3rd lecture signs of food spoilage
TRANSCRIPT
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: [email protected]
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
