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Why do you recommend processing jams and jellies?

puttingjarinBWBUSDA and the Cooperative Extension recommend a boiling water canning process for jams and jellies even though some entrepreneurs or small batch processors are told to just fill the jar hot and close it. Why? Some other sources say processing isn’t necessary for any home canning of jams and jellies — just fill the jar hot and close it. Some others will say to invert the jar (turn it upside down) after putting the lid on, with various numbers of minutes recommended for this inverted position. Why?

A “process authority” advising someone packing jars for sale may indeed not recommend a boiling water process, but then other controls should also be specified for the particular recipe and full preparation procedure, such as a measured minimum hot fill temperature with every batch, specific acidity levels that would allow for no process with that specific product, perhaps measured and documented water activity control or degrees Brix for each batch that allows for no processing, and/or specific processing steps that would support this recommendation. Home canning recommendations for the general public have to cover a wide variety of recipes and methods of cooking the jam or jelly.

Even with a very acid fruit jam or jelly that has good water activity control, there can be some benefits to even a short boiling water process if food safety isn’t the reason. For one thing, molds can be airborne and settle into your jars at filling. The retained heat from filling jars in many home situations may not be enough to kill airborne mold spores. The goal in this case for a boiling water process would be to minimize the risk of spoilage during storage and thereby prevent “economic loss” by product having to be thrown out. Many larger scale commercial operations, in addition to tighter batch-to-batch cooking and filling temperature controls, have equipment systems that force an injection of superhot steam into the headspace before the lid is placed on the jar. This helps with closing temperature, but also forcing air out of the headspace.

So that leads to a second benefit to the home boiling water process. With a properly applied lid, the processing helps force some of the retained air of the headspace in jar. When the jar then cools after processing, this evacuated headspace can lead to better vacuums in the sealed jars (if lids are applied correctly) than just hot filling. Not all vacuum seals are equal. A jar may seal with a weak vacuum. A weaker vacuum is related to more occluded (trapped) air, and therefore oxygen, in the headspace of sealed jars. That oxygen can lead to discoloration and possible flavor changes over time, so quality retention is often better with a processed product than one just hot filled at home.

Finally, one of the considerations discussed when USDA was making recommendations is the potential for burns or leaking jars with the inversion process vs. a boiling water process. Although not in published journals or other sources, there are documentations from some research experiences that leaking and failure to seal are higher risks with inversion than processing. I have read one journal article using inversion that caused the researchers to abandon it in their future studies because of leaking and needing better control of temperature for safety reasons with their particular recipes. Other concerns with inversion include individual variation in practicing this procedure or that unexpected interruptions can result in delays between filling jars, getting lids screwed on, and inverting the jars. If the product cools down too much, the temperature of the product can become low enough to no longer be effective in sealing jars or preventing spoilage. Not ALL jams and jellies/spreads even fit criteria for even a 5 or 10 minute boiling water process; they might need a longer process!

USDA made the decision to recommend processing for all jams and jellies and very acidic foods for reasons of preventing economic loss and physical injury from burns as well as food quality during storage, even if it might not be needed for food safety.   We in Extension consumer education firmly believe the best practice to recommend even for very high acid foods is a boiling water process vs. hot fill only and inversion even though the other may be successful and safe for some food products.

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Summer is a Good Time to Think About the Cold

Why do we emphasize storing frozen foods at 0 degrees F? Even though other freezer temperatures can stop the growth of microorganisms, quality will continue to be lost even at these cold temperatures. The recommended shelf life listings we have for frozen foods are based on a storage temperature of 0 degrees F. and expected retention of good quality. Warmer temperatures, even though the food may still be frozen, will result in shorter retention times for quality.

Even though blanching for specific time at a given temperature is recommended to inactivate enzymes, oxygen around the food as well as the dryness of the air in a freezer will cause other quality losses. And foods that are not blanched, or are inadequately blanched, will have active enzymes. Enzymatic and oxidative changes in stored food will occur more slowly at freezer temperatures than higher ones, but they still will proceed. One chemical reaction that will proceed, even though slowly, in the freezer is oxidative rancidity of fats (including those contained within meats, poultry, etc.).

Another way to protect quality of frozen foods is to achieve a fast rate of freezing. The faster that the water in foods gets frozen, the more protective for quality. Fast freezing promotes the formation of smaller ice crystals than slow rates of freezing. The smaller the ice crystals, the less damage done to cell walls and the texture of foods.

