Study On The Browning Controlling Techniques Of Fresh-cut Lotus Root

Lotus root is rich in nutrients,with beneficial for public health,and has a crunchy or soft texture,which are widely popularity.Fresh-cut lotus root is a kind of convenient food,with a wides range of demand in China.Browning is the main technical issue affecting the processing and storage of fresh-cut lotus root.However,there is no effective and safe way to inhibit browning of fresh-cut lotus root in China and abroad at present.Four primary cultivated varieties of lotus root in Shandong Province were used in this research.And the techniques of controlling browning of fresh-cut lotus root were studied from three aspects:cultivated varieties,modified atmosphere packaging and browning inhibitor.The mainly research results are as follows:1.The organoleptic qualities of four different cultivated varieties Elian No.9,Elian No.6,3735 and Ruby fresh-cut lotus root slices during storage were compared.We found that the browning degree of Ruby lotus root is lower than the other three varieties,which can maintain the commodity quality for a longer time.Fresh-cut Ruby lotus root could be protected from browning for 2 days at 4?6?.And displayed slightly brown on the fourth day.However,other three varieties of fresh-cut lotus root only could be kept for one day without browning.And they showed severely browned and without any commercial value on the fourth day.These results demonstrated that Ruby lotus root is a well material for fresh-cut processing.2.The controlled atmosphere(CA)assays of fresh-cut lotus root slices with different concentrations and ratios of O₂and CO₂were detected.It was showed that 1%O₂+15%CO₂,3%O₂+10%CO₂and 5%O₂+15%CO₂gas component could inhibit fresh-cut lotus root slices browning and prolong their shelf life obviously.3%O₂+10%CO₂displayed the best effective among different gas ratios.The gas-adjustable window spontaneous modified atmosphere packaging(MAP)assays of repressing fresh-cut lotus root slices browning were performed.We found that the best technical parameters of the gas-adjustable window for 1kg fresh-cut lotus root slices packaging bags are as follow:O₂and CO₂transmission rates are 6×10⁵and 2.4×10⁶cm³/m²·d·atm,respectively,with a transmission ratio of 1:4 and 1cm².Under the storage condition of 4?6?,the O₂concentration in the bag can be kept stable for 6 days without rancid smell and the fresh-cut lotus root slices could keep good commercial value with above modified air window packaging bag.3.According to previous reports,36 kinds of fruit and vegetable browning inhibitors were selected to apply on fresh-cut lotus root of 3735 cultivar.We found that treatment with the 0.8%glycine for 5 minutes could extend the shelf life for 4 days compared to the control.Meanwhile,0.8%glycine combined sonication for 10min treatment could extend the shelf life for 5 days compared to the control.22 kinds of new browning inhibitors which may have color protection on fresh-cut lotus root of 3735 cultivar were tested.The results indicated that xylitol,resorcinol,lactitol,p-coumaric acid,etc.could extend the shelf life of fresh-cut lotus root.Among them,the effect of xylitol is the best,which could extend the shelf life for 3days.The role of xylitol in inhibiting enzymatic browning is the first reported.The best conditions for xylitol treatment of fresh-cut lotus root slices are 0.5%concentration and soaking for 5 min.Under 4?6?storage condition,fresh-cut lotus root slices with above treatment could maintain 4 days without browning,and had good commercial value.However,the control of 3735 cultivar had severe browning and lost commercial value on the second day.Meanwhile,polyphenol oxidase(PPO)activity,total phenol content and weight loss rate were also measured.It was found that xylitol could inhibit the activity of PPO,influence the total phenol content and reduce the weight loss of lotus root slices during storage.