Effect of Calcium Gluconate Addition on the Properties of Ume Fruit (Japanese Apricot) Products

Abstract

Two types of ume fruit (Japanese apricot) products, hardened fruit and salted and sun-dried fruit, were prepared using calcium gluconate, a calcium compound which has attracted interest recently because of the proliferation of Lactobacillus bifidus, as a substitute for calcium hydroxide; the properties of the products were compared with conventional products prepared using calcium hydroxide. Calcium gluconate acted as a hardener similar to conventional calcium hydroxide in hardened ume fruit products. The color of the product lost some of its redness and turned more yellowish. Since calcium hydroxide made the surface of the hardened ume fruit product redder, which is not preferred by consumers, calcium gluconate had a favorable effect on the surface color. Another problem regarding taste was also solved by using calcium gluconate. The product prepared using calcium hydroxide tasted bitter, while calcium gluconate did not leave a bitter taste in the hardened ume fruit product, and the difference was significant (p<0.01). The bitterness threshold in the solution was also lower with calcium gluconate compared with the case of calcium hydroxide. The effect of calcium gluconate on the salted and sun-dried ume fruit product was the same as calcium hydroxide and it was apparent that calcium gluconate prevented damage to the skin.