Canadian Pizza Magazine

Tech Slices: Food Safety and Make-Table Tips to Manage Hidden Dangers

By bob mcdougall   

Features In the Kitchen Ingredients

Food Safety and Make-Table Tips

The art of pizza meets the science of food.

The art of pizza meets the science of food.

We’ve all heard the tales of fishermen, and marvelled at the way the size of the fish seems to increase with each telling. I’m told similar effects are found with hunters (whether hunters of game or bargains).

You may not have realized, however, that when food industry technical and quality personnel get together, a related phenomenon can also occur. Over about 25 years in such circles, I’ve unfortunately amassed quite a number of experiences of weird and/or dangerous things associated with or found in food, and have definitely heard some tales that have grown each time they are shared. Someday I’ll tell you the story of the giant salamander in the peanut butter. (See what I mean?)


As you’ll likely be seeing this column sometime after the holiday rush, I hope you will take the time to read it fully and digest it well. The “art and science of clean and safe food” is nothing less than the beating heart of our industry. For ourselves, our families and, most of all, our customers, we need to know as much as possible. There are no exaggerations here.
Classifying Risk
A wise food microbiologist once advised me, “the foodborne dangers of which we are aware are tough enough – the ones we haven’t discovered yet may be truly frightening.” That was in 1979; Listeria was just an interesting bacterium for a few researchers, “mad cow” was virtually unheard of, toxic E. coli were a lab curiosity, and if you just cooked your pork well and kept your milk and eggs cold, food was “pretty much safe.” Looking back 25 years later, that microbiologist was, unfortunately, right on target.

One useful way to understand the types of risks we face involves breaking them down into classes or groups. One such scheme, with typical examples, is shown below.

Biological Dangers

  • Infections: salmonella, hepatitis, amoebae, etc.
  • Intoxications: staph toxin, botulism, etc.
  • Allergies: peanut, shellfish, latex, etc.
  • Sensitivities: sulfites, MSG, peptides, etc.
  • Emerging dangers: CJD, mould toxins, etc.

Physical Dangers

  • Foreign Materials: bone, glass, metal, wood, etc.
  • inherent product risks (but not “unpreventable”): heat, fish bones, pits, etc.

Chemical Dangers

  • poisons: pesticides, cleaning chemicals, boiler chemicals, etc.
  • environmental & misc. contaminants: mercury, lead, PCB’s, monomers, etc.
  • sensitizers and co-reactants: food dyes, alcohol, peptides, etc.

If any reader has taken a course in Hazard Analysis / Critical Control Points or HACCP for food production or for foodservice, you will no doubt recognize these three classes of hazard.

Others may wonder why “unsafe food holding temperature” is not listed above, though it is extremely important that such conditions not occur. In this scientific classification of hazards, the actual hazard would be the presence of a high number of dangerous bacteria, potentially resulting in an infection or intoxication. I know this may seem like splitting hairs, but in analyzing and studying hazards such precise thinking is important.

In this way, we can clearly understand that the best means of preventing the hazard listed is to prevent bacteria being present in high enough numbers to cause harm. It follows then that the means to achieve this can include having low levels of bacteria in the product to start with, maintaining adequate packaging to prevent contamination during storage, and cooking or re-cooking of product before use, in addition to the critical point of maintaining proper holding temperatures. We end up with a more comprehensive understanding of the factors involved. While this example will hopefully have been useful, we can gain a lot from discussing the hazards list from a more practical or hands-on standpoint oriented around the pizzeria. This month, we’ll start with a discussion of the biological dangers, and continue on to physical and chemical hazards in a future issue.

Biological Dangers
Infections occur when bacteria, viruses or parasites set up housekeeping somewhere in or on a human. In all cases purchasing reputable ingredients, and processing and storing according to recognized practices will prevent disaster. Practice good temperature control (keep everything below 5ºC or above 60ºC). Realize that even these practices may not destroy all bacteria. Use clean and sanitary containers and packaging. When cooling or heating foods move them through the temperature danger zones as quickly as possible. Use plenty of heat and stirring, and ice baths where needed. Buy, calibrate and use thermometers!

Intoxications occur when bacteria, or in rare cases other organisms produce chemicals that are poisonous in some way. The bacteria themselves only make the toxin, and may not even be alive anymore when the victim is affected.

Enteropathogenic E. coli produce poisons that can destroy blood and tissue  cells. Botulism is caused by poison produced by Clostridium botulinum bacteria.

Many toxins, even one produced by the Staph bacterium found on the skin of  everyone, are not destroyed by heat. It is essential to prevent their formation!

