This document summarizes the causes and types of spoilage that can occur in canned foods. It discusses both non-microbial spoilage due to chemical and enzymatic reactions, as well as microbial spoilage. Microbial spoilage can be caused by thermophilic sporeformers if cans are improperly cooled or stored at high temperatures, or by mesophilic microorganisms if cans are inadequately heated. Specific bacteria that can cause spoilage are described, including Clostridium, Bacillus, and various molds and yeasts. Signs of spoilage and methods for preventing spoilage in canned foods are also outlined.

1. Presented by
Syed Farhan Ali
M.sc. I semester
Department of Microbiology
KNIPSS ( Sultanpur )
A PowerPoint presentation on
Spoilage of canned food

2. • Canning is also known as Appertization from the name
of its first inventor, Nicolas Appert.
• Canning is a method of preservation of food in which
food contents is processed and sealed in airtight
container such as metal,glass,thermostable plastic or a
multilayered flexible pouch.
• Canning provides a shelf life typically ranging from one
to five years, although under specific circumstances it
may be more or less.
Canning

3. Canning

4. • Canned food spoilage is both due to non
microbial (chemical and enzymatic reactions) and
microbial reasons.
• Production of hydrogen (hydrogen swell), CO2,
browning, corrosion of cans due to chemical
reactions.
• Liquefaction, gelation, and discoloration due to
enzymatic reactions are some examples of non
microbial spoilage
Spoilage of canned food

5. Microbial spoilage is due to 3 main factors:
(1)Inadequate cooling after heating or high-
temperature storage, allowing germination and
growth of thermophilic sporeformers.
(2) Inadequate heating, resulting in survival and
growth of mesophilic microorganisms.
(3) Leakage (can be microscopic) in the cans,
allowing microbial contamination from outside
following heat treatment and their growth.
Microbial Spoilage

6. Thermophilic sporeformers can cause three types of
spoilage of low-acid (high-pH) foods (such as corn,
beans, peas) when the cans are temperature abused at
43 0C and above, even for a short duration.
1. Flat sour spoilage
2. Thermophilic anaerobe (TA) spoilage
3. Sulphide stinker spoilage
Spoilage by thermophilic spore formers

7. •In this spoilage the cans do not swell but the products
become acidic because of germination and growth of
facultative anaerobic Bac. stearothermophilus.
•Germination occurs at high temperature (43 C and
above), but growth can take place at lower
temperature (30C and above).
•The organism ferments carbohydrates to produce
acids without gas but with some off-flavor and
cloudiness.
Flat sour Spoilage

8. • The spoilage is caused by the growth of anaerobic
Clostridium Thermosaccharolyticum.
•The production of large quantities of H2 and CO2 gas
and swelling of cans are encountered with sour and
cheesy odor.
• Following germination in the thermophilic range (43C
and above), the cells can grow at lower temperatures
(30C and above).
TA Spoilage

10. • This spoilage is caused by the Gram-negative anaerobic
spore former Desulfotomaculum nigrificans.
•The spoilage is characterized by a flat container but
darkened products with the odor of rotten eggs due to H2S
produced by the bacterium.
• H2S, produced from the sulfur-containing amino acids,
dissolves in the liquid and reacts with iron to form black
color of iron sulfide. Both germination and growth occur at
thermophilic range (43 C & above).
Sulphide Stinker Spoilage

12. Spoilage by mesophilic Clostridium species
• C. butyricum and C. pasteurianum are mostly
responsible.
• Ferment sugar to produce volatile acids (butyric acid)
• Produce H2 and CO2 gases with swelling.
• Also C. sporogenes, C. putraficiens, C. botulinum are
proteolytic and putrefactive organism
(metabolizes protein).
• Foul smelling compounds H2S, mercaptans, indoles
and ammonia.
• Best grow in low acid canned food such as meat,fish,
corn,pea.
Spoilage by mesophilic spore-forming bacteria

13. Spoilage by mesophilic Bacillus species
•Mesophilic Bacillus spore are not heat resistant as
well as the thermophiles.
•They survive in inadequate heated canned foods (in
low acid home canned foods) at 100 ° C.
•B. subtilis and B. mesentericus cause spoilage in
poorly evacuated cans.
•Mostly spoiled foods are Seafoods, meats and
evaporated milk.
•Usually spoiled food by contamination through
leakage container.
Spoilage by mesophilic spore-forming bacteria

14. •Damaged and leaky containers allow
different types of microorganisms to get
inside from the environment after heating.
•They can grow in the food and cause
different types of spoilage, depending on the
microbial types. •Contamination with
pathogens makes the product unsafe.
Spoilage due to container Leakage

16. YEASTS
• Yeasts and their spores are not thermo tolerant,
thus they are not found in suitably heat treated cans.
Their presence indicates under processing or post
pasteurization contamination through leakage.
• Fermentative yeasts are more prominent and they
produce carbon dioxide, thus causing swelling of
cans. Film yeasts too can grow on the surface of the
food products.
Spoilage by Fungi

17. MOLDS
•Among molds, Aspergilus and Penicillium are most
spoiling organisms. These can grow at high sugar
concentration.
•Acidification is considered method of preventing
growth of molds. Some of the molds are resistant to
heat.
•Molds are more common in home canned foods
where heating as well as sealing is not under total
aseptic conditions.
Spoilage by Fungi

19. • Can has swollen irregular appearance, if sufficient
gas is produced, they may explode from excessive
internal pressure.
• Flexible or non-rigid containers will appear
“ballooned.”
• Can is leaky or corroded.
• Can is rusty.
• Contents smell putrid or alcoholic.
• Contents are discoloured.
• Syrup looks turbid, cloudy, slimy or mouldy.
Signs of spoilage in canned food

21. • To prevent canned spoilage is ensuring that the
outside of cans stays clean and uncontaminated and
that only chlorinated water is used for cooling them if
at all required.
• Store canned foods in a cool, clean and dry place
where temperatures are below 29° C.
• Refrigeration is the most common way to increase the
shelf life of foods. Once you open a can, place it in the
fridge to prevent contamination.
• For liquids like soup, coffee or juices, a high-quality
vacuum flask can prevent environmental factors from
spoiling it.
• As a precaution, never buy canned foods with a foul
odor, bulging jars or rusted lids.
Prevention of canned food Spoilage

22. Thank
you