Calcium bioavailability of quarg with increased calcium content produced by addition of rhubarb

The possibility of increasing the Ca content of quarg product by using rhub arb stalk puree or juice in the manufacturing process was investigated. The studies included (1) production of quarg using rhubarb stalk puree or juic e as coagulant; (2) determination of Ca absorption from the quarg products made with rhubarb; and (3) modifying the oxalate content of the rhubarb coa gulants. The Ca contents of the quarg products made with either rhubarb sta lk puree or juice were significantly higher than the control products made with direct addition of lactic acid (p<0.05), but the Ca absorption ascerta ined in rat feeding studies was significantly lower from the rhubarb contai ning products than from the controls (p<0.05). The low Ca bioavailability w as attributed to the presence of calcium oxalate from the rhubarb. Rhubarb fiber did not affect the Ca absorption. After removing the oxalic acid from the rhubarb coagulants by treatment with CaCl2 and HCl, the Ca content of the resulting quarg decreased but was still higher than in the lactic acid quarg.