مقدمه :
مسموميت هاي غذائي (Food poisoning)
مسموميت هاي غذائي، به مفهوم جامع آن يعني مسموميت هاي ناشي از مصرف مواد غذائي شامل مسموميت هاي ناشي از سموم طبيعي (كه نمونه هايي از آن ها ذكر خواهد شد)، سموم باكتريال، قارچي، سموم شيميائي و مصنوعي (سموم فلزي، سموم دفع آفات نباتي و غيره) و سمومي كه به عنوان متابوليت ناشي از فعاليت هاي آنزيماتيك عوامل خارجي يا داخلي در مواد غذائي پيدا مي شوند بخش مهمي از بيماري هاي ناشي از مصرف غذا را تشكيل مي دهند.
هنگامي كه سخن از مسموميت هاي غذائي به ميان مي ايد غالبا توجه همه به سموم باكتريال و گاهي به مواد سمي شيميائي معطوف مي شود، ليكن علاوه بر اين ها تعداد قابل توجهي از مواد سمي طبيعي در گياهان و محصولات غذائي حيواني يا ناشي از فعاليت هاي كپك ها وجود دارند كه در حد خود، مهم مي باشند .
در بسياري از مواد غذائي با منشا گياهي به طور طبيعي تركيبات شيميائي خاصي يافت مي شوندكه آثار سمي و زيان بخش آن ها مورد مطالعه قرار گرفته است و در مواردي كه مقدار يا طول زمان مصرف آن ها زياد بوده نشانه هاي باليني ناشي از آن ها در اشكال شديد و خفيف ظاهر گرديده است. قبل از اشاره به نمونه اي از فيتوآلكسين ها تذكر يك نكته مهم لازم است: توجه به وجود فيتوآلكسين ها در مواد غذائي مورد مصرف را به هيچ عنوان نبايد به معناي ضرورت اجتناب از مصرف اينگونه مواد غذائي، نتيجه گيري نمود بلكه در كنار آثار نامطلوب شناخته شده براي اين تركيبات شيميائي طبيعي، آثار بسيار مفيدي نيز براي بسياري از آن ها شناخته شـده است (به عنوان مثال مي توان به آثار ضد سرطاني و آنتي اكسيداني بسياري از اين تركيبات و نقش آن ها در خنثي كردن راديكال هاي آزاد مثبت اشاره كرد.
بعضی از اين تركيبات را كه به طور طبيعي در موادغذائي مورد مصرف وجود دارند به شرح زیر می باشند :
· تركيبات سيانوژنتيك: در بادام تلخ، هسته هاي تلخ، لوبيا و برخي حبوبات ديگر، ذرت خوشه اي، مانيوك.
· تركيبات گواتروژن : (تيوسيانات ـ گواترين، آليل ايزوسيانات) موجود در انواع كلم، شلغم، تخم خردل (سفيد و سياه)، سويا، گردو وبادام زميني . . .
· فوراتو كومارين : در پوست ليمو، كرفس، جعفري
· اگزالات ها : در ريواس، اسفناج، سيب زميني شيرين (Pomea Status) (سيب زميني شيرين كه بيش از يك سوم آن معمولا در طول نگهداري و عرضه خراب ميشود در فرايند خراب شدن آن يك تركيب زيان بخش فورانوسزگوئي ترپن بنام Ipomeamaron با اثر هپاتوتوكسيك و تعدادي از مشتقات Ipomeanine با اثر ايجاد كننده ادم ريوي ايجاد مي گردد) كاكائو، چاي، گوجه فرنگي، كنجد و جعفري.
· نيترات ها : در چغندر، اسفناج، هويج.
· سولانين و مشتقات آن : در سيب زميني (در سيب زميني معمولي نيز در فرايند سبز شدن و خراب شدن، لپتين كه مهار كننده آنزيم كولين استراز است ايجاد مي گردد)، سيب زميني جوانه زده و پوست آن، بادنجان نارس، گوجه فرنگي نارس، فلفل سبز ( Capsidiol در فلفل سبز وجود دارد).
· تانن ها : در پوست انار، چاي، قهوه
· گلوكزيدها : شامل گلوكزيدهاي سيانوژنتيك نظير آنچه كه در بادام تلخ و لوبياها وجود دارد، همچنين ساپونين ها، گليكوزينولات ها و . . .
· آلكالوئيدها : كه در برخي گياهان داروئي و مورد مصرف در تغذيه يافت مي شود.
· فاكتورهاي ضد تغذيه اي (Antinutritional) : كه شامل مهار كننده هاي آنزيم هاي گوارشي، لسيتين ها (با خاصيت آگلوتينه كردن گلبول هاي قرمز)، آمينواسيدهاي سمي و غيره مي باشند.
· فلاوينوئيدها
سولانین :
این ماده سمی که مشخصاً در سیب زمینی وجود دارد از نظر شیمیایی یک گلیکوآلکالوئیداستروئیدی است. وجود آن در سیب زمینی با ظاهر شدن رنگ سبز به خصوص در قشر زیر پوست این ماده مشخص می شود . به طور طبیعی سیب زمینی دارای 15-2 میلی گرم به ازای هر صد گرم وزن خود از این ماده است اما قرار گرفتن آن در معرض نور می تواند این رقم را تا صد میلی گرم افزایش دهد . مکانیزم اثر آن ، جلوگیری از اثر آنزیم استیل کولین استراز (Acetylcholinesterase) که در سیستم عصبی نقش اساسی دارد ، می باشد . اگر چه حتی مواردی از مرگ در اثر مصرف سیب زمینیهای دارای مقدار زیاد سولانین گزارش گردیده است ولی به دلیل آنکه به موازات افزایش این ماده ( بیش از 20 میلی گرم در هر 100 گرم ) و گسترش رنگ سبز در سیب زمینی یک تلخی مشخصی نیز در آن ظاهر می گردد از این نظر اساساً چنین سیب زمینی هایی مورد مصرف قرار نمی گیرند .
