Education is light

1. Food hygine and safety
• Haramaya University Jijiga Ethiopia
•Department Mph nutrition

2. Food is essential
Growth and maintaince
keeping physiological process working
keeping the body temprature constant
providing energy and
maitaince proper health

3. The art of preserving foods requires
1. Knowledge of MOs
2. The effect of the environment on these organisms
3. The nature and type of foods
Benefits of food sanitation, hygiene and safety:
– Complying with regulations
– Preventing catastrophes (food-borne illness outbreaks)
– Improving the quality and shelf-life of foods
– Reducing wastages
– Increasing quality and consumer confidence.

4. 1. FOOD:
a) Any raw, cooked, or processed edible substance, beverage, or
ingredient used or intended for use or sale in whole or in part for
human consumption.
b) any material taken in to the body and can actually or potentially
enter into the metabolic mechanism.
c) any substance ingested by an organism resulting in the net addition
of either material substance or energy.
Food Safety (Food Hygiene/Food sanitation)
– All conditions and measures that are necessary in every steps to
ensure that it is safe, sound, wholesome, and fit for human
consumption (FAO/WHO).
– The steps start from
Production,--------Processing, ---------Storage -----Distribution ------Serving preservation of food

5. Food safety/hygiene is a science, which aims to produce food which is
safe for the consumer and of good keeping quality.
– It involves the safe handling of food from the time it has been produced
until consumed:
Food safety Hazards
– Food safety hazards are any biological, chemical or physical agent that are
likely to cause illness or injury in the absence of its control.
– Food hazards can arise from different sources:
1. natural components of the food itself: arise from contamination of the
food during any stage of production, processing, storage and distribution
2. can be a result of decomposition and deterioration of the food items.

6. scheme of food production to food consumption
Production of raw materials
Hazards
•Nutrients
•Natural toxins
•Microbial toxins
•Environmental contaminant
Food Processing
•Reaction products
•Contaminants
•Additives
Storage and transport
•Chemical contamination
•Microbial contamination

7. Food preparation
•Chemical contamination
•Microbial contamination
Food consumption
Risks
•Intoxication by chemical contaminants
•Food-borne infections
•Food poisoning

8. 3. ADULTERATED FOOD (FOOD ADULTERATION):
– Food that may bear any of the following situations/conditions:
i. Bears poisonous or deleterious substances in quantities
injurious to health;
ii. Consists in whole or in part of any filthy, putrid, or decomposed
substance;
iii. Has been processed, prepared, packed, or held under unsanitary
conditions;
v. In whole or in part the product of a diseased animal, or an
animal which has died other than by slaughter;
v. Its container is composed of poisonous substances rendering the
food injurious to health;
vi. Bears or contains color or additives not certified in accordance
with regulations.

9. E.gs. of adulterated foods:
– Skimmed milk;
– Diluting the milk with water and selling it as whole milk;
– Bananas to butter,…
MISBRAND
The presence of any label, writing, printed, or graphic matter
on a food container that is false or misleading-violates
governmental labeling requirements.
Misbranding is made unlawful. This calls for honest labeling of the product
as its:
– Character,
– Origin,
– Constituents,
– As to the amount in the container,
– The date of production, expiry, etc.
– Misbranding is also adulteration

10. AUTOLYTIC/ AUTOLYSIS:
– Self-decomposition of food due to the activity of enzymes internally
existing.
– Most foods of animal and plant origin contain enzymes.
– In live animal/plant enzymes play a facilitation role of physiological
activities on death their activities are destructive.
What is the primary role of MOs?
– While it sometimes appears that MOs are trying to ruin our food
sources by infecting and destroying plants and animals, including
man, this is by no means their primary role in nature.
– The key role in nature is decomposition of complex organic materials
into simpler compounds then made them readily available for reuse
by all other life forms.
– This phenomenon is known as Geo-chemical cycling.

11. Summary points of importance of MOs in human affairs
– Infectious disease
– Decay
– Pollution/eutrophication
– Photosynthesis and Nitrogen fixation
– Foods
– Antibiotics
– Scientific inquiry
– Molecular biology
– Immunology
The Essentials and Function of Food
– Food is a nutritive substance eaten by organism for maintaining
the vital life processes.
– a fundamental human need,
– a basic right, and
– a prerequisite to good health.

12. Growth Requirements of MOs
– Like other higher living organisms, MOs require basic materials and
favorable environment to maintain life and reproduce.
– Generally the requirements for the growth and multiplication of MOs are:
✓Nutrient medium
✓Suitable atmosphere (Oxidation–Reduction potential)
✓Water/ moisture (water activity=Aw)
- Suitable temperature
– Suitable pH
– Suitable osmotic pressure
– Suitable environment
– Time

13. food sources MOs can be divided to two:
1. Autotrophs: These are MOs that are able to produce their
own food from simple inorganic substances.
– e.g.. free living soil bacteria which are normally
non_x0002_pathogenic.
2. Heterotrophs: This group of MOs obtain their foods by
breaking down complex organic compound to simpler form.
• e.g.. When they need nitrogen; they break proteins to
amino_x0002_acids.

