Assessment of Microbial Contaminants of Food and Their Remedies

Dr. Quratulain SyedPCSIR, Labs. Complex,Lahore

Objective

To Provide an overview of the

types of microorganisms involved in food

spoilage and food poisoning, their sources and control .

All Microbes Live in Environment

Microbes are minute living things that are usually unable to be viewed with the naked eye

Bacteria, fungi, protozoa, algae, and viruses are examples!

Food For All

What so ever is nutritionally good for us is equally good for microorganisms

Types of hazard in food

Food can be contaminated by:

• Chemical hazard

• Physical hazard

• Biological hazard

Chemical Contamination

Toxic substances ---- naturally or

added during the processing of food Cleaning solutions Food additives – nitrites, sulfites & MSG etc. Pesticides/insecticides – plant/fly sprays etc. Heavy metals – Cu, Cd, Pb, Zn, & brass Drugs – growth hormones, antibiotics Care must be taken ----------------to

prevent chemical contamination

Physical Contamination

Accidental introduction of any foreign objects

into foodSome examples are as follows•Dead insects• Hair• Jewelery• Glass• Pieces of metal• soil from the ground when harvesting;• a bolt from a processing plant when packaging;

Bacterial contamination

As soon as food is harvested or slaughtered or manufactured into a product ------- change. Main processes:

• Autolysis – self destruction--- caused by enzymes present in the food;

• Microbial spoilage – caused by the growth of bacteria, yeasts and moulds.

Natural Desirable Food Changes

• Autolysis and microbial changes are sometimes desirable (and are not referred to as spoilage)

• Enzymes cause fruits to ripen. • Fermented Foods Like

Bread, Yoghurt, cheese, pickle, Food acids etc.

Types of Bacteria

Pathogen – cause disease

Spoilers cause the quality of food to deteriorate

Beneficial used for food production of value added products.

Food Spoilage

Approximately 1/3rd of all food

manufactured in world is lost to

spoilage

Food spoilage –damage to the edible quality of foodSpoilage affects

Appearance

• taste

• texture

• odour Examples: sour milk, moldy cheese, slimy, rancid meat, discolored vegetables

Color change ---- in the spoilage

Black spots on meat ------- Cladosporium spp.

White spots------- Sporotrichum carnis.

Yellow or green spots ----------- Penicillium species.

A rainbow effect on fish---- Photobacteria ----enable raw fish to glow in the dark

Flavour Changes-----in spoilage

Sour /acid flavour/stale----Clostridium.Bitter flavour------ActinomyceteasBurnt/caramel flavour-----St.lactisSoapiness------PseudomonasTurnip like-----E.coliMalty flavour----P. florescenPotato like ----P.mocidoiensMusty flavour----ActinomyceteasAlcoholic -----yeast

Mould

• Common cause of food spoilage.• Some form toxins that can cause

illness.• Grow in a wide range of foods – high

acid, low moisture.• Freezing does not destroy.• Requires air to grow.

Food

Food

spoilage

Food contamination

Food Types

Support rapid growth & reproduction of infectious bacteria• High Risk: Cooked & ready-to-eat hot foods ,meat products mince, burger patties, roasts, stuffed

meats, seafood, poultry• Medium Risk: Uncooked & ready-to-eat: Sandwiches,

cheese• Low Risk: No further preparation – Peanut butter,

crackers, dry food

Biological hazards

The microorganisms us sick include

Viruses (rotavirus, norwalk virus….) Bacteria (Salmonella, E. coli, Listeria…) Parasites (Toxoplasma, Trichinella spiralis.) Mould (Aspergillus flavus….

BACTERIAL FOOD POISONING IS THE MOST COMMON ALL OVER THE WORLD AND CAN BE FATAL

Toxins

Some bacteria release poisons --- toxins which cause food poisoning.

Exotoxins: Remain in food once they have developed. Endotoxins: Toxins inside the human body only after

the food has been eaten

Toxins are not easily destroyed by cooking

Gram +ve. Gram -ve

Types of Food borne Illness

Infection Eating food contaminated with pathogens

Intoxication Eating food contaminated with the exo- toxin (poisons) formed by bacteria Eating food contaminated with other biological or

chemical toxins (poisons)Toxin-mediated infection Eating food contaminated with pathogens that

grow in the body and form toxins (poisons)

Food Poisoning Bacteria

• The multiplication of bacteria within the food plays an important part in causing diseases

• Usually need millions of bacteria to cause illness.