سیب زمینی حاوی گلیکوآلکالوئید و مواد سمی دیگری است که مهم ترین این مواد سمی، سولانین می باشد. معمولاً با پختن سیب زمینی در حرارت بالا (بالاتر از 170 درجه سانتی گراد) سولانین نابود می شود. گلیکوآلکالوئید معمولاً در زیر پوست سیب زمینی فراوان یافت می شود و اغلب با افزایش مدت نگهداری سیب زمینی (معمولاً در انبار) و همچنین قرار گرفتن در معرض نور، تراکم این ماده در زیر پوست این سبزی افزایش می یابد. مصرف گلیکوآلکالوئید می تواند باعث سردرد، اسهال، دل پیچه و در موارد شدیدتر، سبب رفتن به حالت کما و حتی مرگ شود. البته مسمومیت با مصرف سیب زمینی بسیار نادر است.
قرار گرفتن در معرض نور هم اغلب باعث سبز شدن سیب زمینی می شود و همان قسمت های سبز، احتمالاً سمی هستند. پرورش دهندگان سیب زمینی در حال انجام آزمایشات گوناگون به منظور بررسی میزان آلکالوئید در سیب زمینی های مختلف هستند، چون برخی انواع سیب زمینی میزان بیشتری از این ماده دارند.
برخی تحقیقات نشان داده اند که مصرف آن مقدار سیب زمینی که حاوی 200 میلی گرم سولانین باشد، احتمالاً خطرناک است. این میزان سولانین با خوردن یک عدد سیب زمینی متوسط فاسد و یا 4 تا 9 عدد سیب زمینی سالم در یک وعده، وارد بدن می شود.
سولانين مخدر و آرام بخش است ولي بعلت سمي بودن نبايد مورد مصرف داخلي قرار گيرد و بايد فقط بعنوان ضماد و استعمال خارجي استفاده شود.
سیب زمینی : نام گیاه شناسی آن، (سولانوم توبروزوم) یک ریزوم ساقه زیر زمینی چند ساله از خانواده ی گیاهان تاج ریزی می باشد. این گیاه یکی از مهم ترین سبزیجات است که در سراسر جهان، مخصوصاً اروپا، آمریکای شمالی و جنوبی از آن بسیار زیاد استفاده می کنند. سیب زمینی انواع مختلفی دارد که به روش کشت آن بستگی دارد.
سيب زميني نارس و همچنين برگ ، گل و ميوه سيب زميني داراي كمي آلكالوئيد سمي بنام سولانين است . بنابراين بايد از مصرف سيب زميني نارس و ينز برگ و گل و ميوه سيب زميني خودداري كرد
جوانه زدن سیب زمینی باعث افزایش سولانین(S o l a n in) كه یك الكالوئید است، می شود. سیب زمینی های دارای پوست سبز رنگ، نارس و یا جوانه زده حاوی سولانین هستند و این ماده سبب سمی شدن سیب زمینی می شود. اغلب در ۱۰۰ گرم سیب زمینی های میزان ۴/۹-۸/۱ میلی گرم سولانین وجود دارد افزایش مقدار سولانین به ۱۰ الی ۱۳ میلی گرم در ۱۰۰ گرم باعث مسمومیت انسان می شود. در سال ۱۹۷۸ در تعداد ۷۸ نفر از ۳۰۰ دانش آموز( سن متوسط ۱۳ سال) یك مدرسه انگلیسی كه توسط سیب زمین جوانه زده تغذیه شده بودند، مسمومیت شدیدی مشاهده شد. در فرد بالغ مقدار ۲۵ میلی گرم سو لانین باعث مسمومیت و ۴۰۰ میلی گرم آن باعث مرگ می شود. چنانچه سیب زمینی با آب و سركه پخته شود فاقد سولانین خواهد شد و آب و سركه بعد از پختن باید دور ریخته شود.
نگه داری سیب زمینی
در نگه داری سیب زمینی به روش استفاده از انبارهای سنتی از چهار نوع انبار مختلف خانگی، نیمه زیرزمینی و مخروطی شكل( حفره ای) به شرح زیر استفاده می شود.
در انبارهای خانگی برای نگه داری سیب زمینی در خانه ها بهتر است آن را در حجم كم در جعبه های چوبی كه از كف زمین انبار به اندازه ۴۰ سانتی متر بالاتر است قرارداد. در انبارهای خانگی هوای متعادل باید ۴+ درجه سانتی گراد باشد در غیر این صورت سیب زمینی شروع به جوانه زدن می كند و در آن سولانین به وجود می آید كه برای انسان سمی است.
برگ و ميوه سيب زميني بعلت داتشن سولانين مخدر و آرام بخش است ولي بعلت سمي بودن نبايد مورد مصرف داخلي قرار گيرد و بايد فقط بعنوان ضماد و استعمال خارجي استفاده شود.
بادمجان
بادمجان به علت داشتن یک ماده سمی به نام سولانین برای اشخاصی که سابقه حساسیت دارند خوب نیست. مخصوصا این افراد نسبت به نمونههای تخمدار بادمجان حساسیت داشته و بلافاصله بعد از خوردن دچار چشم درد شده و یا در بدنشان جوش پیدا میشود و دستهای از افراد مبتلا به کهیر میشوند.
در حدود یک سوم از افرادی که از بیماری آرتریت روماتوئید رنج می برند به سولانین ها و یا بعضی گیاهان حساس اند که از آن جمله می توان سیب زمینی, فلفل ها, بادمجان ,گوجه فرنگی و تنباکو را نام برد که باید از رژیم غذایی این افراد حذف شوند.توصیه می شود که حداقل 6 تا 8 لیوان آب خالص در طول روز جهت دفع سموم از بدن مصرف شود.
بادمجان داراي آلكالوئيدي بنام سولانين Solanine مي باشد كه ممكن است در معده هاي ضعيف ايجاد آلرژي و مسموميت كند . بنابراين براي طبخ بادمجان بايد ابتدا اين ماده را از بادمجان خارج كرد و بهترين طرز پخت بدین صورت است که ابتدا باید بادمجان را پوست كند و سپس ورقه ورقه نمود و لابلاي آنرا نمك پاشيد تا آب آن كه زرد رنگ و محتوي سولانين است خارج شود ، سپس آنرا فشار داده و پخت .
