Food Production - Lecture 7

8/13/2019 Food Production - Lecture 7

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Microbiology, Allergies and Nutrition

Andreia Couto

2010/2011 Lecture n 7


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Escola de Hotelaria e Turismo do AlgarveEscola de Hotelaria e Turismo do Algarve

2

COMMON

PATHOGENSINCUBATION

PERIODS

COMMON

SYMPTOMS

Campylobacter 2 to 7 days (usually 3

to 5 days)

Diarrhea (often bloody), abdominal cramps,

nausea and headaches. Typically resolves within

1 to 10 days.

Bacillus Cereus 1-6 hrs (vomiting) 6 -24 hrs (diarrhea) Nausea and diarrhea. Typically resolves within24 to 48 hours.

E. coli O157:H7 24+ hrs to 10 days

(usually 3

to 4 days)

Diarrhea (often bloody), abdominal cramps and

vomiting; usually no fever. HUS may develop in

rare cases. Typically resolves within 1 to 8 days

(in non-complicated cases)

C. Perfringins 8 to 22 hrs (average is12 hrs)

Diarrhea, abdominal cramps and vomiting;usually no fever. Typically resolves within 1 to 2

days.

Hepatitis A 15 to 50 days

(average is 28 days)

Diarrhea, dark urine, jaundice and flu-like

symptoms, including headaches, fever, nausea

and abdominal pain. Duration is variable

(ranging a few weeks to 3 months).


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Listeria 9-48 hrs (for GI

symptoms) 2 to 6

weeks (for invasive

disease)

Fever, muscle aches, nausea, diarrhea;

pregnant

women may suffer flu-like symptoms and

stillbirth; elderly, immune-compromised and

infants can develop sepsis and meningitis.

Duration is variable.

Norovirus 12 to 72 hrs (usually

24 to 48 hrs)

Diarrhea, abdominal cramps, vomiting,

headaches and fever. Typically resolves within 1

to 3 days.

Salmonella 6 to 72 hrs (usually 12

-36 hrs)

Diarrhea, abdominal cramps, nausea, vomiting

and fever. Typically resolves within 4 to 7 days.

Shigella 24 to 72 hrs (usually

36 to 48 hrs)

Watery diarrhea, nausea, vomiting, abdominal

cramps, chills and fever. Stool may contain

blood and mucus. Typically resolves within 4 to

7days.

Staphylococcus 30 minutes to 8 hrs

(usually 2 to 4 hrs)

Diarrhea, abdominal cramps, nausea and

vomiting. Typically resolves in 24 to 48 hrs.

C. Botulinum 12 to 72 hrs (usually

18 to 36 hrs)

Nausea, vomiting, diarrhea, fatigue, headache,

dry mouth, double vision, muscle paralysis,

respiratory failure. Duration is variable (days to

months).


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Because of its severity and distinctive symptoms, botulism is the form of bacterial

food poisoning for which we have the earliest reliable reports.

CLOSTRIDIUM BOTULINUM

The cells are Gram-positive, motile with peritrichous flagella, obligatory anaerobic,

straight or slightly curved rods 2-10 pm long, and form central or subterminal oval

spores.

Strains of C. botulinum display sufficient variety of physiological and biochemical

characteristics to be inconsistent with their inclusion in a single species.


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They are strongly proteolytic and will often betray their presence in food by partialdisintegration of the product and a slight rancid or cheesy odor. Unfortunately

despite these warning signs the potency of the toxin is such that the amount

ingested on sampling the food has often proved sufficient to cause illness.

The minimum pH at which C. botulinum will grow depends very much on factors suchas temperature, water activity and the acid used to adjust the pH. The consensus has

long been that a pH around 4.7 represents an absolute minimum and this fact has

had important practical implications for the canning industry.


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Botulism is an example of bacterial food poisoning in its strictest sense: it results

from the ingestion of an exotoxin produced by Clostridiurn botulinum growing in

the food. The botulinum toxins are neurotoxins; unlike enterotoxins, which act

locally in the gut, they affect primarily the cholinergic nerves of the peripheral

nervous system.

Initial symptoms of botulism occur anything

from 8 h to 8 days, most commonly 12-48 h,

after consumption of the toxin-containing food.

