Food matrix and processing on allergenic activity

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Overviews
Development of Food Processing
Processing induced Modification
Impact of Processing on Food Allergens
Clinical Implication

Overviews
Food processing:
• Modulate allergic reaction(sensitization)
• Processing affects by
– altering their shape, molecular weight and structural
– modulating immunoglobulin E-binding capacity (changing
IgE reactivity) lead to mediator releases.

• Sites on molecule recognized by IgE are called
“epitopes”

Epitopes
• short regions(8 to 15 amino) residues,
• tend to be mobile,
• adopt a disordered secondary structure,
• be stable in food processing.

• various segments of polypeptide chain
and brought together by protein folding,
• food processing affect in folded and
destroy conformational epitopes
• found in unprocessed or raw foods or
reveal new epitopes previously hidden by
protein folding.

Middleton’s Allergy: Principles and Practice 8th Edition

Effects of thermal processing on allergenicity is difficult;
• the time-temperature combinations used in food processing,
• the impact of water activity on the stability of individual
allergens to thermal,
• the different methods employed to determine allergenic
activity.
Allergen
Cow’s milk

Reactivity
raw, pasteurized, or UHT

Safety
extensively heated
e.g., baked products such as
muffins or cakes

* Baking modifies the proteins much more than pasteurization.
Hen’s egg
Peanut

raw, boiling

extensively heated
e.g., roasted and fried

* Cooking usually reduces but does not abolish the allergenic potency of egg.
** Maillard reaction introduced by roasting.

Classification of Allergens
Allergen

Source

Protein molecules

Products

Cupins

plant

• Vicilin-like 7S seed
storage globulins
• Legumin-like 11S
seed storage globulins

legumes (e.g., soybean, peanut, lupin),
tree nuts (e.g., hazelnut, walnut, cashew,
pecan, almond),
seeds (e.g., sesame, mustard).

Prolamin
superfamily
(three group of
proteins)

skeleton of
cysteine
residues.

• 2S albumins
• Lipid-transfer
proteins (LTPs)
• Cereal α-amylase
inhibitors

fresh fruits (e.g., apple, kiwi, peach)
seeds (e.g., peanut, tree nut, sesame)
wheat (monocotyledonous plants) and cereals
(e.g., barley)

Bet v 1
superfamily

fruit

• Bet v 1 homolog
• Gly m 4, Api g 1

apple-Birch pollen (oral allergy syndrome)
soy bean, celery splice

Tropomyosin

shellfish
species

• Met e 1

crustacean and molluscan, greasy back shrimp

Parvalbumin

muscle fish

• apo and holo form

white muscle fish

Caseins

mammalian
milk

• phosphoserine
• phosphothreonine

milk

Others:
-Lipocalins
-β-lactoglobulin
-ovomucoid and
ovalbumin

• Bos d 5
• Gal d 1 and Gal d 2

inhalant allergen
cow’s milk
eggs

• The ability of humans to make
and control fire, which began about
125,000 years ago
• Variety to cook foods including
using heated stones for boiling,
burying food wrapped in leaves in
the hot embers of fires, or baking
fish in clay
• Advent of urban living need to
preserve foods after the harvest
• In the twenty-first century, when
most of the world’s population live
in cities


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Post-harvest treatments
Primary processing
Secondary processing
Complex foods

Nature of Processing
Modified atmosphere for storage of fruit and vegetables
such as cooling, cleaning, sorting and packing
Source: Apple
Impact of Processing
Bet v 1 homologs is upregulated during storage,
levels are higher in fruit stored for 4-5 months
LTP allergens is downregulated during storage
levels are higher in fresh fruit


Primary processing
Removal of outer layers by physical or chemical peeling
Source: Peach
Loss of allergens such as LTPs located in the outer layers



Source


Fruit purees and fresh
juices

Peach,
apple

Labile Bet v 1 homologs are modified.
Prolamin superfamily fruit LTPs retain a native-like
structure.

