Development of ajwain (Trachyspermum ammi) seed essence powder using foam-mat drying technique: a comparison on the effect of guar gum, basil seed gum, and the combination of them

The study aimed to production of ajwain seed essence (ASE) powder using foam-mat drying method. ASE emulsion was stabilized by whey protein isolate (15% w/w). Different foaming agents including guar gum (GG) and basil seeds gum (BSG) with concentrations of 0.1 and 0.2% (w/w), and a mixture of two gums with a concentration of 0.2% with a ratio of 50:50 were used. The highest overrun was observed in a sample prepared with BSG 0.1% (w/w). When GG 0.2% (w/w) was added to the samples, the lowest overrun was observed, whereas the foam stability enhanced significantly (p<0.05). The use of a mixture of the two gums as foaming agent showed less overrun than the independent use of the two gums. In the next step, steady shear behavior, zeta-potential, surface tension, and textural properties of the samples were investigated. It was observed that the ASE foam showed shear thickening behavior. Overrun indicated a reverse relationship with the foam viscosity. Surface tension and zeta-potential could not justify foam stability. The values of diffusion coefficient (D-eff) were found to be in the range of 3.31-7.81 x 10(-8) m(2)/s. D-eff decreased significantly with increasing foam viscosity. Hygroscopicity, water activity, moisture content, and color parameters of the ASE powders were also determined. The lowest values of moisture content and water activity were observed in the samples containing BSG.