زمیمه انگلیسی :
INFORMATION RESOURCE Page 1
1.0 REASONS FOR HYGIENE
Because it is necessary to take into our body, through the alimentary system, all manner of substances providing
nutrients necessary for body energy building repair and maintenance, WE ARE ALL POTENTIALLY AT RISK
FROM FOOD-BORNE DISEASE!
It follows that any person involved in the production, handling processing and serving of food for consumption by
others carries a heavy responsibility. Their action can reflect directly upon the physical health and well-being of
others.
This obligation and responsibility is not just moral and ethical, but is also enshrined in legislation, through various
Food Acts and Regulations made thereunder
Unfortunately, it is not easy to gain a clear measure of the prevalence or incidence of illness due to food ingestion.
Let us take the commonly recognized classification of "Food Poisoning" as an important example. It is true that the
actual level of food poisoning occurring Queensland each year is relatively hidden. Those that are formally notified
and recorded are considered to be only the "tip of the iceberg". This is partly because in many cases symptoms
would be relatively minor and do not receive medical attention. In other cases, circumstances mitigate against
confirmation of a food poisoning diagnosis (eg illness may be attributed to overindulgence in alcohol, or due to
some common infection "going around").
In 1983/84 for example, 392 cases of salmonellosis were notified inQueensland.
In addition, in that year there were 7 notified cases described as food poisoning.
In 1982/83 there were 17 notified cases of food poisoning [in two or more
associated cases] (Annual Report, Queensland Health & Medical Services, 1984).
Those relatively small numbers reported must not induce complacency
"There has recently been controversy over an estimate that up to 100,000 cases of food
poisoning may occur each year in
Australia. This is only one half of the average incidence if each person experienced only one bout
of food poisoning in a lifetime of 70 years. Clearly, the real figure is very much greater and
makes a strong case for improving the microbiological status of
our foods, either by specification or education, or preferably, both" (Christian, 1975)
If you add to food poisoning the wide range of other infections potentially carried by food, plus the array of possible
toxins, both of an acute and also of a more insidious nature, the significance of proper food hygiene procedures to
public health can be readily understood.
Page 2 Food Hygiene Training - Infonnation Resource
It has been argued (Bourke and Isaacson, 1982) that the opportunities for food poisoning cases to occur are
increasing due to lifestyle factors, such as:
• increased communal eating;
• trends towards greater use of frozen, pre-cooked and convenience foods;
• bulk distribution of food; and
• public expectation of more rapid preparafion and serving of food
However, these factors can be readily off-set by an increased commitment to high standards in food handling.
To understand what procedures to apply, and how best to apply them, we need to examine the ways in which food
may be contaminated and made potentially unsafe for human consumption.
Food Hygiene Training - Infonnaiion Resource Page 3
2.0 SOURCES OF CONTAMINATION
Potential sources of food contamination are constantly present within the environment in which food is grown,
transported, processed and displayed. Contamination sources can include dust and soil, insects, source animals
(carcase foods), other animals and birds (including household pets and rodents), humans, water droplets, equipment,
containers and other foods.
The following SEVEN categories of contamination demonstrate how these sources may result in contamination and
will also underline the potential risks to health that can follow.
2.1 CHEMICAL CONTAMINATION
2.1.1 PESTICIDES
Do not spray household (or commercial) pesticides on food, utensils or food surfaces. All pesticides should be
treated as potentially poisonous in relation to food for human consumption.
2.1.2 METALS
Food and drink should be prepared and held only in containers made of metals and other materials which are known
to be suitable. These include stainless steel, aluminium, pyrex and other types of glass, good quality glazed
earthenware, various metals coated with good quality enamel, tin plate and non-stick (teflon and similar) surfaces.
Galvanized iron is unsuitable for cooking and storing foods and drink. The surface of the metal is covered with a
thin layer of zinc and this can easily be dissolved and get into food to poisonous levels, This is especially likely to
happen with liquids, particularly if they are acid. Never put lemon cordials or other such drinks into a galvanized
container, eg a bucket or refuse bin.
The use of discarded metal drums, whether made of steel or any other metaL for preparing and holding food, or for
use by the home beer-maker for fermentation is very dangerous. Large amounts of iron, zinc, lead and other
poisonous metals can be taken up in this way and cause poisoning.
Page 4 Food Hygiene Training - Inf onnat ion Resource
While copper saucepans are traditionally used by the cook, they must be kept perfectly clean. Foods can form
soluble compounds with the metal and these can accumulate on the surface of the pan unless deaned off. The failure
to clean out copper coffee pots and tea boilers, allowing such compounds to build up to dangerous levels on the
inside, has been responsible for instances of food poisoning. Care should also be taken not to use copper vessels for
deep fat frying or other forms of cooking involving oils and fats. The copper can cause the fats and oils to go rancid
and lead to spoilage of the food.
Cadmium-plated steel was used in the past to make ice trays and other parts of refrigerators and coolers. However, it
was discovered that this metal was easily dissolved by foods and drinks and caused serious poisoning when
consumed. Today it is no longer used for food-handling equipment, but cases of cadmium poisoning still occur
where old refrigerators and containers are used. Care should be taken to see that old equipment of this type is not
used for food preparation.
Lead is a very poisonous metal which sometimes gets into food. Poor quality tinplate can sometimes contain large
amounts of lead and this can contaminate food. Care should be taken that cheap tinplate pots and pans are not used
in the kitchen. Lead also enters food from the misuse of solder to repair breaks in metal utensils. Only lead-free
solder should be used wherever it is likely to come into direct contact with food (eg inside seams of containers and
pans).
The glazes on enamel and on earthenware contain poisonous metals such as lead and cadmium. If the glazes have
been improperly applied, as is sometimes the case with "bargain" pottery, casseroles, crockpots and similar utensils,
these metals can be dissolved out by food during cooking and storage, with unpleasant consequences for those who
consume the contents. The same thing can happen with enamel surfaces, especially if they have become chipped and
aacked. Do not try to save money by buying cheap utensils of this type.
Some plastics are suitable for use with food, others are not. Do not use garbage bags, other plastic bags, drums and
containers not designed for food use (eg garbage cans, no matter how well washed out) to hold food and drink.