Preparation of
pasteurized, UHT fruit
juices and milk

Peach,
apple,

Labile Bet v 1 homologs are modified.
Prolamin superfamily fruit LTPs retain a native-like
structure.
Milk allergens retain their native structure.

milk
Boiling
- Maize, lentil, fish,
milk, egg

Wheat,
peanut

Prolamin superfamily LTPs and 2S albumin retain a
native-like structure after boiling, although seeds are
boiled, much of the protein is lost into cooking water.
Alters, the structure of cupin allergens (7S and 11S seed
storage proteins) and can render them insoluble.

Roasting and frying

Peanut

Thermostable, notably prolamin superfamily
2S albumin retain their native structure and solubility
after roasting and frying.
Some cupin allergens (7S and 11S seed storage proteins)
are altered by roasting and become insoluble.
Maillard modification


Source


Preparation of
powdered ingredients

Celery
spice,
milk

Maillard modifications

Deamidation

Gluten

Acidic conditions

Hydrolyzed food
ingredients

Milk, egg, Enzymatic (usually microbial proteases) and chemical
gluten
treatments used to hydrolyze protein ingredients to
change their functional properties

Oil refining

Soybean,
peanut

Proteins are removed during the refining process, and
residual protein levels in highly refined oils are very low.


Complex foods

Source


Fining agents added to
alcoholic beverages

Beer,
wine,
spirits

Certain beverages contain residual levels of fining
agents, usually are highly modified compared with the
raw

Fermented foods

Milk,
soybean

Lactic acid fermentations, to unfold protein and
precipitate or form gelled networks due to reduced pH.
Secrete proteases that can hydrolyze proteins.

Baked foods

Milk, eggs Food ingredients may be included that are raw or have
already been processed (e.g., skimmed milk powder,
pasteurized egg white).
Complex interactions between different food
ingredients


Novel processing techniques
Pulsed electric field and ohmic heating processes
• to preserve more of the natural flavor, texture, and
nutritional quality of foods and
• to address issues of sustainable food production and
energy cost reduction.


Processing-induced Modification
Heating processes(thermal processing)
Process of structural and chemical changes such as denaturation, aggregation and the
Maillard reaction, impacts on allergenicity of protein

Glycation reaction
Conjugation with reducing sugars through Maillard reaction, effect improving functional
properties and masking food protein allergenicity. New epitopes emerged as hydrophobic

High pressure
Processing structural changes, such as denaturation and aggregates, also influence in
allergenic potential. But application of high pressure during enzymatic hydrolysis more
effectively reduce antigenicity and serum IgE-binding properties

Enzymatic hydrolysis
Proteolytic enzyme in animal, plant and organism destroy allergenic epitopes, by hydrolysis
broken down into small peptide molecules and amino acids

Lactic acid fermentation
Proteolytic enzyme during fermentation by lactic acid bacteria(probiotic bacteria) break
some epitopes and partial degradation IgE-epitope
Guanhao Bu. Dairy Sci. & Technol. (2013) 93:211–223

Denaturation and Aggregation

Food processing conditions;
• high temperature
• extremes of pH on structure
• aggregation

Native, secondary structure
elements such as
• α-helices and β-sheets (blue)
• disordered polypeptide segments
(pink)
• intermediate structures with
residual (black)


Maillard modification
Chemical reaction of
amino acid + reducing
sugar
• requiring heat

Carbonyl group +
nucleophilic amino acid

Glucosylamine and
water formation
• BUT unstable

Form a complex mixture
• NEW flavor + odors

Impact of Processing on Food Allergens
A consequence of complexity and diversity of food composition and processing

Proteins in raw foods and ingredients,
• To transformed into carry new adducts(e.g.sugars)
and behave different in digestion
• To affected the way in food proteins are presented to
immune system(antibody responses, food-specific
IgE-binding affected by the conformational state of
molecule )


Food Allergens and Clinical Implications
Classification of these allergens into protein families provides a
framework for examining various aspects of food,
Common structural attributes such as;
• CUPINS,
• PROLAMIN SUPERFAMILY,
• BET V 1 SUPERFAMILY,
• TROPOMYOSINS,
• PARVALBUMINS,
• CASEINS,
• and others: Lipocalins, β-lactoglobulin(Bos d 5),
Ovomucoid(Gal d 1) and Ovalbumin(Gal d 2)

CUPINS
• Share core β-barrel motif in cupin superfamily
– vicilin-like 7S seed(e.g. Ara h 1) and legumin-like 11S seed
storage globulins

• Range of important allergenic foods including;
– legumes(e.g. soybean, peanut, lupin), tree nuts(e.g.
hazelnut, walnut, cashew, pecan, almond), and other seeds
(e.g., sesame, mustard)

• Prone to aggregate formation after heating or
solutions of extreme pH and low ionic strength.


