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A hypoallergenic infant formula was created with the enzymatic hydrolization of casein. The digest was tested for antigenicity, hydrophobicity, net charge and emulsifying activity at different hydrolysis time intervals. Three-phased first-order kinetics could approximate casein antigenicity loss. The first 10% hydrolysis time intervals saw the greatest loss in anigenicity, while few changes occured during the other 90% hydrlysis time intervals. A decrease in hydrophobicity and emulsifying activity and an increase in the magnitude of the net charge was seen with an increasing degree of hydrolysis. Hydrophobicity, emulsifying activity and zeta potential were found to be strongly correlated.

The most common infant food allergen is cow's milk, probably because cow's milk--based infant formula is the most widely used infant feeding substitute for human milk. Infants who develop allergies to cow's milk react: to its casein, whey protein or both. The use of soy-based formula in infants allergic to cow milk is widely practiced but not officially endorsed by pediatric societies. Clinical results for prophylactic use of soy in patients at high risk to develop atopic disease conflict. When animal models of food allergy were used to compare cow's milk--based with soy-based formulas and casein or whey with soy protein isolate, soy formulas and soy proteins were consistently less reactive. We used a hyperimmunization animal models to rank the immunologic reactivity potential of several protein systems that might be used for infants allergic to cow's milk or infants at high risk to develop food allergy. Laboratory animals were hyperimmunized with casein, whey, rice protein, rice bran protein, pea protein, oat protein or soy protein. Immune sera were collected and antibodies to the immunizing proteins were quantitated by using sensitive, antigen-specific ELISA methods. Preimmunization antibody titers were also determined as controls for the immunization process and ELISA specificity. Data were expressed as log immune response [IR; (log d 35 titer) -- (log d 0 titer)]. Geometric mean IR values for the immunogens were compared by ANOVA; this analysis indicated that the proteins fall into three statistically distinct reactivity categories. Cow's milk proteins are highly reactive, i.e., casein IR was 4.49 and whey IR was 4.46. Rice, rice bran and pea proteins showed the same intermediate reactivities, i.e., the IR were 3.99, 3.96 and 3.63, respectively. Oat and soy proteins were least reactive and not different from each other; the IR were 2.71 and 2.22, respectively. The IR of a hypoallergenic casein hydrolysate was 1.28. It is clear that soy and oat proteins are allergenic for some patients. However, well-controlled and standardized animal model data support the current practice of using soy-based infant formula and oatmeal for infants with cow's milk intolerance. The reduced immunologic reactivity of soy and oat may represent intrinsic characteristics of these proteins that might be further exploited in the management of food allergies.