Pickling is a preserving process that can be applied to vegetables, meat, fish, eggs, fruit and even nuts. It also adds flavour to the item being preserved, and can transform one food item, such as cucumbers, into another, such as “pickles.”
The following discussion of pickling provides general guidelines only, and is only a broad survey of general literature on the topic. Contact your local health or agricultural department for guidelines recommended for your jurisdiction. It is important to follow their current recommended procedures, because serious health issues can arise otherwise. Note as well that older recipes may have counted on vinegar which was far stronger than the vinegar now allowed to be sold to consumers in some jurisdictions.
Anything you pickle comes out only as good as the quality of what you start with. Don’t use damaged or blemished produce, or meat, fish or eggs that are past their safe-use dates. Fruit is best pickled when slightly underripe.
Vinegar is perhaps the single most important element needed in pickling.
The vinegar used in pickling solutions needs to be 5 percent acid or higher to be safe, according to the National Center for Home Food Preservation.
Use only vinegar whose acidity level you know for a fact. If your acidity level is too low, you’re playing Russian roulette with the possibility of botulism. Consequently, only use store-bought vinegar, which comes with the acid content clearly indicated — with homemade vinegar, you can’t be sure of the acid content. A lower acid content may not only make your pickle unsafe, but you may find it goes soft as well.
The acid content of vinegar is not affected by heat.
Distilled white vinegar does not affect the colour or taste of the items you are pickling. It is especially preferred by those who are planning to run their preserves in shows and contests, and those who are pickling fish. You will probably definitely want white vinegar when pickling cauliflower, and if you like your pickled eggs and onions white, with those items as well.
Apple cider vinegar can, combined with the spices in the mix, add an interesting fruity flavour, but it can stain certain food items being pickled with its brown colour.
Minimum safe vinegar ratio for pickling
For “refrigerator pickles”, who will spend their lives refrigerated, there are no set rules about acidity ratios for them. (Just don’t try to use oil as the liquid instead — botulism has resulted.)
For shelf-stable jars of pickles, however, there are rules.
In pickling for shelf-stable canning, it is a certain acidity level ( ph of less than 4.6) that prevents botulism spores from ‘germinating’ and creating their deadly toxin while they do. People have got botulism from home made pickles using old, weak-acidity level recipes.
To be clear, the acidity does not kill off botulism spores, it neutralizes them. It should be noted as well that lab testing has revealed other nasties such as listeria, salmonella, etc being resistant to acidity. That is why the final step in making pickles is heat-treatment of the sealed jars. The dual treatment of sufficient acidity to neutralize botulism spores, plus heat treatment to kill off the other nasties is what assures the safety of pickles, relishes, chutneys, etc. As a bonus, it also improves the storage quality by inactivating spoilage organisms.
Food safety experts want to see any pickling solution having a minimum of 50% vinegar in it. That is a 1:1 ratio.
With the 5% vinegar that is the standard today in North America, this ratio gives the combined pickling solution a minimum of 2 1/2% overall acid content. (Bear in mind, food such as cucumbers added will release its own water into the solution — that is why they want it high to start.)
You can go higher on the vinegar, up to 100% but you cannot go lower on it.
Recipes with a pickling solution of 1 part vinegar to 2 parts water (except for lab-tested ones: see further below) do not give a pickling solution strong enough that any food safety expert will certify as safe. These are older recipes that may have assumed a vinegar that had a far higher level of acidity than today’s standards.
Labelled as particularly dangerous are such 1 part vinegar to 2 part water recipes which had you make the liquid into a boiling pickling solution, pour it over raw cucumbers in a jar, and then put the lids on straightaway, with no further heat processing of the jars even to kill moulds and bacteria. Though a seal would form as the hot solution cooled, the pickling solution wasn’t strong enough to stop invisible toxins from forming inside the jars, and the vacuum, being a week one, would often fail.
Exceptions to the rule are lab-tested recipes such as Pickled Grape Tomatoes from the Ball Blue Book Ball Blue Book. Muncie, Indiana: Healthmark LLC / Jarden Home Brands. Edition 37. 2014. Page 94 which uses a 2:4 vinegar to water ratio (owing likely to an assumed border-line acidity level for the tomatoes) and Quick Fresh-Pack Dill Pickles from the USDA United States Department of Agriculture (USDA). Complete guide to home canning. Agriculture information bulletin No. 539. 2015. Page 6-10 which uses a 3:4 vinegar to water ratio.
If you see pickling recipes on the Internet not directly attributed to a modern, reputable source (such as the examples above) giving a vinegar ratio less than 1:1, avoid using those recipes as they may be unsafe. There are always modern, tested safe equivalents to be found.
