Contaminants Produced During Processing - PowerPoint Presentation

Slide1

Contaminants Produced During Processing

Slide2

Acrylamide

What is

Acrylamide

?

Acrylamide

is a

synthetic vinyl compound

produced by the chemical industry mainly as a building block for various

polymers, particularly

polyacrylamide

.

Polyacrylamide

is widely used in various applications, such as:

in the treatment of wastewater

in paper processing

in mining and mineral production.

Acrylamide

is also

present in cigarette smoke

.

The wide use of

polyacrylamide

in industry means that

human exposure to

acrylamide

is probable

.

Slide3

Occurrence in Foods

The

possibility of

acrylamide

contamination of foods

did not become

widely known until 2002

, when a

report

from the

Swedish National Food Administration

was published.

This report revealed that

acrylamide

could be produced

in significant concentrations in

certain carbohydrate-rich foods

processed at relatively high temperatures

, such as:

fried potato (chips)

fried foods

Chocolate

Coffee

baked cereal products such as:

Biscuits

Bread

toasted breakfast cereals

Slide4

Acrylamide

is not confined to commercially processed foods

.

It can

also be found in home-baked food

.

Slide5

Slide6

Effects on Health

Acrylamide

is a

neurotoxin

at high levels of exposure and may cause a range of symptoms such as

numbness

in the hands and feet.

It has also been shown to be

genotoxic

in

animal

studies.

Of more concern to the food industry is the finding that

acrylamide

is also

carcinogenic

in animal studies.

The International Agency on Research on Cancer

(IARC) classifies it as ‘‘

probably carcinogenic

to humans

(IARC Group

2A

).’’

Slide7

Sources

The original Swedish report into

acrylamide

in food in 2002 indicated that the contaminant is produced as a result of

heating

certain foods, especially those containing high levels of

carbohydrate

, at

temperatures

above 120

0

C

.

It is therefore a contaminant generated during processing.

The

major mechanism for the formation of

acrylamide

during cooking

is now acknowledged to be:

the

reaction of the free amino acid

asparagine

with reducing sugars

,

such as

glucose

or

fructose

,

during the

Maillard

browning reactions

that occur during cooking at high temperatures

.

***

Asparagine

is a non-essential amino acid.

Slide8

The

key factors that affect the quantity of

acrylamide

produced appear to be;

amount of free

asparagine

present in the food

amount of sugars

present in the food

cooking time

cooking temperature

.

Slide9

Stability in Foods

The large amount of data collected from food surveys suggests that

acrylamide

is relatively

stable in food

, but this has not been widely studied to date.

Nevertheless,

acrylamide

levels

have been found:

not to decrease

significantly

in

crisps or baked cereal

products

during shelf life

decrease

significantly

in

roast and ground coffee

Slide10

Control Options

1-Product Formulation

One obvious strategy for the control of

acrylamide

formation is to

minimize the amount of free

asparagine

and reducing sugars

in food prior to cooking

.

The development of

low-

asparagine

varieties of potato

is one approach that is receiving attention.

The

modification of product recipes

also shows some promise. For example,

replacing ammonium bicarbonate with other raising agents

in baked products

can

reduce

acrylamide

formation significantly

,

as can a reduction in

pH

.

Slide11

2-Processing

The main factors that can be modified to

minimize

acrylamide

formation are

cooking time and temperature

.

The ‘‘thermal input’’ to a cooking process has been shown to be directly linked to the amount of

acrylamide

produced.

As a general rule,

higher thermal input results in higher levels

, with the

exception

of

coffee production

,

where

acrylamide

levels decrease with longer roasting times and ‘‘darker’’ roasts

.

Slide12

Reducing

acrylamide

by changing processing times and temperatures

results in a

compromise between product quality and safety.

Also,

frying at lower temperatures

may allow

foods to take up higher levels of fat

, which may be

undesirable from a nutritional point of view.

While this may be successful, it must be recognized that the

browning

of baked and fried foods is

an essential component in their sensory acceptability.

Slide13

Legislation

Acrylamide

is not yet covered specifically by legislation

in Europe or North America and no permitted limits have been set.

Slide14

Benzene

What is Benzene?

Benzene is an

aromatic hydrocarbon compound

used extensively in the chemical industry as an intermediate in the

manufacture of polymers

and other products.

It is also a

common atmospheric contaminant

and is present in

motor vehicle

exhaust emissions and

cigarette smoke

.

In

1990

, it was discovered by the US soft drinks industry that benzene could be produced at low levels in certain

soft drinks

containing a

benzoate preservative and ascorbic acid

.

Since benzene is a known human

carcinogen

, its presence in food and beverages is clearly undesirable.

Slide15

Occurrence in Foods

Detectable levels of benzene have been found in:

soft drinks

that contain either a

sodium or potassium benzoate preservative and ascorbic acid

‘‘diet’’-type products

containing

no added sugar

Slide16

Effects on Health

Although benzene can cause acute toxicity, especially when inhaled at high levels, it is its

carcinogenicity

that is of concern in foods and beverages.

Benzene is a proven

carcinogen

and has been shown to cause cancers in industrial workers exposed to high airborne levels.

Much less is known about its effects when ingested at low levels over long periods, but current risk assessments suggest that the contribution of soft drinks to benzene exposure levels is negligible, as is any additional risk to human health.

Slide17

Sources

It has been established that the

source of benzene in soft drinks

is the

decarboxylation

of benzoic acid

with

presence of

ascorbic acid

and trace amounts of a suitable

metal catalyst

(

copper

or

iron

).

Elevated temperature

and

light

are both reported to

stimulate this reaction

, whereas it is

inhibited

by

sugars

and by

salts of EDTA

.

