Survival of Lactobacillus acidophilus and Bifidobacterium bifidum in Ice Cream for Use as a Probiotic Food

¹ Western Dairy Foods Research Center, Department of Nutrition and Food Science, Utah State University, Logan 84322-8700

Probiotic ice cream was made by fermenting a standard ice cream mix with Lactobacillus acidophilus and Bifidobacterium bifidum cultures and then freezing the mix in a batch freezer. Survival of the L. acidophilus and B. bifidum, as well as ß-galactosidase activity, was monitored during 17 wk of frozen storage at –29°C. After freezing of the fermented mix, bacterial counts were 1.5 x 10⁸ cfu/ml for L. acidophilus and 2.5 x 10⁸ cfu/ml for B. bifidum. Seventeen weeks after freezing, these counts had decreased to 4 x 10⁶ and 1 x 10⁷ cfu/ml, respectively. During the same period, ß-galactosidase activity decreased from 1800 to 1300 units/ml.

Probiotic ice cream was prepared at pH 5.0, 5.5, and 6.0 to determine consumer preferences and was compared with standard Utah State University "Aggie" ice cream. All samples were strawberry-flavored and were evaluated by 88 judges. The preferred pH of probiotic ice cream, based on overall acceptance, was pH 5.5.

We demonstrated that probiotic ice cream is a suitable vehicle for delivering beneficial microorganisms such as L. acidophilus and B. bifidum to consumers. The bacteria can be grown to high numbers in ice cream mix and remain viable during from storage.

Key Words: Lactobacillus acidophilus • Bifidobacterium bifidum • ice cream

Submitted on October 8, 1991
Accepted on January 27, 1992