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Mechanistic insights into freezing behavior in sucrose-pectin systems through experiment and simulation
Yitong Xie1, Xin Jin2, Jinfeng Bi1
1Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences (CAAS)/Key Laboratory of Agro-products Processing, Ministry of Agriculture and Rural Affairs, Beijing, 100193, PR China; College of Food Science, Shenyang Agricultural University, Shenyang, 110866, China.
Abstract:
The phase transitions of the aqueous phase during freezing are critical to the quality of frozen and freeze-dried foods, yet the joint regulation by sugars and pectin remains insufficiently understood. In this study, low-field nuclear magnetic resonance, differential scanning calorimetry, Fourier-transform infrared spectroscopy, experimental freezing curves, and a coupled heat transfer-phase change model were integrated to examine the water state, ice crystallization, and freezing kinetics in sugar-pectin systems and restructured peach pulp. At identical soluble solids contents, sucrose generated a larger freezable-water fraction than glucose or fructose. Raising the sucrose concentration from 0 to 40% shortened the transverse relaxation times, lowered the freezing point, and decreased the freezable water. Both high-methoxyl pectin (HP) and low-methoxyl pectin (LP) restricted water mobility. LP caused shorter relaxation times, lower freezing points, and smaller freezable-water fractions than HP. Consistent behavior was observed in the restructured peach pulp. The numerical model accurately reproduced the freezing time, phase-transition plateaus, and cooling rates, with R2 > 0.91 and RMSE < 3.31 °C. The developed model may provide a quantitative tool for formulation design and useful support for engineering decision-making in the processing of frozen and freeze-dried products.
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