Zucchini is one vegetable that seems to grow prolifically.  Come fall and many gardeners have an abundance of zucchini they don’t know what to do with.  Zucchini, because it doesn’t have a particularly strong flavor, is actually a very versatile veggie that can be used in cakes, cookies, muffins, and jams as it lends itself to pairing well with other flavors like chocolate and citrus flavors, for example.

Another recipe I like to use fresh zucchini in is this one for Zucchini Jam.  It is a great spread on toast, biscuits, muffins and scones, or as a dollop on vanilla custard for an easy dessert.  Its bright orange color makes it a showy jam.

TIPS FOR SUCCESSFUL JAM MAKING

 Get Organized

Jam making is a sequential process and it pays to take the extra time to first get organized. The first step is to read and re-read the recipe to ensure complete understanding of the process and that you have all the necessary ingredients and equipment.

The second step in organization is to assemble all equipment and ingredients needed for the jam-making and canning processes. A list of equipment and utensils needed to make the jam can be found further down in this post.

The third step is to start the bottle sterilization process and heating the water for the hot water canner before beginning to make the jam.

Follow the Recipe Exactly – No Substituting, Omitting, or Altering Amounts of Ingredients

For success, follow the recipe exactly, without substituting, omitting, or altering amounts of ingredients (unless an ingredient is listed as “optional”). Each ingredient contributes something valuable to the finished product. For example, it is well-known that jam recipes call for a lot of sugar. Some will ask if they can significantly reduce the amount of sugar called for in a recipe and the simple answer is, no, not without potentially affecting the gelling properties of the jam and sacrificing the quality and preservative functions of the jam. Apart from the sweetness sugar imparts on jam, it also acts as a preservative, protecting the jam against the development of bacteria, yeast, and mold. It is, along with the hot water processing of the jam, what will make the jam shelf stable for several months.

Fresh, not frozen, zucchini is recommended for this recipe as frozen zucchini will have accrued excess moisture which may cause issues and interfere with the jam gelling process.

Use Only Proper Canning Jars for Jam

Ensure that proper canning jars, approved for hot water processing, are used for the jam. These are bottles such as Mason or Ball brand jars that are made of specially tempered glass capable of withstanding heat that will be necessary in the hot water canner for safe home canning of products. The glass jars have a wide mouth top and consist of a two-part lid and screw band/ring. Exercise caution purchasing jars, that look very much like canning jars, at places like discount stores or thrift/second hand shops as they may not, in fact, be tempered glass suitable for canning.

While previous generations may have used just any old bottles they had at their disposal, using recycled bottles from store-bought products like pasta sauce or bought pickles, for example, is not recommended for food safe home canning. First, these jars, having already been sealed by the manufacturer and the seals having been broken by the consumer to reveal the jar contents, no longer have proper sealing covers considered safe for home canning of products. Second, the bottles are generally made of glass not as thick as proper home canning jars and, therefore, are not considered to be resistant to heat extremes. This means they could shatter or explode when placed in the hot water canner.

With the potential for so many air- and food-borne illnesses to occur today and with the changing conditions in which our foods are grown (or modified), along with the fact that most homes today do not have dedicated temperature-controlled cold rooms (or cold cellars like many of our ancestors had) in which to store home canned goods, it is all the more reason why both the proper canning jars and home canning procedures are an essential component to jam making. Do not skip the proper bottle sterilization and hot water canning processes.

Sterilizing the Jars

I recommend the traditional method of sterilizing the jars in hot water as it allows better control of the timing of having the hot jars ready at the express moment the jam is ready for bottling. The jars must be hot when they are filled with the jam as they will be immediately going into the hot water canner of boiling water and cold jars are likely to crack.

Approximately seven to eight (7 – 8) half-pint sized glass canning jars will be required for this recipe. I recommend preparing for eight (8). Begin by inspecting each jar before using it to ensure there are no chips or cracks.

Since this jam involves a quick cooking process, you will want to get the jar sterilization process underway before you start cooking the jam. It takes longer than you might think to get a big pot of hot tap water filled with jars to the boiling stage.

