how to keep romaine lettuce fresh

{"cid":"91169910","title":"Fresh lettuce packaging machine,Fresh lettuce packing machine,Fresh lettuce filling machine,lettuce salad wrapping","imgUrl":"https:\/\/img.chinax.com\/nimg\/87\/81\/da6b6b373cd4b0b32f021a4e0a33-200x200-1.jpg","attrs":{"Brand Name":"Bestar Packaging Machine","Model Number":"green leafy vegetable salad weighting and filling machine BSTV-520AZ","Minimum Order Quantity":"1 set","Delivery Time":"25 working days after receive the 30% payment","Certification":"CE","Place of Origin":"Foshan,China","Payment Terms":"L\/C, T\/T, Western Union","Supply Ability":"80 SETS \/MONTH","Packaging Details":"Use stretch film wrapping ,then use Fumigation-free splint wooden cases to pack strong","Material":"Full set stainless steel 304","Pack":"all kind of vegetables, like iceberg lettuce, romain, spring onion and leek","Suitable":"Fresh lettuce packaging machine","Mating":"Fresh lettuce filling machine","With":"Fresh lettuce packing machine","Email":"onepacking@gmail.com","Whatsapp\/viber":"008613590629511","skype":"coco11283","Wechat":"YECO11","QQ":"277547358"}}

{"cid":"91221123","title":"Custom-Made Transparent Microporous Plastic Bags With Tiny Pores Of 0.1\u20131 Mm On The Surface.","imgUrl":"https:\/\/img.chinax.com\/nimg\/02\/a5\/cb9c19ebfc408dbd9ab83ca1333c-200x200-1.jpg","attrs":{"Price":"$0.03 - $0.05\/pieces","Brand Name":"Customized","Model Number":"WKD-04","Minimum Order Quantity":"30000 pieces","Place of Origin":"Guangdong, China","Supply Ability":"30000 Piece\/Pieces per Day","Packaging Details":"Carton","Industrial Use":"Food","Use":"cake, Bread, Snack, Chocolate, Lollipop, Noodle, Pizza, Chewing Gum, OLIVE OIL, Salad, Sushi, Cookie, Seasonings & Condiments, Canned Food, CANDY, Baby Food, POTATO CHIPS, Hamburger, Nuts & Kernels, Other Food","Material Structure":"OPP \/ CPP","Bag Type":"Micro Perforated Bag","Feature":"Recyclable, Breathable ,fresh","Printing":"full color printing up to 10 color","Color":"customized","Usage":"Package","Size":"Customized Size","Logo":"Accept Customized Logo","Thickness":"Customer's Demands","Design":"Customized Desgin"}}