Food Safety Questions and Answers

Question: How do I safely preserve cherries in brandy?

Answer - The following is a safe recipe for making brandied cherries.

Ingredients:

6 pounds of dark sweet cherries
1 cup sugar
1 cup water
1/2 cup lemon juice
Spices to taste
1 1/4 cups brandy

Wash cherries under cold running water, drain, remove stems and pits

Combine sugar, water, spices, and lemon juice in a large kettle. Bring to a boil, and stir until the sugar is dissolved. Reduce heat to simmer and add cherries, and simmer until the cherries are hot.  Remove from the heat and add brandy.  

Fill hot jars with cherries, leaving 1/2 inch head space.  Cover with hot syrup, wipe rims, and put on lids and rings.  

Process pints in a boiling water bath for 10 minutes.  At the end of processing time, remove the canner from the burner and let the jars rest for 5 minutes before removing them for cooling.  

Source: The Ball Blue Book guide to preserving.

Question: Can you explain why reheating potatoes can make them harmful to eat?

Answer - The problem with reheated potatoes is not the reheating process, but how you store the potatoes after they are cooked. If they are left to cool at room temperature and then left unrefrigerated, conditions may be right for the growth of Clostridium botulinum (botulism), especially if they are sealed in foil so that oxygen is kept out of the potato. This has actually happened in a few cases.

Question: Hard cider fermentation problems. Cider blew its top!

I have an unusual question for you. A man called for his friend. Seems his friend tried to make some hard cider and blew the lid off of his barrel! Anyway, the guy wants to stop the fermentation process before he gets to the explosion part. This man went to buy boric acid from a pharmacist, and thus, the pharmacist has called me. Got any suggestions?

Answer - It sounds like he has not given the cider sufficient time to completely ferment before sealing. He should measure the sugar content with a hydrometer and periodically take measurements as it ferments until the readings level off to a minimum value. Or he can attach a tube to a fermentation vessel, allowing the escaping gas to bubble through a water trap. When the bubbles stop, the cider is done. At this time, the sugar has been fermented into alcohol and very little additional CO₂ will be generated.

Question: Is it safe to make apple butter in a copper kettle that had been lacquered on the inside?

Answer: Most decorative copper pieces are factory-coated with a protective lacquer that keeps them from turning green. If you are planning to use a copper kettle or large pot for cooking, such as preparing apple butter, the lacquer must be removed before using. To remove lacquer, place the item in 2 gallons of boiling water to which 1 cup of washing soda has been added. The lacquer should peel off. An alternate method to remove lacquer is to rub with a cloth saturated with acetone or alcohol. Do this in a well-ventilated area and be very careful to work far away from open flames. Wash the kettle thoroughly with soapy water before using.

There is some evidence that small amounts of copper can dissolve during cooking and get into the food. Although not likely to be at toxic levels, it's a good idea to switch to stainless steel cookware to make apple butter.

Question: Are canned foods unsafe to eat if the can is dented?

Answer - Minor denting across the face of the can is not a problem. But when damage occurs where the lid seals to the body of the can, leakage and entry of spoilage microorganisms into the can can occur. It's best to discard these cans.

Question: Are carrot tops safe to eat?

Answer - Most people throw them out or compost them. However, some use them safely in soups or cook them in the same way as other greens to make them more tender and to reduce bitter flavors.

Question: What are ways to preserve elderberry juice?

Answer - Elderberry seeds, leaves, and stems contain compounds called cyanogenic glycosides that, under the right conditions, can produce cyanide. Therefore, eating raw berries or juice made from them is not recommended. Fortunately, cooking the berries destroys these glycosides and makes them safe to eat. Water bath canning elderberries would satisfy the heating requirement. However, some studies suggest that the pH of elderberries can be higher than 4.6, and we currently do not have a research-tested process for water bath canning elderberries or elderberry juice. It is safe to freeze the raw berries or juice, but once they are thawed, they must be boiled to make them safe.

Penn State Master Gardeners have shared a recipe for elderberry syrup that is made from sugar, citric acid, lemon juice, and the flowers of the plant. We are also aware of recipes for alcohol based extracts or tinctures from elderberries that are claimed to have health benefits. However, we are not aware of any research on the glycoside content of elderflowers or whether there are any health benefits.

