing the extent of starch gelatinisation during hydrothermal processing, and its implications for starch digestibility. Differential scanning calorimetry (DSC) was used to provide a detailed examination of the gelatinisation behaviour of five distinct size fractions (diameters <0.21 to 2.58 mm) of milled chickpea and durum wheat. Gelatinisation parameters were obtained from the DSC thermograms and concomitant microscopy analyses were performed. The estimated terminal extent of gelatinisation (TEG) was compared with our previously published data for in vitro starch digestibility of the same food materials. We observed clear differences in the gelatinisation behaviour of matched size-fractions of chickpeas and durum wheat. In chickpea materials, the TEG values (34-100%) were inversely related to particle size, whereas in durum wheat, no size-dependent limitations on TEG were observed. The TEG values were completely consistent with the extent of starch amylolysis in all size fractions of both durum wheat and chickpea. Microstructural analysis following hydrothermal processing confirmed the presence of some partially gelatinised birefringent starch within intact chickpea cells. Birefringent starch granules were not present in any of the processed fractions of durum wheat. The differences in gelatinisation behaviour of these plant species seem to reflect the individual cell wall properties of these materials. These findings demonstrate the applicability of DSC to real food materials to provide insight into the mechanisms by which the food matrix (particularly the plant cell walls) influences gelatinisation, and consequently, starch amylolysis.

The aeration and rheological properties of bread doughs prepared from strong and weak flours at various mixing speeds and work inputs in a high-speed laboratory-scale mixer were investigated. Dough aeration was quantified in terms of gas-free dough density and gas void fraction using density measurements, while dough rheology was characterized in terms of the strain hardening index, failure strain and failure stress under large biaxial extensional deformation using the SMS Dough Inflation System. Increasing mixing speed had little effect on the gas-free dough density but increased the void fraction of gas occluded in dough. As mixing progressed, the gas-free dough density initially increased, more dramatically for the weak than the strong flour, before reaching a plateau at approximately 30 kJ kg −1 energy input. The gas content tended to increase over the range of work inputs tested. For both flours, the strain hardening index, failure strain and failure stress increased with work input initially, followed by a decrease. The absolute values were all higher for the strong flour, while maximum values and the work input at which the maximum occurred depended on the mixing speed. These results show that both aeration and rheological characteristics of dough are dependent on both the total work input and the work input rate. The results also demonstrate the facility of the Dough Inflation System to describe the mechanical development of dough rheology over the course of high-speed mixing.

roving of bread dough was modelled using classical one-component diffusion theory, to describe the rate of growth of bubbles surrounded by liquid dough containing dissolved carbon dioxide. The resulting differential equation was integrated numerically to predict the effect of initial bubble size and system parameters (carbon dioxide concentration, surface tension at the bubble interface, temperature) on bubble growth. Two situations exist, potentially; the dough could be either supersaturated or subsaturated with carbon dioxide. When the dough is supersaturated, the model predicts a critical bubble size above which bubbles grow inde® nitely, while below the critical bubble size bubbles reach a limiting size and stop growing. The critical bubble size decreases with increasing carbon dioxide concentration and increases with increasing surface tension. Below saturation, all bubbles reach an upper size limit proportional to their initial size. The ® nal bubble size increases with carbon dioxide concentration and decreases with increasing surface tension. Higher temperatures increase the rate of bubble growth and reduce the critical bubble size for supersaturated doughs, by increasing the value of Henry' s Law constant. Higher temperatures also increase the ® nal bubble size for subsaturated systems. The model could be extended to include yeast kinetics and entire bubble size distributions, to develop a full simulation of the proving operation.