Drainage kinetics of pulque foams prepared with egg white protein

Pulque is an ethnic and traditional beverage produced and consumed by the Mexican population; it is obtained from a fermentation process of certain varieties of Agave, and its final alcohol content is around 4 to 7 %. It is rich in protein and its carbohydrate content brings it a characteristic flavor; it has also been reported that there are some probiotic bacteria present in pulque. Due to its intrinsic nature, pulque undergoes a rapid fermentation with a non-pleasant odor and flavor. On the other hand, foams are a colloid system where the air bubble phase is dispersed in a continuous liquid phase. The foaming of liquids has been recognized as a method that shortens processes such as drying and preserves quality attributes. The present work studied the drainage kinetics of different pulque foams prepared with egg white in order to obtain a product suitable for further drying. Different egg white and pulque concentrations were evaluated, as well as whisking times. The drainage volume was recorded for a duration of 120 min, and foam density was determined among different experiments. It was found that the least volume was drained when whisking for 20 min, and the lowest foam density was obtained when egg white and pulque were mixed in a 2:1 ratio. The drainage kinetics of foam determines important information for its further use in a new product with pulque.