Abstract:
Pectin was extracted from the peels of
Tainong No.1 mango via ultrasound-assisted acid hydrolysis, and four types of pectins with different degrees of esterification (DE) were prepared by alkaline deesterification, namely DEMP
1, DEMP
2, DEMP
3, and DEMP
4, with DE values of 66.26%, 55.32%, 47.19%, and 33.67%, respectively. These pectins were added to mango cloudy juice to evaluate their effects on the stability of the juice. Based on Stokes' theory, the gravitational sedimentation time was predicted, and the shelf life of mango cloudy juice was estimated through accelerated storage experiments conducted at 25~45 ℃. The results showed that the addition of low-ester mango peel pectins (DEMP
3/DEMP
4) effectively improved the stability of mango cloudy juice. Specifically, the juice added with DEMP
4 exhibited a centrifugal precipitation rate of 44.46%, with the suspension stability increased by 26.8% and the instability index reduced by 25.47%. Moreover, the gravitational sedimentation time was extended from 0.79 months (control group) to 6.30 months. The sedimentation kinetics were fitted using the Boltzmann and Logistic models, and it was found that DEMP
4 significantly prolonged the time of the sedimentation inflection point. The zeta potential and water-holding capacity of DEMP
4 reached -36.09 mV and 14.72 g/g, respectively, and the particle size increase was the lowest during accelerated storage. These physicochemical properties were significantly positively correlated with the improved stability of the cloudy juice. Regression equations were established between the Gibbs free energy of centrifugal precipitation rate and temperature, as well as between sensory scores and centrifugal precipitation rate, yielding kinetic and thermodynamic models for juice stability. Based on the models, the stability time of the mango cloudy juice at different temperatures was predicted. At 25 ℃, compared with the control group (without pectin addition) which had a stability duration of 21 days, the stability durations of the juices added with DEMP
1, DEMP
2, DEMP
3, and DEMP
4 were extended to 30, 60, 185 and 195 days, respectively. Except for mango juice, the residual coefficients of variation for the prediction models were all below 15%, confirming their high predictive accuracy.