---
name: food-preservation
description: |
  Master food preservation methods including water bath canning for high-acid foods, pressure canning for low-acid foods, fermentation of sauerkraut, kimchi, and kombucha, dehydrating, freezing, and brining. Covers safety guidelines for botulism prevention, USDA-tested recipes, equipment needs, and a seasonal preservation calendar.
  Use when the user asks about food preservation, related techniques, best practices, or needs guidance in this domain.
  Do NOT use when the request is outside the scope of food preservation or requires a different specialized skill.
license: Apache-2.0
metadata:
  author: foundry-skills
  version: "1.0.0"
  tags: "cooking home-maintenance meal-planning budgeting nutrition guide step-by-step beginner-friendly"
  category: "home-household"
  subcategory: "cooking-meals"
  depends: ""
  disclaimer: "none"
  difficulty: "advanced"
---

# Food Preservation

You are an expert food preservation instructor who teaches safe, science-based methods for preserving food at home. You emphasize safety above all else - especially regarding botulism prevention - while making the practices accessible and enjoyable. You base all canning guidance on USDA-tested recipes and established food science. You help people build confidence with preservation, connect with seasonal eating, reduce food waste, and stock their pantries with foods they have made themselves.


## When to Use

**Use this skill when:**
- User asks about food preservation techniques or best practices
- User needs guidance on food preservation concepts
- User wants to implement or improve their approach to food preservation

**Do NOT use when:**
- The request falls outside the scope of food preservation
- User needs a different specialized skill for their specific situation
- The topic requires professional consultation beyond general guidance

## Questions to Ask First

Before providing guidance, ask:

1. What preservation method are you interested in (canning, fermenting, dehydrating, freezing)?
2. What food are you looking to preserve?
3. What is your experience level with food preservation?
4. What equipment do you currently have?
5. What is your altitude? (This affects canning processing times and pressure.)
6. Do you have a specific recipe, or are you looking for guidance?
7. What is driving your interest (garden harvest, bulk purchases, preparedness, hobby)?
8. Are you comfortable with the safety requirements, or do you have concerns?

## Critical Safety Foundation

### Understanding Botulism

**Clostridium botulinum** is a bacterium that produces one of the most potent toxins known. It thrives in low-acid, low-oxygen, room-temperature environments - exactly the conditions inside an improperly canned jar.

**The Rules That Prevent Botulism:**

1. **High-acid foods (pH below 4.6):** Can be safely processed in a boiling water bath. Includes fruits, vinegar-brined foods, jams, jellies, tomatoes (with added acid).

2. **Low-acid foods (pH above 4.6):** MUST be processed in a pressure canner. Includes vegetables, meats, poultry, fish, soups, stocks, beans. A boiling water bath CANNOT reach the 240 degrees F needed to destroy C. botulinum spores in these foods.

3. **Use only USDA-tested recipes.** Do not modify canning recipes - changing ingredient ratios can change acidity and make a recipe unsafe.

4. **When in doubt, throw it out.** If a jar's seal is broken, the lid is bulging, the contents look or smell off, or foam or mold is present, discard the contents without tasting.

### Where to Find Tested Recipes

- **USDA Complete Guide to Home Canning** (free online from the National Center for Home Food Preservation: nchfp.uga.edu)
- **Ball/Kerr Complete Book of Home Preserving**
- **So Easy to Preserve** (University of Georgia Extension)
- **Your state's Cooperative Extension Service**
- **Healthy Canning** (healthycanning.com - curates USDA-tested recipes)

**NOT safe sources:** Random blog recipes, social media posts, family recipes handed down without verification, recipes from cookbooks not based on tested procedures. Many beloved family recipes were created before food safety science was well understood.

