Effect of ultrasound intensity on the functional characteristics of rennet‐coagulated skim milk

Abstract

AbstractThe objective of this study was to examine the impact of ultrasound energy density (USED) on the functional properties of rennet‐coagulated skim milk. Skim pasteurized milk was ultrasonicated at 106 W and 375 W at two different times (3 and 9 min) to produce different USED levels (190.4, 570.7, 674.3, and 2016.9 J g−1). The rheological and textural properties of ultrasonicated milk samples were determined during the rennet coagulation as compared to nonsonicated skim milk. The rennet coagulation time was doubled when 674.3 J g−1 was applied to skim milk; however, applying 2016.9 J g−1 did not lead to milk coagulation. Additionally, gel firmness of rennet‐coagulated milk increased significantly from 80 g to 130 g when USED boosted from 190.4 to 674.3 J g−1. The coagulum strength and curd‐firming rate decreased significantly when USED elevated to 2016.9 J g−1. The outcome provides that using suitable USED could be utilized efficiently in the cheese industry to prolong the renneting time of milk.Practical ApplicationsThe ultrasound process can be applied to milk before making different dairy products, such as cheese or other dairy products that need rennet for coagulation to improve the characteristics of those products. Also, ultrasound can be utilized to fractionate dairy components to improve the functionality or yield of products.