Apart from various toxic organic chemicals, the plastic may also contain lead and other metals which can get into
food, with resultant food poisoning.
2.1.3 DISINFECTANTS
Ensure all containers are properly labelled. Provide separate storage for cleaning agents, etc.
Food Hygiene Training - Information Resource Page 5
2.1.4 Pvc PLASTICS
Leaching out of vinyl chloride monomers from packaging materials is well established.
2.1.5 ADDITIVES
Examples include deliberate or accidental addition of additives to food which may either be not an approved type, or
an approved type in excessive quantities (eg monosodium glutamate leading to "Chinese Food Headache").
It is important that containers not meant for food (eg plastic or galvanized garbage bins, garbage bags, emptied
cleaning containers, etc) are not so used.
NOTE: In the following discussion, scientific terms are used for organisms, This has not been avoided, as, far
most of these organisms, they are also the common-used terms.
2.2 CONTAMINATION BY DISEASE ORGANISMS WHERE FOOD ACTS AS A PASSIVE CARRIER
In such cases, the food is the equivalent of a door knob, tea-towel, hand, etc. It is simply a non-amplifying vehicle
for transmission - a vehicle that does not support the growth of disease organisms.
Examples of disease spread this way are infectious hepatitis (case or carrier), by sharing of items such as utensils
and air, or by water-borne transmission or possibly by vermin (flies, cockroaches, rats and mice).
A likely source would also be seafood grown in contaminated waters, eg adjacent to sewage outfails.
Page 6 Food Hygiene Training - Information Resource
2.3 CONTAMINATION BY DISEASE ORGANISMS (COMMONLY OF HUMAN ORIGIN) WHERE FOOD
MAY SERVE AS A CULTURE MEDIUM FOR GROWTH
Where food served as a culture medium, it is an amplifying vehicle.
Examples: Typhoid - Salmonella typhi Source: Urine and faeces of
patients and carriers
Cholera - Vibrio cholerae Source: Faeces of patients
and carriers
Badillary Dysentery (shigellosis) Source: Faeces of patients
NOTE: A carrier is a person who harbours the organism of an infectious disease in his body, without
showing the symptoms of the disease. This state may occur during the incubation period of an
infection or following an occurrence of the disease when symptoms were evident for a period until
apparent full recovery.
2.4 CONTAMINATION BY DISEASE ORGANISM OF HUMAN AND ANIMAL ORIGIN WHERE FOOD
SERVES AS A CULTURE MEDIUM FOR GROWTH
Examples: Salmonella spp Clostridium perfringens
Staphylococcus aureus
2.5 CONTAMINATION BY DISEASE ORGANISMS OF ENVIRONMENTAL ORIGIN WHERE FOOD
SERVES AS A MEDIUM FOR GROWTH
Examples: Clostridium botulinum - including infant botulism (under processed food
Clostridium perfringens (spore form)
Vibrio parahaemolyticus (shellfish) - cross contamination is
important
Food Hygiene Training - Information Resource Page 7
2.6 CONTAMINATION BY TOXINS FROM FUNGAL GROWTHS ON FOOD
Examples: Alfatoxin (from a fungus that grows on peanuts, grains and animal feeds)
Ergotism (from a fungus which grows on rye)
NOTE: Toxins:
• are water soluble, and may permeate through food from the
fungal growth site; and
• come through the food chain.
When in doubt discard a food item with fungal growths where they are not expected to be. Obviously, such growths
are expected on certain cheeses and fermented sausages.
Food has to be obviously mouldy.
To prevent contamination by toxins:
(a) store food correctly (away from high humidity and high temperatures)
(b) rotate stock regularly;
(c) inspect stock regularly and check stored food before use;
(d) discard contaminated food immediately when found, to reduce cross-contamination; and
(e) ensure susceptible foods are adequately covered in storage.
2.7 CONTAMINATION FROM TOXINS NATURALLY OCCURRING IN A SUBSTANCE INGESTED
Examples: poisonous mushrooms (toxic alkaloids) solanin toxin - "green" potatoes
poisonous fish (puffer fish)
There is another problem similar to the "green" potatoes. The problem is usually referred to as zucchini poisoning
and is due to the formation of a toxic substance CUCTJRBITACIN E in the food. This problem has been reported in
other forms of cucurbits other than zucchini, eg melons. Queensland would receive more than a half dozen
complaints annually.
Page 8 Food Hygiene Training - Information Resource
Ciguatera poisoning can be classified in this category, although stridily speaking, the toxin does not naturally occur
in ALL examples of the particular species which have been incriminated. This is of sporadic occurrence in certain
fish and is related to the food of the fish.
Do not accept non-commercial crops or products.
2.7.1 CIGUATOXIN
Of all the seafood-borne disease occurring in Queensland, the most frequent and possibly the most economically
important has been ciguatera poisoning. This is essentially a tropical to sub-tropical disease, as toxic fish have been
harvested only as far south as the Gold Coast on the east of Australia and Geraldton on the west. In the last four
years, there have been some 300 authenticated cases of ciguatera reported in Queensland. Newspaper reports on
some of these sporadic epidemic "flare-ups", which are often of a strictly local nature, have resulted in dramatic
reductions in the sale of such fish as mackerel and snapper
The word "ciguatera" is an old Cuban term used to describe a shellfish poisoning that afflicted early Spanish settlers
after they consumed a certain marine snail. Today it is a term that refers to a toxin found in more than 400 species of
fish living in and around coral reefs and the margins of tropical islands. The freshness of the fish has no bearing on
its toxicity and the toxin cannot be removed by washing or soaking the flesh in water, vinegar or lemon juice.
It is stable to cooking freezing salting and drying so that there is no culinary method available that will destroy or
remove the toxin. Unfortunately, the presence of ciguatoxin does not alter the appearance, smell or taste of the fish
and its occurrence is both variable and unpredictable. In any one catch, an occasional fish may be toxic while others
of the same species are not.
Ciguatera has both gastro-intestinal and neurological symptoms (listed below) within 4 to 5 hours of ingestion, and
has resulted in one death in Queensland. A second exposure (dose) causes a more severe reaction, as does the
concurrent drinking of alcohol.