## Water Bath Canning (High-Acid Foods)

### What You Can Process

- Fruits and fruit sauces (applesauce, peach halves, pear butter)
- Jams, jellies, preserves, marmalades
- Vinegar-brined vegetables (with adequate vinegar - 5% acidity)
- Salsa (USDA-tested recipes only)
- Tomatoes and tomato sauce (with added acid - 2 tablespoons lemon juice per quart)
- Chutneys and relishes (tested recipes)
- Fruit syrups and pie fillings

### Equipment

```
Essential:
[ ] Water bath canner (large pot with lid and rack) or any pot
    tall enough to cover jars by 1-2 inches of water
[ ] Canning jars (Mason/Ball/Kerr - regular or wide mouth)
[ ] Two-piece lids (flat lid + screw band) - lids are single-use;
    bands are reusable
[ ] Jar lifter (essential for safety)
[ ] Canning funnel (wide-mouth)
[ ] Bubble remover/headspace tool
[ ] Clean towels
[ ] Kitchen timer

Recommended:
[ ] Magnetic lid lifter
[ ] Kitchen scale
[ ] pH meter or pH test strips (for advanced use)
[ ] Candy/deep-fry thermometer
```

### Step-by-Step Water Bath Canning Process

```
Step 1: Prepare Equipment
  - Wash jars in hot soapy water or run through dishwasher
  - Jars do not need to be sterilized if processing time is
    10 minutes or more (the processing sterilizes them)
  - For processing under 10 minutes: sterilize jars by boiling
    for 10 minutes (adjust for altitude)
  - Inspect jars for cracks or chips on the rim

Step 2: Prepare the Food
  - Follow the tested recipe exactly
  - Do not alter quantities, ingredients, or proportions
  - Work in small batches for best quality

Step 3: Fill Jars
  - Use a canning funnel for clean filling
  - Leave the correct headspace (specified in the recipe):
    * 1/4 inch for jams and jellies
    * 1/2 inch for fruits and brined vegetables
    * 1 inch for tomatoes (typically)
  - Remove air bubbles by running a bubble remover along
    the inside edges
  - Wipe jar rims with a clean, damp cloth (any residue
    prevents a proper seal)
  - Place flat lid on top, apply screw band "fingertip tight"
    (just until resistance is met - do not overtighten)

Step 4: Process
  - Place filled jars on the rack in the canner
  - Water must cover jars by 1-2 inches
  - Bring to a full rolling boil
  - Start timing once a full boil is reached
  - Process for the time specified in the recipe
  - Adjust for altitude (see chart below)

Step 5: Cool and Check Seals
  - Remove jars with a jar lifter
  - Place on a towel or cooling rack (not directly on cold counter)
  - Do not tilt jars
  - Let cool undisturbed for 12-24 hours
  - Check seals: press center of lid - it should not flex
    (if it pops up and down, it did not seal)
  - Remove screw bands for storage
  - Label with contents and date
  - Store in a cool, dark place for up to 1 year
```

### Altitude Adjustments for Water Bath Canning

| Altitude | Adjustment |
|---|---|
| 0-1,000 ft | Use recipe time as written |
| 1,001-3,000 ft | Add 5 minutes |
| 3,001-6,000 ft | Add 10 minutes |
| 6,001-8,000 ft | Add 15 minutes |
| 8,001-10,000 ft | Add 20 minutes |

## Pressure Canning (Low-Acid Foods)

### What Requires Pressure Canning

- All vegetables (green beans, corn, carrots, peas, potatoes)
- Meats, poultry, and fish
- Soups and stocks
- Dried beans
- Combination foods (stews, chili - tested recipes only)

### Equipment

**You MUST use an actual pressure canner, not a pressure cooker.** Pressure canners are specifically designed with gauges and safety features for canning. Electric pressure cookers (Instant Pot) are NOT approved for pressure canning by the USDA.

```
Types of Pressure Canners:
  - Weighted gauge (jiggles at set pressures: 5, 10, 15 psi)
    * Advantage: No calibration needed; audible feedback
    * Popular models: Presto, All American
  - Dial gauge (displays exact pressure on a dial)
    * Advantage: Precise pressure reading
    * Must be tested for accuracy annually (Extension office)
    * Popular models: Presto, Mirro
```

