The Kneading Conditions to Produce Sweetened Adzuki Ann (Red Bean Jam) from the Cooked Beans Prepared by the Modified Cooking Method

Studies on the Quality Improvement of Sweetened Adzuki Ann Part III

Abstract

For the final process to produce sweetened Adzuki Ann (Bean Jam), the cooked beans, after washing with water, is subjected to kneading with sugar and water during heating, which is a very important procedure for the quality of products. In the previous paper, the modified method for preparation of the cooked beans to improve the quality, as well as to increase the yield, was reported. And for the modified cooking, Adzuki bean was heated in boiling water by using a metal basket as the container of beans during heating, which was designed to have a definite capacity as much as 2.22 times the volume of the raw beans used so as to limit the expanding volume of swelled beans up to the capacity of the basket. In this paper, using the cooked beans, being boiled for 90min. by the modified method, a result of further studies on the kneading conditions was described. In comparison with the usual method in the same conditions, it was found that the modified one gave more sticky Ann with increased amount of free starch during kneading, showing inferior qualities estimated for the properties of hardness, stickiness, apparent volume, water holding capacity and water activity (Aw). To improve the qualities of the final product by decreasing the free starch content, a new method of kneading was developed with regard to the control of the vigorousness and the length of time of kneading. The results obtained were as follows: (1) Slowing down of the stirring speed of a kneader to about 1/2 of those currently in use was the most effective condition, giving the product as of better or same quality as the usual one. (2) Decreasing the length of kneading time was not applicable, because water was liberated from the tissues of Ann during cold storage by retrogradation of gelatinized starch, though free starch content was decreased. In this case, it was assumed that the amount of sugar dispersed into the cell granules was not enough to prevent retrogradation of starch, for which the length of kneading time was responsible.