Conditions for bacterial growth

Micro-organisms need conditions to survive and reproduce these can include:

Temperature

Moisture

Food

Time

Oxygen

pH level

Water boils at 100ºC

Temperature of hot food is 82ºC

Danger zone for rapid growth of micro-organisms is 5ºC - 63ºC

Temperature of fridge is 1ºC - 4ºC

Freezing point of water is 0ºC

Temperature of freezer is -18ºC

Microorganisms Reproduce by binary fission dividing in two

This is what happens …………

Common Foodborne Bacteria

Salmonella Staphylococcus Aureus Clostridium Perfingens

Bacillus Cereus Found in soil, vegetation,

cereals and spices

Clostridium Botulinum Found in the soil and associated

with vegetables and meats

Salmonella spp.

Salmonella

Sources – intestines of people and animals, animal food, raw meat, poultry, raw milk, raw eggs. infectious people after recovery becomes carrier –gall bladder. Raw milk may contain salmonellaCommon food vehicles –Low acid food, undercooked or cooked meat, raw milk and eggs.Incubation period – 6 to 72 hrs to produce endotoxin in intestine.Symptom – Abdominal pain, diarrhoea, vomit, feverSpecific characteristics. Multiplies from 5°C to 47°C under aerobic or anaerobic conditions. Survive freezing temp. destroyed by heat at 66°C

Control adequate refrigeration of food

Salmonella

On the basis of pathogencity three types of diseases• Salmonella septicemia• Enteric fever (typhoid)• Food poisoning Salmonella typhimorium Salmonella heidelburgIllness appear afetr 24 hrs of ingestionIllness depends on spp. No. of bacteria health status Children are more prone.

Clostridium botulinum

Clostridium botulinum

Sources – Fish, intestine, soil, and vegetables.raw milk

Common food vehicles – Low acid processed foodcontaminated after canning or vacuum packaging.

Incubation period – 2 hrs to 5 days. Heat resistantneurotoxin produced in foods.

Symptom – Difficulties in swallowing, talking andbreathing. Double vision and paralysis.

Characteristics – Spores and exotoxin will survive under normal cooking Temp.Bacteria multiply between 3.3°C and 48°C.vegataive cells detroy at 80 c and sporea st 120 C

Clostridium botulinum

Characters – heat resistance depends upon oxygen, acidity salt conc.pH = 7.0 spores resist boiling for many hourspH=3.5 spores killed in boiling condition for 10 minutesLow and medium canned /bottled food ,processed meat, fish. Vegetables Control suspected food must boil at 100 c for 15 minutes, gas and off odor food must reject . Don’t reheat food

E. coli has 150 serotypes. Most strains are harmless. 18 strains are pathogenic benificial strains are producing Vit K2 Serotype O157:H7 can cause serious food

poisoning in humans UIT infection Neonatal meningitis (E.coli contain antigen k1. IgM antibodis are primary antibodies and absent

from the mother and body recognizes antigen K1

E.coli

E. coli ability to survive for short periods outside the body makes them an ideal indicator organism to test

Most E. coli strains are harmless, but some, such as serotype O157:H7 can cause serious food poisoning in humans

E.coli

Escherichia coli O157:H7

Sources – Animal intestine, soil, and water.Common food vehicles – Undercooked or raw meat, vegetables, unpasteurized milk and apple juice and contaminated water.Incubation period – 2 to 5 days.Symptom – watery or bloody diarrhea, nausea, vomiting, cramps, fever.Characteristics – Hemolytic Uremic Syndrome (HUS).Acute kidney failure in childrenControl prevent cross contamination cooked and raw foodWashing of food

Staphylococcus aureus

Staphylococcus aureus

Sources – Human nose, mouth, skin, hands, spots, boils, septic cuts, etc. mastitis in animal Common food vehicles – Dairy products, cold cooked meat and poultry, etc.Incubation period – 1 to 7 hrs. Exotoxin produced in foods.Symptom – Abdominal pain, diarrhea, vomiting,subnormal temperature.Characteristics – bacterium is facultative anaerobe. Killed at pasteurized temp. Heat resistant toxin, salt tolerant– Toxin may survive boiling for up to 30 minutes. No foul order in food14 types of enterotoxin, toxin are resistant to photolytic enzymes so survive in stomachCooked food poultry milk cheese desserts barbecue

Bacillus cereus

Bacillus cereus

Sources – Dust and soil.

Common food vehicles – Cereals, corn flour, steamed rice, spices, etc. common in rice eating countries

Incubation period – 1 to 5 hrs. Exotoxin produced In foods. toxin is highly resistant to heat hemolytic and non hemolyticSymptom – Abdominal pain, diarrhea, vomiting,subnormal temperature.

Characteristics – Spores and exotoxin will survive under normal cooking Bacteria multiply between 7°C and 48°C.

