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Food Additives: Safety and Limits of Use Food Additives: Safety and Limits of Use

Food Additives: Safety and Limits of Use - PowerPoint Presentation

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Food Additives: Safety and Limits of Use - PPT Presentation

Jasper K Imungi PhD Professor of Food Chemistry Department of Food Science Nutrition and Technology University of Nairobi Paper presented in the Food Additives and Safety Workshop 24th June 2014 Intercontinental Hotel Nairobi ID: 201702

food acid body additives acid food additives body products sodium levels foods include antioxidants weight sweet benzoic flavor times

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Slide1

Food Additives: Safety and Limits of Use

Jasper K. Imungi, PhD

Professor of Food Chemistry

Department of Food Science, Nutrition and Technology

University of Nairobi

Paper presented in the

Food Additives and Safety Workshop, 24th June, 2014 Intercontinental Hotel, NairobiSlide2

Introduction

All over the World food additives are perceived to be evil chemicals that will cause ill health in humans. They are referred to as “chemicals”

The tropical and subtropical countries can not afford to do without some additives like preservatives

The additives allowed for use in food have been subjected to scientific testing and have been found to be safe for use, nevertheless some with caution

There is no chemical that will fail to cause allergic reaction to all peoples of the World – remember the many people who are allergic to some of the foods we eatSlide3

Introduction cont’d

Categorized in two ways:

The manner in which they get into food

: 1) Intentional additives - considered ingredients in food processing/preparation; 2)Unintentional or inadvertent additives - from the environment of the food – contaminants

The manner in which they are used

: 1) Generally recognized as safe (have been in safe use for long) – require no testing before allowed for use, use can be regulated by consumer; Regulated food additives – maximum levels are given beyond which they might cause ill health

The list of grass currently stands at aboutb800 chemicals and is slowly growingSlide4

Introduction cont’d

The additives dealt with in this paper are the regulated that are in common usage, but are sometimes controversial. They include:

Preservatives including - benzoic

acid, sulfur dioxide, nitrites, and

antioxidants

Flavor potentiators - monosodium glutamate

(MSG)

nonnutritive sweeteners – cyclamates, saccharin,

glycyrrhizic

acid, aspartame

The presentation will be limited to the safety and limits of use of these chemicalsSlide5

Preservatives - antimicrobials

Benzoic acid

Occurs naturally in cranberries, prunes, cinnamon and cloves and in smaller amounts in the seeds of many fruits

Undissociated acid is the form with antimicrobial activity, optimum activity at pH 2.5 – 5.0

Suited for use in acid products such as fruit juices, carbonated beverages, pickled products and fermented products

Used at the level of 0.05 – 0.1% by weight, ADI = 0.5mg/kg body weight

Most active against yeasts and bacteria and least active against molds

eliminated from the body after conjugation with glycine (amino acid) to form hippuric acid (benzoyl glycine), precludes accumulation in the body

Caution: Persons with asthma,

or who have recurrent

urticaria

(skin rashes) may be sensitive to benzoic acid Slide6

Sulfur dioxide

Has long been used as a general food preservative

Forms used include sulfur dioxide gas, sodium or potassium salts of sulfite, bisulfite and metabisulfite

Forms sulfurous acid and bisulfite ion in solution

Undissociated acid

dominant below pH 3 and inhibits yeasts and bacteria, but not always to the same extent

Bisulfite ion dominant at

pH 4.5 and inhibits bacteria but not against yeasts

Levels of use to maximum 300ppm, but levels up to 2000ppm found in dehydrated fruits and vegetables. Levels beyond 500 ppm cause disagreeable flavor. ADI = 0.07mg/kg body weight

Suitable for acidic products like in benzoic acid

Also used against

enzymic

and non

enzymic

discoloration during handling, processing or storage

Cleared from the body by oxidation to sulfates – out with urine with no pathology

Caution: No use in infant foods, by asthmatic, kidney and liver impaired. Can cause allergic response in some people (looking like nettle rash, eczema)Slide7

Initially potassium and sodium salts of nitrates and nitrites to develop and fix pink color

Later found to generate carcinogenic nitrosamines, but then found to inhibit clostridium botulinum, organism that produces one of the most lethal toxins known to man (6 mcg kills man)

Accumulation in the liver can cause chronic toxicity (cancer)

Choice of continued use is a choice of the bigger risk, acute botulism or cancer

Maximum levels of use 150 – 200 ppm. ADI = 0 – 0.15mg/kg body weight

Nitrites can also bind the HB to impair blood transport in the body (detrimental specially to small children.

