OPTIMIZATION OF TEXTURAL PROPERTIES OF KONJAC GELS FORMED WITH κ-CARRAGEENAN OR XANTHAN AND XYLITOL AS INGREDIENTS IN JELLY DRINK PROCESSING

The effects of two independent variables: the ratio of konjac and secondary gum (kappa-carrageenan or xanthan) (25: 75 to 50: 50) and the xylitol concentration (2-20%) on the textural properties (hardness, cohesiveness and springiness) of konjac gels were investigated using response surface methodology (RSM). Both independent variables had a significant effect on konjac gel texture, but their interactive effects were insignificant. The konjac/secondary gum ratio had a greater effect, and it affected konjac gel texture differently depending on whether kappa-carrageenan or xanthan was used. Increasing levels of konjac and xylitol decreased the hardness but increased the cohesiveness of the konjac/kappa-carrageenan gel, whereas the opposite results were found with the konjac/xanthan gel. The konjac gels' optimal conditions were applied to the production of no added sugar, 20% grape juice jelly drinks. The konjac jelly drinks containing kappa-carrageenan were more acceptable and achieved a higher consumer purchase rate than those containing xanthan.