Study On The Effect Of Compound Preservative On Browning Control And Preservation Of Fresh-cut Lotus Root

In recent years,fresh-cut fruit and vegetable industry has reached a considerable scale in our country,occupying a large market share.Significantly,fresh-cut lotus root has the characteristics of crisp taste,rich nutrition,and convenient eating,which is widely favored by consumers.However,after peeling and cutting lotus roots,there are problems such as browning,dehydration and shrinkage,nutrient loss,and susceptibility to microbial infection,resulting in waste of resources and economic losses.Therefore,seeking a simple and efficient way of keeping fresh to extend its shelf life is a current research hotspot.In this thesis,‘Elian5’lotus root was used as the test material,and three safe preservatives of calcium chloride（Ca Cl₂）,ferulic acid（FA）and ethanol（Et OH）were selected for optimization.The effect of this treatment on its preservation effect is explored in terms of storage quality,anti-browning effect,anti-oxidation capacity and respiratory metabolism level.It provides theoretical basis for the further application of Ca Cl₂,FA,Et OH in the field of preservation and processing of harvested vegetables.In the meantime,these thesis can provide technical guidance to solve the problem of fresh-cut products preservation.The main findings are as follows:1.Use response surface Box-Behnken design to optimize the compounding conditions of different mass fractions of Ca Cl₂,FA and different volume fractions of Et OH.In the single factor experiment,color,soluble solid content,hardness,weight loss rate and other sensory indicators were used as the evaluation basis,and the optimal conditions were obtained through process modification based on the optimized results of response surface fitting model.The mass fraction of Ca Cl₂ was 0.68%,the mass fraction of FA was 0.18%,and the volume fraction of Et OH was 15%.The three response values ofΔE*,weight loss rate and total number of colonies were 8.64±0.42,（2.85±0.28）%and（7.26±0.10）lg（CFU/g）,respectively,which were significantly different from those in the control group（P<0.05）.The actual verification is in good agreement with the model prediction,which is of reference value in application.2.The effect of the compound preservative on the quality of fresh-cut lotus root during storage was studied,mainly from the maintenance of sensory and nutritional value and the control of degree of browning.The results showed that under the same storage conditions,the control group was severely browned,dehydrated,and accompanied by a strong musty smell at the end of storage.In addition,the decrease of hardness,SSC and Vc contents and the increase of MDA and electrical conductivity in treatment group were significantly inhibited（P<0.05）,maintaining the integrity of cell wall structure and delaying the degradation of starch substance.the effect of the compound preservative on the browning of fresh-cut lotus root during storage is discussed in terms of changes in substrate content,intermediate products and related enzyme activities.By measuring the color and browning degree of fresh-cut lotus root,it was found that the treatment group could effectively inhibit browning,maintain the content of total phenols and phenolic substances such as phenolic gallic acid and catechin identified by HPLC,delay the production of soluble quinones and inactivation of browning related enzymes such as PPO,POD and PAL.3.The effect of the compound preservative on the respiration,energy metabolism and antioxidant system of fresh-cut lotus root was studied.The results found that the treatment group can inhibit the exchange rate of gas components in the package,delay substrate consumption and the process of anaerobic respiration,and increase the activity of Ca²⁺-ATPase,H⁺-ATPase,SDH and other important enzymes related to respiratory metabolism.Fresh-cut lotus root maintains a high ATP content and energy charge level,and maintains the balance of cell energy metabolism.At the same time,the compound treatment can protect the activity of antioxidant enzymes such as APX,SOD,CAT,and inhibit the accumulation of O₂^˙-,H₂O₂,˙OH and other ROS that are toxic to cells,thereby maintaining the total antioxidant capacity and DPPH free radical scavenging rate level,protect normal cell structure function.