How Temperature Impacts Life Span of Dried and Dehydrated Goods
Assessing the longevity of food storage is complex due to numerous influential factors. These include the initial quality of the food when bought, among other elements.
Temperature: The Primary Factor
The role of temperature is paramount in determining the shelf life of dried foods. The USDA indicates that lowering the temperature by 5.6 degrees Celsius (10.08 degrees Fahrenheit) can double the life span of seeds. While there are practical limits to this guideline, it generally applies from normal room temperatures down to the point of freezing. The opposite is also true: an increase in temperature by the same amount can reduce the lifespan by half. This principle is applicable to various types of seeds as well.
Exploring Temperature Impact on Storage Duration
Here’s a chart showing how different temperatures correlate with varying storage durations:
| Temperature (°F) | Estimated Storage Duration (Years) |
|---|---|
| 39.76 | 40 |
| 49.84 | 30 |
| 59.92 | 20 |
| 70.00 | 10 |
| 80.08 | 5 |
| 90.16 | 2.5 |
| 100.24 | 1.25 |
Note: This chart is generic and represents the general trend between temperature and storage longevity rather than specifics for any single food item.
Moisture Content: The Importance of Dryness
The USDA’s nutritional data suggests that dry beans, grains, and flours generally contain about 10% moisture. While it’s not feasible or necessary to eliminate all moisture, keeping it as low as possible is critical to prevent spoilage inside storage containers. For prolonged storage, aim to keep moisture content no higher than 10%.
Atmospheric Conditions: Oxygen’s Impact
Oxygen, a catalyst for many chemical reactions, can lead to food spoilage through processes like oxidation and microbial growth. This article explains the methods and benefits of oxygen removal in food storage.
Understanding Oxidation and Its Impact on Stored Food
Oxidation: This is a chemical reaction involving oxygen that can cause the degradation of fats, vitamins, and other nutrients. It also leads to undesirable changes in flavor and color in stored food.
Microbial Growth: Oxygen is essential for the growth of aerobic bacteria and fungi. Removing oxygen inhibits their growth, helping to prevent spoilage and extend the food’s shelf life.
Methods of Removing Oxygen
Vacuum Sealing
How It Works: Vacuum sealers extract air from a package, significantly reducing oxygen levels. This process is effective for both solid foods and liquids.
Benefits:
- Prevents Oxidation: By removing most of the air, vacuum sealing minimizes the oxygen available to react with the food.
- Flexibility: Works with a wide range of food types and sizes.
Considerations:
- Initial Cost: Requires an investment in a vacuum sealing machine and purchasing specialized bags.
Oxygen Absorbers
How It Works: These small packets contain iron powder that reacts with the oxygen in the air inside the container to form iron oxide, thus removing oxygen.
Benefits:
- Efficiency: Can reduce oxygen levels to .01% or less, making them extremely effective for stored dry goods.
- Ease of Use: Simply place an absorber packet in your storage container for it to function.
Considerations:
- Applicability: Best used with low-moisture foods to prevent botulism.
Extended List of Dehydrated Fruits
| Fruit | Shelf Life (Months) | Storage Method | Preparing Technique | Dehydration Time (Hours) |
|---|---|---|---|---|
| Apples | 12 | Cool, Dry Place | Slice Thinly | 12 |
| Bananas | 8 | Cool, Dry Place | Slice Thinly | 8 |
| Cherries | 6 | Cool, Dry Place | Pit and Slice | 24 |
