The "sponge effect" hypothesis: an alternative explanation of the improvement in the waterholding capacity of meat with ageing.

Bovine M. semimembranosus from different sexes of cattle were held at temperatures ranging from 0 to 35°C until rigor and aged for up to 9weeks. The waterholding capacity (WHC) of the beef increased with ageing as evidenced by the decline in drip loss measured gravimetrically, centrifugally and by pressure. Drip viscosity (P<0.01), meat protein extractability (P<0.05), spreadability (P<0.01) and compressibility also increased with ageing. Evidence of structural changes was seen in SDS-PAGE confirming the physical changes. Meat spreadability under pressure and WHC were higher in samples with inherently higher pH relative to lower pH. The outcome of this study supports a hypothesis that the increase in WHC with ageing is due to the breakdown in meat structure and the creation of "sponge effect", which disrupts the channels through which moisture is lost and physically entraps the free water in meat and reduce the amount that drips out.