Whole butter gives only a slightly positive test for protein and may show no reaction at all. when the same butter is clarified; however, the liquid lower the layer is definitely positive for protein?

Students can conclude that grouping of protein in the entire butter is too low to identify. Spread is a dairy item containing up to 80% butterfat which is strong when chilled and at room temperature in a few locales and fluid when warmed 
Butter is a water-in-oil emulsion coming about because of a reversal of the cream; in a water-in-oil emulsion, the drain proteins are the emulsifiers.

The best way is to swollow and hold in your breath