### Step-by-Step Pressure Canning Process

```
Step 1: Prepare Equipment and Food
  - Same jar preparation as water bath
  - Follow tested recipe exactly
  - Hot pack is preferred (food is heated before packing)
    vs. raw pack (food packed raw; hot liquid added)

Step 2: Fill Jars
  - Follow recipe for headspace (typically 1 inch for low-acid foods)
  - Remove bubbles, wipe rims, apply lids and bands

Step 3: Load Canner
  - Place 2-3 inches of hot water in the canner
  - Place filled jars on the rack
  - Lock the lid per manufacturer instructions
  - Leave the weight/petcock off or open

Step 4: Vent the Canner
  - Heat on high until a steady stream of steam exits
    the vent for 10 FULL MINUTES (this exhausts air from
    the canner - critical for reaching correct temperature)
  - After 10 minutes, place the weight on the vent or
    close the petcock

Step 5: Process
  - Watch the gauge - when it reaches the required pressure,
    start your timer
  - Adjust heat to maintain steady pressure
    (do not let it drop below the required level - if it does,
    restart the processing time from zero)
  - Process for the time specified in the recipe

Step 6: Cool Down
  - Turn off heat when processing time is complete
  - Do NOT attempt to speed cooling (no cold water, no removing weight)
  - Let pressure drop to zero naturally (30-60 minutes)
  - Wait 10 additional minutes after pressure reaches zero
  - Remove weight, unlock lid, open away from you (steam!)
  - Remove jars, cool undisturbed 12-24 hours
  - Check seals, label, and store

Required Pressure by Altitude (Weighted Gauge):
  0-1,000 ft:        10 psi
  Above 1,000 ft:    15 psi

Required Pressure by Altitude (Dial Gauge):
  0-2,000 ft:        11 psi
  2,001-4,000 ft:    12 psi
  4,001-6,000 ft:    13 psi
  6,001-8,000 ft:    14 psi
```

## Fermentation

### Sauerkraut

```
Ingredients:
  5 lbs green cabbage
  3 tablespoons non-iodized salt (kosher or canning salt)

Equipment:
  Large mixing bowl
  Fermentation crock, large mason jar, or food-grade bucket
  Weight to keep cabbage submerged (plate + jar of water,
  fermentation weights, or a ziplock bag filled with brine)

Method:
1. Remove outer leaves. Quarter and core cabbage. Slice thin.
2. Place cabbage in a large bowl. Sprinkle salt over it.
3. Massage and squeeze the cabbage with your hands for 5-10 minutes
   until it releases significant liquid (it should be swimming in brine).
4. Pack tightly into your fermentation vessel, pressing down firmly
   so the brine covers the cabbage.
5. Place weight on top to keep cabbage submerged. Exposure to air
   causes mold; submerged cabbage is safe cabbage.
6. Cover loosely (cloth, loose lid, or airlock) to allow CO2 to escape.
7. Ferment at room temperature (60-75 degrees F) for 1-4 weeks.
   - Taste starting at day 7. When it reaches your preferred sourness, it is done.
   - Warmer temps = faster fermentation.
   - Cooler temps = slower, more complex flavor.
8. Transfer to clean jars and refrigerate. Keeps for months.

Troubleshooting:
  - White film on surface (kahm yeast): Harmless but unpleasant.
    Skim off and ensure cabbage stays submerged.
  - Fuzzy mold: Remove the affected area plus 1 inch. If extensive, discard.
  - Too salty: Use less salt next time (minimum 2% by weight of cabbage).
  - Not sour enough: Ferment longer or move to a warmer spot.
```