- Castro-intestinal symptoms- nausea, vomiting, abdominal pain and diarrhoea;
- persist up to 2 to 3 days.
- Neurological symptoms - headaches, dizziness, itching
temperature inversion and numbness of
hands, feet, mouth and tongue;
- persists up to several weeks or longer.
Food Hygiene Training - Information Resource Page 9
2.7.2 PREVENTIVE MEASURE
(a) Beware of large marine shore or reef fish, particularly spanish mackerel, snapper, coral trout and reef
cod. Choose fish that are less than 3 kilograms in total weight.
(b) Do not eat viscera (brain, heart, liver) or gonads (testis or ovary) from fish caught in tropical or subtropical
waters.
[Information prepare by Dr Peter Wood, Senior Lecture in Microbiology Queensland Institute of Technology]
Page 10 Food Hygiene Training - Infonnatzon Resource
3.0 IMPORTANT FORMS OF FOOD POISONING
3.1 STAPHYLOCOCCUS AUREUS
S. aureus is a small round bacterium or coccus that acts as a common agent of food poisoning. Staphylococci are
frequently present in the nose and throat and on the hands and skin of 30% to 40% of the population, but they are
particularly prevalent on sore throats and in infected cuts, scratches, boils and pimples. In most instances of food
poisoning involving this organism, the food handler acts as the source of contamination. The organism is transferred
to the food by poor personal hygiene such as:
- the direct handling of foods which are not to be further heat treated;
- coughing and sneezing over foods;
- neglecting to cover cuts and sores on the hands with waterproof
dressings;
- touching the face or hair during food preparation; and
- the return of spoons directly to a dish after tasting.
Staphylococcus may also gain access into raw milk from infected udders and teats of dairy cattle (mastitis) and into
pork products from the skin of the pig during manufacture.
Normally, the bacterium is poorly competitive and so tends to dominate in foods in which the natural microflora has
been inhibited or destroyed by cooking, pasteurization or curing eg cooked chicken, pasteurized cream, custard or
sliced ham and corned beef. Should these foods be contaminated by the food-handler and left to stand at ambient
warm temperatures for several hours, the organism will multiply and excrete metabolic toxins into the food. Even if
the foods are reheated to temperatures which would kill the bacteria, the toxins are relatively heat stable and would
persist being present in the food at the time of consumption. The toxins cause rapid onset of symptoms some I to 6
hours after eating. Severe nausea, vomiting, diarrhoea and abdominal pains may be experienced for 6 to 24 hours,
but seldom are fatal.
3.1.1 PREVENTIVE MEASURES
(a) Maintain a high standard of personal hygiene during food
preparation, storage and handling.
(b) Keep foods refrigerated to less than SC to prevent the growth of the bacterium.
(c) Use a fork or tongs to slice and serve cooked or cured meats.
Food Hygiene Training - Information Resource Page 11
(d) Remember that through washing will seldom remove all
staphylococci from the hands, so use disposal gloves when handling or mixing foods.
3.2 CLOSTRIUM BOTIJLINUM
This organism gives rise to the relatively rare but often fatal form of food poisoning called botulism. These rodshaped
bacteria occur in soil and marine muds and produce highly-resistant endospores which may be distributed
throughout the environment. Inadequate heating of these spores in canned food stimulates them to germinate and
multiply, secreting into the food, potent toxins which affect the nervous system. The neurological symptoms that
occur 1 to 8 days after consumption include dilated pupils, double vision, dryness of the mouth, difficulty in
speaking and swallowing loss of muscle control and breathing difficulty due to paralysis of the respiratory system.
Botulism is not normally a disease associated with poor hygiene, but rather the result of under-processing or
sometimes post-heating contamination. It has often been associated with home-preserved, low-add vegetables and
meats that have been boiled instead of being cooked in a pressure cooker. These foods were stored at ambient
temperatures for several months before consumption and eaten unheated. This is important as the toxins are
destroyed by heat. The most important commercially canned product involved in recent outbreaks of botulism has
been canned seafood.
Cases of infant botulism have comprised a small percentage of deaths due to the sudden infant death syndrome.
Endospores present in the baby's general environment gain access to the intestine and become established as part of
the intestinal microflora. The release of low levels of toxin in the intestine results in the death of the child. Although
the spores may be present in the dust and air about the baby, there is evidence that some honeys have contained
viable spores of C. botulin urn.
3.2.1 PREVENTIVE MEASURES
(a) Pressure cook low-acid preserved foods;
(b) Reject canned foods which are "blown", deformed, leaky, corroded or otherwise spoilt. DO NOT
TASTE.
(c) Do not feed honey to babies under one year of age.
Page 12 Food Hygiene Training - Information Resource
3.3 SALMONELLA
There are many strains of Salmonella and all are thought to be pathogenic to man. They are short, thin, rod-shaped
bacteria that reside in the intestines of most forms of animals, including man. They are shed during defecation and
can contaminate the food we eat. Raw meats, including poultry, are often contaminated with low numbers of
salmonella during slaughter and dressing, and so these products must be handled with care in the kitchen to prevent
multiplication and cross-contamination. If the food-handler is suffering from an intestinal upset or is a symptomless
carrier, he may act as a source of infection if he does not wash his hands thoroughly after visiting the toilet.
The organisms can easily pass through the toilet paper and lodge on the hands, particularly if the stools are loose.
The carrier condition is commonly established for several months after a bout of salmonellosis (especially in
infants), although this obvious previous exposure of the organism need not always be evident. The third common
source of Salmonella is the domestic pets, birds, rodents, flies or any other animal that may gain access to the
kitchen or food storage areas. These may defecate directly onto the food or carry the organism on their fur, hait
feathers
or skin.