Symptoms include vomiting, constipation, urine

retention, double vision, difficulty in swallowing

(dysphagia), dry mouth and difficulty in

speaking (dysphonia).


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The patient remains conscious until, in fatal cases, shortly before the end when theprogressive weakness results in respiratory or heart failure. This usually occurs 1-7 days

after the onset of symptoms. Surviving patients may take as long as 8 months to

recover fully.

The botulinum toxins are the most toxic substances known, with a lethal dose for an

adult human in the order of 10-8g.


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Four common features are discernible in outbreaks of botulism:

(1) The food has been contaminated at source or during processing with spores or

vegetative cells of C. botulinum.

(2) The food receives some treatment that restricts the competitive microflora

and, in normal circumstances, should also control C. botulinum.

(3) Conditions in the food (temperature, pH, aW) are suitable for the growth of C.

botulinum.

(4) The food is consumed cold or after a mild heat treatment insufficient to

inactivate toxin.


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The list of foods commonly contaminated are vegetables like canned corn, peppers,

green beans, soups, beets, asparagus, mushrooms, ripe olives, stuffed eggplant andspinach. Seafood and meat items include tuna fish, lobster, smoked and salted fish,

chicken and chicken livers, liver pate, luncheon meats, ham and sausage.

Apart from canning, vacuum sealing is another type of food packaging that may also

harbor botulism. By wrapping food tightly in plastic, oxygen is removed, which

allows bacteria to grow. This is common with vegetables and is the reason why

supermarkets use loose packaging to let in oxygen.


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Shigellaare Gram-positive, nonmotile, nonsporeforming rod-shaped bacteria. Shigella

bateria were discovered over 100 years ago by a Japanese scientist named Shiga, for

whom they are named. Currently, Shigella(shigellosis) accounts for approximately 10%

of reported food-borne illness in the United States.

Shigella

In addition to person to person transmission (through the fecal-oral route), Shigellamay also be acquired from eating contaminated food, or by drinking or swimming in

contaminated water.

Incriminating foods have included salads

(potato, tuna, shrimp, macaroni, and chicken),raw vegetables, milk and dairy products, and

poultry.


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Shigella are highly infectious, and a relatively small number of organisms can cause

illness. In turn, illness is caused when Shigellaorganisms are consumed and then attachto and penetrate the epithelial cells of the intestinal mucosa.

After invasion, the bacteria multiply and spread to contiguous cells resulting in tissue

destruction. Some strains produce enterotoxin and Shiga toxin (similar to the verotoxin

of E. Coli O157:H7). Symptoms include abdominal pain, cramps, diarrhea, fever,

vomiting and/or blood or mucus in stools. Symptoms typically occur between 36 and 48hours after the consumption of contaminated food, and will typically resolve within 4 to

7 days.

As with other common food-borne pathogens, the spread of Shigella can be prevented

by frequent and careful handwashing with soap.


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Food Allergies

Eight foods account for 90 percent of all food-allergic reactions. They are milk, egg,

peanut, tree nuts, fish, shellfish, soy, and wheat.

Some of these allergens may be outgrown, but others, such as peanut and shellfish,

will remain lifelong allergies.

Allergy is a hypersensitive disorder of the immune system. Allergic reactions occur

to normally harmless environmental substances known as allergens; these reactions

are acquired, predictable, and rapid.


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One of the most common food allergies is a sensitivity to peanuts. Peanut allergies

may be extremely severe, but can sometimes be outgrown by children school-age.

Tree nuts, including pecans, pistachios, pine nuts, and walnuts, are another

common allergen. Sufferers may be sensitive to one, or many, tree nuts.

Also seeds, including sesame seeds and poppy seeds, contain oils where protein is

present, which may elicit an allergic reaction.

Egg allergies affect about one in fifty children but are frequently outgrown by

children when they reach age five. Typically the sensitivity is to proteins in the

white, rather than the yolk.


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Milk allergy

Milk allergy is one of the most common food allergies in children. Although cow's

milk is the usual cause of milk allergy, milk from sheep, goats and buffalo also can

cause a reaction. And, some children who are allergic to cow's milk are allergic to

soy milk too.

A milk allergy usually occurs a few minutes to a few hours after you consume milk.

Signs and symptoms of milk allergy range from

mild to severe and can include wheezing,

vomiting, hives and digestive problems. Rarely,

milk allergy can cause anaphylaxis a severe,life-threatening reaction.


