PROBLEM TO BE SOLVED: To develop a further useful food by processing or improving the quality of wheat flour widely used as a food resource in bread making and processed foods, and to improve gluten of protein in wheat flour to achieve the purpose.SOLUTION: A certain amount of calcium ion is dissolved in brewed vinegar, and by using the calcium ion dissolved in brewed vinegar in processing wheat flour, the calcium ion acts on the wheat flour gluten so that the function of the wheat flour gluten is improved. As a result, the quality of wheat flour or a processed food made from wheat flour can be improved. Furthermore, expansion of the range of use of domestic wheat is promoted to contribute to the advancement of the domestic agriculture, and also to the supply of nutrition.