Aim: To investigated the effect of thermal treatment on allergen
structure and IgE-binding capacity, potency to histamine release
and ability to induce T-cell proliferation and cytokine production
from peanut allergic patients.
Patient

35 pts: challenge with Ara h 1 purified from
either raw (N-Ara h 1) or roasted (R-Ara h 1)

Intervention

To observed structure, IgE immunoreactivity,
mediator release assay and cytokine production

Primary outcome

To determined factors affect the allergenic
properties of a major peanut allergen, Ara h 1.

Fany Blanc. Mol Nutr Food Res. 2011(55):1887–1894

Figure1. Characterization of heat-treated Ara h 1 by SDS-PAGE analysis

Boiling(H-Ara h 1) resulted in aggregation and hydrolysis of Ara h 1
• Boiling, alone or with of glucose caused a partial loss of secondary structure
• Roasted peanuts (R-Ara h 1) appeared to be highly denatured

Figure 4. IgE-binding capacity of native and heat-treated Ara h 1.
Native-Ara h 1

Heated Ara h 1

Boiled H- and G-Ara h 1 had greatly
reduced IgE-binding capacities for all pts
•Boiling resulted in either a very slight
native-Ara h 1 or more marked heated
Ara h 1 reduction in IgE-binding.
• Increase in IC50 values for H-Ara h 1 and
G-Ara h 1, significantly less IgE reactive.

Figure5. Effect of thermal treatment on b-hexosaminidase
and proliferating cells and cytokine induction capacity

b-hexosaminidase

IL-5

IL-13

• Boiling Ara h 1(100oc 15min) form complex aggregates resulted in
partial loss secondary structure and reduced IgE-binding capacity.
• The aggregates also reduced capacity to elicit histamine release and
potential reduced allergenic potency.

Aim: To establish the effect of thermal treatment mimicking the
roasting process on the allergenicity of Ara h 1 and a mix of 2S
albumins from peanut(Ara h 2/6)
Patient

12 peanut-allergic pts: purified Ara h 1 and Ara h
2/6, observed after native and roasting ingestion

Intervention

To assess the structure, IgE binding fragments
and degranulation capacities

Primary outcome

To observed roasting process(Ara h 1 and Ara h
2/6 peanut) changes to affect their allergenicity

Y.M. Vissers. Clinical&Experimental Allergy. 41:1631–1642

Fig. 1. SDS-PAGE and Western blot of the native and thermally processed Ara h 1 and Ara h 2/6
Ara h 1

Ara h 2/6

Both Residual soluble Ara h 1, Ara h 2/6 that heating had significant hydrolysis of protein

Fig.4 Analysis of IC50(ng/mL)values obtained using IgE capture inhibition assay

• Increase of the IC50 value corresponds to decrease in IgE-binding capacity.
• IgE-binding capacity of R+g and R-g Ara h 1,decreased 9000- and 3.6-fold,
compared with native Ara h 1

Histamine release (ng/mL)

Extensive heating reduced the degranulation capacity of Ara h 2/6
but significantly increased the degranulation capacity of Ara h 1

Percentage of b-hexosaminidase release


PROLAMIN SUPERFAMILY
• Several groups of proteins, conserved skeleton of
cysteine residues by presence of a-helical globular
domain
• 3 major proteins as: 2S albumins, Lipid-transfer
proteins (LTPs) and Cereal α-amylase inhibitors
• Others as hydrophobic protein(Gly m 1, soybean),
Indolines(wheat) and alpha-globulins(cereal grains)
• Theirs stability to heat and gastrointestinal digestion