As we wait for further research on the preservation of elderberries, your best bet is to remove any seeds, leaves, or stems and then bring the berries or juice to a boil before consuming. 

Question: Is it safe to reuse food packaging materials?

Answer - Here are some tips from the University of Illinois Extension.

1. Packages from products other than food should never be used as food containers. They have not been tested for safety with food systems, and they may contain small amounts of nonfood residues. (For example, do not use plastic laundry detergent buckets for storing dry cereal.)


2. Glass can be reused for all foods and for all processes. This is true regardless of what food was packaged in the glass container. There is an exception to this rule: single-use glass jars should not be used for pressure processing in the home canner. The lid or cover, however, is subject to recommendations discussed below (number 3).


3. Reuse packaging materials only with the following:
   • Foods similar in acidity and in sugar, fat, or alcohol content to the food originally packaged in the material. Do not use a plastic shortening container to make salad dressing containing a substantial amount of vinegar.
   • Foods that will be exposed to the same types of processes. Do not melt butter in the microwave oven using a plastic margarine container. In general, do not subject food packages to heat unless the instructions on the original package give heating information. Many food products are “hot-filled" into containers at low temperatures. These packages will not tolerate heating.
4. Do not reuse porous packaging materials such as paper, paperboard, and expanded foams (for example, Styrofoam cups and foam meat trays). They have air spaces that will harbor food particles and microorganisms.
5. Do not reuse microwave packages that contain “heat susceptors" for browning or crisping. The adhesives that hold the susceptor to the package may be damaged by the original use. The material is more likely to migrate into the food if used again.


6. It is better not to store foods with strong odors or flavors in reused food packages; the packaging material might absorb the chemicals that produce the odor or flavor and release them into a subsequently stored product. Additionally, some packaging materials allow certain chemicals to pass through them, transferring odors or flavors to other foods stored in the same area.



Question: Are green potatoes safe to eat?

Answer - When potatoes are exposed to light, metabolic activity in the skin increases as it prepares to send out shoots. As a result, chlorophyll is formed, which provides the green color. Another product formed is solanine, which is a glycoalkaloid toxin. It has a bitter taste and can irritate the gastrointestinal tract. If enough is eaten, it could cause vomiting and diarrhea. Because of the bitter taste, it is rare for someone to eat enough to actually get sick.

Small green spots can be trimmed off. But if more extensive greening occurs, throw the potato out.

The tendency for potatoes to turn green and form solanine varies among varieties. To prevent this from happening, inspect potatoes at the store before purchasing and store them at home in a cool, dark place with good air circulation.

Question: How can one make butter at home?

Answer - For a small amount of butter, place 40% fat cream into a glass jar. Leave sufficient room for the product to be agitated. Warm the cream up to about 60°F and then begin shaking the cream. In a while (time undefined), the cream emulsion will break, and butter "granules" will start to form. Once the butter granules begin to form, continue mixing, but don't mix too vigorously or you will "whip the butter" and make it difficult to handle. When it appears the butter granules have reached a maximum size, pour off the milk liquid (buttermilk). Now wash the butter particles with cold water. To wash them, add cold water and work them together with a wooden spoon. Wash several times (3-4) until the buttermilk is clear or just slightly cloudy. At this point, separate the butter from the buttermilk. You may use the buttermilk in soup or baked goods. If you want to salt it, add 0.5-1% salt and work it into the butter mass. 

Raw cream or fat from raw milk should never be used without prior pasteurization.

Bob Roberts, Penn State Food Science

Question: I am concerned about pesticides in my food. Is this something I should be worried about?

Answer - The issue of pesticide residue in food is quite controversial. Pesticides are used because they have beneficial properties in terms of crop production and yield. With the use of pesticides, farmers can maximize their efforts in the field, thus minimizing the cost of the produce to the consumer. Yet, pesticides are used by farmers to prevent fungal invasion, insect damage, and the growth of unwanted (and sometimes poisonous) weeds. This has a positive benefit in terms of public health because fungi, insects, and non-crop plants can contaminate crops with many natural toxins.