Wash the jars in hot soapy water. Rinse well and drain jars. Fill a large-sized pot (fitted with a wire rack to keep the jars up off the bottom of the pot), capable of holding at least 8-10 half-pint jars upright (more jars if two canners are needed). Do not stack jars, one on top of another. Place the jars, upright and in single layer, into the water. Ensure the jars are fully submerged, each jar filled with water, and that the water is at least an inch over the tops of the jars, adding more water if necessary. Cover, bring to a boil, and boil gently for 10 minutes. Turn off heat and leave the jars in the hot water to have ready to fill once the jam is ready to be bottled.

Because so many factors can determine exactly how many jars will be needed to accommodate the jam, I recommend having at least one to two extra jars sanitized in case they are needed. Even if they aren’t needed to be filled with jam, the hot empty jars may be needed to fill up space in the hot water canner if it is not completely filled to capacity with jars containing the jam. This is to ensure that the filled jars do not topple over during the hot water processing. Note that, if two canners are needed to process the batch of jam, more hot empty jars will be required to fill canners to capacity.

To protect your countertop from the hot wet bottles and jam drippings, use a heatproof cutting board covered with newspaper to protect the board. Set a wire rack on top of the board as a base for the hot jars to sit.

Lids and Screw Bands/Rings

The metal lids for the canning jars are only intended for single use and are NEVER to be reused for canning food. Always, always use new lids for each canning session. The lids are inexpensive so don’t risk re-using them. Once you finish a bottle of jam, turf the lid. The screw bands/rings, on the other hand, can be re-used so long as they don’t have any rust spots on them or any dents.

While, historically, the lids (with the orange-rust colored gasket on their underside) were preheated in simmering hot water for 1-2 minutes to soften the lid gasket before applying the lids to the hot jars, Bernardin® (the company that manufactures canning lids available here in Canada) is now saying that preheating their own particular brand of lids is no longer necessary to provide a proper seal as the sealing compound they use in their lid manufacturing performs better at room temperature. They recommend washing the lids in hot soapy water, rinsing them, and setting the lids aside until needed in the canning process.

Note this pertains specifically to the Bernardin® brand of lids. Other manufacturers’ lids may differ so, if you are using another brand of lids, do check the manufacturer’s instructions with respect to heating lids or not for their particular brand lids. Typically, if the lids need to be preheated, the method is simply to place the lids in a small pan of simmering hot water over low heat just long enough to heat the rubber piece. This won’t take longer than a minute or two at most. Do not boil the lids.

Filling the Jars with Jam

When the jam is ready to be bottled, use a jar lifter to remove the hot sanitized jars from the water and carefully empty out the hot water back into the stock pot. Drain jars well and transfer them, upright, to the wire rack on the heatproof board. Do be very careful as this is scalding hot water.

Immediately use a heatproof glass measuring cup or ladle to scoop up the jam and transfer it into the hot sterilized jars. A wide-mouthed funnel is useful for this process. Fill the jars, leaving about ½″ headroom in each. Do not let jars cool before filling with the hot jam.

Remove any air bubbles that may appear in the jars by inserting a chopstick or small heat-proof spatula into each bottle and gently moving the jam to remove any pockets of air that may have formed. Add more jam, if necessary, to bring the jam up to ½” from jar rim.

Make sure the rims of the filled jars have been wiped with a clean damp cloth to remove any jam residue. Even a small drop of it may prevent the lids from sealing properly and keeping out harmful bacteria that could cause the jam to spoil or someone to become ill from consuming it.

Center the washed and rinsed lids on jars so the sealing compound on the lid edges aligns with the jar rims. Once the jars have been filled with jam, fingertip tighten ring/screw bands on jars until resistance is encountered. Do not over-tighten.

