Abstract #W140

# W140
Identification of crystalline entities in the rinds of white mold ripened cheese and smear ripened cheese with powder X-ray diffractometry.
Gil F. Tansman*1, Paul S. Kindstedt1, John M. Hughes2, 1Department of Nutrition and Food Sciences, University of Vermont, Burlington, VT, 2Department of Geology, University of Vermont, Burlington, VT.

Curd softening in wheels of surface ripened cheese occurs radially from the surface toward the center and is the result of chemical changes including decalcification. It has been theorized that calcium is removed from the system by depositing as calcium phosphate crystals in and beneath the rind. Although researchers have observed calcium-containing crystals under the bloomy rind in several cheese varieties, no work has adequately determined the identity of the crystals. The present study was conducted to identify the crystals in bloomy rind (white mold ripened) cheeses and compare them to crystals that form in the smears of washed rind cheeses. Four varieties of Vermont soft ripened cheese were obtained from a commercial source; 2 of these were bloomy rind cheeses and 2 were washed rind cheeses. Powder X-ray diffraction (PXRD) patterns were generated for each cheese from fresh samples extracted from 1mm below the curd surface. Diffraction patterns were also generated from the smear material and surface hyphae scraped from the surfaces of washed rind and bloomy rind cheeses, respectively. The PXRD patterns revealed that small quantities of calcite (CaCO3) form below the rinds of both cheese classes, but the diffraction patterns were very weak, due to the limited quantity of crystalline material present. Strong PXRD patterns from smear material revealed the presence of large concentrations of crystalline material. The smear from one cheese contained crystalline ikaite (CaCO3·6H2O) and the other contained both ikaite and struvite (NH4MgPO4·6H2O). Powder diffractions from the bloomy hyphae produced very weak diffraction patterns with characteristic peaks of calcite, which may represent crystalline material that adhered to the hyphae from the cheese-hyphae interface.

Key Words: cheese, crystals, powder X-ray diffraction (PXRD)