Pesticides are probably one of the most regulated chemical products used in the U.S. Several major organizations regulate the use of pesticides. These include the Environmental Protection Agency, the Food & Drug Administration, and the U.S. Department of Agriculture. There are more than 14 separate regulations governing the use of pesticides. All of these regulations are in place to help protect human health.

Despite the many regulations, pesticide residues are found in our food supply. Because residues are an inevitable by-product of pesticide use, many of the current regulations are in place to address the public health implications of pesticide use. Therefore, there are very strict restrictions on the amount of pesticide residues that are allowed in food.

One of the regulations that is currently in place requires that pesticide manufacturers conduct toxicity testing on the pesticide before it can be permitted for use on products either directly or indirectly destined for human consumption (this includes animal feed). This toxicity testing not only determines the health effects of pesticides, but also the level at which there are no toxic effects on the most sensitive population (i.e., children and the elderly). This 'No Toxic Effect Level' (NOEL) becomes the basis for the permitted residue limit. The regulations set the permitted residue level at a level that is from 10 to 100 times lower than the NOEL. Furthermore, if a pesticide is tested and a NOEL can not be determined, then it is unlikely to be permitted for use on food crops. This helps ensure that if a child or adult eats a greater-than-normal amount of a particular food, or several different foods with the same or similar pesticide residue, they will still not reach the level of exposure required for a toxic effect to occur, even if they are more sensitive than the general population.

So, while pesticides may be found in many products, the levels at which they are present fall far below the levels that may cause any health effects. The fact that they are found at all is only due to the significant advances in analytical chemistry. The tests are now so sensitive that the detection level that can be easily reached is equivalent to detecting one teaspoon of salt in one million gallons of water. Levels even lower than that can sometimes be detected. The mere presence of a trace amount of a pesticide does not mean that the product is unhealthy. On the contrary, eating a diet full of a variety of fruits, grains, and vegetables has been shown to significantly decrease your risk of a variety of health problems, from high blood pressure to cancer. Variety is the key to good health.

From: The National Institute of Environmental Health Sciences (NIEHS) is one of 27 Institutes and Centers of the National Institutes of Health (NIH), which is a component of the Department of Health and Human Services (DHHS).

Question: Is it safe to reuse oil used for frying?

Answer: What is the proper food safety for handling deep-fat frying oil? Allow the used oil to cool completely before pouring it into containers for refrigerator or freezer storage.

Leaving used oil out at room temperature for 1-2 days is not recommended because bacteria can grow on the food particles. Therefore, strain the cooled oil each time it is used to remove larger food particles and to prevent them from charring during subsequent frying. According to the USDA Meat and Poultry Hotline, used oil can be stored in the refrigerator for up to a month or placed in the freezer for longer amounts of time. Don't reuse the oil if foaming occurs during heating, changes color (darkens or lightens) during heating, or acquires an off flavor or odd odor.  Restaurants should follow state or FDA regulations for handling oil.

Question: I read that kidney beans are harmful when eaten raw. What is the danger to children?

Answer - Red Kidney Bean Poisoning is caused by a toxic agent called phytohaemagglutinin (Kidney Bean Lectin). Different types of lectins are found in many species of beans, but are highest in concentration in red kidney beans. The unit of toxin measure is the hemagglutinating unit (hau). Raw kidney beans contain from 20,000 to 70,000 hau, while fully cooked beans contain from 200 to 400 hau. White kidney beans, another variety of Phaseolus vulgaris, contain about one-third the amount of toxin as the red variety; broad beans (Vicia faba) contain 5 to 10% the amount that red kidney beans contain.

Several day care and nursery schools have dry beans (different varieties) out for kids to play with. What danger would there be if a child ate a few of these raw beans?

As few as 4 or 5 kidney beans can bring on symptoms within 1 to 3 hours. Symptoms include extreme nausea, vomiting, diarrhea, and abdominal pain. Some people have been hospitalized, but recovery usually occurs about 3 - 4 hours after symptoms appear.

