Main Properties of Konjac
A gelling, thickening, suspending and film-forming agent.
- Water solubility: readily dissolves in water and it can absorb 100-times its own volume in water.
- The solution is a pseudo-plastic liquid. The viscosity of a 1% solution can be as high as 35,000 cps (1% sol by Brookfield
viscometer at 12 rpm), higher than any other natural thickening agent. Konjac flour also shows a synergistic effect with xanthan gum, the addition of 0.02-0.03% to 1% xanthan gum will raise its viscosity by 2-3 times under heating. - Acid stability: konjac remains stable without precipitation even if the pH drops to a level below 3.3.
- Salt tolerance: Konjac solutions are tolerant to higher levels of salts.
- Gelling ability: As a gelling agent, konjac is quite unique for its ability to form thermo-reversible and thermo- irreversible gels under different conditions.
- Thermo-irreversible gels: konjac solution does not form gel because its acetyl group prevents the long chains of Glucomannan from approaching each other. However, it does form gel by heating to 85oC with mild alkali condition (pH 9-10) . This gel behaves stable to heat and it will remain stable under repeated heating at 100oC or even at 200oC. This property has been used to make a great variety of healthy/slim foods in Asian countries such as Konjac cakes, noodles, chips, imitating dishes for vegetarians (vegetarian shrimps, hams, steaks), bread, cookies, edible films, a fat replacer in hams, sausages, meat balls. Thermo-reversible gels: a combination of xanthan gum with konjac can form a gel at any pH although xanthan alone does not form a gel. At a pH of
5, the two gums show the greatest synergistic effect with a ratio of 2:3, konjac has a gelling ability very similar to carob gum but much more pronounced. Konjac is synergistic with Kappa-carrageenan to form strong water gels at very low dosages. It has been used for soft candy, water jelly, jam, ham, yogurt, puddings, ice cream, pet food to replace carob gum and gelatin. It has also been used in fruit/vegetable juice as suspending agent. It also as some interaction with starch.
Additional information on konjac structure, botany and health can be accessed using the arrows in the Further Reading box below.