Effects Of Ultraviolet-B Irradiation On The Quality And Storage Of Mung Bean Sprouts (Vigna Radiate L.Wilczek)

Mung bean sprouts,a common sprout vegetable,germinated in the dark for three or 4 days from mung bean(Vigna radiata)and has a history of more than two thousand years.Some research have showed that the mung bean sprouts has very high value of nutrition,containing active substance of plant which has strong antioxidant activity,such as ascorbic acid,polyphenols and flavonoids which plays an important role for prevention of chronic diseases.With the growth of the national economy and the application of modern science and technology,the process and the scale of production of the bean sprouts have great changed.Higher requirements rose for the nutritional value and the safety quality of bean sprouts.In addition,because of the high moisture content and the crisp character of mung bean sprouts,make it vulnerable to damage during storage transportation,leading to shorter shelf life,producing lower profits.UV-B,which has the character of pollution-free and no residue,conform to the current trend of pursuing the safe and nutritious food.Particularly,the UV-B treatment can not only a good preservation effect of fruits and vegetables,but also the quality regulation of fruit and vegetable is of great significance.Therefore,in this study,we optimize the UV-B processing condition and get the best condition of UV-B treatment.Research the regulating effect of UV-B irradiation treatment on the quality and storage of mung bean sprouts and its corresponding physiological and biochemical mechanism.The experimental results are as follows:1.In this study,we measure the influence of UV-B on mung bean sprouts quality.Through the optimization of the UV-B processing conditions,we determined the best treatment condition is after 60 h of the growth of mung bean sprouts.After applying UV-B treatment,the results showed that UV-B treatment can leads to a great change in mung bean sprouts physical quality.Although UV-B have a negative effect with the mung bean sprouts in bud length,shoot weight and soluble protein content,but a appropriate doses of UV-B treatment can significantly increase the content of soluble sugar,ascorbic acid and total polyphenols and flavonoids the antioxidants content and increase the DPPH free radical scavenging ability,reduce MDA content and did not result in hypocotyl epidermal microstructure change significantly.In addition,UV-B can affect the antioxidants in different degree by changing related enzymes activity,illustrated by the correlation analysis which showed that the corresponding correlation between the change of secondary metabolites content and the related enzyme activity all reached extremely significant level.Compared to the control group,a low dose effect of UV-B radiation can bring the biggest benefit for mung bean sprouts.However,a higher dose of UV-B radiation not only as the effect of a low dose,but also not as good as the control group.So,according to the experimental results,while maintaining the quality of mung bean sprouts and improves the content of antioxidants,the best irradiation dose of UV-B is 0.369kJ/m~2;only consider the raise of antioxidant's content,the best irradiation dose of UV-B is1.845kJ/m~2.2.The effects of UV-B in keeping the quality of mung bean sprouts were studied.After UV-B treatment,mung bean sprouts were stored at 4±1 ? and relative humidity 95% for five days,then the relevant indicators were measured.Research results showed that after storage,the freshness of mung bean sprouts reduced to some extent,but the UV-B treatment can affect the quality decline mung bean sprouts in different extent.Compared to the control group,when the irradiation dose is 0.738kJ/m~2,UV-B treatment can obviously inhibit the rising trend of water loss rate,the content of MDA and microorganism,Browning index rose,and delay the contents of antioxidants,DPPH free radical scavenging ability and related enzymes activities.However,when the dose of UV-B is 2.583 k J/m~2,the effect of UV-B was not only as the effect of a low dose,but also not as good as the control group.In contrast,it accelerates the deterioration of quality of mung bean sprouts.Microstructure was observed under scanning electron microscopy(SEM),which found that after treated with UV-B at lower dose of 0.738kJ/m~2,the hypocotyl surface of mung bean sprouts is smooth,and the epidermal cells are full,epidermal stoma closure,whereas the control's hypocotyl uneven surface,cell crimple seriously,and the stoma in open state.The preservation effect of a high dose of 2.583kJ/m~2 UV-B was not only as the effect of a lower dose,but also worse than the control group.This illustrates the fact that using low doses of UV-B(0.738 k J/m~2)can have very good effect in the storage of mung bean sprouts,but high doses of UV-B are not suitable for the preservation of mung bean sprouts.