This disclosure pertains to methods of preparing dairy products that include starch that has been modified by reaction with n-octenyl succinic anhydride (nOSA). The modified starch may be substituted for some or all of the fat or lipids in the dairy products. Alternatively, the nOSA-modified starch may be used as an additive in the dairy products. This disclosure also pertains to compositions of dairy products that include starch that has been modified by reaction with n-octenyl succinic anhydride. Specific exemplary compositions of yogurts, sour creams, puddings, cheese sauces, and process cheese foods containing nOSA-modified starch are described.