Information for Consumers
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FAQ:
Cooking, Baking, and Serving
- Is it safe to bake in tin cans?
- Are decorated plates food safe?
- What are non- reactive pots?
- Are there safety concerns with reusing a single use temperature indicator?
- Can I use gelatin molds that are lined with copper or tin?
- Can a microwave produce "Exploding Water"?
- Can you safely microwave vegetables in plastic storage bags?
- Are old Pyrex dishes safe to use in the microwave?
- Can frozen meat be placed in a slow cooker, along with other ingredients, to cook all day?
QUESTION:
Is it safe to bake in tin cans?
ANSWER:
It depends on whether you mean in SEALED cans or open cans. If open cans,
there is not a problem. If closed cans, there are problems. First, it
is difficult for the product to be leavened when it can't expand. Second,
the vacuum in the can sets up conditions for botulism.
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QUESTION:
Are decorated plates food safe?
ANSWER: I do not believe there is
any safe way to put pictures on a plate and have the plate still be safe
to use with food. One would have to use some type of paint, glue or adhesive
and I am not aware of any that are approved for food use. Therefore, the
plates should be used only for decorative purposes OR the individual could
put a liner, paper napkin, doily, etc., on top of the plate before placing
food on it. However, the liner must completely cover the surface.
Source:
Angela Fraser, North Carolina State University, Food Safety Specialist.
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QUESTION: What are non-reactive pots?
ANSWER: Non-reactive pots are used on ranges that do not have the usual coils that heat up. It is a flat surface and will not get hot unless a non-reactive pot is used on it. A non-reactive pot is defined as one made of stainless steel, enameled aluminum (not regular aluminum because it is affected by acid) or anodized aluminum, such as Circulon or Kafflon. The anodized aluminum has gone through a hardening process that makes it nearly as hard as stainless steel.
Source: Meat and Poultry Hotline, 800-535-4555. May 25, 2000.
QUESTION: Are there safety concerns with reusing a single use temperature indicator?
ANSWER: Single-use thermometers are paper thermometers (they look like strips). At the base of the thermometer there is a patch that changes color when the product reaches temperature. Once the patch changes color it cannot revert back to no color, which is why they cannot be reused. They cannot be sanitized because they are paper and so must be stored in a sanitary manner, such as within their package.
Source: Angela Fraser, Ph.D., Assistant Professor, Food Safety Specialist, North Carolina Cooperative Extension Service, North Carolina State University.
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QUESTION: Can I use gelatin molds that are
lined with copper or tin?
ANSWER: Use these molds for decorative purposes. To begin with, it is not recommended to use copper implements for food preparation because of the possibility that copper could leach into the food. This recommendation would not include copper pots lined with stainless steel-in this instance, the food would not come in contact with the copper. If the food contact surfaces were aluminum, the molds would be safe to use. If not, then use them only for decorative purposes.
Source:
Angela Fraser, Ph.D., Assistant Professor and Food Safety Specialist,
North Carolina State University.
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QUESTION: Can a microwave produce Exploding Water?
ANSWER: Following is an explanation for the "exploding" water from the "How Things Work" Web site. It was written by Louis A. Bloomfield, Professor of Physics, University of Virginia, January 17, 2000. Yes, this sort of accident can happen. The water superheats and then boils violently when disturbed. Here's how it works:
Water can always evaporate into dry air, but it normally does so only at its surface. When water molecules leave the surface faster than they return, the quantity of liquid water gradually diminishes. That's ordinary evaporation. However, when water is heated to its boiling temperature, it can begin to evaporate not only from its surface but also from within. If a steam bubble forms inside the hot water, water molecules can evaporate into that steam bubble and make it grow larger and larger. The high temperature is necessary because the pressure inside the bubble depends on the temperature. At low temperature, the bubble pressure is too low and the surrounding atmospheric pressure smashes it. That's why boiling occurs only at or above water's boiling temperature. Since pressure is involved, boiling temperature depends on air pressure. At high altitude, boiling occurs at lower temperature than at sea level.
