First, you can alter the amount- cutting in half makes everything cook faster and there’s no shame in small batch canning- a few jars adds up! Doubling is popular but here’s some tips: Doubling a batch of jam leads to longer cook times and that can make your pectin cook off. Double the prep work (cut twice the strawberries, peel twice the apples, and cook in separate batches.
You can alter flavor with spice: Dried spices and herbs can give flavor without changing the pH significantly or at all. Try peppercorns, bay leaf, clove (ground or whole) juniper berries (start with just a few in a brine),
Use essential oils- 1-3 drops of oregano in tomato sauce packs a huge punch much faster than chopping a ton of fresh herbs that won’t have great quality after canning anyway. A drop of cinnamon goes a long way in applesauce, etc. Rosemary, black pepper, lime (so useful in salsa), lemon, grapefruit, basil, etc.
You can add salt or sugar without changing pH or safety, but remember that both are preservatives and sugar in particular can change the texture of a preserve.
Adding alliums or other low acid flavors (garlic, onions, leeks, peppers (spicy or mild) is problematic because those ingredients LOWER the pH level. For safe canning, use the amounts specified and if you are cutting the recipe in half or doubling, double check your math and make sure you have the ratios correct.
Ideas for spicing up recipes: essential oils like we said, pairing a spice with a sweet (refer to our canning for charcuterie episode for more ideas) but try jalapeno (Anna, how much for a jam recipe?) with high acid fruit (raspberry, peach, pineapple, etc), dried pepper for kick (link the one from the charcuterie episode) to taste, food coloring doesn’t change taste or pH but can enhance the wow factor (https://suncorefoods.com/collections/superjuice-powders) for safe coloring rather than artificial coloring.
When making safe recipe substitutions, check out the Acid and Canning chart. You can swap out the same volume of similarly acid fruit but the result may be different. Raspberries for example have an acid value of around a 3 but they have a lot of natural pectin. You could safely swap them out for another fruit with a similar level, but know you’ll likely not end up with a preserve that is naturally as stiff or set.
If you want to change a recipe and add a low acid ingredient, you need to find a similar recipe that’s been tested for a pressure canner. You can listen to our episode all about using a pressure canner for more about them but they get hot enough (240 degrees) to kill any spoiler present in any acid level. They aren’t difficult to use and they allow for an even greater variety of ingredients to be preserved.
How to know if you SHOULD alter a recipe: If you have an old recipe, look up other similar recipes (raspberry jam + cooperative extension) is a surefire search path to find a tested recipe. One alteration many old recipes need is for old tomato recipes- they often need the addition of an acidifying ingredient. If your old tomato recipe doesn’t have citric acid, lemon juice, or vinegar at all, that’s a definite red flag that you need to alter the recipe and/or find a similar but different recipe that has an acidifying ingredient.
You may also need to alter the processing time or method of an old recipe. It is recommended that you add 5 minutes for every 1000 feet elevation, and that you always use either a water bath, steam canner, or pressure canner to process jars. Refer to our episode all about Canning Mistakes for more information about unsafe canning methods but know that if your recipe encourages you to use open kettle, paraffin wax, or the oven, you need a more up to date recipe.