Optimisation of Process Parameters for Vacuum Concentration and Foaming Behaviour of Aloe vera (Aloe barbadensis Miller) Gel

Abstract

This study on Aloe vera gel was conducted to investigate the optimum condition for vacuum concentration in relation to its physicochemical properties and optimum foaming condition of the concentrated products which was used as raw material of foam mat drying. Twenty experiments were conducted for vacuum concentration at different temperature and time combinations. Solutions of numerical optimisation were obtained by using Design-Expert program 7.0 of stat-Ease software for the optimum concentration condition covering the criteria as temperature 55⁰C and time 60 min for concentration are- ascorbic acid 4.095%, total soluble solids  3.6 ºBx, total solids 3.7% , acidity 0.0698 % (as malic acid) and pH 4.97, while the experimental values at temperature 55⁰C and time 60 min for concentration were - ascorbic acid 4.167 % , total soluble solids 3.8 ºBx, total solids 4.0%, acidity 0.0737 % (as malic acid) and pH 4.96. For optimising the foaming behaviour of vacuum concentrated, optimised Aloe vera gel sixteen experiments were conducted using different selected additives [viz. pectin, glycerol monosterate and methyl cellulose (1:1), egg albumin and methyl cellulose (1:1), pectin and methyl cellulose (1:1)] in the concentration range of 0.25 to 1% (w/w). Similarly solutions for the optimum foaming condition were obtained by using same software covering the criteria as pectin and methyl cellulose concentration (1:1) 1% (w/w) are- foaming density 0.39 g/cm³, drainage volume 0.15 ml and expansion volume 122.53%, while the experimental values for pectin and concentration (1:1) 1% (w/w) were-foaming density 0.42 g/cm³, drainage volume 0.0 ml and expansion volume 123.21%. Biological activity of fresh Aloe vera gel can be preserved by concentrating upto 3.8 ºBx and converting the same into stable foam which exhibits foaming density 0.42 g/cm³, drainage volume 0.0 ml and expansion volume 123.21%.