Before the refrigerator became commonplace, people made up for the ups and downs of crops by storing surpluses for months to come. Making preserves was one of the most popular methods of preserving fresh ingredients over time. Although most foods need to be processed at high temperatures and under conditions of high pressure, classic attributes of the pressure cooker, acidic foods (with a pH below 4.6) can be processed safely even with a simple full pot. of boiling water.
The first basic rule of the preparation of preserves is to be able to kill all the microorganisms that cause food spoilage, while the second is to completely seal the jars to prevent them from entering. For these reasons it is essential to pay extreme attention to the degree of sterilization, cleanliness and hygiene.
Steps
Part 1 of 6: Choosing the Foods to Store
Step 1. Decide which ingredients you want to turn into preserves
Of course, it's best to store the foods you like best. Unless you're planning on giving gifts or organizing a sale, there's no point in saving pounds and pounds of something you or your family members don't like to eat.
If you are the lucky owner of a vegetable garden or orchard, choose ingredients that grow in abundance. If the peach tree has been particularly generous this year, make a peach preserve instead of using the few strawberries you managed to harvest this season. If you have a surplus of tomatoes or apples at harvest time, processing them into preserves is an equally good choice
Step 2. If you've never made preserves before, start with something simple
Some foods require more work, time, and preparation than others.
If you are a complete beginner, start with a serving of tomatoes or jam, not twenty kilos of apples. If you find that you like making preserves, you can always make up for it as soon as you become familiar with the process. Remember that making a cherry preserve is possible, but you must first remove the stones
Step 3. Choose ingredients in good condition
Fruits and vegetables must be firm and ripe, free from mold or bad parts. In order to be processed into preserves, foods must be beautiful. If you love to grow tomatoes or buy them in large quantities, you can prepare tomato preserves directly at your home (in the second case, well-ripened tomatoes that may not be "beautiful" to look at should be cheaper than those normally found in supermarket sale). If you love pickled gherkins you can prepare them in preserves by consulting this article.
Part 2 of 6: Prepare the Ingredients
Step 1. Consult a recipe or a current guide (also read the "Tips" and "Sources and Citations" section of the article) to identify the specific time and techniques for the ingredients you have chosen to keep
Different foods require different processing. Nothing prevents you from using the old family recipes, but it is better to compare them to similar preparations by consulting a modern cooking guide to perfect the times and methods of processing. Thanks to the new findings, food safety dictates may be different than when those old directions were written.
Consult a modern guide dedicated to canned food, for example the one published by Slowfood, to find out the exact preparation times based on the content and size of the jars, especially if you have decided to follow an old recipe. Processing times have changed over the years because new research has been done in terms of food safety; also, certain ingredients are grown differently. Tomatoes, for example, may be far less acidic than they once were
Step 2. Wash your hands carefully, also remember to keep them clean throughout the preparation
The goal is to minimize the amount of bacteria that could contaminate food. Wash them again if you happen to sneeze, go to the bathroom, or touch objects other than the food you are preparing.
Step 3. Prepare the ingredients following the directions in the recipe
Most foods will need to be cut up to make it easier to get into the jars.
- Peel and cut the fruits and vegetables. Some ingredients can be "peeled" easily after being immersed in boiling water for a few moments. For example, to remove the peel of peaches and tomatoes you can cut it slightly on the opposite side of the stalk; once the ingredients have been dipped into the boiling water, the peel will begin to rise: at that moment you can remove them from the water with a slotted spoon and transfer them to an ice water bath. As soon as they are cool enough to touch, you will be able to peel them easily.
- Remove pits, stalks, cores, and any other parts that you will not eat. Note that the harder flesh of the nectarine (or nectarine) variety peaches comes off the stone more easily. Take these details into account when choosing ingredients.
- Make the jam.
- Cook or pickle the vegetables.
- Prepare the sauces, creams and gravies following their respective recipes.
Step 4. Prepare the preservative liquid, if the recipe calls for it
Most fruits and vegetables are stored in a syrup (a mixture of water or juice and sugar) or brine (a mixture of water and salt). Read the directions in your recipe to find out what is best to use.
