The nature and cause of seaminess in Cheddar cheese

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Abstract
Summary: Microscopical and chemical studies of seaminess in Cheddar cheese revealed that the white lines or seams characteristic of the defect are sections through layers of crystals lying between the milled curd particles. The crystals were identified from their X-ray diffraction pattern and by their refractive index as calcium orthophosphate dihydrate, CaHPO4. 2H2O. On each side of the adjoining curd surfaces in affected cheese there is a zone about 20 μm thick of strongly contracted protein which is almost devoid of crystals.Adding sodium chloride to cheddared curd increased the quantities of calcium, phosphorus and water released. The increases were proportional to the amount of salt applied within the range 0–2·5 g NaCl per 100 g curd.The solubility of calcium orthophosphate was found to rise from about 0·0025 M in water to a maximum of 0·008M in 2 M sodium chloride solution.It is postulated that calcium and phosphate ions released from the curd into the seam crystallize in the form of CaHPO4. 2H2O as the solubility of the compound is lowered by diffusion of salt from the surfaces into the curd particles.