Hot Water Processing of Filled Jam Jars

The jars of hot jam need to immediately be processed in a hot water bath to ensure that any microorganisms are destroyed and the jam is shelf-stable for several months. At its most basic, home canning of jam is the process of heating the hot sealed jars of jam in a canner of boiling water to destroy microorganisms that can cause the jar contents to spoil or people to become ill from consuming the contents contained in the jars. The process of hot water canning also gives the jam shelf stability over several months. Note that hot water processing times vary according to the altitude of the area in which you live and, of course, the size of jars used. The processing time indicated in this recipe are for half-pint sized jars and for altitudes up to 1000 ft (305 m).

As mentioned above, with the potential for so many air- and food-borne illnesses to occur today and with the changing conditions in which our foods are grown (or modified) and stored in homes, proper home canning procedures are an essential component to safe jam making. Do not skip the proper hot water canning process for this jam.

Canners come in different sizes and depths to accommodate different sizes of jars.  The canner must have the capacity to hold jars the size and number called for in a recipe and allow for boiling water to cover the jars by 1″ when they are placed in the canner basket inside the canner. This recipe can be expected to yield 7 – 8 half pint jars so you will need to check your hot water canner’s load capacity. If it cannot accommodate this number of jars then two canners will need to be operating at the same time as the jars of hot jam have to be hot water processed as soon as they are filled and must not be allowed to cool down before going into the canner.

Here in Canada, hot water canners are relatively inexpensive and can usually be found at stores like Walmart, hardware stores (e.g., Home Hardware and Canadian Tire) as well as some large supermarkets and other places.

For any one wishing to learn more about home canning, there are a number of reputable and reliable sources of information available on the current proper methods of canning. Books on the topic are available at libraries, bookstores, and online. The internet is also a good place to start your research but do ensure you consult reputable sites. I find, for example, a lot of university extension department websites contain good information on proper home canning procedures as do canning jar and lid manufacturing sites.

Before beginning to make the jam, fill the canner(s) about one-half full of hot tap water and, over medium-high heat, bring the canner water to the boiling stage to have ready when the jam is finished and ready for its hot water bath. Reduce heat to keep the water hot while the jam is being made.

It’s also a good idea, while the jam is cooking, to get a kettle of boiling water ready in case extra is needed to top up the canner after the filled jars are added. The hot jars of jam need to immediately go into the hot water bath as soon as they are filled so, after the jam is bottled, there will be no time then to start boiling the canner water which can take a significant period of time.

Note that I recommend adding 1 to 2 extra half-pint jars to the pot with those being sterilized for the jam. While they may not be needed to fill with jam, they may be needed (depending on the canner size and design) to fill up extra space in the canner basket so those jars filled with jam do not topple over in the hot water process. Most canner baskets will hold 6 – 7 half-pint jars and, if a batch of jam has less quantity than that, the bottles will fall over unless the basket is filled with bottles.

This particular batch of jam should yield approximately 7 – 8 half-pint jars so it is likely that there will be enough filled bottles for a full load in the canner but it is always difficult to say, with exact assurance, the precise quantity of jam a recipe will yield – it could be a bottle or two less or more. The exact amount of jam is difficult to predict with 100% accuracy as it depends on many factors including the age and quality of zucchini, how fine/coarse the zucchini is grated, how loosely/firmly the grated zucchini is packed for cup measurement, the stove temperature at which jam is cooked, etc. For this reason, I do recommend having 1-2 extra jars ready to fill up the canner space, if they are needed. While the empty jars for this purpose do not need to be sanitized, they must be hot going into the boiling water in the canner as, otherwise, the temperature change could cause cold jars to crack when they are submerged into the boiling water. The easiest way I find to heat them is to simply put them in the pot with the jars being sterilized.

Using jar lifter tongs, carefully place filled jars upright and in a single layer in the wire basket or rack positioned in the canner, ensuring jars do not touch each other or fall over.  If a canner is not completely full to capacity of filled jars, add one or more hot empty jars, upright, to the basket to fill up space so the filled jars do not topple over during processing. Should this be necessary, let the empty jars fill with water from the canner as they are submerged.

Ensure the water level is at least 1” above the tops of jars, adding more boiling water as necessary. When it gets to this stage in the process, I recommend having a kettle of boiled water already available should it be needed to top up the canner water levels.

