| Fresh-cut lotus root is convenient to cook with rich nutrients.It has now developed into a new situation of lotus root sales and has broad prospects for development.However,the process of peeling and slicing of lotus root causes cell integrity to be destroyed,respiratory rate is accelerated,enzymatic browning is enhanced,and microorganisms are easily invaded and nutrient components are rapidly lost,resulting in shortened product shelf life.In this research,the color protection and sterilization of fresh-cut lotus roots were studied,and the quality and microbiological changes of fresh-cut lotus roots treated at different temperatures were studied,The shelf-life prediction model of fresh-cut lotus root was initially established.Concrete research contents and results are as follows:1.Fresh-cut lotus root was used as test material to inoculate Escherichia coli and Staphylococcus aureu to study the bactericidal effect of different concentrations of chlorine dioxide on inoculated pathogenic bacteria,lotus root self-carrying mold,yeast and total bacterial count.The control was treated with 100 mg/L sodium hypochlorite and tap water.The results indicate that,Chlorine dioxide can effectively kill fresh-cut lotus root surface microorganisms,and the higher the concentration is,the stronger the bactericidal effect is.75 mg/L chlorine dioxide bactericidal effect is equivalent to 100 mg/L sodium hypochlorite bactericidal effect.2.Different concentrations of citric acid,D-sodium erythorbate,and calcium chloride were used to soak fresh-cut lotus roots and stored at 10°C.The color difference?L*?was measured periodically to study the effect of a single color-protecting agent on the color protection of fresh-cut lotus roots.Combined with chlorine dioxide,the best sterilization color protection combination of fresh-cut lotus root was obtained by orthogonal test.The results showed that the best bactericidal and color protection combination for fresh-cut lotus root was 0.6%citric acid,0.3%sodium D-ascorbate,0.8%calcium chloride,and50mg/L chlorine dioxide3.The fresh-cut lotus root was sterilized and treated for 10 min and stored at four different temperatures of 0°C,5°C,10°C and 25°C.The physical and chemical characteristics and total bacterial count of fresh-cut lotus root were periodically monitored,and sensory evaluations were performed.The results indicate that with the prolongation of storage time,the browning degree,total bacterial count,total phenolic content,POD activit gradually increased,the hardness,soluble solids and sensory scores gradually decreased.The activity of PPO first increased and then decreased.During the entire storage process,the higher the temperature,the faster the physical and chemical indicators of fresh-cut lotus roots change,the faster the corresponding lotus root metamorphic rate,and the shorter the shelf life.4.According to the changes of various indices of fresh-cut lotus roots at different temperatures,we selected certain regular characteristics to determine the reaction rate at different temperatures.The results showed that with the increase of storage temperature,browning degree,hardness,and soluble solids were increased.The rate of change of the indicators has gradually increased,and the changes are in line with the law of zero-order response.Three shelf-life prediction models of browning degree(SLBD),hardness?SLG?and soluble solids(SLSSC)were established combined with Arrhenius equation and the accuracy of models was evaluated later.Accuracy evaluation between predicted and observed shelf-life shows that the predictive accuracy of shelf-life prediction model SLBD?preexponentialfactor:k0=2.94×103,activationenergy:Ea=3.02×104?and SLG?preexponential factor:k0=-3.97×109,activation energy:Ea=4.22×104?are high.and the shelf-life of fresh-cut lotus roots can be predicted at the storage temperature from025?.The kinetics model of Pseudomonas at different temperatures was researched.The results indicated that,the cruves of total number of colonies on fresh-cut lotus roots could be well described by the modified Compertz equation.It was observed that?max?maximum specific growth rate?increased with increasing temperature while??lag time?decreased with increasing temperature.Using the Belehradek equation,based on the relationship between the growth of total colonies?max and?and the storage temperature T,and the shelf life prediction model SL of fresh-cut lotus root was established.The fresh-cut lotus root was stored at 15°C,and the reliability of the model SL was verified by measuring the growth value of the total number of colonies and the predicted value of the shelf life model.The results showed that there was no significant difference between the predicted curve and the measured curve of fresh-cut lotus root.Their accuracy and deviation were1.0351 and 1.0293,respectively,and the relative error was 2.2%.It indicated that the shelf-life of fresh-cut lotus root from 0 to 25?can be predicted availably by the prediction model SL. |
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