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Simple syrup: For a light syrup, boil 1 ½ liter of water with 500 g of sugar. You will get about 1.75L of syrup. For a medium syrup, boil 1 ½ liter of water with 750 g of sugar. You will get about 1.6 l of syrup. For a strong syrup, boil 1 ½ liter of water with 1 kg of sugar. You will get about 1.75L of syrup.
To reduce the number of calories, you can replace sugar with a sweetener such as sucralose or stevia; do not use aspartame
- Base for pickles: Pour 1, 2 l of vinegar, 240 ml of water, 20 g of salt, 30 g of sugar and 2 cloves of garlic (optional, but useful for giving flavor) into a saucepan. Bring the mixture to a boil; once it reaches a boil, let the ingredients simmer over low heat for 10 minutes. Remember to remove the garlic cloves the moment you turn off the heat.
Part 3 of 6: Sterilizing the Jars
Step 1. Sterilize the glass jars doing them boil in water for 10 minutes.
Sterilizing them is very important, because any bacteria present would cause food spoilage. If you are in the mountains, calculate an additional minute for every 300 meters above sea level. After removing them from the water, turn the jars upside down, place them on a clean kitchen towel and cover them with a towel until ready to use.
If you want, you can sterilize the jars by washing them in the dishwasher at a high temperature
Step 2. Boil about 2.5cm of water in the bottom of a medium-sized saucepan
Remove the pot from the heat source, then dip the jar lids into the water. Separate them from each other and push them down so they stay submerged while heating up evenly. Leave them to soak for a minute or two to soften. If you can organize yourself correctly, you can take this step while filling the jars and cleaning the edges.
Part 4 of 6: Filling the Jars
Step 1. Fill the jars
This step is sometimes called "potting". The product can be potted "hot" or "cold", depending on the preparation; generally, the ingredients that have undergone cooking will be placed in jars while still hot, while those that have only been washed and cut will be cold. In some cases this difference can affect the cooking time of the same food, so make sure you have read the recipe carefully.
- The use of a large funnel will facilitate the potting process, especially for liquid, semi-liquid or small pieces preparations.
- Individual ingredients, for example green beans, must be placed in the jar manually. Try to be as neat as possible. If you intend to sell or give the preserves, you must give due importance to the aesthetic aspect. Otherwise, if you just want to add it to your soups, it may be pointless to align the content perfectly.
Step 2. Leave some empty space without filling the jars to the brim
Some air must remain inside them. The amount of blank space may vary by recipe; generally, it will be between 3 and 25 mm. Check the instructions for your specific preserve.
Step 3. Add preservatives according to the recipe
Preservatives used to make homemade preserves include sugar, salt, and acids, such as lemon juice or ascorbic acid (better known as vitamin C; can be purchased in powdered form online or at a pharmacy). Add preservatives before pouring in the liquid - this will help the syrup or brine to help distribute evenly.
Step 4. Pour the liquid into the jar
Leave about 1-1.5 cm of free space.
Step 5. Remove the air bubbles
When the liquid is poured on individual ingredients, air pockets tend to form. To get rid of them, you can slide a long plastic knife (available at specialty canning stores) along the inside of the jar, while moving or pushing the food slightly downwards.
Step 6. Clean the edges and threads of the jars with a clean, damp cloth to remove any droplets or food residues
Pay particular attention to the area that will adhere to the lid.
Step 7. Place the lids on the jars after allowing them to soften
A magnetic lid lifter is very useful for taking them out of boiling water without burning yourself. Once placed on the jar, you can release the lid by tilting the tool slightly.
If you don't have a magnetic lid lifter, you can use a pair of kitchen tongs. The important thing is not to touch the clean, hot lids with your bare hands
Step 8. Screw the rings tightly around the lids
You will have to close them firmly, but without applying excessive pressure to avoid the risk of crushing too much any gasket, which could come out of its seat.