Salmonella do not form spores and so are readily killed by adequate cooking. The minimal internal temperature of a
food necessary for their destruction is 65k. This is most important when roasting large pieces of meat or poultry and
should be checked with a meat thermometer. If this is done, the remaining problem is the prevention of
contamination of the food after cooking. The food-handler, benches, storage shelves, equipment, utensils, cuffing
boards or contact with other raw meats may all act as a source of the organism. Once located on the cooked food, the
cells will multiply rapidly if left at ambient warm temperatures and soon build up an infective dose. The organism
invades the intestinal lining and generates symptoms of fever, headache, abdominal pains, diarrhoea and vomiting
12 to 36 hours after eating. The infection can be severe and may require medical assistance or hospitalization,
especially if the patient is young, elderly or debilitated.
3.3.1 PREVENTIVE MEASURES
(a) Wash hands thoroughly after visiting the toilet or when changing
from handling raw foods to cooked foods.
(b) Report an intestinal upset to the person in charge.
(c) Cook meat and poultry to a minimal internal temperature of 65'C. Use a meat thermometer.
Page 13
Food Hygiene Training - Information Resource
(d) Use separate benches, equipment, cutting boards and utensils for raw and cooked foods and wash
thoroughly between each use.
(e) Domestic animals, birds, rodents and flies must be excluded from the food storage and
preparation areas.
(0 Eat foods soon after cooking otherwise keep hot at 6WC or greater, or promptly refrigerate to less
than 5~C.
(g) Raw foods for storage or thawing should be placed below cooked foods in the cold room or
refrigerator to prevent drip contamination.
(h) Frozen meat and poultry should be thawed for 24 to 48 hours in the cold room or refrigerator,
depending on its size, to avoid the practice of thawing at room temperature, which may promote the
growth of the organisms.
* If the microwave oven is being used for thawing the cooking process should continue IMMEDIATELY by either
transferring to a conventional oven, or proceeding uninterrupted in the microwave oven. Observe manufacturer's
instructions regarding power levels and thawing/cooking time in relation to food types and weights.
3.4 CLOSTRIDIUM PERFRINGENS
C. perfringens is an anaerobic, rod-shaped bacterium that produces high resistant endospores when conditions are
unfavourable for growth. It is frequently present in human and animal intestines and the spores are shed into the
environment where they contaminate soil and dust or are picked up by flies. Animal carcases are often contaminated
during slaughter and dressing and it is most often that raw meat or poultry acts as the source of the organism in the
kitchen.
This irritates the intestinal mucosa and gives rise to abdominal pains and
explosive diarrhoea some 8 to 20 hours after eating. The patient rarely
vomits.
Perfringens food poisoning commonly arises from foods prepared in bulk, eg
large roasts, chickens or turkeys, casseroles, stews, soups and gravies.
Page 14 Food Hygiene Training - Infonnation Resource
3.4.1 PREVENTIVE MEASURE
(a) If cooked meats, meat dishes or meat gravies are to be kept for several hours before serving,
either keep hot 60'C or divide into small
portions and refrigerate to less than 5'C.
(b) If food is to be reheated, do so thoroughly to >7(YC and eat soon
after.
(c) Raw and cooked foods should be physically separated during
storage and each should have their own preparation area, utensils
and cuffing boards.
(d) Wash hands thoroughly after visiting the toilet or after handling
raw meats or vegetables.
(e) Exclude domestic animals, rodents, ifies and cockroaches from the
food preparation area.
3.5 BACILLUS CEREUS
Like the clostridia, B. cereus is a rod-shaped bacterium that produces endospores, but it can
grow aerobically as well as anaerobically They are often present in high
numbers in cereals, flours and spices. Again, cooking seldom destroys the
spores present in these food ingredients, but rather stimulates them to germinate. Slow
cooling or storage at ambient temperatures will give rise to rapid
multiplication. Large numbers of cells need to be consumed for onset of
symptoms.
B. cereus can cause two distinct forms of food-borne illness. The diarrhoea type
is similar to perfringens poisoning and gives rise to abdominal pain and
profuse watery diarrhoea some 10 to 12 hours after eating. Various meat and
poultry dishes containing flour or spices and desserts containing custard
powder have been implicated. In all instances, the food was left to stand at room
temperature for several hours and often overnight. The vomiting type is similar to staphylococcal food
poisoning and gives rise to an acute attack of nausea and vomiting some I to 5
hours after a meal. The most commonly implicated food has been boiled or fried
rice from Chinese restaurants or take-away shops. The major problem has been
leaving boiled rice booked in bulk to "dry off" at kitchen temperature for
from 3 hours to 3 days, but commonly overnight.
Food Hygiene Training - Information Resource Page 15
3.5.1 PREVENTIVE MEASURES
(a) Ideally, prepare meat and rice dishes a short time before serving.
(b) Boiled or fried rice should be kept hot at >6XC or spread in
shallow containers and refrigerated at <5t. Under no circumstances
should cooked rice be stored at room temperature for longer than 2
hours.
(c) To reduce the storage time before frying, rice should be boiled in
small quantities on several occasions during the day
(d) Vanilla custards and similar desserts should be refrigerated and
not
left to stand on a bench or shelf at room temperature.
3.6 VIBRIO PARAHAEMOLYrICUS
V parahatmolyticus is a marine vibrio of worldwide distribution that occurs in
unpolluted coastal waters and sediments. Its isolation from such areas appears
temperature-dependent, in that it may be isolated all year round from tropical
and sub-tropical waters, but only in summer months from temperate waters when
the water temperature is greater than 1St.
Hence, although outbreaks of this type of seafood poisoning in Japan and the
USA occur mainly in the summer months, here in Queensland it is an ever
present menace. Because of the sensitivity of the organism to heat processes, cold temperatures
and fresh water, it can be controlled by good food handling practices. In the
food preparation area, raw seafoods and sea water are the most common source
of the organism.
Approximately 12 to 15 hours after consumption of contaminated food, a person
suffers abdominal pain, diarrhoea, vomiting, fever, chills and headaches, but
seldom requires hospitalization.
Page 16 Food Hygiene Training - Information Resource
3.6.1 PREVENTIVE MEASURES
(a) Do not consume raw or semi-cooked fish or shellfish.
(b) Do not use sea-water to thaw, cool or freshen foods which are not
to
be further heat heated before consumption.
(c) Do not allow proliferation of low numbers of the organism to an
infective dose by leaving contaminated food at ambient temperatures for several
hours.
