New procedure for estimating the modulus of deformability of cheese from uniaxial compression tests

The gradient of,the inflection at the lowest strain in a stress versus stra in curve was used to estimate the modulus of deformability (E-d) of cheese from the commonly used uniaxial compression test. The procedure required a sufficiently high sampling rate (e.g. 50 Hz at an initial strain rate of 0. 0332 s(-1)) to give data that provided fine structure to the measurements w hich is not usually reported. This procedure was based on the empirical obs ervation that there was an initial concave up region I;prior to the usually reported concave down region of the curve for all samples studied. Numeric al estimation of the gradient was used to locate the inflection point, and to estimate the gradient at that point. The procedure gave a well-defined m easurement in the region of interest at small strain. It did not assume tha t all samples had the same strain region for compaction-dominating and frac ture-dominating processes. Thus, in effect, it took account of the differen t strains at which E-d should be measured and eliminated differences in E-d between samples induced by differences in these processes. This procedure was compared with three existing procedures, for three cheeses. The procedu re used responded differently to each cheese at the 1 % level. Values of E- d from the inflection point were similar to those from the gradient over 0. 5 to 1.5 times the inflection strain, and higher than those from the gradie nt over 0 to 0.04 strain or from the linear term in a fifth order polynomia l fit to the data up to fracture. The ranking of E-d for each cheese was th e same for each procedure and the relative magnitude oft,for each cheese wa s similar for each procedure.