| Light-emitting diode(LED)radiation technology has been proven to delay the post-harvest aging of fruits and vegetables and extend the shelf life.Because of its green safety,energy saving and environmental protection,it has been widely used in the field of post-harvest preservation of fruits and vegetables in recent years.In this paper,the fresh leaves of Arugula(Eruca sativa Mill.)were taken as the research object.Firstly,different light-emitting LEDs were irradiated(red,blue,green,red:blue 59:6,red:blue 48:12,White light)on the regulation of senescence yellowing and antioxidant activity of postharvest arugula,on this basis,screen out suitable LED light quality suitable for storage and preservation of arugula(composite light Ⅰ(red light:blue light 59:6)and composite Light Ⅱ(red light:blue light 48:12)),then study the red and blue complex light I and red and blue composite light Ⅱ on the main aging yellowing parameters and antioxidant content,antioxidant enzyme activity and resistance of arugula during storage The main research results of the regulation of oxygen activity are as follows:The effects of different LED light quality on the relative value of chlorophyll(SPAD),color change,chlorophyll fluorescence parameters,polyphenol relative content,total flavone content and antioxidant activity of sesame during postharvest storage were studied.The results showed that compared with the dark control group,LED light treatment could effectively retard the yellowing and senescence of leaves,better preserve their physiological quality,maintain higher SPAD value of leaves,and maintain the contents of chlorophyll,carotenoids and antioxidant activity of Postharvest leaves of sesame vegetables under red,blue and two red-blue combined light.The maximum photochemistry efficiency and actual photochemistry efficiency of the product were significantly higher than those of the dark control group.Two kinds of red-blue composite LED light significantly increased the chlorophyll content and antioxidant activity of sesame during the pre-harvest period.On the 9th day of storage,the SPAD values of the samples treated with red-blue composite light Ⅰand red-blue composite light Ⅱ were 58.1%and 54.2%higher than those of the dark control group,respectively.The antioxidant activities measured by FRAP method were 74.1%and 60.6%higher than those of the dark control group,and the antioxidant activities measured by ABTS method were 74.1%and 60.6%higher than those of the dark control They were 24.0%and 15.9%higher than those in the dark control group,respectively.Based on the preliminary investigation of the effects of LED illumination on the regulation of leaf senescence yellowing and antioxidant activity during postharvest storage of arugula,the red-blue complex light Ⅰ and red-blue composite light Ⅱ were further explored for anti-aging during the postharvest storage of arugula.The main research results are as follows:yellowing parameters,oxidizing substance content,antioxidant activity and antioxidant enzyme activity:(1)To study the effect of LED red-blue combined light irradiation on leaf senescence yellowing during postharvest storage of arugula.The results showed that on the 9th day of storage,the red-blue composite light Ⅰ and red-blue composite light Ⅱ treatment group were compared with the black control group.Leaf SPAD values were 37.8%and 25.2%higher,respectively;the chlorophyll index was 31.5%and 34.2%higher than the dark control group,respectively.LED red-blue composite light I and red-blue composite light Ⅱirradiation can maintain the chlorophyll and carotenoid content of postharvest leaves of arugula.At the 6th day of storage,the chlorophyll a in the leaves of red-blue composite lightⅠ and red-blue composite light Ⅱ treatment group The content was 60.0%and 34.3%higher than that of the dark control,and the total chlorophyll content was 56.2%and 31.2%,respectively;the carotenoid content was 38.8%and 18.3%higher than the dark control group,respectively.The two kinds of LED red and blue composite light irradiation had significant effects on the color of postharvest arugula leaves.On the 9th day of storage,the a*values of the red-blue composite light Ⅰ and red-blue composite light Ⅱ treatment group were lower than those of the dark control group.28.3%and 16.6%.However,there was no significant difference in the effects of the two red and blue composite lights on the flavonoid index and the anthocyanin index.In summary,compared with the dark control group,the two LED red and blue composite light treatment significantly slowed the reduction of chlorophyll during the postharvest storage of arugula and maintained the leaf color,thus delaying the leaf senescence yellowing.(2)Study on the effects of LED composite light irradiation on the antioxidant substances(total phenolics,total flavonoids,ascorbic acid),antioxidant enzyme activities(SOD,CAT,APX,DHAR)and antioxidant activities of arugula during storage..The results showed that compared with the dark control group,the two LED red and blue composite light treatments could increase the antioxidant content of the leaves of arugula after harvesting.Compared with the dark control,the red and blue composite light Ⅰ treatment group was stored on the sixth day of storage.The contents of total phenolics,total flavonoids and ascorbic acid in the leaves were 22.7%,6.1%and 67.6%higher than those in the dark control group,respectively.The leaves in the red-blue complex light Ⅱ treatment group were 14.0%,9.0%and 61.4%higher than the dark control group,respectively.Antioxidant activity analysis(FRAP method,ABTS method,DPPH method)showed that the antioxidant activity measured by the three methods was 57.6%higher than that of the dark control group when the leaves of the red-blue complex light Ⅰ treatment group were stored on the 9th day.FRAP method),37.6%(ABTS method)and 66.1%(DPPH method);leaves of red-blue composite light Ⅱ treatment group were 49.1%higher(FRAP method),34.1%(ABTS method)and 49.3%(DPPH method).The analysis showed that the two kinds of LED red-blue composite light irradiation can improve the antioxidant activity of the leaves of arugula after harvesting.In addition,LED red-blue combined light treatment can increase the activity of antioxidant enzymes in postharvest leaves of arugula.SOD and CAT activities peaked on the 6th day.At this time,the SOD and CAT activities of the red-blue composite light Ⅰ treatment group were compared.The initial activity increased by 6.6%and 50.0%,respectively,5.9%and 40.6%higher than the dark control group,respectively;the SOD and CAT activities of the red-blue composite light Ⅱ treatment group increased by about 14.3%and 58.3%,respectively,compared with the darkness of the same period.The control group was 13.6%and 48.4%higher.LED red-blue combined light treatment can also significantly inhibit the decrease of APX and DHAR activity.The APX activity and DHAR activity in the same period are always higher than those in the dark control group,especially when stored on the 9th day,the red-blue composite light Ⅰ treatment group The DHAR activity was still 29.4%higher than that of the dark control group,and the red-blue complex light Ⅱ treatment group was 32.3%higher than the dark control sample. |
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