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Allergens

Allergens are chemical substances that in very small amounts may cause a severe reaction in susceptible individuals.  An allergy is an over-reaction (hypersensitivity) disorder of the immune system when it comes into contact with an allergen.

Allergen reactions involve excessive activation of white blood cells called ‘mast cells’ and ‘basophils’ by IgE antibodies, causing an extreme inflammatory and nervous system response.

Persons suffering from an allergy or suspect that they have allergic symptoms can be ‘allergen tested’ by an immunologist.  Initial testing is usually a ‘scratch test’, where a series of standard allergens are tested for by scratching small quantities into the surface skin on the forearm and measuring inflammation response.  Blood tests can identify the presence and levels of allergen-specific IgE antibodies.  It is important to correctly identify the allergen to enable treatment and management strategies.

Allergen treatment

Treatment for allergy sufferers include allergen avoidance, use of medications such as histamine antagonists (antihistamines) and steroids or specific immunotherapy to desensitise the response to the allergen. Steroids such as hydrocortisone and prednisolone control the overall immune system response whereas histamine antagonists suppress the histamine-induced swelling and flare responses.

In emergency situations where respiratory distress symptoms occur, allergen sufferers may need to self-administer an ‘Epi-Pen’ injection (or equivalent device) to prevent or treat ‘anaphylaxis’.  Anaphylaxis is a severe whole-body shock reaction to an allergen that may result in death through loss of blood pressure, breathing difficulties and organ failure.  Epi-Pen devices deliver an intramuscular dose (300ug) of epinephrine that increases heart rate, constricts blood vessels and dilates air passages.

Food intolerance

Food intolerance is not the same as a food allergen.  Food intolerance is a negative and often delayed response to a food, beverage, food additive or other substance in food.  A food intolerance does not activate an IgE antibody-mediated immune response to the food substance.  Food intolerance may arise from the absence of specific chemicals or enzymes needed to digest the food or the body’s inability to absorb compounds in the food. Food intolerance is a term applied to all negative non-allergy responses to food.

Coeliac disease is an autoimmune disorder of the small intestine that can occur in genetically predisposed people of all ages.  It is caused by a reaction to gliadin (gluten protein) found in many cereals.  Exposure to gliadin activates an enzyme to modify the protein which then cross-reacts with the small-bowel tissue to cause inflammation. This interferes with the ability to absorb nutrients and causes symptoms such as diarrohea, abdominal pain, abdominal distention and irritable bowel syndrome. It may also lead to lactose intolerance. While Coeliac disease is caused by a reaction to wheat proteins, it is not the same as a wheat allergy.

Food allergens

Food allergen reactions vary and affect only a small percentage of the population.  Most of the population can eat the same foods with no negative effects.

It is estimated that 1-2% of adults and 4-8% of children are affected by a true food allergy.  The discrepancy in adult and child populations affected by allergies is explained by some of the more common childhood allergies (e.g. milk, eggs) declining beyond 5-7 years of age.

Allergic reactions to foods may include:

  1. skin reactions - hives, itching, dermatitis and eczema

  2. gastrointestinal reactions - nausea, vomiting diarrhoea and abdominal cramping

  3. respiratory reactions - rhinitis, throat swelling, asthma (rare in food allergies)

  4. anaphylaxis - loss of blood pressure / consciousness, organ failure, heart arythmia, death

The food groups that are responsible for approximately 90% of all food allergy reactions are:

  1. cereals containing gluten and their products, namely wheat, rye, barley, oats, spelt and their hybridized strains other than where these substances are present in beer and spirits

  2. crustacea and their products

  3. eggs and egg products

  4. fish and fish products

  5. peanuts and soybeans and their products

  6. milk and milk products

  7. tree nuts and sesame seeds and their products

  8. added sulphites in concentrations of 10mg/kg or more

Food allergen management

The only successful strategy for the food allergen sufferer is the avoidance of foods containing the allergen.  Food allergen sufferers are restricted with their processed food choices and need to study food labels and scrutinise ingredient lists.  Food may also cost more as many generic products and house branded foods are poorly labelled with ‘may contain’ allergen statements that are of little help.

Chemical toxins

Sulphites in concentrations of 10mg/kg or more must be identified on labelling or in the absence of labelling displayed on or in connection with the display of the food or provided to the purchaser on request. 

An important issue relevant to the fresh produce industry is the use of sulphur dioxide (SO2) pads in packed / stored grapes.  The pads are designed to slowly release SO2 gas in the high humidity atmosphere within the plastic-lined package to control fungal spoilage organisms that often affect stored grapes.

The pads are removed before presentation for sale, but occasionally pads might break and suplhites directly contact the grapes. New generation packaging that uses thin films impregnated with SO2 will minimise this risk.

