Effect of temperature and inoculum concentration on gel microstructure, permeability and syneresis kinetics. Cottage cheese-type gels

Effects of coagulation temperature and inoculum concentration on microstructure, permeability and syneresis of cottage cheese gels were investigated. Relationships between coagulation parameters (obtained by rheology and near infrared light backscatter) and rate and extent of syneresis were studied. Mass of drained whey was fitted to first order equation W = W-infinity(1-e(whey)(-k)(t)) (determination coefficient, R-2 = 0.994 +/- 0.005). Temperature coefficient and activation energy for syneresis were estimated. Increasing temperature significantly enhanced the rate of syneresis, due to bond relaxation. Increasing inoculum concentration decreased rate of syneresis, suggesting that faster acidification rate inhibited network rearrangement during whey expulsion. Syneresis parameters were highly correlated with the rates of acidification and network formation and with the loss tangent. Permeability coefficient, rnass of whey drained and kinetic rate constant for syneresis were predicted by equations that included temperature and coagulation parameters. The close interactions between coagulation and syneresis kinetics suggested that it may be possible to develop optical sensors to simultaneously monitor both of these processes.(c) 2005 Elsevier Ltd. All rights reserved.