Spoilage of Canned Food

Canned food

Heated canned food is microbiologically more stable that most other foods . Better keeping the quality of heated canned food is due to.

• Heat treatment applied during canning kills most of the microorganism present in original food.
• Recontamination of food outside is prevented by sealed by .

Spoilage of heated canned food

Spoilage of canned food occurs by 2 ways ;

• Survival of spores of some thermophilic bacteria during heating of canned food .
• Recontamination of microorganism from outside through leak in the container.

Types of biological spoilage of canned food

Tye of spoilage of canned food by the microorganism . Usually, are divided into those caused into those caused by thermophilic bacteria and those caused by mesophilic bacteria .Other methods of classification are based on kind of charge in food like acid production , purification blacking .

Spoilage by thermophilic spore-forming bacteria

Due to heat resistant nature of these organisms, they produce three type of spoilage i.e flat sour , TA ( Thermophilic spoilage ) spoilage and sulfur or sulfide strikes.Spores of thermophilic bacteria are not easily by heat treatment applied during canning .

1. Flat sour : This type of spoilage occurs mainly in low acid foods and its caused by species of Bacillus such as Bacillus coagulants and Bacillus stearothermophilius spores of these thermophilic are not killed by heat treatment applied during canning . Later spores germinate in food and cause spoilage . They produce acid without gas in food and cause spoilage , Therefore , the can remains flat during spoilage and hence spoilage can not be detected by examination of the can from outside. The spoilage likely acidic food such as peas , commonly etc.and is caused by species of Bacillus .Their organism is responsible for production number of acid without gas in food.
2. Thermophilic anaerobic (TA) spoilage :Thermophilic anaerobic strains for thermophilic anaerobes . The causative agent of such spoilage is thermophilic spore-forming anaerobic such as Clostridium thermal saccharolytic , which from acid and gas ( Mixing of carbon dioxide and hydrogen) swells The can if it help long enough at high temperatures and many eventually cause bursting . The spoiled food usually has sour , cheesy odour , the source of the organism . The spoiled food has usually sour odour or taste
3. Sulphides or sulfur striker spoilage :It is caused by Desulfotomoculumnigrificans spoilage usually occurs in low acid food . Spore of this organism is usually less heat resistant than those of flat sour and TA bacteria . Therefore , spoilage by this organism indicates inadequate heat treatment during canning . The organism produced hydrogen sulphide that reacts with a tin of canned to from black spots of fees in food and the inner wall of the can . Hydrogen sulphide produced give putrid odour which is evidenced when the can is opened.

Spoilage caused by mesophilic spore forming bacteria

These spoilage measures from spore-forming bacteria of the genera Clostridium and Bacillus .

1. Spoilage by mesophilic ( Clostridium species ) :Clostridium species such as clostridium butyric . Clostridium Pastorium causes the butyric acid type fermentation in acid food with swelling of the container ( due to the production of hydrogen ) other species such as Clostridium Sporogenes, Clostridium putrefacient , Clostridium ,botulinum are proteolytic and putrefactive organism demo posting proteins with malodorous compounds. Such as hydrogen sulphide , indole, mercaptans , ammonia , ate . The per refractive anaerobes grow best in low-acid canned food such as meat, fish, corn ,peas etc.
2. Spoilage by mesophilic ( Bacillus species) :Many species of Bacillus are aerobic and therefore can not grow in a well-evacuated can . They cause spoilage especially in Polymyxa and Bacillus mesenteric cause spoilage of many control food. Since spores of the organism are heat resistance . They usually spoiled food by contamination through leakage container .

Spoilage by non-spore forming bacteria

Nonspore forming bacteria cause spoilage of canned food if mild heat treatment of applied during canned or when they enter into the can through leakage . Most of the nonspace forming bacteria enter into the canned through leakage during cooling by contamination water. Many Thermo bacteria such as Enterococcus streptococcus thermophiles , Micrococcus ,Lactobacillus and Leuconostoc species can survive pasteurization temperatures and spoiled the canned food . However , in most cases , spoilage by spore-forming bacteria indicate leakage of the container .Type of spoilage depend on the type of microorganism eg. coliforms and heterofermentative lactic acid bacteria swell the can by the production of gas . Nongas forming bacteria such as Pseudomonas , Alkaligenes , Micrococcus , Proteus etc .also spoiled canned food.

Spoilage of yeast

When yeast is grown in canned food they cause swelling of canned by the production of carbon dioxide spoilage by yeast indicates recontamination through leakage of heat processing during canning plus poor evacuation . Many yeasts are killed by resterilization temperatures and their presence indicates inadequate heating canned fruit , jam jalis .juices etc when spoiled by yeast swelling of canned due to the production of carbon dioxide .

Spoilage by mold

Some species of the mold such as Sclerotia and Bysschlamys fully are same what heat resistant and survive mild heat treatment . Other molds enter through leakage in the can . Mold cause spoilage of high acid and high sugar food such as jam species of Aspergillus , Penicillium etc. are found commonly in canned food.

References

Frazier, WC and Westhoff DC. Food Microbiology. 3rd. New Delhi: Tata McGraw-Hill Publishing Company Limited, 1986.

Jay, MJ. Modern Food Microbiology. Ed. India. 3rd. Delhi: CBS Publications and Distributions, 1987.