Cover the canner with its lid. Increase the heat to return the water to a full rolling boil then decrease the heat to just keep the water at a moderately rolling boil but not boiling over. Process the half pint jars in the hot water bath for 10 minutes, adjusting time as and if necessary for altitude. Start timing the processing from the point at which a full rolling boil is reached after jars have been added to the canner. At the end of the processing time, turn off heat and remove canner lid. Note that, if jars used are a different size than the half-pint size called for in this recipe, this will affect the hot water canning times and adjustments will need to be made.

Let jars sit in the hot water for 5 minutes then, using jar lifter tongs, carefully remove the jars filled with jam, one at a time, upright, and transfer them to a heat-proof cutting board, that has been covered with a towel to protect it, to cool completely. Listen for the “pop” or “ping” sound as the bottles seal over the next few minutes or hours. The lids of properly sealed jars will curve downward.

Check Processed Jars for Proper Sealing

Let jars rest, undisturbed and covered with a towel to keep light out, on counter for 24 hours. Then, test each jar for proper sealing by lightly pressing down on the center of each jar lid. If the lid is already pressed downward, and does not pop back up, it is properly sealed. Any jars that do not pass this test should be refrigerated and the jam used within a week or so.

Storing Jam

Store properly sealed jam bottles in cool, dry, dark place and let rest for at least 1 -2 weeks before opening to allow flavors to develop. Use jam within one year of bottling. Refrigerate jam once jar has been opened.

Zucchini Jam

Supplies and Equipment Needed:
8 half-pint glass canning jars for the jam (plus several more half-pint-sized jars to take up extra space in the canner basket, if needed, during the hot water process)
8 – two-piece lid and screw band sets (lids must be brand new and NOT previously used)
Grater or food processor for grating zucchini
Measuring cups for measuring grated zucchini
Heat-proof cutting board(s) and wire rack for sitting hot jars on
Medium-sized, heavy-bottomed, stock pot for jam
Large-sized pot fitted with wire rack for sterilizing jars
Large, heat-proof spoon for stirring jam
Hot water canner(s) with basket or rack
Jar lifter tongs
Wide-mouthed canning funnel
Ladle or heat-proof glass measuring cup
Clean damp cloth for wiping rims of jam-filled jars
Chopstick or small non-metallic heat-proof spatula to remove any air bubbles/air pockets from filled jars
A timer

Ingredients:
6 cups grated fresh zucchini (peel and inner membrane matter removed before grating)
6 cups granulated sugar
1 cup canned crushed pineapple, with juice
3 tbsp bottled lemon juice
1 tbsp bottled lime juice
1 (85g) pkg orange jello powder
1 (85g) pkg lemon jello powder

Method:

Wash canning jars and lids in hot soapy water. Rinse. Drain jars.

Fill a large-sized stockpot about two-thirds full of hot tap water. Fit stockpot with wire rack. Place the jars, on the rack and upright and in single layer, into the water. Use more than one stockpot if necessary to accommodate all jars needed for the recipe. Do not stack jars on top of each other in stockpot. Ensure the jars are fully submerged, each jar filled with water, and that the water is at least an inch over the tops of the jars, adding more if necessary. Cover, bring to a boil over medium-high heat, then reduce heat slightly and boil gently for 10 minutes. Turn off heat and leave the jars in the hot water to have ready to fill once the jam is cooked and ready for bottling.

Check the capacity of your canner. Though it is difficult to say with certitude exactly how much jam this recipe will yield (see Note 1 below), the recipe can be expected to yield 7 – 8 half-pint jars that need to be hot water processed immediately upon them being filled with jam. If your canner cannot accommodate this number of jars all at the same time, two canners will need to be in operation at the same time and more empty jars than indicated will need to be used to fill up empty spaces in the second canner. Fill the hot water canner(s) about half full of hot tap water. Cover and bring to a boil over medium-high heat to have ready for processing of the filled jars. Reduce heat to keep canner water hot.

