Comparison of Enterococci and Coliform Microorganisms in Commercially Produced Pecan Nut Meats

Abstract

Pecan nut meats in the unbroken shell are sterile for enteric microorganisms. Recovery of coliform microorganisms or enterococci from finished pecan nut meats indicated contact contamination, assuming the tempering procedures to be satisfactory. Results of specific studies, designed toward developing background data on the sanitary significance of enterococci and coliform microorganisms in the production of pecan meats are reported. Unbroken pecan nuts or nut meats from various stages of shelling operations were diluted with a phosphate-buffered diluent. Serial dilutions were inoculated into Lactose Broth and Azide Dextrose Broth. The lactose fermentors were carried through indole, methyl red, Voges-Proskauer, and citrate reactions; the positive Azide Dextrose cultures were confirmed in Ethyl Violet Azide Broth and microscopically. Viable plate counts were obtained. Enterococci were found resistant to many deterrent factors affecting coliforms. Recoveries of enterococci were detected long after pollution had occurred. Little correlation was found between enterococcal recovery and observed insanitary practices in commercial shelling operations. Using the coliaerogenes group and, specifically, Escherichia coli as a sanitation index, microorganisms allowed accurate appraisal of tempering, personnel practices, and contact surface contaminating factors. It is felt this was due, in part, to the more delicate growth characteristics of E. coli. The fact that other pathogenic microorganisms, capable of causing gastrointestinal upsets, are associated with the presence of E. coli introduces a health factor which is important to regulatory agencies concerned with consumer protection.