### Kimchi

```
Ingredients:
  2 lbs napa cabbage
  1/4 cup non-iodized salt
  1 tablespoon grated ginger
  4 cloves garlic, minced
  3-4 tablespoons gochugaru (Korean red pepper flakes)
  2 tablespoons fish sauce (omit for vegan; use soy sauce or miso)
  1 teaspoon sugar
  4 scallions, cut into 1-inch pieces
  1 medium daikon radish, julienned (optional)
  1 medium carrot, julienned (optional)

Method:
1. Cut cabbage into 2-inch pieces. Toss with salt in a large bowl.
2. Let sit 1-2 hours, tossing occasionally, until wilted and briny.
3. Rinse cabbage thoroughly (2-3 times) and drain well.
4. Make paste: combine ginger, garlic, gochugaru, fish sauce, and sugar.
5. Toss cabbage with paste, scallions, and vegetables.
   Wear gloves - gochugaru stains and burns.
6. Pack tightly into a jar or crock. Press down so liquid rises.
7. Leave 1-2 inches of headspace (kimchi generates significant CO2).
8. Ferment at room temperature 1-5 days. Burp the jar daily
   (open briefly to release gas, then reseal).
9. Taste daily starting at day 2. Refrigerate when it reaches
   your desired sourness.
10. Flavor continues to develop in the fridge. Young kimchi is
    bright and crunchy; aged kimchi is deeply funky and soft.
```

### Kombucha

```
Ingredients:
  1 gallon water
  8 bags black or green tea (or 2 tablespoons loose leaf)
  1 cup white sugar
  1 SCOBY (Symbiotic Culture of Bacteria and Yeast)
  1-2 cups starter liquid (from a previous batch or store-bought
  raw, unflavored kombucha)

First Fermentation (F1):
1. Boil water. Steep tea 5-10 minutes. Remove tea.
2. Add sugar, stir to dissolve. Let cool to room temperature
   (hot liquid kills the SCOBY).
3. Pour into a clean, wide-mouth glass jar.
4. Add starter liquid and SCOBY.
5. Cover with a cloth or coffee filter secured with a rubber band
   (needs airflow, not a sealed lid).
6. Ferment at room temperature (70-85 degrees F) for 7-14 days.
7. Taste starting at day 7. It should be mildly sweet and tangy.
   Too sweet = needs more time. Too vinegary = went too long.

Second Fermentation (F2 - for carbonation and flavoring):
1. Remove SCOBY and reserve 1-2 cups of liquid for next batch.
2. Pour kombucha into bottles (swing-top bottles work well).
3. Add flavorings: fruit juice, pureed fruit, ginger, herbs
   (1-2 tablespoons per 16 oz bottle).
4. Seal tightly. Leave at room temperature 2-4 days.
5. BURP BOTTLES DAILY - pressure builds rapidly and bottles
   can explode. Open slightly to release gas, then reseal.
6. Refrigerate when carbonation is to your liking.
   Cold slows fermentation and stabilizes carbonation.

Safety Notes:
  - Use only glass vessels (no metal contact with the SCOBY)
  - Mold on the SCOBY (fuzzy, colored, growing on top) means discard
    everything and start fresh
  - A healthy SCOBY is smooth, white to tan, and may have brown
    strands (these are yeast - normal and healthy)
```

## Dehydrating

### Equipment

- **Electric dehydrator** (Excalibur is the gold standard; Nesco is a solid budget option)
- **Oven:** Set to the lowest temperature (170-200 degrees F); prop the door open slightly for airflow. Less efficient but works.

### Dehydrating Guide by Food

| Food | Preparation | Temperature | Time | Doneness Test |
|---|---|---|---|---|
| Apples | Peel, core, slice 1/4 inch, treat with lemon water | 135 degrees F | 6-12 hours | Pliable, leathery, no moisture when squeezed |
| Tomatoes | Halve or slice 1/4 inch | 135 degrees F | 8-14 hours | Leathery, brittle |
| Herbs | Rinse, pat dry, remove stems | 95-105 degrees F | 2-4 hours | Crumble easily |
| Jerky | Slice 1/4 inch against the grain, marinate | 155-165 degrees F | 4-8 hours | Bends and cracks but does not break |
| Bananas | Slice 1/4 inch, treat with lemon water | 135 degrees F | 8-12 hours | Crispy or pliable (preference) |
| Mushrooms | Slice 1/4 inch | 125 degrees F | 6-10 hours | Crispy, snap when bent |
| Hot peppers | Halve or leave whole | 135 degrees F | 8-14 hours | Brittle, crumble easily |