Shigella

Shigellosis

Bacillary dysentery Most cases Shigella sonnei cases every year

Sources: Human fecal contamination of food, beverages, vegetables,

water Signs:

Watery or bloody diarrhea, nausea, vomiting, cramps, fever Onset: 2 days Duration: 5-7 days

Campylobacter

Campylobacteriosis

Campylobacter jejuniSources

Raw or undercooked poultry from feces Non-chlorinated water Raw milk mastitis Infected animal or human feces Poultry, cattle, puppies, kittens, pet birds

Clinical signs Diarrhea, abdominal cramps,

fever, nausea headache and muscle pain Duration: 2-5 days Control cross contamination

Campylobacteriosis

Chorionic diarrhoeaDysentery ------bloody diarrhoeaCholera-------dehydration diarrhoeaTyphoid fever---prolonged abdominal painOthers contaminants • Legionella pneumophila ---------upper respiratory

infection (resemble, flu/pneumonia)• Vibro cholerae---choler• Fungus--- Toxicosis---- mycotoxin Aflatoxins( M1 M2 G1 G2 B1 B2) Zeralenone ochratoxin ergotamine citrinin tricho-thecenes

Sources of Food Contamination

Food infection – caused by harmful live microorganisms that are present in food when consumed

Common Causes of Food Spoilage

12 % Food from unsafe sources 63% Improper STORAGE temp. 28% Poor personal hygiene 23% Contaminated equipment 21% Inadequate cooking 20% Other things

How are foodborne illnesses prevented?

Strategies to prevent food poisoning

Good personal hygiene Only allow healthy workers to handle food. Have all workers wash their hands and nails thoroughly with warm, running water and soap properly and frequently. Cover cuts and infections on hands.

Prevent cross-contamination

Store foods properly. Only use cleaned and sanitized utensils and surfaces for food preparation.

Keep the kitchen clean When cleaning plates and equipment, we need

to scrape and rinse off surface food

We need to do---

Wash fruit and vegetables to be eaten raw under running waterCook food immediately after defrosting. keep cooked food at 60°C or above until

served Cook or reheat packaged food strictly in

accordance with any directions on the label.

We need to do---

Thoroughly cook meat (145–165ºF), poultry (165ºF), and eggs (145ºF).

Cooked food should be reheated to 165ºF. Hot foods should be kept hot at 135ºF or

above.

Keeping cold food

We need to take cold groceries home to the refrigerator quickly as possible

Thaw frozen food in the refrigerator or Microwave

Refrigerate leftovers promptly. Separate large volumes of food so

they will cool more quickly. Keep purchased food chilled until

you get home from the store

Pest control and animals

Stop pests such as cockroaches and mice coming into the area where food is kept

Discourage pests by not leaving food or dirty dishes out on the benches

keep animals out of the kitchen.

Prevention of Food Poisoning WHO Ten Golden Rules

Food processed for safety Thoroughly cook Eat immediately Store carefully Reheat thoroughly No contact between raw & cooked Wash hands Keep food preparation surfaces clean Protect from pests Use potable water

Cooking high-risk foods thoroughly

Methods of Food Preservation - remove moisture

Dehydration: removing water under vacuum or by heating it (sun drying). Good for many foods, including vegetables.

Salting: adding salt not only sucks water out of food and microbes, but most organisms cannot live in a high salt environment. Good for fish & meats, changes the taste of the food.

Methods of Food Preservation - remove oxygen

Vacuum packing: get rid of oxygen by sucking it out under a vacuum. Good for many kinds of foods, and lasts as long as the vacuum is good.

Inert gas: storing food under an inert gas like nitrogen prevents many microbes from growing.

Methods of Food Preservation - cooling

Refrigeration or freezing: very common & easy, lasts as long as food stays frozen. Some microbes can survive freezer temperatures, so freezing should be used in combination with another method.

Methods of Food Preservation - heating

Cooking & boiling: one of most effect methods. Often changes taste of food, destroys or removes nutrients. Must be done long enough to ensure microbes are killed, but once done, you don’t have to keep heating.

Pasteurization: is the process of heating foods hot enough to kill bacteria, but not so long that you ruin the taste (e.g. milk & juice)

Methods of Food Preservation cont--

SterilizationKills virtually all microorganisms and their spores.Once food is batch-sterilized, or individually sterilized, must be stored in a hermetically sealed container, like a can, glass bottle, jar, or flexible plastic container.

Methods of Food Preservation - pickling

Pickling: not very common. Most microbes cannot live outside a certain pH range. Storing food in an acidic solution (contains salt & vinegar) kills bacteria, but can still be eaten. Pickling works by lowering the pH in the microbe’s environment

Chemicals Methods

Disinfection: use of chemicals (bleach) to kill microbes to control infectious diseases on surfaces where food is stored or prepared.