Part 5 of 6: Vacuum Packing the Preserves
Step 1. Use a canning kettle if required by the recipe
This method is suitable for many of the cooked preparations (jams, pickles) and sour fruits (applesauce, peaches, pears, apricots). Follow the directions of a modern guide to make sure it's the right pot for your preserves.
Arrange the jars in the basket, then place it in the kettle. If you don't have a pasteurization kettle, you can use any large pot. Add enough water to completely submerge the jars (they should be covered by about 2.5-5cm of water). Remember that if you have done a hot pot, you must use hot water; on the other hand, if you have cold ingredients in jars, use cold water. Do not expose the jars to a sudden temperature change; also, remember to order them in a single layer without ever stacking them on top of each other
Step 2. If you are using a common pot, place a grid or other object on the bottom that allows you to space the jars from the base (for example a small towel)
Cover the pot, then wait for the water to boil slightly. At this point, start the cooking time, without forgetting to increase it if you are more than 900m above sea level
Step 3. Use a pressure cooker if required by the recipe
This method is indispensable for preparing meat preserves and for almost all vegetables, as they are naturally low acid ingredients. Using a pressure cooker can also reduce the cooking time of some foods, such as peaches and tomatoes. To prevent the formation of dangerous bacteria it is necessary to pasteurize low-acid foods under high pressure. The temperature inside the pressure cooker rises with increasing pressure. Generally, it needs to be raised to around 120 ° C to kill harmful bacteria.
- Place the jars in the pressure cooker. As long as you arrange them alternately, you can stack the smaller jars on top of each other. When creating the second layer, make sure the bottom of the top jars rest half on one lid and half on another, rather than line up perfectly with the jar below.
- Check the consumable parts of the pressure cooker: the safety valve gasket and the lid gasket. Both tend to harden due to weather and high temperatures. In some cases it is possible to put them back into use by immersing them in boiling water, but if they are too old or cracked it is essential to replace them. Typically, you will need to change the gaskets every one to two years.
- Place the lid on the pan by matching it with the hooking guides. Often, the handle acts as a lever that opens and closes the pot. Lower the handle to seal it. If your pot has a pressure regulator, remove it from the lid.
- Bring the water to a boil. Watch the steam escaping from the vent valve where the pressure regulator was screwed. Generally, there is also a pressure indicator on the lid which is activated as soon as the pot is pressurized.
- Let the steam escape for as long as necessary. After a while, an intense and even jet will come out. At that point, wait 7 minutes (or the time specified by your recipe or the instruction manual of the pot).
- Put the pressure regulator back on the lid of the pot, then start calculating the cooking time. If there is a pressure gauge that measures the pressure inside the pot, you will see the relative indicator move.
- Adjust the intensity of the flame so that the pressure in the pot is as required by the recipe (remember to make the necessary changes based on the altitude). Generally, the required pressure is 0.69 bar at sea level. Most likely, you will have to make several small corrections to reach the correct level. Whenever you change the degree of heat, wait a few moments before evaluating the effects; the pot you are using is very large, as well as full of water and jars, so it will take a while for the desired change to take place inside it, which will then be shown by the indicator.
- Don't lose sight of the pot during the entire cooking process, changing the degree of heat whenever necessary. Steam escaping and any other changes will cause constant changes. Reduce the flame slightly if the pressure rises too much; conversely, turn it up a little if the pressure drops. In any case, do not assume that you have reached the optimal setting; as we have said, the jet of steam and any other variation can reduce the pressure quickly. When the pressure is too low, the heat inside the pot may not be enough to cook the ingredients properly; on the contrary, when it is too high, the jars can risk breaking.
- Respect the cooking time indicated by the recipe. Once done, turn off the flame and leave the pressure gauge in place until the indicator goes down. At that point, you can remove it and let the pot vent for a few minutes.
- Open the lid very slowly, then hold it between you and the jars for a few moments. If you want, you can leave it resting on the pot, just slightly away from the edge, for a few minutes. It almost never happens (especially if you are careful to gradually decrease the pressure), but it can happen that the pressure cooker breaks when the pressure is released.