Peel zucchini and slice it, lengthwise, into quarter strips. If zucchini is particularly large, slice again into thinner strips manageable for grating. Remove inner membrane matter. Either using a grater or food processor, grate enough zucchini to make 6 cups, loosely packed.

Place zucchini and sugar in stockpot and stir well. Let sit for 10 minutes to allow the sugar to dissolve into the grated zucchini. Bring mixture to boil, uncovered, over medium heat Cook for 15 minutes, stirring frequently. Reduce heat slightly if jam is boiling too vigorously.

Stir in pineapple and the lemon and lime juices. Return mixture to a boil. Boil, uncovered 5-6 minutes, stirring frequently. Skim off, and discard, any foam that may form.

Add the orange and lemon jello powders, stirring until incorporated and the jellos dissolved, about 1 minute. Remove from heat and skim off and discard any remaining foam.

Boil a kettle of water to have ready, if needed, to top up water levels in the canner once the filled jars are added.

Use jar lifter tongs to carefully remove the hot sterilized jars from the water, one at a time, emptying the water from the jars back into the pot. Drain jars well and place on heat-proof board. Do be very careful as this is scalding hot water.

Using a ladle, or a heat-proof glass measuring cup, and a wide-mouthed canning funnel, fill the hot sterilized jars with the jam, leaving about ½“ headroom in each jar to allow for expansion during the hot water processing. Remove any trapped air bubbles in the jars with a chopstick or small heatproof spatula. Add more jam to jars, if necessary, to bring jam up to ½“ from jar rims. Wipe the jar rims with a clean damp cloth to remove any stickiness that could prevent the lids from sealing properly to the jars.

Center the lids (See Note 2 below) on jars so the sealing compound on the lid edges aligns with the jar rims. Fingertip tighten screw bands/rings until resistance is encountered. Do not over-tighten.

Immediately upon jars being filled with jam, use jar lifter tongs to carefully place filled jars upright in wire basket or rack positioned in the canner, ensuring jars do not touch each other or fall over. If a canner is not completely full of filled jars, add enough hot empty jars to fill it to capacity to prevent filled jars from toppling over during processing. Make sure the empty jars are already hot as cold jars immersed in boiling hot water are likely to crack. Let the empty jars fill with water from the canner as they are submerged.

Ensure the water level is at least 1” above the tops of jars, adding more boiling water as necessary. Cover with canner lid. Increase the heat to return the water to a full rolling boil then decrease the heat to just keep the water at a moderately rolling boil but not boiling over. Process jars in the hot water bath for 10 minutes (see Note 3 below), adjusting time as and if necessary for altitude. Start timing the processing from the point at which a full rolling boil is reached after jars have been added to the canner. At the end of the processing time, turn off heat and remove canner lid.

Let jars sit in the hot water for 5 minutes then, using jar lifter tongs, carefully remove the jars filled with jam, one at a time, upright, and transfer them to a heat-proof cutting board, that has been covered with a towel, to cool completely. Listen for the “pop” or “ping” sound as the bottles seal over the next few minutes or hours. The lids of properly sealed jars will curve downward.

Cover jars with a towel to keep light out and let jars rest, undisturbed, on counter for 24 hours. Then, test each jar for proper sealing by lightly pressing down on the center of each jar lid. If the lid is already pressed downward, and does not pop back up, it is properly sealed. Any jars that do not pass this test should be refrigerated and the jam used within a week or so.

Store properly sealed jam bottles in cool, dry, dark place and allow to rest for at least 1-2 weeks to allow flavor to fully develop before opening. Refrigerate jam once jar has been opened.

Yield: Apx. 7 – 8 half-pint jars

NOTE 1: Exact amount of jam is difficult to predict as it depends on many factors including the age and quality of zucchini, how fine/coarse the zucchini is grated, how loosely/firmly the grated zucchini is packed for cup measurement, stove temperature at which jam is cooked, etc.