Nitrates wide spread in our vegetables such as spinach and carrots esp. those grown with high levels of fertilizer (Be aware of carrot juice esp. on children)Slide8

Antioxidants

Many antioxidants existing in nature include polyphenol compounds, carotenoids and tocopherols, also ascorbic acid. These mediate against diseases.

Important here are synthetic antioxidants that are used for preservation of fats and fatty foods against oxidation of fats to cause off-flavors

Some of the oxidation intermediate products have been known to be carcinogenic

The common antioxidants include

Butylated

hydroxy

anisole (BHA),

Butylated

hydroxy

toluine

(BHT), Propyl

gallate

(PG) and

Tert

-butyl hydroquinone (TBHQ)

Recommended maximum use 0.01% for single or similar amount of each if more than one are used. If with a

synagist

0.028, but antioxidant same level.

All polyphenol compounds are implicated in carcinogenesis

The ADI: Propyl

gallate

0 – 0.5mg, BHA 0 – 0.5mg, BHT 0.05, but ascorbic acid 300mg/kg body weight

Slide9

Common antioxidantsSlide10

Flavor potentiators – Monosodium glutamate (MSG)

Flavor potentiators – substances with little or no

flavour

but enhance desirable flavors or depress undesirable flavors in food

Commonly used

flavour

potentiators are MSG and some 5’-nucleotides

MSG is a derivative of the amino acid glutamic acid by neutralization of one carboxyl group only.

Abudant

in many foods esp. wheat and maize gluten, soybean protein and casein

Used in levels of 2 – 5g/kg of food. Taste threshold 300mg/liter

Manufactured by fermentation, chemical process or extraction from plant or animal tissues, mainly by AJINOMOTO in Japan. Known by the name in the Kenyan markets.

Local products containing it include

aromat

, cooking mixes, beef and chicken cubes and soups and sauces

Judicious use causes Chinese restaurant syndrome (CRS) – characterized by

headaches, facial pressure, chest pains, gastric distress, and burning sensations over various parts of the body.

Clearance from the body is the normal way of glutamic acidSlide11

Non-nutritive sweeteners

Broad

group of substances that have been found to evoke a sweet taste or enhance the perception of sweet taste. They do not yield calories

on m

etabolism. Their use is regulated by the consumer taste. Include:

Sodium cyclamate (sodium cyclohexane

sulfamate

):

also

available as

calcium cyclamate. Burned for use in many countries including Kenya. Metabolizes into

cyclohexylamine

which is a known carcinogen.

Exposes the bladder to cancer.

Sodium saccharin (sodium

ortho-benzosulfimide

):

M

ost

commonly available sweetener,

sold simply as saccharin

,

300

times sweeter than

sucrose. Allowed in Kenya only for dietetic products (Is it so? – sold freely). Many imported products contain saccharin – evidence of use in manufacturing in the country.

Glycyrrhizic

acid:

Natural sweet-tasting substance found in the licorice root as calcium and sodium salts of

glycyrrhizic

acid .

50 times as sweet as sucrose. mainly

used in

tobacco. Slide12

Non-nutritive sweeteners cont’d

Substances structurally related to

glycyrrhizic

acid have recently been discovered. The most important is

stevioside

,

found

in the leaves of

Stevia

rebaudiana

Bertoni

. I

t

is 300 times as sweet as sucrose.

Stevioside

is available in the market in this country under the name

SteviaAspartame (aspartylphenylalanine methyl ester): A dipeptide and therefore not to be categorized as non-nutritive. About 200 times sweeter than sucrose. Use may be limited because it lacks stability in food systems especially during storage. The amide-linked amino acids and the methyl ester are potentially labile to both chemicals and microbiological

attackSlide13

In conclusion

Many products local or imported contain food additives. It is difficult to validate good manufacturing use of additives in this country

Food additives are a necessary evil and in the tropical and subtropical countries we have to learn to live utilizing them cautiously

In consuming/or preparation of food with specific additives, know yourself and members of your family

Consume foods processed with food additives in moderation (this applies more to the children)

Read the label of a processed food before purchase, it could contain a chemical that you or your family member could be sensitive to.

Eat from a variety of foods, both fresh an processedSlide14

THANK YOU VERY MUCH

You are what you eat