Don’t use iodized salt or table salt as a pickling ingredient. The issue is quality, not safety. Anti-caking ingredients in both of those salts will make your brine cloudy, and iodine in iodized salt will discolour the items you are pickling, and when pickling fish, iodized salt may give the fish a bitter flavour.
You need to use a pure salt: pickling salt, kosher salt or dairy salt.
Don’t alter the amount of salt in fermented recipes — it’s there for a reason, which is health safety, and as a side point, too little salt may cause the item you are pickling to go soft and slimy.
In other tested home canning or pickling recipes from modern, reputable sources, salt, in the quantities used, is almost always used for flavouring or other purposes only and not for safety.
Note to North Americans: when swapping one (acceptable) salt for another, it’s best done by weight, because salts have different grain sizes, which can lead to volume cup measurements being off.
Firming Agents are ingredients added to make the items being pickled come out less soft.
They were used a great deal in the past, but now items such as alum, lime (the mineral) and grape leaves are no longer required. They were more useful back in the old days, when vinegar would have been homemade, and probably not of a high enough acid content on a regular, reliable basis to crisp up the food — now that we have 5% vinegar, that high acidity is enough to reliably do the firming.
Lime is a tricky firming agent to use. You soak food items in a lime and water solution before starting pickling. But, if you don’t get all excess lime out after the soaking, you risk serving your family and your guests jars of pickled botulism. After the pickles are soaked in a lime solution, you have to rinse the pickles in running water, then soak them in fresh water for an hour, then repeat the rinsing and fresh water soaking two more times.
Alum used to be added to fermentation style pickles. Any recipes calling for it are old; food safety people are now trying to steer home canners towards modern recipes, with modern procedures, that don’t call for it or need it. One of the procedures suggested instead is crisping cucumbers in ice water for about 5 hours prior to starting.
Alum doesn’t work as a firming agent with the quick process method.
Some older recipes call for adding a grape leaf to each jar of pickles. Grape leaves have something in them that inhibits the enzymes which would make pickles soft. The same purpose can be achieved by trimming off the blossom ends of cucumbers, where those enzymes are likely to be (see Soft Pickles below.)
Generally, this means spices You are generally safe to alter the spices in a pickling recipe, if you choose.
Use whole spices, not ground ones, and make sure they are fresh — it’s pointless to use spices that have all the aroma and flavour of sawdust. Pickling won’t magically bring their taste back.
There are several different picking methods. Refrigerator Pickles are the crispiest, followed by Fresh Pack, with the least crispy being Fermented Pickles.
Dry Salt Method
This method is used for sauerkraut, Moroccan pickled limes and lemons, umeboshi in Japan , etc. It works by drawing water out of the food item. A brine forms as the water comes out into the salt. The process creates the right pH to encourage the bacteria that create lactic acid.
Refrigerator / Freezer / Refrigerated Pickles
These are made in the refrigerator as for the quick method (see below), but they are not processed in a water bath. Instead, they are refrigerated immediately, and must be kept refrigerated through their shelf-life, which is shorter than for pickles which have been water bath processed.
The fermentation takes place in the refrigerator. When the proper time necessary has passed, the pickles are ready to eat (or in the case of commercial processing, ship.)
They can be very crispy.
Be sure to store in the refrigerator at home all the time.
Fermented Pickles (aka Brined Pickles, Processed Pickles)
The pickling process is done at room temperature.
The acid to keep the food safe, called lactic acid, is produced through fermentation. The ideal room temperature for fermentation to encourage the lactic acid bacteria to grow is 70 to 75 F (21 to 24 C.)
The fermentation invites a certain good kind of bacteria (Lactobacillaceae) to grow in your pickles. They digest the sugar in your produce, producing in return lactic acid. This acid both gives the produce a desirable sour tang and preserves the food items, and in eating the sugars, they deprive bad bacteria of a potential food source.
Salt, in raising the salinity of the environment, helps lactic-acid producing bacteria because they thrive in it. This gives them the winning edge in the race against time to see whether they or bad bacteria will win out in the fight to colonize the items you are pickling (too much salt, though, can hinder the good bacteria as well, so that they won’t produce enough lactic acid, allowing bad bacteria that don’t mind that level of salt in.)
The vessel that you are doing the fermenting in needs to be kept covered, to deprive it of a fresh supply of oxygen which the bad bacteria like.
During fermentation, the cucumbers will absorb salt from the brine, so recipes will call for you to add more salt as you go to keep the brine salty enough to be safe.
At the end of a proper fermentation, the cucumbers should still be crisp enough to snap and break when you try to bend them.
You need to remove the scum daily, as it can lower the acidity levels, and keep the food items covered in brine at all times.
