TEXTURAL AND OPTICAL PROPERTIES OF GELATIN GEL AND APPLICATION OF KUBELKA-MUNK THEORY ON ITS MEASURED COLOR

Abstract

The effect of gelatin concentrations and glucose syrup to sucrose ratios on textural and optical properties were investigated using texture analyzer and spectrophotometer. Three gelatin concentrations (7.75%, 8.00% and 8.25%) and five glucose syrup to sucrose ratios (0:0, 0:100, 30:70, 70:30 and 100:0) were experimented. Gelatin gel samples were prepared using a 5 cm (L) x 5 cm (W) x 2.5 cm (H) silicone mold. The addition of sugar affected the hardness and gumminess of gelatin gel samples at all conditions (p ≤ 0.05). Springiness and cohesiveness of gelatin gel samples at all conditions were slightly different ranging from 0.95-0.99 and 0.93-1.00, respectively. Puncture test indicated that gel with 8.25% gelatin concentration had the highest rupture force (p ≤ 0.05). The addition of sugars increased the rupture force and distance of rupture point (p ≤ 0.05). The reflectance spectra of all gelatin gel samples showed the same trend against white background. The addition of glucose syrup into the mixture resulted in an increase in lightness, and the addition of sucrose into the mixture resulted in an increase in chroma. Spectral distributions of K/S calculated from the Kubelka-Munk model with Saunderson's correction and modified Kubelka-Munk model for semitransparent products were more precise in describing the optical characteristics of gelatin gel samples. The relationship between absorption coefficient and concentration of colored gelatin gel showed a linear relationship (r = 0.94), which can be used to predict the reflectance at various concentrations of color