• 3 majors group of proteins
– 2S albumins, a low-molecular-weight major of seed
storage proteins of dicotyledonous plants such as Sin a 1
from yellow mustard, Ara h2 and Ara h 6 from peanut
– Cereal α-amylase inhibitors, structurally similar to LTPs
and 2S albumins, storage protein in seeds of wheat, barley,
rye, corn and rice of inhibitors trypsin and α-amylase


Lipid-transfer proteins (LTPs), a disulfide bonds to mediate
phospholipid between vesicles and membranes
– High concentration in epidermal tissue of Rosaceae family
in fresh fruits and vegetables
– Apple(Mal d 3) is greatest soon after picking, but it tends to
decrease during postharvest storage in a modified atmosphere.
(Sancho AI, et al. J Agric Food Chem 2006;54:5098-104)

– Peach(rPru p 3) is removed of outer layers, such as peeling,
significantly reduces the potential for an allergic reaction.
(Fernandez-R.M., et al. Clin Exp Allergy 1999;29:1239-47)


Aim: to study the effect of heat-induced structural changes on
allergenicity of 2S albumins, N-Ara h 2/6 was then further heated
for 15 minutes at 110uC in the presence or absence of glucose.
Patient

34 peanut-allergic pts: observed after heating
and glycation treatments of 2S albumins(Ara h
2/6) peanut ingestion.

Methods

To assessed cellular proliferative potency and IgE
reactivity and functionality of allergens

Primary outcome

To evaluated effect of processing on structure
and IgE reactivity/functionality of peanut
protein.

Yvonne M.V. PLoS ONE/journal.pone. 2011:6(8)

Figure1. Effect of heating on secondary structure and oligomeric state of Ara h 2/6.


Effect of thermal treatment on the IgE
binding capacity of Ara h 2/6.

Effect of thermal treatment on activation of
effector cells induced by Ara h 2/6

No effect on T-cell reactivity via heat induced denaturation, reduced IgE
reactivity and subsequent functionality of Ara h 2/6.
Conversely, Ara h 2 and 6 purified from roasted peanut retained the structure
and IgE reactivity/functionality of the native protein.


BET V 1 SUPERFAMILY
• Major birch pollen allergen, relevant sensitizing protein
causing called ‘birch-fruit-vegetable syndrome’
• Belongs to related protein family 10(PR-10)such as
– fruits of Rosaceae (Mal d 1 in apple, Pru a 1 in cherry, and Pyr c 1 in
pear)
– vegetables of Apiaceae (Api g 1 in celery and Dau c 1 in carrot)
– Hazelnut(Cor a 1.04), soybean(Gly m 4), mungbean(Vig r 1) and
peanut (Ara h 8)

• Reactions confined to the oropharynx in termed of ‘oral
allergy syndrome(OAS)’ and occasionally systemic reactions.


Aim: To evaluate whether cooked Bet v 1–related food allergens
induce IgE- and T cell–mediated reactions in vitro and in vivo
Patient

Patients birch pollen allergy who experienced
OAS and AD on ingestion of fresh apple, celery,
or carrot

Intervention

To determined protein structures, mediator
release, Bet v 1–specific T-cell lines with epitope
specificity compared native and cooked food
allergens.

Primary outcome

To evaluated T-cell epitopes of Bet v 1 were
relevant for cross-reactivity with each food
allergen. And conformational changes, resulting
in diminished IgE-binding capacity not structure
Bohle et al. J Allergy Clin Immunol 2006;118:242-9

Bet v 1 and Api g 1 partly restored structure, but Mal d 1 and Dau c 1 did not

• Incubation at 40C hardly reduced basophil activation by all allergens
• At 60C reduced the mediator-releasing capacity of Api g 1 completely and to a lesser
extent the capacity of Bet v 1, Mal d 1, and Dau c 1.
• at 80C and 100C abolished their mediator-releasing capacity.
In vitro, cooked food allergens lost the capacity to bind IgE and to induce mediator
release but had the same potency to activate Bet v 1–specific T cells as native proteins.
In vivo, ingestion of cooked birch pollen–related foods did not induce OAS but caused
atopic eczema to worsen.

