(1) Bacterial soft rot. Bacterial soft rot, due to Erwinia carotovora, is a
problem in carrots. Lesions develop anywhere on the root, usually at injury sites.
Lesions are soft, watery, and gray to brown. Advanced infections are slimy and have a
(2) Gray mold rot. Gray mold rot is a disease of stored carrots. Affected
tissues are water-soaked, spongy, and light brown. Gray to brown mold and spore
masses develop on the lesions.
g. Potatoes. Bacterial soft rot, due to Erwinia carotovora, is also a problem in
potatoes. Soft rot enters tubers at bruised or heat-injured areas. Soft rot is at first light-
colored, but with time and exposure to air, it becomes dark brown to black.
h. Sweet Potatoes. Black rot of sweet potatoes is due to Ceratocystis fimbriata.
Most of the damage in the form of root decay occurs during storage. The early signs of
black rot are round, slightly sunken spots. As the infection grows, the spots enlarge and
become black to greenish black. Affected internal tissues are dark colored and have a
bitter taste which affects the entire root when cooked.
A summary of microbial conditions of vegetables is found in figure 5-2.
Soft rot, mushy, Black rot, soft, Black mold rot, Blue mold
Fresh vegetables in general
Leaf spot, Gray mold
Soft rot, Fungal rot, Wet rot
Fungal rot, Pink rot
Neck rot, Brown rot, Black mold rot
Ring rot, Dry rot
Figure 5-2. Microbial conditions of vegetables.
OVERVIEW OF MICROBIAL SPOILAGE OF FRESH FRUITS AND VEGETABLES
a. General. You, the inspector, will examine the product and note abnormal
color(s), odor(s), and/or texture(s) and suspected microbial deterioration. You will
identify the cause of these conditions.
b. Causes. Microbial spoilage may be caused by bacteria, mold, and/or yeast;
however, microbial spoilage of FF&V is primarily due to mold.