Compositions and methods reduce symptoms of human allergy to cats. The effectiveness of a molecule which specifically binds to Feline domesticus allergen number 1 (Fel Dl) is enhanced by prolonging the time the immunoglobulin stays within the mouth of a cat to whom the anti-Fel Dl molecule is administered in a pet food. The compositions and methods use a powder that is a dried hydrogel encapsulating the anti-Fel Dl molecule, and the hydrogel is based on gelatin, collagen peptides, or gelatin and collagen peptides； and carrageenan. The methods of making the powder provide a high encapsulation efficacy, sustained release of the anti-Fel Dl molecule in the cat's mouth, and oral adhesion of the anti-Fel Dl molecule in the cat's mouth.