Lectins are inactivated with cooking, so fully cooked or canned kidney beans are safe to eat. Undercooking may actually increase lectin activity and increase the hazard. This could be a problem when using slow cookers (crock-pots) if time/temperature conditions are not adequate to cook the beans fully. Therefore, when kidney beans are called for in slow cooker recipes, make sure they become tender, or use pre-cooked or canned beans rather than raw beans.

Question: Some stores sell pasteurized cider at room temperature; the label reads "Refrigerate after opening." Is it safe?

Answer - Pasteurized cider needs to be kept refrigerated to prevent the growth of spoilage yeasts and molds. Despite the heat treatment applied, the heat treatment only kills a fraction of the spoilage organisms present. Those that remain may continue to grow if the product is not refrigerated.

Some stores display unrefrigerated cider in the produce aisle. Generally, this cider is severely heat-treated to delay the growth of spoilage microbes, and refrigeration is not necessary before it is sold. However, a "Keep Refrigerated after Opening" label is required. 

Question: Should you rinse poultry before cooking?

Answer - No. Washing poultry risks spreading harmful bacteria. The U.S. federal government guidelines advise cooks not to rinse poultry. The turkey should go straight from the bag to the pan to avoid spreading potentially harmful bacteria, such as Salmonella or Campylobacter, all over the kitchen.  

USDA scientists recommend inserting a meat thermometer into the thigh to ensure the temperature reaches no higher than 180°F. To prevent excessive drying of the meat, others recommend a maximum thigh temperature of 170° F and 160° F for breast meat. 

Some cooks prefer to soak the bird in a salt solution before cooking. Brining may slow the growth of bacteria, but the salt does not completely destroy them. Therefore, carefully transfer the salted bird to the oven to prevent cross-contamination. Thorough hand washing with hot water and soap is also important to prevent cross-contamination, especially when handling ready-to-eat produce or food that has been cooked.

From: The National Post, December 24, 2004

Question: How safe are home-grown sprouts?

Answer - Commercially grown sprouts have caused foodborne illness in populations with reduced ability to fight off illness (the very young, the elderly, and those taking immune-suppressing drugs). Those in this group are advised to only eat cooked sprouts, not raw. The recommendation for at-risk people not to eat raw sprouts stands since contamination, if it does occur, happens before the seeds reach the consumer. It doesn't matter how they were sprouted.

Read What You Should Know about Sprouts

Question: Is there a food safety concern about soaking dry beans overnight before cooking?

Answer - It is possible that vegetative pathogenic microorganisms could grow to harmful levels during soaking. However, the high temperatures required to cook the beans would be sufficient to kill them. However, spore-forming bacteria or toxins produced by bacteria might survive the cooking process. To be safe, use the quick soak method: Bring water and beans to a boil, cover, and simmer for 2 minutes. Then, remove from heat and let stand 1 hour. Immediately drain and further cook. Another option is to soak the beans in the refrigerator overnight.

Question: Why does "higher fat milk" last longer than skim milk in the refrigerator?

Answer - It is unlikely that refrigerated milk actually turns sour (that is, fermented by cold-loving (psychrotrophic lactic acid bacteria to make buttermilk) since this doesn't occur at low temperatures. It is more likely that the other types of bacteria have grown to high enough levels to curdle the milk and produce bitter flavors.

There are two or three potential reasons why the skim might "go off" faster. First, the rate of spoilage depends on how often it is in and out of the refrigerator. If the skim is out more often than the fat-containing milk, it would spoil faster. Second, because of the lack of fat in the skim milk, any small changes in flavor are noticed earlier than with high-fat milk. It is also possible that free fatty acids (naturally present in the fat-containing milk) act as natural preservatives in the system.

Note that the above answers assume you purchased these products at the same time, that they have the same original date of manufacture (or sell-by date), and were manufactured by the same company.

Bob Roberts, Associate Professor of Food Science

Question: I heard that Ziploc plastic bags can make omelets in the microwave. Is this a safe practice?

Answer - Cooking foods in Ziploc, or other brands of plastic bags, is not a recommended practice. This is because the material is not designed to withstand the extreme heat of boiling, and plastic compounds could leach into the food. Use plastic containers only for the use they were intended.