(d) Prevent cross-contamination from raw seafoods to cooked foods or salads via direct contact, workers'
hands, refrigerator drip, shelving, cutting boards, knives or storage containers.
Food Hygiene Training - Information Resource Page 17
4.0 CONDITIONS NECESSARY FOR FOOD POISONING TO OCCUR
There are five conditions or circumstances which must normally be met for food
poisoning to eventuate. They are:
(a) Contamination of the food with the organism or toxic substances.
In the latter case, sufficient must be present to produce symptoms.
(b) The food must be a good culture medium for multiplication of the
organism to reach an infective does or in the case of S. aureus and C.
perfringens, for example, for the production and accumulation of
sufficient toxin.
(c) Temperature must be favourable for growth (50C to 60'C).
(d) Enough time must elapse, at the above temperature range, to permit
appreciable growth.
(e) The food must be ingested in a sufficient amount so that an
infective does is consumed.
In some circumstances, not all the above conditions need apply, eg viruses do
not multiply in foods. But these are essentially the five key areas where we
can intervene to ensure the safety of the food. In the case of forms of
contamination other than the food poisoning organism, our lines of defence can
only be drawn at Conditions (a) and (e).
Now, let us look in more detail at each of these conditions.
4.1 CONTAMINATION OF THE FOOD WITH THE ORGANISM
This area provides us with our greatest range of possibilities for
intervention. Contamination may occur through:
(a) Poor personal hygiene.
(I,) Inadequate environmental hygiene (accumulated dirt and dust,
presence of animals and birds, poor garbage disposal, vermin).
(c) Cross-contamination (contact with a contaminated food item or appliance - including previously
contaminated food received at premises).
(d) Organisms occurring naturally in or on food (especially poultry carcase, meat, and soil on fruit and
vegetables).
Page 18 Food Hygiene Training - Information Resource
Prevention comes through putting up BARRIERS TO CONTAMINATION (eg good
personal hygiene, cleaning and sanitizing, vermin control, etc)
4.2 FOOD MUST BE A GOOD CULTURE MEDIUM FOR GROWTH
The three main factors are:
- high protein food
- moisture present
- low add (Ph >4.5)
The foods which are most frequently implicated are: -
- meat (and meat products)
- poultry
- eggs (and egg products)
- seafood
Food Hygiene Training - Information Resource Page 19
4.3 TEMPERATURE MUST BE FAVOURABLE FOR GROWTH
For general commercial purposes, the following temperature scale should be
used
as a guide:Eood spoilage organisms may be active beyond this range (5~C to
6(YC) and at
any temperature where liquid water is available.
Freezing of food does not destroy bacteria or "fix up" the food. Freezing
places bacteria in a dormant (sleep) stage.
A frozen contaminated food remains a hazard - and during the thawing process
the hazard is likely to magnify.
Frozen foods, in the commercial environment, which have thawed through
refrigeration breakdown or flaws in the transport system or storage, MUST BE
DISCARDED.
Frozen food is to be held at -15"C. frozen seafood is to be held at -18~C for
transport and -25~C to -3O~C for freezer storage.
4.4 ENOUGH TIME MUST ELAPSE
Time and temperature are clearly linked togethet
The fundamental rule is that foods (particularly the perishable or more
susceptible foods) must be handled as quickly as possible while within the
growing (or danger) temperature zone (5"C to 60'C).
Zone of destruction - >60C
Zone of growth
(temp danger zone) - 5-60'C
Zone of inactivity - c5'C
Page 20 Food Hygiene Training - Information Resource
In commercial circumstances where highly perishable food is to be~ kept for a
period longer than 48 hours, the refrigerated storage temperature should not
exceed 2'C.
The thawing of a frozen food (at <5"C) should not exceed 48 hours. Thawed
foods should be discarded after a maximum of 24 hours form initial
preparation, providing a maximum temperature of 10'C has not been exceeded.
No food should be left longer than one hour at room temperature.
The speed at which bacteria multiply depends upon prevailing conditions, but
they can double every twenty minutes. As an exercise, use a calculator, and
staffing with one bacterium, calculate how many may be present after six
hours. Unfortunately, a food item would not carry just one bacterium, but is
likely to have at least hundreds!
4.5 THE FOOD MUST BE INGESTED
Food that is unsafe to consume does not necessarily look or smell "off". In
fact, food can appear perfectly wholesome and yet be heavily contaminated with
food poisoning bacteria. Pathogenic bacteria do not compete well with spoilage
organisms (the ones producing odour and slime) and grow best when spoilage
organisms are absent or few in number
If spoilage organisms are obviously present, however, it could be a clear
indication that there has been a breakdown in hygiene and handling procedures.
NOTE: Infants, the very old, and the debilitated in general, can be infected
at lower dosage levels. Therefore, particular care is needed with baby food,
hospital food, and special diets (eg diabetic food).
THE STORAGE RULE
KEEP IT HOT - >60~C
KEEP IT COLD - c5~C OR
DON'T KEEP IT!
Food Hygiene Training - Information Resource Page 21
5.0 BASIC PRINCIPLES OF FOOD PROTECTION
5.1 ERECTING BARRIERS TO CONTAMINATION
The avenues available to us include:
(a) establishment of high standards of personal hygiene;
(b) the hygienic handling of food;
(c) hygienic procedures and appropriate facilities for food storage
and display;
(d) cleaning and sanitizing of equipment, surfaces and building
(e) controlled and efficient garbage disposal facilities and methods;
(f) effective pest control; and
(g) work area layout and construction designed to facilitate hygiene
and efficiency - encouragement of use of facilities.
5.2 PRUDENT USE OF TEMPERATURE CONTROLS
5.2.1 THE "ZONE OF DESTRUCTION" END OF THE TEMPERATURE RANGE FOR COOKING AND
RE-HEATING
Large pieces of food and "pocketed" foods (including chicken carcases) should
be thawed before cooking.
Cooking: Minimum internal temperature - 65'C (based upon Salmonella). (Food can
still be rare at the above temperatures. Well-cooked requires
temperatures between 70'C and 8O'C).
(a) Cooking destroys cells that do not produce heat-resistant spores.
