Tim Long, UC Master Food Preserver Online Program Volunteer

Why do recipes call for bottled lemon juice when preserving, when I have all these fresh lemons I can juice and use?

Bottled lemon juice is standardized, or uniformly acidified, per FDA regulations.  (See article: https://blogs.extension.iastate.edu/answerline/tag/bottled-lemon-juice/)  This means it is consistent at a level of safety for food preservation.  The final acidity of a food product is critical to deter the growth of microorganisms that can cause spoilage or foodborne illness.

Fresh lemons have an inconsistent acid, or pH, level. This can vary due to the lemon variety, but also vary due to the level of maturity, growing conditions, soil, fertilizer, rootstock, and storage conditions. Although safe to eat fresh for a great meal, they are not the safe choice for food preservation.

How do I get the best citrus from my trees for preserving and can I store it before processing?

Unlike many fruits, citrus fruits do not continue to ripen once picked. However, if you pick over-ripened fruit, it will be more susceptible to rotting. On the other hand, you do not want to pick unripe fruit because its sweetness and nutritional value will be hampered.

You, therefore, need to pick well-ripened fruit. Always look for fruit with vibrant colors, but which are firm to touch. Greenish color on oranges might mean that they are under ripened. However, oranges with tinges of green and green lemons are okay, as they tend to keep well for longer.

Oranges store best at cooler temperatures and go bad quickly at warmer temperatures. To refrigerate them properly, place them in a mesh, as opposed to a plastic, bag. This allows air to circulate and slows down the growth of mold, lesions, or softened rind. If you place them in the veggie section of your refrigerator and turn them occasionally to allow airflow, they should remain fresh for about 30 days. You can do the same with grapefruit as well. To refrigerate lemons, however, put them in a sealed plastic bag before placing them in the fridge.

Whether you refrigerate or keep your citrus fruits on a countertop, keeping them dry is key. Bundling them together when wet encourages mold growth and lesions which could break down the peel and compromise the flesh of the fruit.

What is a kumquat?

Kumquats, sometimes called “Winter Citrus,” are a sweet and juicy fruit. Unlike most other citrus fruit, you can eat a kumquat’s rind, center, and even the seeds if you want. Seek out firm and bright orange kumquats when you’re at the grocery store.

Here is a link to a document from the UCANR (University of California Agriculture & Natural Resources) about Kumquats with some recipes: https://ucanr.edu/sites/fresnonutrition/files/14352.pdf