Transcript 1_05 Food chain - ILSI SEA Region

Chapter 1.5 :Food Production and Supply Chain
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Food chain: production, processing, supply
Primary and Secondary Producers of Organic Matter
• Prokaryotes and Eukaryotes
• Autotrophs and Heterotrophs
Suggested reading : Brimer, Chemical Food Safety, Chapter 2
Food Raw Materials
• Human beings are omnivorous i.e. we eat plants (primary producers) as
well as from secondary producers (animals) such as meat, eggs and milk
for nutrition
• After production or gathering of raw materials these are further processed
into different kinds of intermediate products (to reduce weight prior to
transport or obtain a prolonged shelf-life) or ready-to-eat foods/dishes.
• In the following sections we will examine different groups of raw food
materials and how chemical compounds may enter the food chain
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Food Production and Processing Chain
Terrestrial Plants
• Most of the food consumed for the necessary energy production
worldwide originates from terrestrial plants. Examples include:
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Rice (Oryza sativa),
Wheat, (Triticum, aestivium and other Triticum spp)
Maize (Corn, Zea Mays)
Starch rich tubers of Irish potato (Solanum tuberosum)
Cassava (Manihot esculenta)
Yam (includes a number of Dioscoria spp)
Sweet potato (Iponoea batatas)
Traditional cereals – sorghum, finger millet, teff, white fonio, kodo millet,
pearl millet
• Pseudocereals – quinoa, amaranth
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Food Production and Processing Chain
Terrestrial Plants (Cont’d)
• Some starch-rich tubers such as cassava have low protein and
vitamins and essential fatty acids needed for adequate nutrition.
Other protein-rich plants play a particularly important role as
protein and vitamin sources. Examples include:
• Beans
• Peas
• Lentils
• Fruits
Humans consume nearly every part of plants, including: immature seeds,
seeds, newly sprouted seeds seedlings, whole mature fruits, whole
immature fruits, pericarps, flower buds, flower stigmas, immature
influorescences, influorescences, leaves, leaf stalks, barks
rhizomes/rootstocks and roots (for examples see Brimer, Chapter 2).
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Food Production and Processing Chain
Terrestrial Plants (Cont’d)
• Food safety problems may arise from meals prepared from
different plant raw materials. Examples include but not limited to:
• Mycotoxins in cereals
• Selenium in maize (e.g. in US states of Dakota, North Dakota, Missouri and
Kansas)
• Glycoalkaloids in Irish potato
• Cyanogenic alkaloids and their breakdown products in cassava
• Trypsin inhibitors in different pulses
• Pesticide, insecticide and fungicide levels in different crops
• Toxic haemolysis in individuals deficient in the enzyme glucose-6phosphate dehydrogenase (G6PD) after intake of faba beans
• Diarrhoea, failure to thrive and fatigue as symptoms of coeliac disease
(gluten intolerance) after eating wheat (food safety risk to 1 in 100 to 200
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people)
Food Production and Processing Chain
Animals
• Varied species consumed as food (see Brimer, Chapter 3 p6-7)
• Food safety problems may arise from meals prepared from food of
animal origin. Examples include but not limited to:
• Pig kidneys and livers may contain mycotoxins such as ochratoxin A (OTA
from animal feed)
• Cattle kidneys and livers may contain concentrated levels of cadmium
• Milk contaminated with aflatoxin M1 (AFM1) formed from the mycotoxin B1
contained in animal feed
• Fatty fish (e.g. salmln) may contain mercury, lead, dioxins and dioxin-like
polychlorinated biphenyls (PCBs) at concentrations that may impair health
(cause toxicity)
• Bivalve molluscs may contain toxic levels of algal toxins.
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Food Production and Processing Chain
Fungi/Algae
• Varied species consumed as food and used in production of
foods (e.g. yeasts ;see Brimer, Chapter 3 p7-9)
• Food safety problems may arise from meals prepared from
food of fungal and algal origin. Examples include but not
limited to:
• Mushrooms may contains naturally inherent liver, neurological
and gastrointestinal toxins and carcinogens if picked wrongly.
• Mushrooms may contain high levels of heavy metals such as
cadmium and mycotoxins.
• Algae (e.g. specific seaweeds) may contain high levels of
iodine and arsenic, and are being used more extensively as
components of dietary supplements.
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Production of Raw Materials
See Brimer, Chap. 2, p9-12 for overview)
•Production and processing parameters with
influence on food safety through to the
consumers eating the final product, are:
•Production
•Processing
•Packaging
•Storage
•Preparation
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Production and Processing Parameters
Meat and
Vegetable
Production
Processing and
Packaging
Storage
Sold To the
Consumer
Preparation
Storage
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Processing: An Overview
•Food raw materials eaten “raw” and
“processed”.
•Processing may be used to obtain:
•Easier digestibility
•Better tasting
•Longer shelf-life
•Safer.
