Question

There are many Firmicutes and Proteobacteria that are associated with food spoilage and foodborne illness. Several methods used to prevent foodborne illness and food spoilage during beer brewing and other food processing are presented.

• List a few species of Firmicutes and Proteobacteria and the issues that they cause that are associated with a) Food spoilage (min. 3 species) and b) foodborne illness (min. 3 species)

• How are these organisms controlled during food processing?

Answer 1

FIRMICUTES associated with FOOD SPOILAGE and FOOD BORN illness

Firmicutes are a phylum of bateria ,most of which have Gram positive cell wall structure.It can be found in a great variety of habitats.They are grouped in the class bacilli or class clostridia.

SPECIES of FIRMICUTES in Food spoilage and food born illness.

(a)- Lactobacillus

(b)-Carnobacterium

(c)-Leuconostoc .

These are the three prevailing spoilage organisms in packaged cold stored  bacterias involved in food spoilage.Spoilage activities of these organisms include excessive formation of buttery and sour off- odors.Leuconostoc spoilage activity mainly associated with discoloration and formation of gas and slime.

Firmicutes are called the bad guys due to their negative influence on glucose and fat metabolism.Increased ratio of firmicutes lead to obesity and Type II diabetes.

PROTEOBACTERIA

They are gram negative bacteria.They include a wide variety of pathogenic genera.

SPECIES of PROTEOBACTERIA associated with FOOD SPOILAGE and FOOD BORN illness.

(a)-Shewanella putrefaciens:It plays a role as a spilage bacterium in marine fish , some vaccuum packed meats and chicken due to its ability to produce volatile sulfides,amines,and the fishy smelling compound trimethylamine.

(b)-Lactococcus piscium : Its role in food spoilage vary according to the strain and food matrix.Its action is mainly in meat.

(c)-Lactobacillus oligofermentens : These are the prevailing spoilage organisms in refrigerated modified , atmosphere packaged meat products.

CONTROL OF SPOLAGE ORGANISMS

(A)---Reducing PH

(b)---Addition of preservatives

(c)---Addition of desirable microflora against undesirable organisms

(D)---Food process under high temperature

(e)----Adding food additives -sugar, salt ,acids