Study On Vacuum Freeze-drying Technology And Rehydration Kinetics Of Poached Meatball

Poached meatball is a traditional flavor snacks, and it has a delicious taste, andcontains rich nutrition, and is easy to digest. With the enhancement of people’s livingstandards and the speed of life pace, convenient instant food attract people’s attentionmore and more. Freeze dried food can sustain the color, smell, savor, and shape oforiginal food, and especially those who are not volatile loss of heat-sensitivecomponents, and maximize their original nutrients, and can inhibit the harmful effectsof bacteria and enzymes to effectively prevent the drying process of oxidation. Thefreeze-dried food can be conserved at room temperature, and have better rehydrationproperties than other drying methods. On the other hand, it consumes more energyand the rehydration properties are still far from people’s satisfaction comparing to thedemands of fast-paced life. To solve this problem, in this project, and the freezing-drying process and the kinetics of rehydration process have been studied in order todecrease energy consumption and increase the rehydration properties: thefreezing-drying conditions for decreasing the drying time and an appropriatemicrostructure can be obtained by optimizing the freezing-drying process andtechnical parameters; the effects of additives on the microstructure and rehydrationproperties of freeze-dried products are researched, and the rehydration kinetics arestudied. The contents and conclusions of this research are the follows:1) The craftsmanship of poached meat balls has been studied, and the effect ofmaterial ratio, diameter, and boiling time on rehydration ratio and rehydration ratewere studied. On the basis of single-factored experiments and orthogonal experiment,the optimized craftsmanship of poached meat balls were obtained: material ratio(meat: shallot) is1:0.5, diameter of poached meat balls is2cm, and the boiling timeis4min.2) The freeze drying technology of poached meat balls has been studied, and theeffects of prefreezing time, drying temperature, and loadage on technological processwere inspected. Through single-factored experiments and orthogonal experiment, the optimizational freeze drying conditions of poached meat balls were obtained:the prefreezing time is4h, drying temperature is45℃, and loadage is320g/m2. At this moment, the drying rate is3.31%/h and rehydration ratio is2.37.3) To improve the rehydration properties of poached meat balls, some dehydration agents, such as composite phosphate, dextrin, β-cyclodextrin, Transglutaminase (TG enzyme), xanthan gum, guar gum, carrageenan, konjac gum, carboxymethylcellulose sodium, and lecithin were selected. The effects of the dehydration agents on rehydration properties of poached meat balls have been studied. Through single-factored experiments, orthogonal experiments, and their synergism’s experiments, the suitable synergistic results were obtained:when one single additive is added, the best drying rate and rehydration ratio and additive amount of composite phosphate is0.3%, dextrin is5%, β-cyclodextrin is4%, TG enzyme is0.5%, guar gum is0.3%, carrageenan is0.3%, and konjac gum is0.2%. And TG enzyme has a rehydration ratio of2.889while β-cyclodextrin has a value of2.760; when two additives are added together, carrageenan:konjac gum is0.24:0.16, rehydration ratio is2.920; carrageenan:xanthan gum is4:3, rehydration ratio is2.712; xanthan gum: konjac gum is5:3, rehydration ratio is3.342; konjac gum:guar gum is3:2, rehydration ratio is2.689; xanthan gum:guar gum is3:3, rehydration ratio is2.917. β-cyclodextrin has an excellent synergetic effects with xanthan gum, konjac gum and guar gum, and the rehydration ratio can reach3approximately; when several additives are added together, gums together with β-cyclodextrin or composite phosphate have a better effect, and the rehydration ratio can reach3approximately, and the combination of composite phosphate, β-cyclodextrin and lecithin can improve the qualities of poached meat balls obviously, and rehydration ratio can reach3.145, and the sensory index is also the highest.4) The kinetics of rehydration process for poached meat balls had been studied. Through the effect of dehydration agents on rehydration process, a curve of rehydration rate with time has been established. What’s more, the data has been fitted by first order kinetic model, Peleg model and Weibull model. And first order kinetic model used to depict rehydration process is described as R=Re-(Re-1) exp(-kt), where k=1.764×104T1;+7.021×10-5T2+0.002633and Re0.02664(T/T)30.2928(T/T)221210.8844(T2/T1)2.090and theapparent activation energy is5.542kJ/mol. And the kinetic model was tested andverified by experiments, the example systems demonstrated the validity andreliability of the method. Moreover, kinetic models provide us with a useful tool forunderstanding the rules rehydration process of poached meatballs and guidingproduction practice.