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Milk allergy or milk intolerance?

It's important to differentiate a true milk allergy from milk protein intolerance or

lactose intolerance. Unlike a milk allergy, intolerance doesn't involve the immune

system. Milk intolerance causes different symptoms and requires different treatment

than does a true milk allergy. Common signs and symptoms of milk protein or lactose

intolerance include digestive problems, such as bloating, gas or diarrhea, afterconsuming milk or products containing milk.


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Eggs are one of the most common allergy-causing foods, especially in children.

However, most children eventually outgrow their egg allergy.

An egg allergy usually occurs a few minutes to a few hours after eating eggs or

foods containing eggs. Signs and symptoms range from mild to severe and can

include skin rashes, hives, vomiting or inflamed nasal passages. Rarely, egg allergy

can cause anaphylaxisa severe, life-threatening reaction.

The key to preventing an egg allergy is avoiding eggs and foods that contain eggs.

This can be a challenge because eggs are a common food ingredient.

Egg allergy


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Egg allergy symptoms differ from person to person and occur within a fewminutes to a few hours after exposure to eggs. Egg allergy symptoms can

include:

Skin inflammation or hives, the most common egg allergy reaction

Allergic asthma

Allergic nasal inflammation (rhinitis)

Gastrointestinal symptoms, such as cramps, nausea and vomiting


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Anaphylaxis

Egg allergy can cause anaphylaxis, a life-threatening reaction that can block the

airways and breathing. Anaphylaxis is a medical emergency and requires treatment

with an epinephrine (adrenaline) shot and a trip to the emergency room.

Signs and symptoms start soon after eating eggs and can include:

Constriction of airways, including a swollen throat or a lump in your throat that

makes it difficult to breathe

Shock, with a severe drop in blood pressure

Abdominal pain and cramping

Rapid pulse Dizziness, lightheadedness or loss of consciousness


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Peanut allergy

Peanut allergy is common, especially in children. Peanut allergy symptoms can

range from a minor irritation to a life-threatening reaction (anaphylaxis). For some

people with peanut allergy, even tiny amounts of peanuts can cause a serious

reaction.

Peanut allergy is one of the most common causes of severe allergy attacks. It's

important to get even a minor reaction to peanuts checked out.


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An allergic response to peanuts usually occurs within minutes after exposure, andsymptoms range from mild to severe. Peanut allergy symptoms can include:

Skin reactions such as hives, redness or swelling

Itching or tingling in or around the mouth and throat

Digestive problems such as diarrhea, stomach cramps, nausea or vomiting Tightening of the chest

Shortness of breath or wheezing

Runny or stuffy nose


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Anaphylaxis

Peanut allergy is one of the most common causes of anaphylaxis, a medical

emergency that requires treatment with an epinephrine (adrenaline) injector (EpiPen,

EpiPen Jr or Twinject) and a trip to the emergency room.

Anaphylaxis signs and symptoms can include:

Constriction of airways

Swelling of your throat that makes it difficult to breathe

A severe drop in blood pressure (shock)

Rapid pulse

Dizziness, lightheadedness or loss of consciousness


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Tree nut allergy is one of the most common food allergies in children and

adults. Like peanuts, tree nuts (almonds, cashews, walnuts, etc.) tend to cause

particularly severe reactions, even if a person is exposed to only a tiny amount.

Tree nut allergy

Many experts advise patients allergic to tree nuts to avoid peanuts and other treenuts because of the high likelihood of cross-contact at processing facilities, which

process peanuts and different tree nuts on the same equipment. Further, a person

with an allergy to one type of tree nut has a higher chance of being allergic to

other types.


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Probably the most common tree nuts allergy is a skin irritation. The area may feel

hot and a red rash may develop. Some people will break out in hives on their backand experience swelling in the face. The area may be extremely itchy as well,

especially around the mouth. Feeling sick to your stomach, throwing up, and even

diarrhea can also result from this type of allergic reaction.

For some people their heart is affected, and it can cause cardiac arrest. Arrhythmia

is also possible which means that the heart is beating irregularly. It may be too fastor too slow but either way it isnt healthy for you. The symptoms of tree nuts

allergy can be very severe so a person needs to not take any chances when they

find out they are allergic to them. Getting the treatment that is available as soon as

they have been exposed is also very important.