Asthmatics have been known to be particularly sensitive to SO2.  The best strategy is to use a clearly visible printed warning statement e.g.  “Preservative 220 in use” as per Australian labelling laws.

Food industry risk management

Risk management and mandatory product labelling for the key food allergens have become critical food safety matters for businesses in the food industry.

Standard 1.2.3 of the Australia New Zealand Food Standards Code requires a mandatory declaration for all the main food allergens and their products (listed above) that may cause an allergenic reaction, even if these products are ingredients or processing aids.  However, there is no current legal requirement for mandatory declarations in the event of unintended cross contamination.

Guidelines and tools to assist food producers to comply with the Australia New Zealand Food Standards Code and minimise the risk of unintentional consumption of allergenic products include:

  1. Food Industry Guide to Allergen Management and Labelling, 2007 (Australian Food and Grocery Council www.afgc.org.au)

  2. Voluntary Incidental Trace Allergen Labelling (VITAL) (Allergen Bureau) www.allergenbureau.net)

VITAL is a tool developed by the Allergen Bureau that allows food producers to assess the impact of allergen cross contact and provide appropriate precautionary labelling on their products.  It includes a decision tree that can assist a business in understanding when labelling is required.

In the fresh produce sector the risk of contaminating produce by cross contact is low, but must be considered.  Cross contact is when a residue or other trace of an allergenic substance is unintentionally added to a food not intended to contain that allergenic substance.  Examples include:

  1. fruit, vegetable or nut in shell waxes containing soy, casein (milk protein), peanut or sesame

  2. use of tree nut waste materials as mulch on vegetable crops

  3. peanuts or peanut shells in growing site

  4. packing nuts in facilities used to pack other produce

Latex allergy

There are allegations that latex glove use in food handling may cause consumer reactions in latex allergy sufferers.  Estimates for latex allergy sufferers range anywhere between 0.8-8.2% of the population, depending on the literature source.  Reported rates of latex allergy are higher in those industries and populations where exposure levels are higher.

The campaign to eradicate latex gloves from food handling is driven primarily by the Latex Allergy Support Group (LASG) UK that have been lobbying large UK supermarket chains to ban the use of latex gloves in food preparation.  The LASG allege that the use of latex gloves in food preparation may explain some of the unexplained cases of allergic responses to foods.  

The latex allergens are proteins from the sap of the rubber tree (Hevea Brasiliensis).  Most soft latex/rubber (stretchable) products have not undergone vulcanisation. Temperature and pressure during vulcanisation change the original protein structure and bonding.  Non-vulcanised rubber products remain potential sources of the allergy-causing protein.

Latex allergy sufferers may be allergic to many products that contain natural rubber latex e.g. rubber gloves, elastic bands, balloons, nipples on baby bottles, shoes, car parts and clothing containing natural rubber elastic.  Allergic responses may range from contact dermatitis to anaphylaxis.  A potential pathway for latex allergen contact or ingestion from food is via dust from food preparation workers putting on and taking off latex gloves – cornstarch inside the gloves may be contaminated with natural latex proteins and the dust residue may be on the food surface.

There is published research supporting workplace dermatological and inhalation sensitisation effects in occupations where latex gloves and other products are commonly used (such as the medical professions) but there are no studies demonstrating that fresh food handled using latex gloves has caused latex allergy responses.

The issue is further complicated by the ‘Latex-Fruit Syndrome’.  This refers to the cross-reactivity of many latex allergy sufferers with many different types of fruits and vegetable.  Cross-reactivity also occurs with pollen and some medicinal plants. The cross-reactivity is caused by the high conservation across plant species (plus mushrooms) for several types of proteins involved in plant self-defence.  Their presence and concentration in produce may vary, governed by variety and stress responses to pest, disease and environmental growing conditions.

Reported estimates for latex allergy cross-reactivity with fruits and vegetables range between 40-70%. Cooking (heating) fruits and vegetables denatures the proteins and enables cross-reactive latex allergy sufferers to consume these products safely.

Uncertainty also remains in the published literature as to the initial cause of sensitisation – exposure to latex or exposure to fruits and vegetables.

Latex alternatives include synthetic elastics such as elastane and neoprene or modification of the rubber manufacturing process with chemical treatments that produce materials such as ‘Vytex’.

answers to some frequently asked questions about Allergens


to find out more             - simply click on the icon links on these pages or click on the documents to download the files

Epinephrine is also known as ‘adrenaline’ - it is a hormone and neurotransmitter affecting the sympathetic nervous system

Epi-Pen

go to VITAL website

Allergens_files/AFGC%20Allergen%20Guide.pdf

AFGC Allergen Guide

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‘Vulcanisation’ is the process of hardening and cross-linking the long chain polymers in latex using high temperature and pressure

- named after Vulcan, the Roman god of fire

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