Applying insecticides: spraying chemicals onto crops has long been used to control microbes and insects. Chemicals are very effective, easy to apply, but can be harmful to the environment (plants, animals, humans).

Methods of Food Preservation - Irradiation

Irradiation is the deliberate process of exposing an item either packaged or in bulk, to certain types of radiation energy to bring about desirable changes.

Irradiation : Additional Tool for Improving Food Safety

Seriousness of the food safety issues and the lack of adequate

control measures to ensure 100% bacteria free food.

Does not and Can not Make Foods Radioactive It has the potential to significantly reduce both food

production losses and food born illness.

Irradiated foods need to be stored, handled and cooked in the same way as un-irradiated food.

Below 10 kGy there are no known toxicological, microbiological, or nutritional problems

Advantages

1. Reduce food borne disease

2. Reduce food spoilage

3. Reduce insect infestations

4. Prevent spouting/delay ripening

5. Reduce use of fumigants

6. Physical improvement

Irradiation Doses

Sterilize food products above 10 kGy

Pasteurize food 1-10 kGy Insect disinfestatin (less

than 1 kGy) Sprout inhibition in potatoes and

onions (less

than 0.5 kGy) Delay ripening of certain fruits (less than 0.3 kGy)

Changes in Food by Irradiation

Chemical changes

0.01% of the chemical bonds are affected

Biological effects

Biological function is changed by highly reactive hydrogen and hydroxl radicals

1. causes base damage, target DNA strands– broken down lose ability to reproduce.

Changes in Food by Irradiation

Changes in proteins:

▪ opening of peptide chains ▪ polymerization▪ coagulation ▪ precipitation

Enzymes:

Less sensitive to radiation. Complete inactivation requires abt. 5 times

the dose required to destroy microorganisms.

Changes in Food by Irradiation

Carbohydrates:

Depolymerization degradation

Vitamins: Are sensitive to radiation,

destruction similar to

heat process,

Lipids, natural antioxidants and pigments: are also sensitive

Effectiveness of the Process

Depends upon the amount of DNA in target organisms

Parasites and insect /pests large amounts of DNA rapidly killed at extremely low dose of irradiation.

Bacteria takes more irradiation to kill as they have less DNA.

Viruses resistant to irradiation at doses approved for foods

Effectiveness of the Process

Anaerobic conditions /freezing reduce the lethal effect of irradiation

Higher temperatures/oxygen conc. enhance the lethal effect of irradiation

Gram negative bacteria < Gram positive bacteria/molds/yeast < spores and viruses

Some microorganisms logarithmic phase are more susceptible to irradiation at low doses than during the stationary phase

Effect of Irradiation on Spoiled Food

Neither irradiation nor any other food treatment can

reverse the spoilage process

Organizations that Endorse Food Irradiation

World Health Organization

American Medical Association

Institute of Food Technologists

American Council on Science and Health

Food and Agriculture Organization

American Dietetic Association

Some of our hot selling food exports items are:MangoesCitrusApplesPeachesDry fruits and datesRiceVegetablesMedicine herbs and spices

condiments Wild edible mushroomsSeafood

Different Quarantine treatments

Chemical treatments Physical treatments

Fumigation Hot Water treatment

Methyl Bromide High temperature forced Air

Fumigation + Refrigeration of fruits

Vapors Heat

Cold treatment + Fumigation of fruits

Cold Treatment Radio Frequency heating

Control Atmosphere High Temperature

Quick Freeze

Treatments(CATTS) Ionizing Irradiation

MICROBIOLOGY TESTING LAB,PCSIR LABS COMPLEX, LAHORE

ISO-17025 Accredited Lab.NA &PNAC

Demonstrate that the lab. Operates a quality systemTechnically competent to carry

out specific task Able to generate technically

valid results that cold be interpreted globally

Formal and international recognition of the labs.

Facilitates bilateral and multilateral trade

SCOPE OF MICROBIOLOGY TESTING LAB. AT LLC

Water/Drinks testing (APHA)

Enumeration of Heterotrophic Plate

CountEnumeration of Total Coliforms

Enumeration of Fecal coliforms

Enumeration of E.coli

Enumeration of Pseudomonas spp.

FOOD MICROBIOLOGY TESTING

Enumeration of Total coliforms

Enumeration of Total Plate count

Enumeration of Fecal coliforms

Enumeration of E.coli Detection of

Salmonella Enumeration of

Staphylococci aureus Enumeration of Yeast Enumeration of Mould

Key actions for Important Food Issues Food Safety, Quality and Consumer Protection

ELEMENTS OF A NATIONAL FOOD CONTROL SYSTEM.

Food Law and Regulations Food Control Management Inspection Services Laboratory Services: Food Monitoring and

Epidemiological Data Information, Education, Communication

and Training