Preserving pesto is a wonderful way to capture the fresh flavors of summer basil for use all year long. Many home cooks wonder whether homemade pesto or store-bought pesto is better suited for canning, and what the safest and most flavorful approach is. This guide compares homemade and store-bought pesto for canning, focusing on food safety, taste, and practical steps. You’ll learn what equipment and ingredients are needed, how to prepare and preserve pesto properly, and how to avoid common mistakes. Whether you’re a seasoned canner or a curious beginner, this guide will help you safely enjoy pesto from your pantry.
What You’ll Need
- Fresh basil (for homemade pesto)
- Pine nuts or walnuts (for homemade pesto)
- Fresh garlic cloves
- Parmesan cheese or hard cheese (optional; see safety notes below)
- Extra virgin olive oil
- Salt
- Food processor or blender
- Clean glass jars with tight-fitting lids (for freezing or refrigerated storage)
- Pressure canner (for shelf-stable canning; see safety notes below)
- Labels and marker for dating jars
- Freezer-safe containers (for freezing pesto)
Step-by-Step
- Decide on Your Method: Determine if you want to preserve pesto by canning or freezing. Freezing is the safest and most common way to store pesto long-term. Canning pesto for shelf storage is not recommended with water bath canning due to safety risks, but pressure canning may be used with modifications.
- Make Homemade Pesto (If Not Using Store-Bought): In a food processor, combine 2 cups fresh basil leaves, 1/2 cup nuts, 2-3 garlic cloves, 1/2 cup grated Parmesan (optional), and 1/2 cup olive oil. Pulse until smooth. Add salt to taste. Note: For canning, omit the cheese and nuts for safety; add them fresh before serving.
- Store-Bought Pesto: If using store-bought pesto, check the ingredient list. Many contain cheese, nuts, and sometimes preservatives. Most store-bought pestos are not designed for home canning but can be frozen or refrigerated.
- Prepare Jars: Wash jars and lids in hot, soapy water. Rinse thoroughly. If freezing, make sure the jars or containers are freezer-safe and leave headspace for expansion.
- Choose Preservation Method:
- Freezing: Portion pesto into small jars or ice cube trays. Cover with a thin layer of olive oil to prevent browning. Seal and label with the date. Freeze for up to 12 months.
- Pressure Canning (Not Recommended for Traditional Pesto): Traditional pesto is not safe for water bath canning or pressure canning due to its low acidity, oil content, and inclusion of dairy/nuts. If you wish to can a basil sauce, use a tested, low-oil, no-dairy recipe designed for canning, and follow USDA guidelines strictly.
- Refrigerated Storage: Place pesto in a clean, airtight jar. Top with olive oil. Store in the refrigerator for up to one week. Always use a clean utensil to avoid contamination.
- Label and Date: Clearly label each jar or container with the contents and date of preparation. This helps track freshness and safety.
- To Serve: Thaw frozen pesto in the refrigerator. If you omitted cheese or nuts for safety, stir them in just before serving.
Common Mistakes
- Canning with Cheese, Nuts, or Oil: Traditional pesto recipes with cheese, nuts, and oil are not safe for canning using water bath methods. These ingredients create a low-acid environment where dangerous bacteria, such as Clostridium botulinum, can thrive.
- Using Water Bath Canning: Never use water bath canning for pesto. The oil and low acidity make it unsafe, even with added lemon juice or vinegar.
- Overfilling Jars: Filling jars too full can cause lids to pop off or jars to break, especially when freezing.
- Not Labeling: Forgetting to label jars can lead to confusion about the age and contents of each batch.
- Improper Storage Temperature: Storing pesto at room temperature without proper canning is unsafe and can cause spoilage or foodborne illness.
Tips
- Freeze in Small Portions: Use ice cube trays or small jars to freeze individual servings of pesto. This reduces waste and makes it easy to thaw only what you need.
- Use High-Quality Olive Oil: The flavor of your pesto depends greatly on the quality of the olive oil you use, whether homemade or store-bought.
- Omit Cheese and Nuts for Preservation: If you plan to freeze or pressure can, leave out cheese and nuts. Add them fresh when serving for best flavor and safety.
- Cover with Oil: Pour a thin layer of olive oil over the top of pesto in the jar before sealing. This helps preserve color and freshness.
- Try Herbs Beyond Basil: You can substitute some or all of the basil with other leafy herbs like parsley or cilantro for a unique twist.
- Check for Off Smells or Mold: If pesto develops an unusual smell, color, or visible mold, discard it immediately.
Troubleshooting
- Pesto Turns Brown: Basil oxidizes quickly. To minimize browning, blanch basil leaves in boiling water for 5-10 seconds, then plunge into ice water before making pesto. Always cover with a layer of oil before freezing or refrigerating.
- Separation or Oiliness: It’s normal for oil to separate during storage. Stir well before serving.
- Jar Lids Pop or Leak: If freezing, leave at least 1/2 inch headspace in jars to allow for expansion. Use only freezer-safe containers.
- Pesto Tastes Bitter: This can happen with over-processed basil or low-quality olive oil. Pulse ingredients gently and use fresh, high-quality oil.
- Unusual Odor or Mold: Discard any pesto that smells off or has visible mold. Do not taste to check safety.
- Unclear on Safety: When in doubt, freeze rather than can. Home-canned pesto is not recommended for shelf storage unless using a tested recipe specifically designed for pressure canning without cheese, nuts, or large amounts of oil.
Frequently Asked Questions
- Can you safely can homemade pesto at home?
Traditional pesto with cheese, nuts, and oil is not safe for home canning due to low acidity. Freezing is the safest method for long-term storage. - Is store-bought pesto safer to can than homemade?
No. Most store-bought pestos also contain oil and cheese, making them unsafe for home canning. Stick to freezing or refrigeration. - How long does frozen pesto last?
Frozen pesto keeps well for up to 12 months. For best flavor, use within 6-8 months and keep it well sealed. - Can I add cheese and nuts after thawing frozen pesto?
Yes! For best safety and flavor, add cheese and nuts just before serving if you left them out for freezing or canning. - What happens if I accidentally canned pesto using a water bath?
Unfortunately, this is not safe. Discard the pesto—do not taste or use it. Next time, use freezing or a properly tested pressure canning recipe for sauces. - Can I pressure can pesto safely?
Only if you use a tested, low-oil, no-dairy, no-nut basil sauce recipe from a trusted source. Never can traditional pesto with oil, cheese, or nuts.
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