Research And Application Of The Interaction Between The Limitied Hydrolyzed Konjac Glucomannan Andκ-carrageenan

The Konjac glucomannan(KGM) is the main active ingredient of Konjac gum. In this study, we obtained a series of hydrolyzed KGM products with appropriate viscosity from the limited degradation of Konjac gum by enzyme and extended the application of Konjac gum in production. We analyzed the mixture of Carrageenan and enzyme digested Konjac gum and provided a inner view of its application in the production by adding the mixture into the jelly sweets to improve the elasticity and chewiness of Carrageenan jelly sweets.Firstly, among three enzymes including composite cellulase, it was discoveredβ-mannanase had the best performance on the controlled degradation of KGM, then usingβ-mannanase under specific temperature, pH, substrate concentration, degradation time and the amount of the enzyme, three hydrolyzed products were obtained with viscosity of 1060 mpa·s (KGM-1), 2010 mpa·s (KGM-2)and 3960 mpa·s (KGM-3) respectively. Among them, the optimum conditions for abtaining the KGM-2 was as follows: temperature 55℃, substrate concentration 12% (deionized water), the amount of the enzyme 3.5 U/g, hydrolysis time 90 min. The molecular weights of the hydrolyzed Konjac gum were significantly decreased and varied with different surface viscosity. Even with different surface viscosity, it was analyzed that more than 90% of the hydrolyzed Konjac gum's molecular weight was above 105, so the compound is still exo-polysaccharides, which means a limited enzymatic hydrolysis occurs in the reaction. Texture profile analysis was adopted for comparing the four samples that mixedκ- Carrageenan with ND, KGM-1, KGM-2, KGM-3 respectively and the kC-KGM-2 compound had a higher hardness than the other three samples. We analyzed the gel characteristic of kC-KGM-2 and kC-ND in terms of the hardness and springiness, and found the kC-KGM-2 had better performance on heating time and gelation time with a better transparency, and no significant valuation in water retention was observed. It was proved by the rheological study that both kC-KGM-2 and kC-ND form a very stable gel structure, konjac gum before and after degradation had little effect on the thermal characteristics of the mixed gel, and sol temperature was higher than kC by approximately 5℃. The results above show that KGM-2 is more proper than ND to be used withκ- Carrageenan in actual production.The mixture of KGM-2 andκ-Carrageenan was used in the jelly sweets production under an optimized condition and the mixture was compared with the jelly sweets only addedκ- Carrageenan in it using a standard of sensory evaluation and texture analysis. The gel mixture kC-KGM-2 greatly reduced the amount ofκ- Carrageenan with a better elasticity and chewiness.