The literature concerning cooked-potato texture is reviewed and discussed in the light of three new hypotheses. First, that "mealiness" is the subjective perception of the flow characteristics ("viscosity") of cooked tissue and that this aspect of texture is controlled primarily by the solids content of the tuber. Second, that the reduction in tissue strength which occurs on cooking is due to water uptake by the polysaccharides of the cell wall. This increases the thickness of the cell wall and reduces the viscosity of the cell wall matrix: both effects combine to reduce the stress required to separate cells. Third, that, when the intrinsic properties of the cell wall material lead to excessive hydration, the adhesion between cells may be sufficiently reduced to allow spontaneous separation or "sloughing".

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New methods are described for the objective assessment of mouthfeel (mealiness) using a Kramer Shear Press and for the amount of breakdown by sedimentation of sloughed tissue. Their application to several hundred samples of canned potatoes is reported. These objective methods correlate significantly (P < 0.001) with their subjective counterparts and demonstrate a clearer separation of mouthfeel and breakdown than do subjective methods. Examination of partial correlation coefficients indicates that mouthfeel is more significantly related to the specific gravity of the raw material than is breakdown. In separate experiments, late planting was shown to affect mouthfeel but not breakdown and the addition of calcium chloride to affect breakdown whilst leaving mouthfeel unaltered. Evidence is presented that mouthfeel is a rheological property controlled primarily by solids content; in contrast breakdown is interpreted as a failure of intercellular adhesion.

The perceived textural attributes of an English Cheddar were measured by a trained panel at various intervals during ripening, including those corresponding to mild and medium maturation times for this variety. The moisture content and pH were also monitored. After the recommended ripening period of 50 weeks the matured cheese was significantly less springy, firmer, harder, crumblier and creamier, indicating that textural attributes are related to the age of the Cheddar. Measures beyond the recommended maturation period revealed further signijicant differences. Comparisons of the measures taken at mild, medium andfull maturity also revealed differences in the textural properties of the different classes of Cheddar, Significant correlations @< 0.01) between pH and springiness, crumbliness by fingers and creaminess suggested a strong relationship between these textural attributes and the extent of proteolysis. The results of this study revealed a strong relationship between age and the textural attributes of cheddar when restricted to one particular variety.