Natural anti-blackening agent for shrimps as well as preparation method and application thereof

The invention relates to a natural anti-blackening agent for shrimps as well as a preparation method and application thereof. The preparation method comprises the following steps: crude extraction: soaking mung beans, mashing, carrying out centrifugal treatment, and taking supernate to obtain crude extract; heat treatment: heating the crude extract, cooling, centrifuging, and taking supernate to obtain a crude solution; ultrafiltration membrane separation: separating the crude solution by adopting an ultrafiltration membrane with a molecular weight cutoff of 11-16 KDa, and collecting permeate; separating the permeate by using an ultrafiltration membrane with a molecular weight cut-off of 4-6 KDa, and collecting liquid which does not permeate through the ultrafiltration membrane to obtain a concentrated solution; and drying and powdering: drying and powdering the concentrated solution to obtain the natural anti-blackening agent for shrimps. The natural anti-blackening agent can remarkably prolong blackening ti