Studies On The Hardness And Test Conditions Of Chinese Steamed Bread

This project detected the hardness of the current popular steamed breads: Northern style,Southern style and Guangdong style, by using the hardness tester while changing the testconditions (plunger size, slice thickness and depth of compression).25mm diameter plunerand35mm diameter pluner were selected and the thick of the steamed bread slice sampleswere chosen as15mm,20mm and25mm. The steamed bread slices were also measured under10%,20%,30%,40%,50%,60%,70%and80%compression of the slice thickness. Thisproject investigated the test conditions’ influence on the hardness of steamed bread, discussedthe mechanism, and aimed to conclude the appropriate test conditions of hardness. Throughthe analysis of the specific volume and hardness, the general relationship between the specificvolume and hardness of steamed bread were obtained. The differences of hardness betweenthree types of steamed bread were studied by using the appropriate test conditions andreasonable parameters, in order to help to the classification of steamed bread.The research results showed that,25mm diameter or35mm diameter of plunger werechosen for the Northern style steamed bread for its larger volume,25mm diameter of plungerwas chosen for Southern style and Guangdong style steamed bread for their smaller volume.For all types of steamed bread, the20mm thick slice was the best choice, which will help toreceive the smooth slice and easier operation. For all kinds of steamed bread,40%-50%compression of the slice thickness was recommended, in this range, within the samecompression depth, it is much easier to distinguish the influence on steamed bread hardnessfrom different flours. If the compression was too thin or too thick, it may cause excessive testerror.In certain conditions, with the same test comparison, all types of steamed bread havesignificant differences in hardness, among them, the northern style steamed bread was thehardest, the southern style was the second, and the Guangdong style was the softest. Thehardness of staple steamed bread which purchased from the supermarket was significantlybigger than quick-frozen steamed bread.The specific volume of three steamed bread had significant differences, among them, theGuangdong style steamed bread was the largest, the southern style was the second, and thenorthern style was the smallest. The specific volume of quick-frozen steamed bread was similar to the Guangdong style steamed bread, the staple steamed bread which purchasedfrom the supermarket was similar to the northern style steamed bread.The correlation results between the specific volume and hardness indicated that using the25mm diameter of plunger, within three thick slices and30%-60%compression depth, thespecific volume had a significant negative correlation with hardness(p<0.05), or evenreceived the highly significant negative correlation(p<0.01).