Fast freezing can be promoted by making sure hot or warm foods are completely cooled before putting them into the freezer, using small package size, and then spreading your packages out within the freezer until the food is frozen. The packages can then be stacked or arranged together if you wish, but while they still becoming frozen, make sure the cold air can surround all sides of the package. It is a good organizational plan to package your foods into suitable serving sizes anyway, but a good rule of thumb to promote fast freezing is to keep each package size fairly small. If you know you will be placing a large quantity of foods into the freezer at once, consider setting the temperature control of your freezer to -10 degrees F. or lower about 24 hours in advance. Usually about 2 to 3 pounds of food per cubic foot of storage space can freeze within 24 hours.

Speaking of freezing foods that are first blanched or cooked, make sure they are completely cooled before even putting them into your freezer containers or bags, also. An important reason is to promote quick freezing once inside the freezer for food quality and energy efficiency; however, another reason is the size of those ice crystals again! Moisture that condenses on a lid or sides of a package from hot steam will lead to quality-damaging large ice crystals inside the package.

Freezing food is an excellent way to preserve the freshness in most foods, as well as the nutrients, colors and tastes. However, there are best practices to make sure these advantages are realized. For more readings on this topic:

Freezing Pointers: http://nchfp.uga.edu/how/freeze/pointers.html

General Shelf Life of Frozen Foods: http://nchfp.uga.edu/how/freeze/freezer_shelf_life.html

How to Freeze Specific Foods: http://nchfp.uga.edu/how/freeze.html

Frozen Shouldn’t Mean Lack of Action

I have a confession to make. No, it’s not that I’ve been silent on this blog site for 11 months. Our followers know that, and I am sorry.  My confession is that despite my teaching others to manage their inventory of frozen foods well, it turns out I am not a good example this month.

IMG_1781For the past few weeks I’ve had to clean out some freezers in our food preservation lab. Some foods were missing labels and dates and others obviously had been poorly packaged (but just a few of them, really!).  I am sure the intent of our workers had been to take care of an immediate need cleaning up after a workshop or late night experiment. But the outcome was that no one had gone back very quickly and corrected the situation.  And that chest freezer, where there was not a great demand on the space, had become quite unorganized and full of really old and some freezer-burned food near the bottom.

Now I want to clean out my home freezer so I can buy a new one. The labeling of packages is in much better situation at home. However, I am finding some that “got lost” and pushed to the back of this upright.  They are older than should still be in there.  So here is my message for beginning of summer.  This article starts a short series on freezing of foods.

Freezing is a great food preservation method, especially for being able to store uncooked, or barely cooked, foods that can be used in many ways when thawed. I am dreaming of the fresh strawberries now in our fields, and the blueberries, blackberries and other fruits to come this summer.  If frozen without sugar and tray-frozen before packaging, I know I can decide later whether to make jam, syrups, cobblers or pies. However the quality of foods in the freezer will deteriorate over time.  Certain practices can better preserve that quality.

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Choose packaging (e.g., bags, wraps, boxes or jars) that will prevent moisture loss from the food. Moisture and oxygen can pass through some packaging material itself and of course through poorly connected lids and seals. Drying of food surfaces (i.e., freezer burn) results in poor quality texture and taste. Best packaging also prevents transmission of odors within the freezer. Most people prefer bags and wraps, although glass jars and rigid plastic freezer containers with tight seals keep food quality very well. Choose plastics and foils that indicate freezer quality and weight (versus just those marked “food storage”). Not all plastics and foils are the same in the way they allow or block transmission of moisture and oxygen.

Whether you choose boxes, bags or wraps, make sure all seals and folds are very tight and prevent air loss or entry. Boxes with snap-on lids and jars with twist-on lids are not all the same, either. Snap-on lids should have a deep and tight overlap of the lid channel for sealing and the top rim of the bottom part.  Twist- or turn-on lids should have some type of gasket to prevent air gaps.

freezerheadspaceThe shape and type of package, as well as type of food, can also influence how much headspace is needed. Headspace is empty space between the food and top of the container (or bag) that allows room for expansion as water in the food freezes to ice.  But, too much air left in the package is not good for food quality.  See guidelines for headspace at our website.  More about packaging  is written here.

