The invention relates to a method for prolonging
shelf life of fresh-
cut lettuces through composite bacterium restraining, and belongs to the technical field of fresh keeping storage of raw and freshfoods. The method comprises the following steps of fresh
cutting fresh lettuces without mechanical damage, putting the fresh
cut lettuces into a two-frequency ultrasonic cleaning
machine, setting thetemperature and the time of the ultrasonic cleaning
machine, performing dual-stage
frequency conversion ultrasonic treatment, after first-stage frequency treatment is completed, injecting epsilon-
polylysine having a certain concentration into the ultrasonic cleaning
machine, performing second-stage frequency treatment,
after treatment is completed, performing draining, then charging
nitrogen,
oxygen,
argon and
krypton in a certain proportion, performing modified-
atmosphere packaging, and performing
refrigeration. Through the adoption of the method disclosed by the invention, growth of microorganisms can be restrained, enzymatic activity is reduced, better color is maintained, and the texture and the
nutrient components of the fresh-
cut lettuces are maintained. During the
refrigeration period, compared with separate ultrasonic
waves or epsilon-
polylysine, synergistic treatment of the epsilon-
polylysine and the ultrasonic
waves can notably prolong the
shelf life of the fresh-cut lettuces.