Fermenting time varies by the food item being pickled. Sauerkraut and dill pickles are about 3 weeks.
Once fermented, the food items are removed from the brine, rinsed to get excess salt off them, then packed in jars with a pickling solution.
Fermenting brines 
Saltiness of brine solutionRatio of salt to waterUse for5%6 oz (3/4 cup / 150 g) per US gallon (4 litres)short-term for cucumbers, green tomatoes, green beans10%12 oz (1 1/2 cups / 350 g) per US gallon (4 litres)Starting level for cucumbers and cauliflower15%19 oz (2 1/4 cups / 500 g) per US gallon (4 litres)Final strength for cucumbers and cauliflower
Quick Method (aka fresh-pack pickles)
This means as opposed to the fermented method. It doesn’t mean, though, an hour or two — it means it takes a day or two.
The acid is added right at the start — acetic acid, from the vinegar.
Some have you brine the produce overnight or for several hours, then apply the pickling solution.
Processing & Packing
Processing the sealed jars of pickled items in a hot water bath does two things: it kills all organisms that could cause the items to spoil, and when the jar cools, it creates a vacuum seal.
Essentially, it pasteurizes the jars. It destroys bacteria, moulds and yeasts, as well as enzymes that could affect the quality in terms of colour, texture and flavour.
For pickling, the water in the hot water bath should be at a simmer, rather than a full boil.
Don’t use pressure canners for pickles — it will turn them to moosh.
Don’t pack the food in the jar too tightly. There needs to be a reasonable amount of room between them so that they are all flooded and soaking in the pickling solution.
You start counting your processing time from when you place the jars in the simmering water.
Processing times have to be adjusted for high-altitudes.
Problems encountered are typically food items going soft or slimy, food items being shrivelled, hollow cucumber pickles, dark or stained looking pickles, sediment in the jar — and spoilage.
The blossom end (that’s opposite to the stem end) may contain an enzyme that can make pickled cucumbers go soft. Always shave 1/16 inch (1 1/2 mm) off that end. The blossoms are always removed from the cucumbers before pickling for the same reason.
Soft pickles can be caused by too little vinegar, or too little salt. It can also be caused by allowing scum to build up on top of fermented pickles – skim daily and discard.
If you are lucky enough to have this level of control, some old-timers advise that for the crunchiest of pickle, the produce should be picked in the morning, stored out of the sunlight, and processed within 24 hours.
Shrivelled Pickles can be caused by:
- too much salt, vinegar or sugar;
- using produce that was past its prime or that you let sit around too long before pickling it, that should have been pickled the day you picked it;
- overprocessing in the hot water bath.
Hollow Cucumber Pickles
While you are washing cucumbers, if any float on top of the water, that means that they are hollow inside. These are best eaten fresh, or chopped up for processing into a relish.
It can also be caused by:
- using produce that was past its prime or that you let sit around too long before pickling it, that should have been pickled the day you picked it;
- there was too much or too little of something in the brine;
- you were making fermented pickles, and the room temperature was too high.
Bear in mind that some pickles are meant to be dark, e.g. Branston Pickle or English Pickled Onions. The following doesn’t apply to these.
Dark Pickles can be caused by:
- using ground spices instead of whole spices, colouring the pickling solution;
- hard water (soft water won’t cause it; minerals in hard water such as iron will);
- using a dark vinegar;
- using the wrong kitchen utensils. Some metals such as copper, bronze, galvanized metal, and iron can react with pickling solutions. Prefer instead ones made of glass, stainless steel, stoneware or unchipped enamelware. Sometimes, a darkening issue caused by such a reaction may only become apparent after your preserves have been sitting happily on the shelves for a few months, and suddenly start darkening on you;
- using iodized salt;
- using brown sugar instead of white sugar.
A table salt with an anti-caking in it may have been used. Use instead a pickling-grade salt.
Sediment may also be caused by bacteria during fermentation.
Spoilage can be caused by:
- produce not washed well enough before use;
- damaged produce or produce that was past it;
- jars and lids not properly sterilized;
- unwise cutting back on required amounts of salt or vinegar, or not using vinegar that was strong enough;
- improper processing of the jar or, not processing it at all;
- not using a modern, tested recipe from a reputable source.
Remember the golden rule about spoilage with pickled items — if there’s any doubt, throw it out.
 Source: Barbara H. Ingham. Homemade Pickles and Relishes. University of Wisconsin-Extension Cooperative Extension. B22687. 2002.
If any mould ever appears in a jar of pickles, discard the entire contents of the jar without hesitation.
Colbert, Libby. Pickle pointers affect safety and quality. Colorado State University Cooperative Extension, Arapahoe County. 17 August 2004.