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Soy, a product of soybeans, is one of the common foods that can cause allergies.

In most cases signs and symptoms of soy allergy are mild. In rare cases, soy allergy

can cause a life-threatening allergic reaction (anaphylaxis). You can reduce your risk

of having an allergic reaction to soy by knowing as much as you can about soyallergy and how to avoid soy-containing products.

Soy allergy


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For most people, soy allergy is uncomfortable but not serious. Rarely, an allergic

reaction to soy can be frightening and even life-threatening. Signs and symptoms

of a food allergy usually develop within a few minutes to an hour after eating soy-

containing food.

Soy allergy symptoms can include:

Tingling in the mouth

Hives, itching or eczema

Wheezing, runny nose or trouble breathing

Abdominal pain, diarrhea, nausea or vomiting

Dizziness, lightheadedness or fainting

Swelling of the lips, face, tongue and throat, or other parts of the body


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A severe allergic reaction to soy called anaphylaxis is rare. It's more likely tooccur in people who have asthma or are also allergic to other foods such as

peanuts. As mentioned previously anaphylaxis causes more extreme signs and

symptoms.


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Shellfish allergy is one of the most common food allergies. If you have a shellfish

allergy, you may have an allergic reaction to only certain kinds of shellfish, or you

may have an allergy to all shellfish. Shellfish include marine animals with shells,

such as clams, lobster and shrimp, as well as octopus and squid.

Shellfish allergy can cause mild symptoms, such as hives or nasal congestion, ormore-severe and even life-threatening symptoms. For some people, even a tiny

amount of shellfish can cause a serious reaction.

Shellfish allergy


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Shellfish allergy symptoms include:

Hives, itching or eczema

Swelling of the lips, face, tongue and throat, or other parts of the body

Wheezing, nasal congestion or trouble breathing

Abdominal pain, diarrhea, nausea or vomiting

Dizziness, lightheadedness or fainting

Tingling in the mouth

A severe allergic reaction to shellfish (anaphylaxis) is rare but can be life-

threatening if it interferes with your breathing.


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Wheat allergy

Wheat allergy is an abnormal immune system reaction to one or more proteins

found in wheat. Allergy to wheat is one of the more common food allergies.

If you have wheat allergy, you will likely experience symptoms within a few minutes

to a few hours after eating something containing wheat. Wheat allergy symptoms

include:

Swelling, itching or irritation of the mouth or throat

Hives, itchy rash or swelling of the skin

Nasal congestion

Itchy, watery eyes

Difficulty breathing

Cramps, nausea or vomiting

Diarrhea

Anaphylaxis


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Anaphylaxis caused by wheat allergy

For some people wheat allergy may cause a life-threatening reaction called

anaphylaxis. In addition to other signs and symptoms of wheat allergy, anaphylaxis

may cause:

Swelling or tightness of the throat

Chest pain or tightness

Severe difficulty breathing

Trouble swallowing

Pale, blue skin color

Dizziness or fainting

Weak pulse


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Fish allergy

Fish allergies are similar to shellfish allergies in that they are more likely than many

food allergies to start during adulthood and less likely than other allergies to be

outgrown. While fish is easier than many other allergens to avoid, fish allergies are

often quite severe.

People who are allergic to one type of fish, such as cod, often react to other types

of fish such as hake, haddock, mackerel and whiting as well. This is because the

allergens in these fish are quite similar. Cooking doesn't destroy fish allergens. In

fact, some people with fish allergy can be allergic to cooked but not raw fish.


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Fish allergy is linked to an increased risk of severe asthma in adult patients. Fish has

been linked with the oral allergy syndrome (in which the mouth itches or tingles after

eating an allergen) in people with occupational contact with fish. The greatest risk from

fish allergies is anaphylaxis.

There is high allergic cross-reactivity among different types of fish, meaning thatpeople with allergies to one type of fish are likely to have (or to develop) allergies to

others. This is because of a protein (parvalbumin) that is present in many fish. For this

reason, most people with an allergy to one fish are advised to avoid all fish (including

eel and shark). Some fish--specifically tuna and mackerel--are considered less

allergenic than others.


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Food Production - Lecture 7

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