MICROORGANISMS IN FOOD

-microorganisms are ubiquitous . They are harmful and also useful for the mankind . Different kind of foods can be prepared by microorganisms .

1. Microorganisms in food ANJALI SHARMA M.Sc. DEPARTMENT OF MICROBIOLOGY MEERUT INSTITUTE OF ENGINEERING AND TECHNOLOGY

2. WHAT IS FOOD MICROBIOLOGY ? “ Food microbiology is the discipline that includes the microbiological aspects of food spoilage and food-borne diseases and their effective control and bioprocessing of foods for human and animal consumption , in addition to the basic information of microbial physiology , metabolism and genetics”.

3. DEFINITIONS … SPOILAGE : bad food microbiology undesirable changes to food; sour milk, moldy bread. preservatives and refrigeration inhibit the growth of microorganisms

4. FERMENTATION : good food microbiology food that have been intentionally altered such as sour cream, cheese,beer. any desirable change a microorganism makes to food.

5. TOXINS : bad food microbiology Toxin [L. Toxicum = poison ] any substance that is poisonous to other organisms . Can induce the disease in the absence of the toxin – producing organisms . E.g. – 1) botulinum toxin causes botulism , 2) salmonella toxin causes salmonellosis .

6. FOOD POISONING : bad food microbiology Or food intoxication is a food borne disease that results from ingestion of exotoxin secreted by bacterial species growing on food . For example : botulism , or staphylococcal food poisoning .

7. Microorganisms in food . There are three main sort of microorganisms present in the food , they are as follows :- BACTERIA MOLDS YEAST {FUNGI} While other can be consideration as parasites , protozoan , viruses as well as algae .

8. BACTERIA • Rod, spiral, spherical, comma shaped with or without flagella. Covered with endospores that protect them from changess in temperature. They divide every 20 mts. Uses: converts ethyl alcohol to acetic acid. This helps in preparation of vinegar and also idli, dhokla, curing coffee and cocoa beans. Some are used in developing stabilizers for preparation of jelly and ice creams . Diseases caused are sore throat, cholera, syphilis,typhoid, dysentery and food poisoning.

9. Figure : common bacteria infecting human

10. Harmful effects Spoil food by producing acid . Slime or rope as in curd Putrefy food products leading to bad odour

11. FUNGI ARE LOWER PLANTS THAT LACK CHLOROPHYLL . YEASTS : Unicellular(single cell). Grow in foods high jams, bread in sugar and salts
Colour less,white in colour.
Not harmful, mostly useful.
Like A Phalloides

12. MOULDS: Multi cellular (many cells)
grow on pickles,cheese.
red, pink, blue, yellow, black,
produce toxins like alfa toxins, Parasitic ringworms.

13. USES OF YEAST : Yeast ferments sugar to alcohol and carbon dioxide.
It is rich in B complex.
Yeast grown on industrial waste is used for making Beer and wine.

14. ALGAE : Are both unicellular and multi cellular. Usually green in colour( red also) and found in water.
Usually not pathogenic, but some of them have an unpleasant odours. Uses: important source of agar.Agar is used as a veg substitute for gelatin in preparation of desserts.
In water purification and sewage treatment plants. They are a source of food to the aquatic animals.
Blue green algae are used as fertilizers.
Alginic acids and its salt are used in ice cream preparation to prevent crystallization and give it smooth texture.
Also used in preparation of cheese.

15. PARASITES / PROTOZOAN : Parasites are micro organisms dependent on living organisms for thei growth. Unicellular and parasitic in nature.
Used as source of food by aquatic animals. Harmful protozoa cause amoebic dysentery and contaminated water or salad vegetable cause mlalarial fever.
Contaminated meat of pigs (uncooked pork) can infect humans and cause gastrointestinal diseases. It causes cysts and also muscularspasms.

16. Food and nutrients : They need protein andcarbohydrates to grow. pH level: Neutral pH is ideal for their growth . Moulds and yeast grow well in acidic medium 4 -4.5 In general a majority of the microbes will not grow in high pH levels. Foods like pickles have a better keeping quality because of high pH. FACTORS RESPONSIBLE FOR THE GROWTH OF MICROBES :

17. Moisture: water is the main constituent of the living cell. Salt and sugar are hygroscopic substances. They bind water, thus making it unavailable to microbes. Squashes stay longer for the same reason. Temperature : temp range of 5- 63 degrees is called danger zone. Above and below this a number of microbes die. Oxygen: Moulds and yeast grow best in the presence of oxygen. Only some bacteria are aerobic

18. Time: Microbes multiply very fast in a very short time given favourable conditions. Osmotic pressure : Presence of sugar and salt has an osmotic effect on the food. Moulds and yeasts grow fast on pickles and jams also. Sunlight and UV rays: well lit and well ventilated areas inhibit the growth of microbes. UV rays sterilize food partially as their penetrating power is low .