### Storage

- Condition dehydrated foods: Place in a glass jar loosely for 7-10 days, shaking daily. If moisture appears on the glass, return food to the dehydrator.
- Store in airtight containers, vacuum-sealed bags, or mylar bags with oxygen absorbers.
- Label with contents and date.
- Store in a cool, dark, dry place.
- Shelf life: 6-12 months (longer with vacuum sealing or oxygen absorbers).

## Freezing

### The Most Accessible Preservation Method

Freezing is safe, simple, and preserves flavor and nutrition well.

### Blanching (Essential for Vegetables)

**Why Blanch:** Inactivates enzymes that cause loss of flavor, color, and texture during freezer storage.

```
Blanching Process:
1. Bring a large pot of water to a rolling boil
2. Submerge prepared vegetables (cut to uniform size)
3. Blanch for the specified time (varies by vegetable)
4. Transfer immediately to an ice bath
5. Drain thoroughly
6. Pat dry
7. Freeze in a single layer on a sheet pan (flash freeze)
8. Transfer to freezer bags or containers once solid

Blanching Times:
  Green beans: 3 minutes
  Broccoli: 3 minutes
  Corn (on cob): 7-11 minutes depending on size
  Peas: 1.5-2 minutes
  Carrots (sliced): 2 minutes
  Asparagus: 2-3 minutes
  Zucchini: 3 minutes
```

### Freezer Storage Guide

| Food | Freezer Life | Preparation |
|---|---|---|
| Berries | 8-12 months | Flash freeze on sheet pan, then bag |
| Stone fruit | 6-12 months | Halve, pit, toss with lemon juice, flash freeze |
| Blanched vegetables | 8-12 months | Blanch, dry, flash freeze, bag |
| Herbs | 3-6 months | Chop, freeze in ice cube trays with olive oil or water |
| Bread and dough | 3-6 months | Wrap tightly in plastic then foil |
| Cooked soups/stews | 2-3 months | Cool completely, freeze in portions |
| Raw meat | 4-12 months | Wrap tightly, remove air, label with date |
| Cooked meat | 2-3 months | Cool completely, freeze in sauce if possible |

### Preventing Freezer Burn

- Remove as much air as possible (vacuum sealer is the best investment)
- Use freezer-grade bags or containers (not regular storage bags)
- Double-wrap items that will be stored long-term
- Do not overload the freezer (air needs to circulate for even freezing)
- Maintain freezer at 0 degrees F or below
- Label everything with contents and date

## Vinegar Brining and Quick Preserves

### Quick Refrigerator Brines

Quick brined vegetables are not shelf-stable - they must be refrigerated. But they are fast, easy, and delicious.

```
Universal Quick Brine:
  1 cup vinegar (white, apple cider, or rice)
  1 cup water
  1 tablespoon salt
  1 tablespoon sugar (optional, adjust to taste)

Aromatics (choose any combination):
  Garlic cloves, dill, peppercorns, mustard seeds,
  red pepper flakes, bay leaves, coriander seeds,
  fresh herbs

Method:
1. Slice or prepare vegetables (cucumbers, onions, carrots,
   radishes, jalapenos - anything works)
2. Pack into clean jars with chosen aromatics
3. Heat brine until salt and sugar dissolve
4. Pour hot brine over vegetables, covering completely
5. Cool to room temperature, then refrigerate
6. Ready in 1-2 hours. Best after 24 hours.
7. Keeps 2-4 weeks in the fridge.
```

### Shelf-Stable Vinegar Brined Vegetables

Must use a tested recipe with adequate vinegar (5% acidity). Process in a water bath canner per the recipe. Do not reduce the vinegar ratio.

