| Fresh food safety incidents occur frequently,and adequate cleaning and disinfection is particularly crucial,as it is the first line of defense to ensure the safety and quality of food.At present,electrolytic water is widely used in the large-scale food industry to clean and disinfect it.To improve its effectiveness,a large amount of electrolytes are usually added to the electrolytic solution,thereby improving the effective chlorine concentration(ACC)and oxidation reduction potential(ORP)of the electrolytic water.However,high effective chlorine concentrations are irritant and pose certain hazards to fresh food and human body,which is not conducive to application in household and small-scale food industry scenarios.The development of a portable sterilizing instrument has made up for the shortcomings of the electrolytic water mentioned above.Usually,tap water is used as the electrolytic original solution,and the electrolytic water prepared with it is non irritating,green,and environmentally friendly.Moreover,the instrument is compact and convenient,and is suitable for daily household life.However,at present,there are few reports on the relevant research on using tap water as an electrolyte to clean fruits and vegetables,and the research on the impact of this type of electrolytic water on the sensory quality of fruits and vegetables remains to be carried out.Based on this,this topic uses a portable sterilizing instrument made in the laboratory to prepare electrolytic water and investigate its effect on the sensory quality of fruits and vegetables.The main research content and results are as follows:(1)To study the basic indicators of electrolytic water prepared by a portable sterilizing instrument and its sterilization and pesticide residue removal effects on fruits and vegetables.The physical and chemical properties of electrolytic water were measured and it was found that the values of various physical and chemical indicators were correlated with electrolysis time,that is,the longer the electrolysis time,the lower its p H value,the higher its ORP value,ACC value,and the ability to generate hydroxyl radicals.When the electrolysis time is 20 minutes,the prepared electrolytic water is slightly acidic(p H 6.11),with an ORP value of 71.38,and an ACC value of 1.60 mg/L.The ability to generate hydroxyl radicals is as high as 5.39 U/m L.By comparing the germicidal efficacy of electrolytic water(EW)produced by a portable disinfection instrument with that of clean water treatment(TW)on fruits and vegetables,it was found that under the same treatment time,electrolytic water can significantly reduce the total number of bacterial colonies,total number of Escherichia coli,and total number of Staphylococcus aureus on the surface of fruits and vegetables(P<0.05),indicating that this electrolytic water is effective in sterilization of fruits and vegetables and improves the biological safety of fruits and vegetables,The bactericidal mechanism is mainly the joint action of slightly acidic p H and the generated hydroxyl free radicals.By establishing a model of malathion contaminated Chinese cabbage and washing it with TW and EW,it was found that EW treatment for 15 minutes significantly reduced the pesticide residue rate on the surface of Chinese cabbage(P<0.05),which was 27.53% lower than that of the TW treatment group.Moreover,the longer the EW treatment time,the lower the pesticide residue rate on the surface of Chinese cabbage;Surface pesticides were extracted from the samples of the EW treatment group and the control group for 20 minutes.GC-MS analysis showed that the degradation products of malathion after EW treatment mainly included O,O-dimethyl S-hydrodithiophosphate,triethyl phosphate,diethyl 2-mercaptosuccinate,diethyl maleate,and malathiophosphate.The results show that the strong oxidation performance of the electrolytic water effectively degrades malathion and ultimately decomposes into non-toxic small molecular substances.(2)Taking cucumbers,blueberries,and fragrant pears as research objects,the effects of portable sterilization and disinfection instruments on the sensory quality of fruits and vegetables were investigated,using texture and sensory evaluation as evaluation indicators.Using TW and EW for 5,10,15,and 20 minutes,respectively,and without treatment as a control,the texture indicators of three types of fruits and vegetables were measured using a texture analyzer.The results showed that after 20 min of EW treatment,the flesh hardness and crispness of cucumber and fragrant pear significantly increased(P<0.05);The skin hardness of blueberries decreased,but there was no significant change in flesh hardness,elasticity,cohesion,and chewing ability;Moreover,the longer the EW treatment time,the smaller the epidermal thickness of the three fruits and vegetables.Further storage experiments were conducted on fragrant pears.It was found that on the 10 th day of storage after EW treatment,fragrant pears could still maintain high skin hardness,pulp hardness,and crispness.The longer EW treatment time,the slower the decline in quality of fragrant pears.SPME-GC-MS technique was used to analyze the flavor components of fruit and vegetable juices from cucumber and fragrant pear treated with TW and EW for 20 minutes.The results showed that TW and EW treatments did not affect the total relative content of effective volatile components in fruit and vegetable juices;According to the quantitative description and evaluation of sensory characteristics of fruits and vegetables,the study found that the brittleness and hardness of both fruits and vegetables after EW treatment were significantly improved,consistent with the results of texture determination;There was no significant change in the fragrance and taste,which was the same as the analysis results of flavor substances;These research results indicate that the portable sterilizing instrument can improve the taste characteristics of fruits and vegetables without damaging their flavor,such as skin thickness,flesh crispness,and hardness.(3)Select fragrant pears and cucumbers with significant sensory quality changes after EW treatment,and explore the mechanism of the effect of portable sterilizing instrument on the sensory quality of fruits and vegetables around the waxy changes in the skin of fruits and vegetables.Qualitative and quantitative analysis of the epidermal wax components of two types of fruits and vegetables using GC-MS showed that compared with TW treatment,the decrease in the total epidermal wax content of fragrant pears and cucumbers treated with EW significantly increased by 15.2% and 35.6%,respectively(P<0.05),and the organic composition showed a trend of decreasing alkane content and increasing terpene content.Further,scanning electron microscopy was used to observe the microstructure changes of the epidermis wax of fragrant pears and cucumbers.The study found that the epidermis wax of fruits and vegetables without any treatment and TW treatment groups were rough and uneven,while the microstructure of the epidermis wax of fruits and vegetables after EW treatment was smooth and smooth.These research results indicate that electrolytic water prepared using a portable sterilizing instrument can change the sensory quality of fruits and vegetables by removing some of the epidermis wax(mainly the outer epidermis wax)from the surface of the fruits and vegetables. |
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