FOOD SPOILAGE, TYPES & CAUSES

Definition:

“Food spoilage can be defined as the undesirable changes in appearance, color, flavor and texture of food which make it unacceptable for human consumption.”

  • Sour milk, moldy bread, overripe fruits and mushy vegetables as well as insect-infested grains are examples of spoilt food.
  • Ingestion of spoilt food is generally not harmful for human health unless disease-causing organisms are also present.

TYPES OF SPOILAGE:

From the time it is harvested or slaughtered, food is prone to undergo progressive spoilage through chemical reactions.

1.Putrefaction

2.Fermentation

3.Oxidation

These may occur alone or in combination with each other leading to deterioration in quality of food and making it unfit for consumption.

PUTRIFECTION:

  • It refers to the decomposition of food which is associated with anaerobic breakdown of proteins and production of foul smell.
  • Generally it is caused by proteolytic and anaerobic bacteria such as Clostridium which produce enzymes to break proteins into simpler compounds.
  • Many of these compounds contribute to foul smell, for e.g.: in spoilt meat.
  • Softening of texture and darkening of color often accompany putrefaction.

FERMENTATION:

  • It is the process of breakdown of carbohydrates by microorganisms into simpler compounds such as organic acids, alcohol and carbon dioxide.
  • The term is generally used for desirable fermentation carried out to prepare wine, beer, cider, bread, cheese, yogurt and sauerkraut (sausage).
  • However, when fermentation is uncontrolled, it can lead to food spoilage, for e.g. souring of dough, curdling of milk and deterioration of fruit juices.
  • Lectic acids bacteria (lactobacillus and leuonostoc) and yeast (saccharomyces cerevisiae) are saccharolytic mirco-organisms which are responsible for fermentation of simple sugar.

OXIDATION:

  • This was earlier recognized as the addition of oxygen to a compound but now it is defined as the loss of electrons by a molecule, atom or ion.
  • Autoxidation has been observed in almost all foods of plant and animal tissues.
  • This process gets accelerated upon rupturing of tissues as witnessed during primary processing.
  • Mechanisms of oxidative deterioration in fats and oxidative enzymatic browning in fruits and vegetables.

CASUES OF FOOD SPOILAGE:

  • Foodborne illness symptoms may range from mild to severe and may differ depending on the germ you swallowed.
  • Common symptoms of foodborne illnesses, which can start within hours of eating contaminated food, are nausea, vomiting, stomach cramps, and diarrhea. However, symptoms may differ among the different types of foodborne diseases.
  • Symptoms can sometimes be severe and some foodborne illnesses can even be life-threatening. Although anyone can get a foodborne illness, some people are more likely to develop one. Those groups include:
  • Pregnant women
  • Young children
  • Older adults
  • People with immune systems weakened from medical conditions, such as diabetes, liver disease, kidney disease, organ transplants, HIV/AIDS, or from receiving chemotherapy or radiation treatment.
  • Most people with a foodborne illness get better without medical treatment, but people with severe symptoms should see their doctor.
  • According to the Centers for Disease Control and Prevention (CDC) estimate, each year in the United States, 31 pathogens caused 48 million foodborne illnesses, 128,000 hospitalizations, and 3,000 deaths

BACTERIA/VIRUS/PARASITES:

  • Clostridium botulinum produces a toxin which causes botulism, a life-threatening illness that can prevent the breathing muscles from moving air in and out of the lungs. 
  • Sources of Clostridium botulinum: improperly prepared home-canned foods; honey should not be fed to children less than 12 months old.
  • Campylobacter is the second most common bacterial cause of diarrhea in the United States. 
  • Sources of Campylobacter: raw and undercooked poultry and other meat, raw milk and untreated water.
  • E. coli O157:H6 is a bacterium that can produce a deadly toxin and causes approximately 73,000 cases of foodborne illness each year in the U.S. 
  • Sources of E. coli O157:H7: beef, especially undercooked or raw hamburger; produce; raw milk; and unpasteurized juices and ciders.
  • Listeria monocytogenes causes listeriosis, a serious disease for pregnant women, newborns, and adults with a weakened immune system.
  • Sources of Listeria monocytogenes: unpasteurized dairy products, including soft cheeses; sliced deli meats; smoked fish; hot dogs; pate’; and deli-prepared salads (i.e. egg, ham, seafood, and chicken salads).
  • Norovirus is the leading viral cause of diarrhea in the United States. Poor hygiene causes Norovirus to be easily passed from person to person and from infected individuals to food items.
  • Sources of Norovirus: Any food contaminated by someone who is infected with this virus. 
  • Salmonella is the most common bacterial cause of diarrhea in the United States, and the most common cause of foodborne deaths. Responsible for 1.4 million cases of foodborne illness a year.
  • Sources of Salmonella:raw and undercooked eggs, undercooked poultry and meat, fresh fruits and vegetables, and unpasteurized dairy products.
  • Staphylococcus aureus is a bacterium that produces a toxin that causes vomiting shortly after being ingested. 
  • Sources of Staphylococcus aureus: cooked foods high in protein (e.g. cooked ham, salads, bakery products, dairy products) that are held too long at room temperature. 
  • Shigella causes an estimated 448,000 cases of diarrhea illnesses per year. Poor hygiene causes Shigella to be easily passed from person to person and from infected individuals to food items.
  • Sources of Shigella: salads, unclean water, and any food handled by someone who is infected with the bacterium. 
  • Toxoplasma gondii is a parasite that causes toxoplasmosis, a very severe disease that can produce central nervous system disorders particularly mental retardation and visual impairment in children. Pregnant women and people with weakened immune systems are at higher risk.
  • Sources of Toxoplasma gondii: raw or undercooked pork.
  • Vibrio vulnificus causes gastroenteritis, wound infection, and severe bloodstream infections. People with liver diseases are especially at high risk.
  • Sources of Vibrio vulnificus: raw or undercooked seafood, particularly shellfish.