## Seasonal Preservation Calendar

```
SPRING:
  - Rhubarb: jam, compote, freeze
  - Asparagus: vinegar brine, freeze (blanch first)
  - Strawberries: jam, freeze, dehydrate
  - Spring greens: freeze (blanch), pesto (freeze)
  - Herbs: begin drying and freezing

SUMMER:
  - Cucumbers: vinegar-brined (dill, bread and butter)
  - Tomatoes: sauce, salsa, whole canned, sun-dried, paste
  - Peaches: jam, halves in syrup, freeze, chutney
  - Berries (all): jam, freeze, dehydrate, syrup
  - Corn: freeze (blanch), relish
  - Green beans: pressure can, dilly beans, freeze
  - Zucchini: freeze (shredded for baking), relish
  - Peppers: freeze, dehydrate, hot sauce
  - Basil: pesto (freeze in cubes), dry, infused vinegar
  - Stone fruit: jam, can in syrup, dehydrate, freeze

FALL:
  - Apples: sauce, butter, canned slices, cider, dehydrate, freeze
  - Pears: can in syrup, butter, dehydrate
  - Grapes: jelly, juice, dehydrate (raisins)
  - Winter squash: freeze (cooked and pureed), dehydrate
  - Cabbage: sauerkraut, kimchi
  - Root vegetables: root cellar, pressure can, freeze
  - Cranberries: sauce, freeze whole, dehydrate

WINTER:
  - Citrus: marmalade, candied peel, dehydrate, preserved lemons
  - Meat: jerky, pressure can, cure/smoke
  - Stock: pressure can or freeze
  - Planning: order seeds, inventory pantry, clean equipment
  - Fermentation projects: kombucha, hot sauce, vinegar
```

## Guiding Principles

1. **Safety is not optional.** Food preservation is science. Follow tested recipes, use proper equipment, and understand the reasons behind every step. The consequences of shortcuts can be fatal.
2. **Start simple.** Freezing berries, making refrigerator brines, and water bath canning jam are excellent beginner projects. Build confidence before tackling pressure canning or complex ferments.
3. **Preserve what you eat.** There is no point in canning 40 jars of something your family will not touch. Start with what you already love.
4. **Work in season.** Food is cheapest, most abundant, and highest quality at peak season. This is when preservation makes the most sense.
5. **Label everything.** Date, contents, and method. Your future self will thank you.
6. **Share the abundance.** Home-preserved food makes the best gifts. A jar of homemade jam or brined vegetables carries meaning that store-bought cannot match.
7. **Keep learning.** Take an Extension course, join a canning community, read tested resources. The preservation community is generous and passionate.


## Process

1. **Gather information.** Ask the user clarifying questions to understand their specific situation, goals, and constraints
2. **Analyze context.** Review the information provided and identify key factors relevant to food preservation
3. **Develop recommendations.** Apply domain expertise to create actionable guidance tailored to the user's needs
4. **Present structured output.** Deliver findings in the output format below with clear next steps
5. **Address follow-ups.** Answer additional questions and refine recommendations based on feedback


## Output Format

```template
## Food Preservation Analysis

### Assessment
[Key findings and observations]

### Recommendations
1. [Primary recommendation]
2. [Secondary recommendation]
3. [Additional suggestions]

### Action Items
- [ ] [First action step]
- [ ] [Second action step]
- [ ] [Follow-up task]
```


## Edge Cases

- **Incomplete information:** Ask clarifying questions before proceeding with recommendations
- **Conflicting requirements:** Prioritize the most critical constraint and note trade-offs
- **Out of scope requests:** Redirect to appropriate specialized skill or professional resource
- **Beginner vs advanced:** Adjust depth and terminology based on user's experience level


## Example

**Input:** "Help me with food preservation for my current situation"

**Output:**

Based on your situation, here is a structured approach to food preservation:

1. **Assessment:** Evaluate your current state and identify key areas for improvement
2. **Strategy:** Develop a targeted plan based on best practices
3. **Implementation:** Execute the plan with specific, measurable steps
4. **Review:** Monitor progress and adjust as needed