Aim: To determined information about the allergenicity of
processed celery in celery-allergic patients
Patient

12 pts with allergic reactions to raw or raw and
cooked celery, DBPCFCs with raw celery, cooked
celery and celery spice

Intervention

To performed thermal stability of celery allergen
and mediator release assay to assessed
allerginicity of processes

Primary outcome

To assess the allergenicity of processed celery by
cooked celery and celery spice

B.K. Ballmer-Weber. Allergy 2002:57:228–235

Thermal stability of celery by EAST inhibition

• Monosensitized to celery allergen, Api
g 1, almost complete inhibition
• shortest heating period decrease of
inhibition potency of celery

RBL cell mediator release assay.

• IgE raised against raw celery reacted
with Api g 1, the major celery allergen
• But, IgE-heated celery did not react
with Api g 1

B.K. Ballmer-Weber. Allergy 2002:57:228–235

TROPOMYOSINS
• Allergen from crustacean and molluscan shellfish
• α-helical structural protein in both muscle and
nonmuscle cells, highly conserved across kingdom.
• Greasy back shrimp (Met e 1) is the major heatstable allergen in many crustacean species.


Aim: To detected shellfish-derived tropomyosin range of
crustacean and mollusc species and to analysed impact of heatprocessing on antibody recognition for improved allergen.
Patient

Fresh or frozen specimens of 11 different
crustacean and 7 mollusc species

Intervention

To determined protein profile of shellfish in raw
and heated extracts and effect of heat treatment

Primary outcome

S.D.Kamath et al. Food Chemistry 141(2013);4031–4039

• The heated-shellfish displayed a more protein-banding pattern.
• The heated-crustacean signified of heat-stable proteins.
But the heated-mollusc have different intensities.


Fig. 4. Inhibition-ELISA for the quantitative analysis of cross-reactivity of the mAb
• Lobster and crab heated
were able to inhibit
reactivity in a dosedependent
• Molluscs heated were not
able to achieve any inhibit,
even concentration.
Cross-reactive tropomyosin was detected in crustacean species, with partial
in detect in molluscs but none in oyster, octopus and squid.
Heating has a profound effect on major shellfish allergen tropomyosin,
targetting N-terminal region of tropomyosin, must be developed to
differentiate in crustaceans and molluscs


PARVALBUMINS
• major allergen found in the white muscle of fish.
• apo form reduced IgE-binding capacity, lacks the
calcium ions found in the holo form
• Thermal processing usually reduces but does not
abolish the allergenic activity of fish


Aim: To investigate the effect of glycosylation on the digestibility
and IgE-binding of codfish parvalbumin
Patient

21 pts: positive history of immediate-type
hypersensitivity reactions to fish, with specific
IgE >5 kU/L

Intervention

Native and glycosylated parvalbumins at various
conditions were analysed for apparent
molecular weight and IgE-binding

Primary outcome

To investigated result of thermal treatment on
the digestibility and IgE-binding of codfish
parvalbumin

Harmen H.J. BioMed Research International. Volume 2013,10:756-789

Figure 3: Secondary structure content of different forms of parvalbumin

• The difference in intensity is slightly difference in protein concentration.
• Native parvalbumin is structurally sensitive to low pH conditions, while
glycosylation provides some protection against such sensitivity.

• Glycosylation of parvalbumin,
formation of higher structures,
are more potent IgE- binders than
native

Fish allergen can potentially lead to increased allergenicity, even while the
protein’s digestibility is not affected by such processing.

CASEINS
• A mammalian milk proteins with a loose tertiary,
highly hydrated structure.
• To possess clusters of phosphoserine and
phosphothreonine residues that bind amorphous
calcium phosphate


Aim: To compare the allergenicity of caseins(CSN) and whey
proteins(WP) of thermally processed cow and buffalo milk
Patient

3-4 wks-old male mice were sensitised by CSN or
WP from cow or buffalo milk then obtained raw
and different thermal processed milk

Intervention

To assessed humoral response(IgG, IgE level) and
splenocyte stimulation index.

