Preparation of konjac glucomannan/casein blending gels optimized by response surface methodology and assessment of the effects of high‐pressure processing on their gel properties and structure

BACKGROUND In order to improve the compatibility of polysaccharide–protein mixtures and enhance their performance, a response surface methodology was used to optimize the preparation conditions of konjac glucomannan/casein blend gel. Moreover, the effects of high‐pressure processing (HPP) on the gel properties and structure were also investigated. RESULTS The optimal preparation parameters were a temperature of 60 °C, a total concentration 40 g kg −1 , and a dietary alkali concentration 5 g kg −1 . Under these conditions, the experimental value of hardness was 38.7 g, which was close to the predicted value. HPP increased gel hardness by 161–223% and led to a more compact structure at 200–600 MPa/10 min, while a hardness increase of ∼120% and damaged structure were observed at 600 MPa/30 min. Fourier transform infrared spectroscopy showed that noncovalent interactions are likely the most important factor in the modification of gel hardness; indeed, hydrogen bonding interactions in the gels are enhanced when subjected to HPP, but are weakened at 600 MPa/30 min. COUCLUSION Protein–polysaccharide complexes with excellent properties could be obtained through this method, with broad application prospects in the food industry. © 2018 Society of Chemical Industry