Effect of Various Foaming Agents in Foam-mat Drying of Pineapple Juice

Foam-mat drying is a process in which liquid foods are whipped into stable foams and then air-dried. During heatedair-drying, it is desirable that the foams remain stable and retain their typical open structure to facilitate rapid drying. This research describes technological pro-cess of foam mat drying of pineapple juice. Foams were prepared by adding foaming agent Egg Albumin (0.25% and 0.50%) and Soy Protein Isolate (2% and 5%), methyl cellulose (0.5%) as stabilizer for various sugar concentrations (20, 25 and 30^o brix) at air velocity of 3 m/s, whipping for 2 min at different temperature (55, 65 and 75°C) of pineapple juice. The foam expansion was significantly influenced by foaming agents, their quantity and sugar brix. The maximum foam expansion and stability of 121 percent was obtained when 0.5% egg albumin was added in 20^o sugar brix at 55°C juice temperature. The minimumfoam density of 1.0683 g/cm³ was found when egg albumin 0.25% was added for 20^o brix at 55°C temperature. The optimized solution predicted foam expansion of 117.306%, foam stability of 120.667% and foam density of 1.06301 g/cm ³ when pineapple juice was blended with 0.5% egg albumin with 20^o brix sugar syrup at 55°C. The developed powder was safe from microbial growth and enzymatic activity. The maximumvalueof chromawas obtainedas 22.89. The sensory values for foam mat dried pineapple powder were more than 7.5 for colour, taste, appearance and overall acceptability respectively. Thus, foam mat dried pineapple powder could be consumed as an instant juice powder or as a flavoring agent.