| Popis: |
The effects of two independent variables: the ratio of konjac and secondary gum (κ-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 κ-carrageenan or xanthan was used. Increasing levels of konjac and xylitol decreased the hardness but increased the cohesiveness of the konjac/κ-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 κ-carrageenan were more acceptable and achieved a higher consumer purchase rate than those containing xanthan. Practical Applications Response surface methodology can be used to describe the effects of konjac/secondary gum ratio and xylitol concentration on the textural properties of konjac gels. When using an alternative secondary gum, κ-carrageenan, the konjac gel formed was harder (more brittle) and less springy compared with gels containing xanthan. An increase in xylitol concentration may feasibly make the konjac/κ-carrageenan gel more cohesive. This information will help in correctly applying the konjac gel to certain health food product applications; for example, panelists preferred the gel texture of a no added sugar, 20% grape juice konjac jelly drink containing κ-carrageenan to the drink containing xanthan. |
