Effects of κ-carrageenan on pullulan's rheological and texture properties as well as pullulan hard capsule performances

kappa-Carrageenan (kappa-Ca) is often used to facilitate gelling of aqueous solutions of polysaccharides. However, studies on its effects on pullulan's rheological and texture properties and pullulan (PUL) hard capsule performances have rarely been reported. Herein, effects of kappa-Ca on PUL solutions, hydrogels, films and hard capsules were investigated. It was found that the gelling temperature of 15 % (w/w) PUL solutions with 0.07 % KCl increased from 34 degrees C to 42 degrees C as the concentration of kappa-Ca increased from 0.6 % to 1.2 %, and the gelling temperature rose from 25 degrees C to 37 degrees C by adding a small amount of KCl (0.07 %) for 15 % PUL solutions with 0.9 % kappa-Ca. As the kappa-Ca concentration increased, hardness, fracturability and adhesiveness rose for PUL gels and tensile stress increased for PUL films. PUL capsules could be easily prepared by the aid of kappa-Ca, and performances of capsules could be adjusted by changing the amount of kappa-Ca.