NOTE 2: While, historically, the lids (with the orange-rust colored gasket on their underside) were preheated in simmering hot water for 1-2 minutes to soften the lid gasket before applying the lids to the hot jars, Bernardin® (the company that manufactures canning lids available in Canada) is now (2024) saying that preheating their particular brand of lids is no longer necessary to provide a proper seal as the sealing compound they use in their lid manufacturing performs better at room temperature. They recommend washing the lids in hot soapy water, rinsing them, and setting the lids aside until needed in the canning process.

Note this pertains specifically to the Bernardin® brand of lids. Other manufacturers’ lids may differ so, if you are using another brand of lids, do check the manufacturer’s instructions for lid preparation of their particular brand lids. Typically, if the lids need to be preheated, the method is simply to place the lids in a small pan of simmering hot water over low heat just long enough to heat the rubber piece. This doesn’t take longer than a minute or two at most. Do not boil the lids.

NOTE 3: Using jars other than the size indicated in the recipe (half-pint) will require adjustment to the hot water processing time of 10 minutes.

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Zucchini Jam

Use some of the garden-fresh zucchini when in season to make this delicious and gorgeous orange-colored Zucchini Jam. Lovely on toast, biscuits, muffins, and scones. May also be used as a filling for cookies or dollop on top of vanilla custard for a quick and easy dessert.

Course Jam

Cuisine Canadian

Keyword jam, zucchini, zucchini jam

My Island Bistro Kitchen Barbara - My Island Bistro Kitchen

Ingredients

• 6 cups grated fresh zucchini (peel and inner membrane matter removed before grating)
• 6 cups granulated sugar
• 1 cup canned crushed pineapple, with juice
• 3 tbsp bottled lemon juice
• 1 tbsp bottled lime juice
• 1 (85g) pkg orange jello powder
• 1 (85g) pkg lemon jello powder