14. Based on oxygen requirements MOs can be divided into three in some cases:
relation in oxygen
1. Strikt anaerobeMO- grow only in the presece of oxygen (pseudomonades moudls)
2. Anarobic MO-even trace amount of oxygen is Toxic ( Colostridium )
3. Facultive aerobic -grow both in and without the presence of oxygen ( lactobacallius)
MOs are divided in to three categories with reference to Tempreture
requirement :
1. Psychrophilic,
2. Mesophilic, and
3. Thermophilic.
– Most pathogenic organisms belong to the mesophilic categor

15. a. Psychrophilic:
– Grow best at low temperature.
– Their optimum rage is from 100C to 200C
– The group is not pathogenic to humans
Examples include:
• the pseudomonas and
• Moraxella-Acinetobacter

16. b. Mesophilic:
– Moderate T0
lovers
– Their optimum range is form 300C to 400C
– Most pathogenic organisms belong to this group
e.g.:
– Most Lactobacilli and
– Staphylococci
c. Thermophilic:
– Organisms of this group grow best at highT0
– Their optimum ranges from 500C to 600C.
– Usually found in thermal springs and similar places.
– Non pathogenic to human beings.
e.g.:
– Bacillus stearothermophilus,
– Bacillus coagulans, and
– Lactobacillus thermophilus.

17. Osmotic pressure:
– A favorable osmotic pressure is highly required for MOs.
– Osmosis is the passage of water through a semi-permeable
membrane from a place of low concentration to high
concentration.
– This osmotic pressure has a direct effect on the growth and
multiplication of organisms.
Growths and multiplication of MOs
– Bacteria reproduce by a simple division of a cell; binary fission,
(asexual reproduction).
– Expressed in terms of geometric progression.
– By dividing into two every 20 minutes.
– This way a single bacterium could increase to 2,097,152 within 7
hours.

18. The growth cycle of bacteria can be expressed by a growth curve:
– When bacteria are inoculated into an ideal culture medium (in the lab.) the
pattern of the growth curve exhibits four distinct phases; namely
– The lag phase
– The log (logarithmic/exponential) phase
– The stationary phase
– The decline phase (accelerated and reduced decline phases)
1. The lag phase:
– Period of acclimatization:
– a phase of adjustment to new environment.
– No significant increase in number of organisms in this phase
– This phase can be extended with less microbial proliferation through
reduced T0 and improved sanitation (low range of initial
contamination)
– High initial contamination would decrease the lag phase and increase
bacterial proliferation.

19. 2.The log (logarithmic) phase:
– After the lag phase.
– Optimum environment favoring maximum rate of reproduction and
growth.
– The growth curve is: a straight line.
– Rate of growth is in geometric progression/Exponential
3. The stationary phase:
– In this phase available food supply declines/ dwindles due to
maximum use by the ever increasing bacterial population.
– The growth of new cells becomesrelatively stable.
– B/c dying no. relatively equals to the no. of new cell increases.
– Total bacterial population remains more or less constant.

20. 4.The decline phase:
– In this phase most of the bacteria start dying mainly due to:
a. Depletion of food supply.
b. Accumulation of bacterial metabolic wastes which becomes toxic
and
choking to the bacteria.
c. Competition among the bacterial population for the dwindling food
supply.

21. General principles underlying spoilage
(food spoilage and its causes)
Definition of spoilage:
– The process of change of the physical and or chemical property of the
food.
This affects directly its color, taste, odor, consistency or the texture, etc..
– Decay or decomposition of an undesirable nature usually is implied when
the term “spoiled” is applied to food, while food unfit to eat for sanitary
reasons usually is not called spoiled.
--Spoiled food is more of aesthetic problem than disease causation.
– The presence of odor/smell in food is an alarm signaling a problem with
the food.

22. Causes of food spoilage
– Food that is not properly preserved spoils:
– Fore-example;
– meat, fish, eggs turn putrid,
– fat turns rancid, milk becomes sour,
- fruits turn moldy and fermented,
- vegetables will rot,
- grains become moldy or germinated.
Parasitic infections:
–
- Cysts of tape worms
- Liver flukes
- Trichina spiralis
- Hadiatid cyst etc..

23. Chemical Poisoning/ or effects of toxic plants and animals:
– Food may come to spoil as a result of contact to poisonous and
toxic chemicals from
– contaminated containers,
– pesticide spray or
– other accidental contacts with toxic chemicals which render the
food unfit.

24. Factors Affecting the Kind and Numbers of MOs in Food
– The kind of spoilage of foods by MOs and enzymes will depend on the
kinds and numbers of these agents and the environment about them.
– Most raw foods contain a variety of MOs and also may contain plant
or
animal enzymes.
– However, b/c of env’ntl and other factors only small proportions of
MOs
present will grow rapidly and cause spoilage.