Primary outcome

To determined boiling and sterilisation of cow
and buffalo milk may be affect the allergenicity

Umesh K.S. J SciFoodAgric 2013; 93:2287–2292

Relative percentage change in allergenicity of cow’s and buffalo’s milk
compared to raw milk with respect to milk protein-specific IgE response.

The boiling and sterilisation of milk clearly affect the allergenicity by
decreasing humoral and cell-mediated responses.
CSN and WP of sterilised milk are less allergenic than raw milk.

Others ALLERGEN FAMILIES
• Inhalant allergens: Lipocalins
• Cow’s milk protein: β-lactoglobulin(Bos d 5)
• Egg white proteins: ovomucoid(Gal d 1) and
ovalbumin(Gal d 2).


Clinical Implications
Individuals with birch pollen–related fruit allergies may tolerate freshly picked but not
stored fruit.
Individuals may experience reverse symptoms, although severity of LTP allergies may
completely preclude consumption of problem fruit
Primary processing
Peeling fruits can make them safe for consumption by certain individuals with LTP
allergies.
Complex foods


Primary processing
Fruit purees and fresh juices
Individuals Bet v 1–related fruit allergies usually can consume pureed fruit products.
These foods can still trigger reactions in individuals with LTP fruit allergies.
Preparation of pasteurized, UHT fruit juices and milk
Individuals Bet v 1–related fruit allergies usually can consume UHT-processed fruit
products.
Processing is insufficient to make UHT juices safe for individuals with LTP fruit allergies.
The allergenic potential of UHT milk resembles that of pasteurized and raw milk.
Boiling
Boiling seeds and milk reduces their allergenicity but does not abolish it.
For some foods (e.g., polenta), the extent of cooking affects the residual level of
allergenic activity
Complex foods

Primary processing
Roasting and frying
The major peanut 2S albumin allergens retain their allergenic activity, explaining why
roasted peanuts possess significant allergenic activity.
Allergenic activity of the 7S and 11S globulins is retained to some extent after roasting.
Maillard modifications may further contribute to the allergenic activity of roasted
peanuts.
Preparation of powdered ingredients
Powdered food ingredients have allergenic activity similar to unprocessed foods and
can promote trigger reactions when included in recipes or through cross-contact in
other foods (e.g., residual milk powder in foods otherwise free from milk).
Complex foods


Primary processing
Deamidation
Induces formation of novel IgE epitopes through glutamine deamidation, which results
in individuals reacting to foods prepared with deamidated gluten ingredients who can
otherwise safely consume wheat flour–containing foods.
Hydrolyzed food ingredients
Hydrolysis reduces IgE reactivity but does not abolish it completely
Oil refining
In the EU, highly refined soybean oils are considered safe for consumption
Highly refined peanut oils do not appear to cause adverse reactions, but these do not
have EU labeling derogation.
Complex foods


Primary processing
Complex foods
Fining agents added to alcoholic beverages
Individuals with allergies to fish triggered by collagen or egg can react to alcoholic
beverages
Reactions to fining agents are rare, and many individuals with egg, milk, or fish allergy
can safely consume these beverages.
Fermented foods
Although fermented milk and yogurt may retain some allergenic activity, other highly
modified foods, such as soy sauce, may have substantially reduced allergenic activity
and may not present a hazard to certain allergic patients.


Aim: To determine traces of egg, milk, and fish-derived
processing aids used in wine making might elicit clinical reactions
in food-allergic patients.
Patient

14 pts: allergy to egg (n=5), milk (n=5), or fish
(n=4)

Methods

Skin prick tests with fining agents, and
fined/unfined wines
Double-blind placebo-controlled food challenges
with fined and unfined wines.

