3rd lecture Signs of Food Spoilage

3Signs of Food Contamination &/Or Spoilage

By:

Dr. Waleed FoadMSc.Public Health in Nutrition

Clinical Nutrition SpecialistEuropean Society of Gastrointestinal

Endoscopy (ESGE)Member of the American Society of

Nutrition Email: wfoad@outlook.com

Topics Covered in Previous Lectures

Some Definitions:NutritionHygieneFood HygieneFood SpoilageFood ContaminationFoodborne disease (Food Poisoning)

Introduction toNutrition and Food Hygiene

Topics Covered in Previous Lectures

Types and Characteristics of Microorganisms that affect Food.

Symptoms of Bacterial Food PoisoningTypes of Bacterial food poisoning:

1. Food intoxication 2. Foodborne Infection

Bacterial food poisoning

Factors needed for Microbial GrowthMicrobial Growth and multiplication is influenced

by: 1. Food (nutrients for bacteria). F2. Acidity (Suitable pH) A3. Time. T4. Suitable Temperature. T5. Oxygen (Most of them, but not all). O6. Moisture (Water content) M

Remember: Bacteria need “FAT TOM” to Multiply

Topics Covered in Previous Lectures

Temperature of foodUnder ideal conditions, bacteria multiply rapidly between 5°C and 60°C (the danger zone for food).

Below 5°C, bacteria multiply slower. At freezing temperatures, bacteria stop multiplying and become dormant. Freezing does not kill bacteria. Most bacteria are killed at temperatures above 60°C.

Topics Covered in Previous Lectures

Temperature Danger Zone

5°C and 60°C

Topics Covered in Previous Lectures

Food Preservation Methods

Topics Covered in Previous Lectures

Changing Acidity: e.g. Chemical preservatives.

Changing Temperature: e.g. Cooking, Refrigeration, Pasteurization, Freezing.

Oxygen Deprivation: e.g. Smoking, Vacuum and Canning.

Water (Moisture) Deprivation: e.g. Drying, Salting and Sugaring.

Preservation using Multiple techniques.

Combined 2 or more techniques for food preservation may be used, Example:Canning: Heating and oxygen deprivation.Pasteurization: Heating and oxygen deprivation.Salted Fish Canning: Salting & oxygen deprivationFreeze Drying: Freezing, Drying & Oxygen

Deprivation.

Topics Covered in Previous Lectures

Classification of Food

According to

The Risk of Food Spoilage

Risk of Food spoilage Some foods are high-risk, as they provide the ideal conditions needed for micro-organisms to grow.

These include: Meat & Poultry products. Milk and dairy products; Fruit.

Risk of Food spoilage in Meat & Poultry

Risk increases when: Sliced or Minced.

Kept uncovered.

Kept Moist. Kept at Danger Zone Temperature

Risk of Food spoilage

Risk of Food spoilage Food Can be Classified into:

Perishable food: meats, fish, poultry, eggs, milk, most fruit and vegetables

Semi-perishable food: potatoes, apples, nuts

Nonperishable food: sugar, flour, rice, dry beans, or Processed prepackaged food

Non-perishable prepackaged Food

Canned soda Boxed juice Bottled water Chips Pretzels Granola bars Crackers Candy

Cooked Food Risk of SpoilageGeneral rule after Cooking:“Keep Hot Food Hot, Keep Cold

Food Cold”High Risk of Food spoilageHigh Risk of Food Borne diseases.Leftovers should be stored carefully, Doubtful food shouldn’t be consumed.

Signs of Spoilagein

Preserved Food

Canned Food Generally, Canning has excellent

keeping quality of Food, Why?

Compined 2 or more techniques for food preservation

Sealing (Oxygen Deprivation) ±Heating ±Salting + Acidification

Spoilage in Canned Food Spoilage occurs due to some faulty

technique: Eg:

Not properly Sealed Not properly Heated Acid from food reacts with iron of container

Canned food which is doubtful should be discarded without tasting the contents.

Signs of Spoilage inCanned Food

Can has swollen irregular appearance Can is leaky or corroded. Can is rusty Contents smell putrid or alcoholic Contents are discoloured Syrup looks turbid, cloudy, slimy or

mouldy. Contents spurt out when the can is

opened.

Signs of Spoilage in Canned Food

Signs of Spoilage in Canned Food

Signs of Spoilage in Canned Food

Signs of Spoilage in Canned Food

Signs of Spoilage in Canned Food

Frozen Food Its is hard to detect spoilage in frozen food,

unless there are obvious changes in colour and smell, mainly when it is thawed.

Freezing only slows bacterial growth, but doesn’t completely kill bacteria if present in food.

Bacteria can multiply again when food is thawed and temperature reaches the “Danger Zone”.

Rule: Frozen Food, once thawed is highly perishable.

Temperature Danger Zone 5°C and 60°C

Rules for handling Frozen Food Don’t use frozen food if it has a bad

smell, taste or colour. Thaw only what you need. Don’t re-freeze thawed food. Don’t buy or use damaged outer package Don’t keep frozen food out of the freezer

long before cooking or serving Don’t accept frozen food which has a

large quantity of ice crystal formed inside the package.

Spoilage of Frozen Food

Spoilage of Frozen Food

Questions?For Further Support:

Dr. Waleed FoadEmail: wfoad@outlook.com