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Processing : An Overview
•Food Processing and preservation
technologies (sometimes called post-harvest
technology used for highly perishable raw
materials of plant origin), includes :
• primary processing or conversion of raw
materials to food commodities (e.g. milling of
cereals to flours), and
• secondary processing which is conversion of
ingredients into edible products (e.g. baking).
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Processing : An Overview
Some of the most common operations used by the modern
food industry include:
• Size reduction – grinding, cutting, emulsification
• Mechanical separation – sieving, filtration, extrusion,
centrifugation, sedimentation and flotation
• Mixing
• Drying/dehydration/evaporation
• Thermal processing – cooking, blanching, pasteurisation,
baking, roasting/frying, canning, smoking
• Cold preservation – refrigeration (chilling), freezing
• Contact equilibrium processes – extraction, washing,
crystallisation, membrane separations, distillations
• Irradiation
• Fermentation.
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EXAMPLES: Processing and Storage – Chemical
Food Safety - Raw to modified
• Raw products such as meat and vegetables may contain food
contaminants as a result of their production. This however should
be reduced by good manufacturing practices (GMP’s).
• Both meat and vegetables occur as raw products that are usually
processed in some way by a food processing industry or sold as is
through a wholesaler and/or a specialized retail shop or
supermarket.
• A wholesaler may modify the raw products to some extent e.g.
cut meat to smaller portions.
• After having processed/modified the raw products packaging
usually follows.
• During modification and storage it is important to avoid
contamination with moulds and bacteria. This should be
controlled through application of GMP and HACCP principles.
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Food Chemical Safety - In the Shop or on
the Market
• The food product to be sold is usually put on display for the
consumers.
• The type of arrangement when on display has a great
influence on contamination possibilities and storage
conditions.
• In shops situated inside buildings with drain and cooling
facilities etc. the risk of contamination could be assumed to
always be less than in shops or markets where these facilities
are not present. However this assumption can be proven
wrong, if the storage and /or hygiene conditions are
insufficient.
• In e.g. open markets and small stalls along roads
contamination can occur from air, dust and lacking hygienic
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conditions etc.
Food Chemical Safety - The Consumers
Part
• After having bought a food item, it has to be
transported to where it is destined for consumption,
usually at home.
• Transportation requires packaging /containers (bags),
and food items without any packaging may come in
contact with the transportation media or with other
food or non-food items in the same bag.
• The conditions during transportation may influence
food safety (e.g. the weather, duration).
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Food Chemical Safety - The Consumer’s Part
(Cont’d)
• Handling by the consumer is yet another way of
possible contamination: hygienic considerations
(hands/cross contamination between raw products),
materials to come in contact with food and duration
and storage conditions.
• Preparation can add or produce further toxicants,
again materials in contact with food (e.g. Teflon
covered frying pans where the surface is incomplete)
or process toxins formed during heating
(premelanoidines, HAA’s, PAH’s (later ppt on process
toxins))
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In slaughter house
(consumer)
In shop after packaging
Before
preparation
Steak after
packaging
Steak After
slaughter
Bacteria and moulds
From packaging toxins
can be transferred
/handling
Final product
Steak for
consumption
At home
HygienicPreparation /
considerations
cooking
During preparation processtoxins can be formed
The Final Product
• The final product can contain many unintended compounds as a result of
having been through several steps in the manufacturing, distribution and
sales chain and the preparation / handling by the consumer
• Health hazards can thus originate from :
From storage: microbes
(present in the product can
produce toxins during
storage)
From storage: Chemicals
(packaging materials)
Steak
From processing and
handling (both microbes
and chemicals)
From the raw product
(Contamination during
production, pesticides, pollution,
drug residues, natural toxins in
i.e. some plants /plant products)
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Processing and Storage – Food Chemical Safety
Examples
• Lack of processing, or inefficient/faulty processing can lead to food
safety risks e.g. mycotoxins in dried raw materials that have not
been processed and stored properly according to GMP.
• Processing generally leads to safer products, but can lead to
formation or transfer of toxic substances. Examples include:
• Mechanical separation – sieving/floating used to separate toxic
schlerotia in grain contaminated with ergot
• Size reduction (cutting/milling) – used to lessen concentrations of
cyanogenic glycosides in cassava root.
• Thermal processing (grilling/frying/roasting) – can produce
mutagenic and carcinogenic compounds such as heterocyclic
aromatic amines.
• Contact equilibrium processes (extraction) – used to prevent
contaminations of certain legumes with lectins.
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Conclusion
What we have learned:
• Health-impairing chemical compounds may enter
food (plants, animals, fungi. Algae) at a number of
different points of the food production and
processing chain.
• For animal products, contamination can occur
from plant contaminants as well as inherent
natural toxic plant constituents from feedstuffs,
and also residues of veterinary chemicals.
• Food Production and Processing can make food
safer, but may also contribute to levels of toxic
substances.
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