Primary outcome

The allergenicity of fining agents: ovalbumin,
lysozyme, casein and fish protein

S Kirschner. J InvestigAllergolClinImmunol 2009; Vol.19(3):210-217

Skin prick test with fined and unfined wines in patients allergic to egg, milk and fish.
ovalbumin or lysozyme

casein

fish protein

Although concentrated fining agents containing ovalbumin, lysozyme, and
casein were allergenic in the skin prick test, no patient reacted adversely in
the provocation test to fined wine
S Kirschner. J InvestigAllergolClinImmunol 2009; Vol.19(3):210-217

Primary processing
Complex foods
Baked foods
Evidence from oral food challenge studies indicates that baking reduces the allergenic
activity of milk, and foods with baked milk may be given to children whose infantile
cow’s milk allergy is beginning to resolve.


Aim: To evaluate the natural history of tolerance development
who incorporated baked-milk products into their diets.
Patient

88 egg-allergic children: underwent sequential
food challenges to baked-cheese (pizza)
followed by unheated-milk.

Methods

comparison group, Immunologic parameters
were measured at challenge visits.

Primary outcome

To evaluated tolerance to baked-milk underwent
sequential food challenges followed by
unheated-milk.

Jennifer S. Kim. J AllergyClinImmunol. 2011;128(1):125–131

Initially baked-milk-tolerant are 7.6 times more likely to develop unheatedmilk tolerance than subjects who were initially baked-milk-reactive over
the follow-up period; HR=7.62 [1.75, 33.14] P=.007
Jennifer S. Kim. J AllergyClinImmunol. 2011;128(1):125–131

Aim: to determine whether SPT wheal size and/or serum sIgE
levels to milk proteins could be used to predict successfully
passing a baked milk challenge
Patient

35 children: history of allergic reactions to milk
and food challenges to baked milk

Methods

retrospective chart review, determined by a
positive SPT or elevated serum sIgE

Primary outcome

To determine serum sIgE and SPT that may be
useful in predicting outcomes to baked milk
challenges.

Lisa M.B. Ann AllergyAsthmaImmunol. 2012;109(5):309–313

Milk SPT wheal size was a better marker for food challenge outcome to
baked milk, compared to casein SPT and milk protein sIgE levels.
Identified >90% NPVs

Symptoms at first reported

Immunologic responses


Aim: to investigate the mechanisms responsible for the reduced
allergenicity displayed by heat-treated egg white allergens
Patient

39 C3H/HeJ mices: orally sensitized with
ovalbumin (OVA) or ovomucoid (OM) and
challenged native or heated proteins

Methods

Evaluate allergenicity by Immunoreactivity and
digestibility by mediator release assay and
basophil activation assay

Primary outcome

To investigate factors behind reduced
allergenicity of two major egg white allergens,
ovalbumin (OVA) and ovomucoid, when to heattreatment.
Gustav BS. J Allergy ClinImmunol. 2011;127(4):990–7

Reduced allergenicity of heated egg white proteins partially resulting
from altered digestion and absorption in the gastrointestinal tract may
explain the clinical tolerance of extensively heated egg in the majority of
egg-allergic children

Aim: To characterize immunologic changes associated with
ingestion of baked egg and evaluate the role that baked egg diets
plays in the development of tolerance to regular egg.
Patient

79 baked egg-tolerated children: incorporated
baked egg into their diet.

Methods

comparison group, Immunologic parameters
were measured at follow-up visits.

Primary outcome

To evaluate predictors of baked and regular egg
tolerance and assess the time to development of
regular egg tolerance.

Stephanie AL. J AllergyClinImmunol. 2012;130(2):473–480

Recommendations to perform baked egg challenge
based on clinical status and testing

Dietary baked egg is safe, convenient, and well accepted by patients.
Introducing baked egg to egg-allergic children presents an important shift in
the treatment paradigm for egg allergy

• Food processing and food matrix can affect the structure
change and allergenic activity(IgE-binding capacity and
mediator release)
• Processing triggers chemical changes including unfolding,
aggregation, addition of glucose(Maillard modification)
• Heat resistant allergen, retained structure and allergenic
activity after severe thermal processing(e.g. canning, roasting)
• Thermal treatments such as baking can reduce the
allergenicity of certain foods (e.g. milk, eggs) and induced
early tolerance.

Food matrix and processing on allergenic activity

Food matrix and processing on allergenic activity

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