Make-table tips – fastest heating and cooling occurs in tinned steel or aluminum inserts or copper bottom / aluminum pots. Stainless is slower but often acceptable if kept closed, but plastic inserts are often deficient in their ability to keep product cold enough. Heat enters an open insert faster than it can be taken away through the insulating plastic wall of the insert. Plastic inserts usually keep contents adequately cold if held in crushed ice, but not in air-cooled make-tables. Use clean, undamaged vinyl gloves. Sanitize them often, change them before they tear and release millions of skin bacteria.

Allergies to food components are becoming more common, and can be deadly.

Any protein can trigger an allergic reaction, but a number are very much more common and often more deadly. These include shrimp or shellfish, peanut, eggs and others. The only defense is a strict and total ban on these substances in or around an eating establishment. Insist on full allergen disclosure by all suppliers, including non-food items.

Make-table tips – DO NOT use latex gloves – a small proportion of the population can be lethally affected by the traces of latex shed by using these gloves to handle ingredients or even pizza boxes. Prohibit employees bringing allergens to work (like peanut butter sandwiches or shrimp salad). Follow industry guidelines for allergen awareness.

Sensitivities are often confused with allergies, and can have the same deadly  effects. Many operators now know that sulfites can trigger lethal reactions. Some do not realize, however, that “sulphur” and “sulphurous acid” openly declared on certain sauces, garnishes and even dried mushrooms are the same thing, and can have the same deadly effects.
Another sensitivity seen in some is an apparent reaction to protein breakdown byproducts called peptides. This can be present as MSG added to certain foods, or as naturally-occurring peptides in  tomatoes and other fresh or processed foods.

Most operators are unaware of the  fact that some extremely strong and reactive peptides are formed by  fermentation, bacterial breakdown or degradation of protein-containing  substances. For example, there are numerous scientific articles detailing the potential dangers of fresh mushrooms either temperature abused or held too long prior to use. Use fresh, un-discoloured mushrooms or quality canned or brined product. Discard sticky or overly dark, old mushrooms. Avoid waste by slicing or buying in just enough product for two to three days at a time, and watch holding  temperatures. Another similar danger of forming reactive peptides
is from anchovy fillets held without refrigeration. Anchovies, though they’re canned, are NOT shelf stable. Make sure your supplier receives and holds them refrigerated as well. Pay strict attention to Use By dates.

Maketable tips – After slicing mushrooms, repack them loosely and chill well. Slicing mushrooms causes them to generate heat, which can cause them to sour quickly if not cooled. Use the fans in your walk-in cooler to direct clean, cold air across packages of freshly sliced mushrooms to recool them. Discard excessively old dough, or dough which has been severely temperature abused, since excessive buildup of byproducts of yeast breakdown can generate levels of bioactive peptides.

Emerging dangers include some of the complicated biological risks we are hearing about with greater regularity lately. In some cases, research is far from complete and we have only indications and best guesses to work with. There seems adequate evidence to maintain scientific vigilance against BSE-affected cattle, given a likely link to human variant-CJD disease. This is not the sort of risk against which the average operator can have an effect. Like so many other such risks, it is statistically only a very small risk.
This is cold comfort if you are the unlucky statistic.

There is, however, a means to assist in managing emerging risks. This consists of knowing how your ingredients should look, taste and smell and being vigilant that they remain that way. Spec changes must have a reason, and must improve, or at minimum not degrade, the resultant product.
As an example, for decades the ability of moulds to produce extremely dangerous and cancer-causing chemicals called mycotoxins on such dry materials as grains and nuts has been recognized. Flour mills and peanut butter processors regularly conduct screening. Over the last few years research has shown that under some conditions similar compounds may be produced on moister foods such as cheeses. This concern is not directed at the mould-ripened cheeses such as Camembert or various “blue” cheeses, but at the contaminant moulds that can affect industrial cheese trims and downgrades, which may be used for cheese powders and further processed cheese products.

Though this specific risk may not have been well known to many operators, it can be managed with vigilance as outlined above. Knowing how your ingredients should look, taste and smell is the key. If a cheese which is not customarily associated with mould smells mouldy or a coloured cheese is for no apparent reason quite discoloured, be suspicious. Intimate knowledge of how things should be and of how they typically are, provides a strong weapon and one of the most useful tools against an unsuspected or emerging risk.

In future articles, physical and chemical risks will be discussed. Please feel free to forward any questions, queries or quibbles to the e-mail address given below. Tell us what you like seeing here, or what you want to see here. This is your column!

Bob McDougall is a microbiologist, with postgraduate training in biochemistry and food science. The Food Technical Consultancy, and freely admits to having pizza sauce in his veins. Contact Bob at

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