A bioplastic additive and antimicrobial plastic includes a polyphenol and an organic polymer. The polyphenol may be a phenol, polyphenol, bioflavenoid, flavonoid, tannin, coumarin, lagman, quinone, stibene or qurcuminoidstenin. The organic polymer may be chitosan, chitin, cellulose and keratin. In one advantageous form, the polyphenol is hesperidin and the organic biopolymer is chitosan.