(b)Staphylococcal contamination can create a problem to the extent
that if conditions have existed which have permitted growth and
development of toxins, final cooking may destroy the bacterial
cells, but may not destroy the heat-stable toxins.
Food Hygiene Training - Information Resource Page 22
It is strongly recommend that a probe thermometer be used.
When re-heating an internal temperature in excess of 70C should be obtained.
Food warmers (whether using heated air or water bath) should be kept at a
constant temperature of 70'C. They should be switched on and brought to the
required temperature before use. Do not use warmers for heating or re-heating -but for the reception of already hot
food.
5.2.2 USING THE "ZONE OF INACTIVITY" END OF THE TEMPERATURE RANGE
This, naturally enough, revolves around refrigeration. There needs to be
adequate provision of refrigeration capacity to provide for rapid cooling and
storage of foods at <5"C.
Freezer storage is recommended at - 15C or below.
Thawing of frozen meat, poultry, fish and other foods is best accomplished
over a 24 hour period in a refrigerator or cold room set at 4"C or in a
microwave oven.
NEVER THAW HAZARDOUS FOODS AT ROOM TEMPERATURE.
NOTE: ALWAYS CHECK TEMPERATURE RECORDING DEVICES TO
ENSURE THAT THEY HAVE BEEN PROPERLY AND ACCURATELY
RECORDED. These devices should be regularly checked to ensure that
they are functioning correctly.
Food Hygiene Training - Information Resource Page 23
6.0 ENSURING FOOD QUALITY
The foregoing reinforces the earlier observation that the preparation and
service of food to the public carries with it a significant responsibility for
the maintenance of public health.
While many in the industry acknowledge this responsibility, and indeed act
appropriately to meet it, the need for some monitoring and control is obvious.
The mechanisms that are available to provide the oversight can be divided into five categories:
• Microbiological Standards
• Chemical and Physical Standards - including foreign bodies / adulteration
• Packaging and Labelling Requirements
• Legislation establishing minimum food handling standards/practices
• Codes of Practice - and the establishment of rules and standards for the
construction and alteration of premises.
The prime responsibility for carrying out the monitoring and enforcing of standards, rests with the Health Surveyor
at either State or Local Government level.
6.1 MICROBIOLOGICAL STANDARDS
Many people ask, "Well, why don't we jut have set microbiological standards
for everything and establish procedures for regular testing?" It sounds a straight forward a'nd
simple guarantee for safe food. So what is the problem?
Let us consider the issue further.
Indeed, microbiological standards can achieve:
(a) a general improvement in quality
(b) reduction in faulty end products (reduced losses to the industry);
(c) better value for the consumer; and
(d) increased safety (health protection)
Food Hygiene Training - Information Resource Page 24
But, there are difficulties such as with sampling, statistics and timing associated with setting microbiological
standards.
While certain limited areas of the food industry may establish their own "in
house" standards, probably the more important from a broader public health perspective
are the statutory requirements initiated and administered by the State Department of Health.
In Australia, microbiological standards do exist for several foods, including milk and frozen pre-cooked foods.
6.2 CHEMICAL STANDARDS
Statutory food chemical and physical standards apply under the provisions of relevant Food Acts and Regulations.
These are to ensure the supply of food free from adulteration and contamination and establish standards for the use
of food additives.
Such possible food contaminants as pesticide resides and heavy metal traces are the concern of these provisions.
Regular food monitoring through sampling is undertaken by units of the various State Health Departments, and local
authorities in some regions.
6.3 PACKAGING & LABELLING (UNDER PROVISIONS OF THE FOOD ACT AND FOOD
STANDARDS REGULATIONS)
Food labelling may be used to:
(a) describe the food;
(b) list the ingredients;
(c) indicate the presence of preservatives, colours and flavours;
(d) advise on conditions of storage and/or handling
(e) advise on recommended life of food (date marking);
(f) indicate a batch number;
(g) advise on appropriate use of food;
(h) indicate the name and address of manufacturer (packer or vendor);
and
(i) indicate country of origin and importer
Food Hygiene Training - Information Resource Page 25
Such information on the label can assist in ensuring that:
(a) there is proper identification of food;
(b) handling and storage is adequate;
(c) quality food only is used;
and increases the manufacturer's and supplier's responsibility for the produce
being provided.
Food labelling is therefore an important provision enhancing the overall
standard of food hygiene.
6.4 CODES OF PRACTICE
There are many Codes of Practice operating within the food service industry. For example, local routines are
established and enforced by owners, managers and supervisors. These may include appliance operating instructions,
cleaning schedules, dress requirements, etc. In fact at the local business leveL operators should be encouraged to
establish planned, written guidelines, so that all staff know clearly what is expected of them. Further, it makes it
easier to maintain checks on the operational and maintenance procedures.
The large franchise organizations are noted for their very precise and diligently-enforced standards of practice.
Industry sectors can also establish voluntary or self-regulated codes of practice. Simply, these are in-house" routines
and procedural guidelines monitored and administered by supervisors and managers.
Codes are often developed to compliment and clarify some provisions of legislation which are intentionally drafted
to enable broad interpretation.
6.5 ~LEGISLATION ESTABLISHING MINIMUM STANDARDS OF
PRACTICE
Statutory requirements, administered under the authority of the relevant Food Acts, establish compulsory standards
for premises (use, construction and modification) facilities, equipment, handling practices and personal hygiene.
Sections 7.0 to 12.0 following, incorporate most of the provisions established through legislation.
These regulations are primarily administered by local authority Environmental Health Officers.
Page 26 Food Hygiene Training - Information Resource
7.0 PERSONAL HYGIENE
The observance of a high standard of personal hygiene is important for the following reasons:
(a) to promote the health of the individual; and
(b) to prevent the spread of disease from one person to another
These reasons are valid enough in our ordinary day to day living and contact with one another
But, when it comes to food handling, then the risks are compounded and the
need for extra diligence in personal hygiene is of paramount importance.
Essentially, there are three ways in which the food handler can provide the e
link in the chain of infection; as a:
(a) Case (a person with symptoms);
(b) Carrier (a person carrying the organism, but without symptoms);
and
(c) Passive