After packaging your food, label it with the food type and date. Then, actively manage your inventory. One option is to make a table or chart of foods going in your freezer by date that can be checked off as your remove items. Paper and pencil work as does one on a tablet or computer. (Some of you may be lucky enough to have built-in computer technology on your newer freezer!)  If you are not a person to keep up with lists, at least re-organize your inventory when you add new foods. Put the newest foods toward the bottom or back and bring older foods toward the front or top.  Labels should be easy to read and follow.  Find a system that works for you.  It’s a shame to waste good food, let alone the time and expense of packaging you put into preserving your food.

In my next article, I’ll cover some other tips for successful freezing. You can also read more at the National Center for Home Food Preservation website, under “How Do I…..Freeze.”

Oh, and actually, that lab freezer still will be storing some of that freezer-burned food. I need those example for the next class I’m teaching or photos!  But your own, real food supply, like mine, shouldn’t include those items.

It’s Berry Season!

Some of us are in the middle of it, some have seen strawberries come and go for this year, and some of us are still waiting for blueberries. Berries are a favorite for jams, whether a full flavor using one berry, or in combinations that allow our creative streak to show.  Strawberry-raspberry, blueberry-blackberry, or even 3 or more berries in combination.  Yum! As I write this, I’m past my morning breakfast decisions but now my mind is thinking ahead to what I can stir into my yogurt at lunch.

Another way to preserve our delicate, hand-picked berries is by freezing. Now we can start thinking about future pies, cereal toppings, or a quick, refreshing smoothie.

A dry pack is simply placing clean berries in freezer containers, sealing the container, and freezing. Unless they are tray packed (see below), they might clump together and be difficult to separate into individual berries.  Note:  If you do wash blueberries before freezing, dry blueberries completely after rinsing, or else the moisture on the blueberry skin will cause tougher skins.

A tray pack works well to help maintain the shape of each individual berry and keeps them easy to remove from the container and separate from each other. This method is called a tray pack because after rinsing the berries, you spread them in a single layer on a shallow smaller_Blueberry tray close-uptray (like a cookie sheet), then carefully lift the tray into the freezer without causing berries to touch each other.  As soon as they freeze, seal the berries in an airtight container and place them back into the freezer so they don’t get freezer burn.

A sugar pack is like a dry pack but with one extra step – gently mix ¾ cup sugar per 1 quart (1⅓ pounds) berries before filling into freezer containers, sealing, and placing in the freezer. You can view step-by-step directions and photos for a sugar pack by selecting the PowerPoint presentation under “Strawberries” on the National Center’s ‘Freezing’ page.

A syrup pack surrounds the berries in a sweetened liquid, changing the sweetness and texture of the berries quite noticeably. Based on the natural sweetness of the berries and your own preference, you can decide the proportion of sugar to water from very light syrup (10% sugar) to very heavy syrup (50% sugar).  More tart berries may produce the most desirable flavor from using a 40%-50% syrup.  Exact proportions for the range of syrups are listed on this Syrups chart, along with directions to make the syrup and notes about replacing part of the sugar with corn syrup or honey.

Crushed or puréed is an option for berries like blueberries and huckleberries that you might use an ingredient in other recipes. The berries can be crushed, pressed through a fine sieve or puréed in a blender or food processor.  Mix 1 cup (or 1⅛ cups) sugar with each quart (2 pounds) of crushed or puréed berries.

IMPORTANT! If you add sugar to the berries before freezing (as in the sugar pack, syrup pack, or crushed/puréed), then label the container with exactly how much sugar you add, so that you can include that quantity as part of the amount of sugar called for on the ingredient list of your final product recipe.  If you know you want to use the fruit in jam later, you can also measure the amounts of sugar and fruit now for a specific recipe and freeze those together; then use the total contents when thawed to make the jam.

For all types of pack, remember to leave at least ½-inch headspace (more for some styles of pack; see chart for exact measurements) between the berries and the lid of each container so that the containers don’t break open while expanding in the freezer.

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And most importantly, protect your fragile berries with the right kind of packaging for freezing. You don’t want the air inside the freezer to dry out your packs, or for flavors from one food to mingle with others. Freezer-weight plastic bags with good tight seals are a must if going the bag route. Glass jars with straight sides or wide mouth openings, plastic freezer boxes or re-purposed plastic tubs from frozen whipped toppings work well (as long as the seal between the lid and bottom is still intact and not misshapen from use).