Part 6 of 6: Getting the Job Finished
Step 1. Take the jars out of the pot
The best thing to do is to use a specific pair of tongs for this use, so as not to run the risk of scalding yourself with hot water or jars. Better yet, if your pot has one, you can lift the basket that the jars sit in and take them out all at once. At this point, place them on a clean towel to cool.
Step 2. Let the jars cool for 24 hours in a draft-free location
You may hear a metallic sound indicating that the contents are cooling by creating a partial vacuum inside the jar. For now, don't touch the lids; let them seal themselves.
Step 3. After several hours, you can check if the jars are properly sealed
The vacuum created when the contents cooled should have "pulled" the center of the lid down. Press it with your fingers: if you can squeeze it, it means that the process has not happened correctly. Once released, it shouldn't come back. If any of the jars have not sealed properly, you can put new lids on and repeat the process. Alternatively, you can keep them in the refrigerator, consuming their contents quickly.
Step 4. Wash the jars with warm soapy water to remove any remaining food on the outside
You can also remove the rings from the lids, which should stay firmly in place; wait until both are perfectly dry before repositioning them to prevent rust.
Step 5. Label your preserves, specifying at least the year of preparation
You can also indicate the content, since in a few weeks it will be difficult to distinguish apples from peaches. Don't forget to add your name if you intend to give them as a gift. You can use an adhesive label or permanent marker.
If you want to reuse the jars, mark the lids. Store them in the pantry, away from light and heat. Once opened, keep them in the refrigerator
Advice
- Eat your preserves, don't just leave them in plain sight on the shelf to be pleased with all the work done. Homemade preserves have a limited shelf life, try to consume them within 1-2 years at the latest.
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Take notes. From one year to the next, you may forget what you did and what you discovered. A simple notebook kept in the pantry next to the preserves will help you remember important steps. Note the following points:
- The amount of starting ingredients and the number of jars you got (specify the size of the jars).
- The number of preserves you have prepared and how many you have eaten during the year.
- The techniques and recipes you have learned.
- Where did you buy the ingredients and how much did you spend.
- Depending on the type of stove, you may need to use a diffuser to have an even heat and move the bottom of the pan away from the direct flame, thus avoiding that the temperature in that point is excessive.
- Rings and jars are reusable. On the contrary, the covers must be replaced, since the soft parts tend to deform with use. Also replace rusty or dented rings.
- If you want to use jars that you have used before, inspect them carefully to make sure they are perfectly intact. Slowly slide your finger along the edge to check that it is flawless and free from damage.
- If, at the end of the pot, you have a jar only half filled, save it for the next batch (add the contents immediately to the other ingredients), transfer the preserves to a smaller jar or put it in the refrigerator to consume that portion quickly.: this is an excellent opportunity to test the result of your work.
- If you want to make a large quantity of preserves, visit more than one store to find fruit or vegetables at the cheapest possible price.
Warnings
- The method used by the grandmothers to seal the preserves consisted in letting the jars cool upside down so that the heat given off by the contents sealed them. New discoveries in terms of food safety have decreed that this technique is not capable of safeguarding health. The use of paraffin is also questionable. It is best to use metal lids and boil the jars for the recommended time.
- Deterioration or incorrect storage of preserves can cause serious illnesses, which in some cases can lead to death. Always respect the required boiling times, wash and sterilize jars adequately before use and throw away preserves that are not sealed properly. If, after opening a jar, the contents are moldy, discolored or smelly, do not hesitate to throw it away.
- Do not immerse cold jars in boiling water or vice versa. Due to sudden changes in temperature, the glass can shatter into a thousand pieces.
- While you can reuse empty jars from store-bought foods (as long as you have rings of the same size), it's always best to buy jars specially formulated to preserve preserves. Being made of thicker glass, the latter are able to withstand numerous processes. The common empty jars can be used to contain small objects of common use, for example a collection of coins.
- Do not use empty jars of sauces, pickles, etc., as they are not designed to be boiled for a long time in water or pressure cooker.