Instructions

1. Wash canning jars and lids in hot soapy water. Rinse. Drain jars.
2. Fill a large-sized stockpot about two-thirds full of hot tap water. Fit stockpot with wire rack. Place the jars, on the rack and upright and in single layer, into the water. Use more than one stockpot if necessary to accommodate all jars needed for the recipe. Do not stack jars on top of each other in stockpot. Ensure the jars are fully submerged, each jar filled with water, and that the water is at least an inch over the tops of the jars, adding more if necessary. Cover, bring to a boil over medium-high heat, then reduce heat slightly and boil gently for 10 minutes. Turn off heat and leave the jars in the hot water to have ready to fill once the jam is cooked and ready for bottling.
3. Check the capacity of your canner. Though it is difficult to say with certitude exactly how much jam this recipe will yield (see Note 1 below), the recipe can be expected to yield 7 – 8 half-pint jars that need to be hot water processed immediately upon them being filled with jam. If your canner cannot accommodate this number of jars all at the same time, two canners will need to be in operation at the same time and more empty jars than indicated will need to be used to fill up empty spaces in the second canner. Fill the hot water canner(s) about half full of hot tap water. Cover and bring to a boil over medium-high heat to have ready for processing of the filled jars. Reduce heat to keep canner water hot.
4. Peel zucchini and slice it, lengthwise, into quarter strips. If zucchini is particularly large, slice again into thinner strips manageable for grating. Remove inner membrane matter. Either using a grater or food processor, grate enough zucchini to make 6 cups, loosely packed.
5. Place zucchini and sugar in stockpot and stir well. Let sit for 10 minutes to allow the sugar to dissolve into the grated zucchini. Bring mixture to boil, uncovered, over medium heat Cook for 15 minutes, stirring frequently. Reduce heat slightly if jam is boiling too vigorously.
6. Stir in pineapple and the lemon and lime juices. Return mixture to a boil. Boil, uncovered 5-6 minutes, stirring frequently. Skim off, and discard, any foam that may form.
7. Add the orange and lemon jello powders, stirring until incorporated and the jellos dissolved, about 1 minute. Remove from heat and skim off and discard any remaining foam.
8. Boil a kettle of water to have ready, if needed, to top up water levels in the canner once the filled jars are added.
9. Use jar lifter tongs to carefully remove the hot sterilized jars from the water, one at a time, emptying the water from the jars back into the pot. Drain jars well and place on heat-proof board. Do be very careful as this is scalding hot water.
10. Using a ladle, or a heat-proof glass measuring cup, and a wide-mouthed canning funnel, fill the hot sterilized jars with the jam, leaving about ½“ headroom in each jar to allow for expansion during the hot water processing. Remove any trapped air bubbles in the jars with a chopstick or small heatproof spatula. Add more jam to jars, if necessary, to bring jam up to ½“ from jar rims. Wipe the jar rims with a clean damp cloth to remove any stickiness that could prevent the lids from sealing properly to the jars.
11. Center the lids (See Note 2 below) on jars so the sealing compound on the lid edges aligns with the jar rims. Fingertip tighten screw bands/rings until resistance is encountered. Do not over-tighten.
12. Immediately upon jars being filled with jam, use jar lifter tongs to carefully place filled jars upright in wire basket or rack positioned in the canner, ensuring jars do not touch each other or fall over. If a canner is not completely full of filled jars, add enough hot empty jars to fill it to capacity to prevent filled jars from toppling over during processing. Make sure the empty jars are already hot as cold jars immersed in boiling hot water are likely to crack. Let the empty jars fill with water from the canner as they are submerged.
13. Ensure the water level is at least 1” above the tops of jars, adding more boiling water as necessary. Cover with canner lid. Increase the heat to return the water to a full rolling boil then decrease the heat to just keep the water at a moderately rolling boil but not boiling over. Process jars in the hot water bath for 10 minutes (see Note 3 below), adjusting time as and if necessary for altitude. Start timing the processing from the point at which a full rolling boil is reached after jars have been added to the canner. At the end of the processing time, turn off heat and remove canner lid.
14. Let jars sit in the hot water for 5 minutes then, using jar lifter tongs, carefully remove the jars filled with jam, one at a time, upright, and transfer them to a heat-proof cutting board, that has been covered with a towel, to cool completely. Listen for the “pop” or “ping” sound as the bottles seal over the next few minutes or hours. The lids of properly sealed jars will curve downward.
15. Cover jars with a towel to keep light out and let jars rest, undisturbed, on counter for 24 hours. Then, test each jar for proper sealing by lightly pressing down on the center of each jar lid. If the lid is already pressed downward, and does not pop back up, it is properly sealed. Any jars that do not pass this test should be refrigerated and the jam used within a week or so.
16. Store properly sealed jam bottles in cool, dry, dark place and allow to rest for at least 1-2 weeks to allow flavor to fully develop before opening. Refrigerate jam once jar has been opened.

Recipe Notes

Yield: Apx. 7 – 8 half-pint jars

[Copyright My Island Bistro Kitchen]

NOTE 1: Exact amount of jam is difficult to predict as it depends on many factors including the age and quality of zucchini, how fine/coarse the zucchini is grated, how loosely/firmly the grated zucchini is packed for cup measurement, stove temperature at which jam is cooked, etc.

NOTE 2: While, historically, the lids (with the orange-rust colored gasket on their underside) were preheated in simmering hot water for 1-2 minutes to soften the lid gasket before applying the lids to the hot jars, Bernardin® (the company that manufactures canning lids available in Canada) is now (2024) saying that preheating their particular brand of lids is no longer necessary to provide a proper seal as the sealing compound they use in their lid manufacturing performs better at room temperature. They recommend washing the lids in hot soapy water, rinsing them, and setting the lids aside until needed in the canning process.

Note this pertains specifically to the Bernardin® brand of lids. Other manufacturers’ lids may differ so, if you are using another brand of lids, do check the manufacturer’s instructions for lid preparation of their particular brand lids. Typically, if the lids need to be preheated, the method is simply to place the lids in a small pan of simmering hot water over low heat just long enough to heat the rubber piece. This doesn't take longer than a minute or two at most. Do not boil the lids.

NOTE 3: Using jars other than the size indicated in the recipe (half-pint) will require adjustment to the hot water processing time of 10 minutes.

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 [This post and recipe were last updated on August 28, 2024]