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College of Education

School of Continuing and Distance Education 2014/2015 – 2016/2017

UGRC 145:

FOOD AND NUTRITION IN

EVERYDAY LIFE

Session 7 – Food Safety I

Lecturer: PROF. MATILDA STEINER-ASIEDU, SBS, CBAS; University of Ghana, Email: [email protected]

Session Overview

Learning Objectives:

At the end of this lecture you should be able to: – List agents that cause food borne illness – Describe ways in which food borne

microorganisms can cause illness in the body – Explain the importance of food safety in nutrition

and Health – Describe how pesticides enter the food supply,

and suggest possible actions to reduce consumption of residues

Slide 2 Prof M. Steiner-Asiedu

Session Outline

The key topics to be covered in the session are as follows:

• Topic One: Food Safety and Hygiene-I

• Topic Two: Assignment/Discussion For Next Session

Prof M. Steiner-Asiedu Slide 3

FOOD SAFETY AND HYGIENE-I

Topic One


What is food safety?

• It is the practical certainty that illness or injury will not result from the consumption of food.

–It refers to ways in which food is handled, prepared and stored to avoid contamination and foodborne illnesses


Important definitions

• Foodborne illness – illness of an infectious or toxic nature that is caused

by the consumption of food or water.

• Food hazards – biological, chemical or physical agents in food, or

condition of food with the potential to cause an adverse health effect.

What are some potentially harmful biological,

chemical or physical agents that you can think of?


Biological Agents

Biological agents are collectively referred to as microorganisms –Microorganisms are minute organisms too

small to observe without a microscope. • Include bacteria, viruses and others. • Occur naturally in the environment.


Biological Agents

• 80% of foodborne illnesses are caused by microorganisms.

• Microorganisms and parasites infect humans and cause specific diseases after being consumed in contaminated foods. –Many pathogenic (disease causing)

microorganisms are passed out of the body in faeces and infect another human beings when they reach the mouth through unwashed hands, utensils or flies


Biological agents

• Bacteria • Viruses • Moulds that produce toxins or poisons • Parasites: mainly protozoa and

helminthes (round and flat worms)


Bacteria and other biological agents

• Bacterial pathogens can grow in foods. Can multiply from low, possibly harmless

levels to higher levels sufficient to cause illness in relatively short time.

• Viruses and parasites will multiply only in the cells of the infected individual but can survive in foods, and be transmitted by foods.


Chemical hazards

Cleaning agents and lubricants that are used in food processing factories around the house

Additives used in food processing for example to much of nitrites and nitrates added to sausages

Pesticides and fungicides sprayed on crops in the farms

Naturally occurring toxins or poisons in foods

e.g. cyanogenic glycosides in cassava release cyanide


Physical agents

• stones • plastic material • glass • pieces of bone • hair strand I am sure you have all encountered some of

these items in food. They can be dangerous, example stones can

break a tooth.


Figure 1: Sources of food contamination


How do microorganisms in food cause illness?

• Microorganisms can cause foodborne illness in two ways- by

1. Infection 2. Intoxication


Food Infection

• This results when food containing the pathogen (agent) is eaten.

• The pathogen grows and invades the host’s tissue or release toxins in the host’s intestines which initiate the illness.


Table 1: Sources and symptoms of illness from some foodborne infections


Food Intoxication

• Food-borne illness caused by the consumption of food containing a toxin already formed by the microorganism in the food before the food is eaten.


Table 2. Sources and symptoms of illness from some foodborne intoxications


Food intoxication

• The most common cause of food intoxication is by the organisme Staphylococcus aureus bacterium.

• The most infamous organism is however Clostridium

botulinum: • an organism that produces a toxin so powerful that an

amount as tiny as a grain of salt can kill several people within an hour. • To reproduce and produce the toxin, Clostridium

botulinum requires an atmosphere without air such as those found in improperly canned/bottled (especially home canned) foods.

• Botulinum toxin unlike staphylococcal toxin is easily

destroyed by heat.


Dangerous symptoms of foodborne illness


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Food Safety: From farm to table

• Food safety must be applied at all levels of the food chain- “farm to table”.

• Careful food handling is required to prevent the effects of microrganisms: • on the farm (food that is produced) • in the processing factories • during transportation to stores, restaurants etc • during storage and cooking in the home.

• Cleanliness along the food chain is the major preventive measure to avoid disease from contaminated food.


Food Safety: From farm to table


ASSIGNMENT/DISCUSSION FOR NEXT SESSION Topic Two


Take home

• What are the physical agents in food that can cause health problems

• List some of the problems that may arise when one eats food that is not safe


Next week

• We shall continue with food Safety Part II.

• Make sure you go over handout 5A & 5B before the next lecture.


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