25. General principles of food preservation
A. Prevention or delay of microbial decomposition
4 cardinal principles to prevent the undesirable effects of Mos:
a. By prevention of contamination: keeping out MOs (asepsis; e.g intact
skin covers of foods, covering and wrapping)
b. By removal of MOs: By filtration, washing, and trimming away spoiled
portions of foods)
c. By inhibition/ retarding/ hindering the growth and activity of MOs: by
low temperatures, drying, anaerobic conditions, or chemicals.
d. By destruction/ killing the MOs: by heat or radiation)

26. B. Prevention or delay of self-decomposition of the food:
1. By destruction or inactivation of food enzymes, e.g., by
blanching
2. By prevention or delay of purely chemical reaction, e.g.,
prevention of oxidation by means of an antioxidant.
C. Prevention of damage because of insects, animals,
mechanical causes, etc
Pasteurization
– Pasteurization is a heat treatment that kills part but not all of the MOs
present and without affecting the nutritional quality of the food.
– Usually involves the application of temperatures below 100 C and promptly
cooling the food to below 10 C.
– The heating may be by means of steam, hot water, hot oil, dry heat, electric
currents, and the products are cooled promptly after the heat treatment.

27. Preservative methods used to supplement pasteurization include:
1. Refrigeration
2. Keeping out MOs, usually by packaging the product in a sealed
container
3. Maintenance of anaerobic conditions
4. Addition of high concentrations of sugar, as in sweetened
condensed milk and
5. Presence or addition of chemical preservatives, e.g., organic acids

28. Canning
– The word ‘’canning’’ is a general term and is often replaced by
‘’hermetically sealed containers’’, vacuum packing (in the absence of
air: evacuating all the air in the can).
– Canning is one of the most widely used methods of processing and
preserving food.
– Involves the careful preparation of food packed in to a sealed tin,
glass or plastic container.
How to detect spoilage in canned foods:
– Appearance of the can (swelling or bulging) and
– Taste and odor of the contents.
- It should be emphasized here however, that C. botulinum and its toxin
might be present in under-processed foods without objectionable taste
or smell.

29. Swelling/bulging ends of cans may be caused by:
– Acid and gas produced by bacterial growth.
– Chemical reaction b/n the food contents and the metal container in w/c H2 or
CO2
gas is released. This is called “Chemical swell”.
– Physically induced swell due to overfilling, low atmospheric pressure or rough
handling on the container.
Advantages of drying:
1. Dried foods have low weight and reduced bulk –easy to
store and distribute.
2. End product may be stored at room temperature.
3. Reconstitution occurs readily.

30. Disadvantages of drying:
1. Processing equipment are expensive and complex.
2. Is a slow operation.
3. Difficult to get uniform application of heat throughout the
product.
Methods of drying:
– Moisture may be removed from foods by any of a number of methods, from the ancient
practice of drying by the sun’s rays to the modern artificial ones. Examples include:
– Solar drying (hot sun drying)
– Drying by mechanical dryers (using evaporators or kiln)
– Freeze drying (the sublimation of water from a frozen food by means of a vacuum
plus heat applied at the drying shelf, is used for a number of foods, including meats,
poultry, seafood, fruits, and vegetables).
– Drying during smoking
– Microwave drying,..etc

31. • Factors in the control of drying:
– A consideration of the proper control of dehydration includes the following
factors:
1. The temperature employed (varies with the food and the method of drying)
2. The relative humidity of the air (varies with the food and method of drying
and with the stage of drying)
3. The velocity of the air.
4. The time of drying.

32. • Fermentation and Pickling
- Certain microorganisms are necessary adjunct in the preparation and
preservation of many foods and beverages.
- Fermentation (controlled microbial action) is a process of anaerobic or
partially anaerobic oxidation of carbohydrates with production of acid
and alcohol.
- Is one of the oldest methods of food preservation.
- Preservation by fermentation technique is achieved by transforming
foods into an acid state based on principle of pH control.

33. Factors influencing effectiveness of radiation treatments:
– Time of exposure to a given concentration.
– Intensity of the rays reaching the food.
– Penetration depending on the nature of the object (food).
– The kind and species of organisms
– The number of organisms (or spores) originally present.
– The composition of the food.
– The presence and absence of oxygen (undesirable side reactions may appear).
– The physical state of the food during irradiation (moisture, temperature)

34. 1. Radappertization: is the term used to define “radiation
sterilization” which would imply high dose treatments, with the
resulting product being shelf-stable.
2. Radurization: refers to radiation pasteurization “low-dose
treatments, where the intent is to extend a product’s shelf-life.
3. Radicidation: also is a low-dose “radiation pasteurization”
treatment, but with the specific intent being the elimination of a
particular pathogen.