But pay attention to the phrase "if a steam bubble forms" in the previous paragraph. That's easier said than done. Forming the initial steam bubble into which water molecules can evaporate is a process known as "nucleation." It requires a good number of water molecules to spontaneously and simultaneously break apart from one another to form a gas. That's a rare event. Even in a cup of water at several degrees above the boiling temperature, you might have to wait minutes before such a rare event occurred. In reality, it usually occurs at a defect in the cup or an impurity in the water--anything that can help those first few water molecules form the seed bubble. When you heat water on the stove, the hot spots at the bottom of the pot or defects in the pot bottom usually assist nucleation so that boiling occurs soon after the boiling temperature is reached. But when you heat pure water in a smooth cup using a microwave oven, there is virtually nothing present to help nucleation occur. The water can heat right past its boiling temperature without boiling. The water then superheats--its temperature rises above its boiling temperature. When you shake the cup or sprinkle something such as sugar or salt into it, you initiate nucleation and the water then boils violently.
Fortunately, serious microwave superheating accidents are unusual. You could minimize the chance of this sort of problem by deliberately nucleating boiling before removing the cup from the microwave. Inserting a metal spoon or some food product into the water should trigger boiling in superheated water. A pinch of sugar will do the trick, something I've often noticed when I heat tea in the microwave.
Source: HOW THINGS WORK, Louis A. Bloomfield, Professor of Physics, University of Virginia.
Another
problem is the "bumping" that may occur in microwave cooking.
This popping or spattering is the explosion of food particles, not the
boiling of liquids. It is the result of local superheating. The container
shape does influence the heating pattern of a product and influence bumping.
Source: Oregon State University, More information can be found at http://www.urbanlegends.com/ulz/microwave.html.
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QUESTION: Can you safely microwave vegetables in plastic storage bags?
ANSWER: It is best not to because there has been insufficient research to determine how risky this practice is. Plasticizers -- chemicals used by some manufacturers of food wraps and other pliable plastic products B belong to a class of substances known to cause abnormalities in animals. Research is being conducted to determine if exposure to plasticizers is associated with low sperm counts, blunted IQs and other problems. At this time, there is no conclusive evidence to say yes or no.
To be safe, do not microwave food in plastic bags that are NOT labeled for microwave use. Tests done by Consumer Reports found that plasticizers did indeed migrate to foods when heated, but only where food came in contact with plastic. (High-fat foods such as cheese tended to absorb other chemicals found in the plastic.) Manufacturers thus recommend leaving a gap between food and plastic when heating, which is not possible with a storage bag.
Consumer Reports did not find plasticizers in microwavable Rubbermaid and Tupperware bowls.
The bottom line -- microwave foods only in microwave-safe containers. Also, do not use plastic bags for reheating foods in water on the stovetop. Under these high temperature conditions, the plastic could break down, allowing the plasticizers to migrate into the food.
Source:
Angela Fraser, Ph.D., Assistant Professor, Food Safety Specialist, North
Carolina Cooperative Extension Service, North Carolina State University.
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QUESTION: Are old Pyrex dishes safe to use in the microwave?
ANSWER: Here's a quick test to determine if the dishes are microwave safe. Microwave the empty container for one minute. It is unsafe for the microwave if it is warm; it is ok for reheating if it is lukewarm; and it is ok for actual cooking if it is cool.
Source:
Angela Fraser, Ph.D., Assistant Professor, Food Safety Specialist, North
Carolina Cooperative Extension Service, North Carolina State University.
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QUESTION: Can frozen meat be placed in a slow cooker, along with other ingredients, to cook all day?
ANSWER: Frozen meat can be put in a slow cooker if the meat is in pieces (during the initial cooking, the frozen pieces will separate, providing increased surface area for heating through thoroughly) or if it is a cut of no more than 1 inch. The thicker the cut, the longer time the meat will be in the danger zone. Under these circumstances, C. perfringens might be able to grow.
Source: Angela Fraser, Ph.D., Assistant Professor, Food Safety Specialist, North Carolina Cooperative Extension Service, North Carolina State University.