This may be why

benzene

is most likely

to be found

in

diet drinks

containing

low sugar levels

.

Slide18

Stability in Foods

There is

little information

available on the stability of benzene in soft drinks during storage.

Slide19

Control Options

The

preferred approach

for controlling the production of benzene in soft drinks is to

reformulate the product

.

Once a specific soft-drink formulation has been shown to be capable of generating benzene during storage,

alternatives to benzoate preservatives

,

such as potassium

sorbate

, should be evaluated.

Benzene generation

may be effectively prevented by the

removal of benzoates from the product.

However, it should be noted that the majority of soft drinks containing benzoates and ascorbic acid have not been shown to produce benzene and may not need to be reformulated in this way.

Slide20

Legislation

Current US and European legislation does not set maximum limits for benzene in soft drinks.

However, the

FDA

has adopted the Environmental Protection Agency (EPA) maximum contaminant level (MCL) for

drinking water

of 5 parts per billion (ppb)

as a quality standard for bottled water.

This MCL has been used to evaluate the significance of benzene contamination in the soft drinks tested in recent surveys.

The

UK Food Standards Agency

has used the

World Health Organization (WHO) guideline

level for

benzene in

water

of 10 ppb

as a point of reference for its own survey results.

Slide21

Chloropropanols

What are

Chloropropanols

?

The

chloropropanols

are

a group of related chemical contaminants

that may be produced in certain foods during processing.

They

first became a concern to the food industry

in the late 1970s when small concentrations were found

to be generated during the manufacture of

acid-

hydrolysed

vegetable protein (acid-HVP)

used as a

savoury

ingredient

in:

Soups

Sauces

…

Chloropropanols

are potentially

carcinogenic

and their presence in food, even at low levels is therefore undesirable.

Slide22

Occurrence in Foods

The

highest levels of

chloropropanols

have been found in

acid-HVP

and in

soy sauce

and related products.

It is thought that the contaminant is usually produced during the manufacturing process, especially at high temperatures, but the

mechanism is not known

in all cases.

Slide23

Effects on Health

Although

chloropropanols

can cause

acute toxicity

at high concentrations

, it is extremely

unlikely

that this could occur through consumption of contaminated food

, and it is the effect of low doses over a long time that is of most concern from a food safety point of view.

Chloropropanols

have been shown to be

carcinogenic

in animal studies and are therefore potential human carcinogens.

Slide24

Sources

The

mechanism for

chloropropanol

production

in

acid-HVP

is known to be a

reaction

between hydrochloric acid (

HCl

) and lipids.

The reaction occurs

more rapidly at the high temperatures

used in processing.

In bread and other baked products

,

chloropropanols

are thought to be

formed

by a

reaction during the

baking process

between the chloride in added salt and glycerol from flour and yeast.

In other foods, the mechanisms of

chloropropanol

production are unclear.

Slide25

Stability in Foods

Chloropropanols

are relatively

non-volatile and may be quite

persistent in foods

once formed.

Slide26

Control Options

The control of

chloropropanols

in foods focuses on limiting their production during processing.

This has been achieved by a number of changes to the manufacturing process.

replacing acid hydrolysis with an enzymatic process

reducing lipid concentrations in the raw materials

effective control of the acid hydrolysis process

use of an over-

neutralisation

treatment with

NaOH

to

remove chlorohydrins

after acid hydrolysis

.

Slide27

Furan

What is Furan?

Furan is a

volatile heterocyclic organic chemical

often found as an intermediate in industrial processes for producing

synthetic polymer materials

.

It is a very different

compoud

from the diverse group of chemicals sometimes referred to collectively as

‘‘furans’’,

which

includes various antimicrobials (

nitrofurans

) and dioxin-like toxins

.

Concern over furan in foods dates back only to 2004

, when a Food and Drug Administration (

FDA

)

survey of heat-processed foods in the USA

revealed that

low levels of furan could be found in an unexpectedly large proportion of products processed in

closed containers

,

such as cans and jars

.

Furan is a possible human

carcinogen

, and therefore, even low levels in foods are undesirable.

Slide28

Occurrence in Foods

Detectable levels of furan have now been found in:

Coffee

Canned fruits

Juices

Canned vegetables

Ready-to-use gravies

Breakfast cereals

Canned beans

Soups

Sauces

…

Slide29

Effects on Health

Furan is

cytotoxic

and the

liver

is the

target organ

for acute toxic effects.

However, it is the effect of prolonged dietary exposure to furan and its

possible carcinogenic

potential

that is of concern for food safety.

For this reason, it has been classified by the

International Agency for Research on Cancer

(IARC) as ‘‘

possibly carcinogenic to humans

.’’

Slide30

Sources

It is thought probable that f

uran is a by-product of the high temperatures involved in the

heat processing of foods

,

but the means by which it is produced is not known.

Proposed sources of furan formation

include:

Thermal degradation

of

reducing sugars

alone, or in combination with

amino acids

Thermal degradation

of some

amino acids

Thermal oxidation

of

ascorbic acid

,

poly unsaturated fatty acids

and

carotenoids

The

presence of furan residues in canned foods

is probably a consequence of the

volatile compound

being trapped in the container

.

Slide31

Stability in Foods

There is little data as yet on the stability of furan in food, although

it is a highly volatile compound and is likely to be

driven off quite quickly if foods are :

“Cooked or reheated in open vessels”

Slide32

Legislation

As yet there is

no legislation limiting levels of furan

in foods.

Any future regulation will be based on the results of ongoing risk-analysis activities.

Slide33

Reference

:

Lawley

R., Curtis L. and Davis J. The food safety hazard guidebook. RSC Publishing.