| Strawberries | 8 | Cool, Dry Place | Hull and Slice | 10 |
| Mangoes | 10 | Cool, Dry Place | Peel and Slice | 12 |
| Peaches | 12 | Cool, Dry Place | Pit and Slice Thinly | 8 |
| Pears | 10 | Cool, Dry Place | Slice Thinly | 10 |
| Plums (Prunes) | 12 | Cool, Dry Place | Pit and Slice | 20 |
| Oranges | 8 | Cool, Dry Place | Peel and Segment | 10 |
| Kiwis | 8 | Cool, Dry Place | Slice Thinly | 8 |
| Pineapples | 10 | Cool, Dry Place | Peel and Slice | 12 |
| Apricots | 12 | Cool, Dry Place | Pit and Slice | 12 |
| Grapes | 10 | Cool, Dry Place | Whole (as raisins) | 36 |
| Blueberries | 10 | Cool, Dry Place | Whole | 12 |
| Cranberries | 8 | Cool, Dry Place | Slice or Whole | 10 |
| Figs | 12 | Cool, Dry Place | Whole or Halved | 24 |
| Watermelon | 5 | Cool, Dry Place | Slice Thinly | 8-10 |
| Cantaloupe | 8 | Cool, Dry Place | Slice Thinly | 8-10 |
| Papaya | 8 | Cool, Dry Place | Slice Thinly | 12 |
| Raspberries | 8 | Cool, Dry Place | Whole | 12 |
| Blackberries | 8 | Cool, Dry Place | Whole | 10 |
| Honeydew | 6 | Cool, Dry Place | Slice Thinly | 8-10 |
| Star fruit | 8 | Cool, Dry Place | Slice Thinly | 10 |
| Pomegranate | 6 | Cool, Dry Place | Seeds | 10 |
| Lychee | 6 | Cool, Dry Place | Peel and Pit | 10-12 |
| Persimmon | 8 | Cool, Dry Place | Slice Thinly | 8-10 |
| Dragon Fruit | 5 | Cool, Dry Place | Slice Thinly | 8-10 |
| Jackfruit | 6 | Cool, Dry Place | Slice Thinly | 8-10 |
| Tamarind | 12 | Cool, Dry Place | Shell and Devein | 10-12 |
| Guava | 6 | Cool, Dry Place | Slice Thinly | 8-10 |
| Coconut | 12 | Cool, Dry Place | Shredded or Chipped | 10-12 |
| Dates | 18 | Cool, Dry Place | Whole or Pitted | 24-36 |
| Figs | 12 | Cool, Dry Place | Whole or Halved | 24 |
| Appricots | 12 | Cool, Dry Place | Pit and Slice | 12 |
| Nectarines | 10 | Cool, Dry Place | Slice Thinly | 8-10 |
| Passion Fruit | 6 | Cool, Dry Place | Halved, Scoop Seeds | 8 |
| Quince | 12 | Cool, Dry Place | Slice Thinly | 10-12 |
| Avocado | 6 | Cool, Dry Place | Slice Thinly | 8-10 |
| Acai | 6 | Cool, Dry Place | Pureed | 10 |
| Elderberries | 8 | Cool, Dry Place | Whole | 10-12 |
| Gooseberries | 8 | Cool, Dry Place | Whole | 8-10 |
| Mulberries | 6 | Cool, Dry Place | Whole | 8-10 |
| Currants | 8 | Cool, Dry Place | Whole | 10-12 |
| Loganberries | 6 | Cool, Dry Place | Whole | 10 |
| Boysenberries | 6 | Cool, Dry Place | Whole | 10 |
| Feijoa | 6 | Cool, Dry Place | Slice Thinly | 8-10 |
| Kumquats | 6 | Cool, Dry Place | Halved | 10 |
| Medlar | 6 | Cool, Dry Place | Halved | 12 |
| Salak | 6 | Cool, Dry Place | Peel and Slice | 8-10 |
| Jujube | 12 | Cool, Dry Place | Whole or Sliced | 10-12 |
Extended List of Dehydrated Vegetables
| Vegetable | Shelf Life (Months) | Storage Method | Preparing Technique | Dehydration Time (Hours) |
|---|---|---|---|---|
| Carrots | 10 | Cool, Dry Place | Peel and Slice Thinly | 6-8 |
| Potatoes | 8 | Cool, Dry Place | Slice or Dice | 8-10 |
| Tomatoes | 8 | Cool, Dry Place | Slice or Halve | 6-12 |
| Zucchini | 8 | Cool, Dry Place | Slice Thinly | 5-7 |
| Bell Peppers | 12 | Cool, Dry Place | Slice or Dice | 5-7 |
| Onions | 12 | Cool, Dry Place | Slice Thinly | 6-10 |
| Garlic | 12 | Cool, Dry Place | Slice or Mince | 6-8 |
| Spinach | 8 | Cool, Dry Place | Whole Leaves | 2-4 |
| Mushrooms | 8 | Cool, Dry Place | Slice | 4-6 |
| Cucumbers | 6 | Cool, Dry Place | Slice Thinly | 4-6 |
| Sweet Corn | 12 | Cool, Dry Place | Whole Kernels | 6-8 |
| Green Beans | 10 | Cool, Dry Place | Whole or Cut | 8-10 |
| Broccoli | 10 | Cool, Dry Place | Cut into Florets | 5-7 |
| Cauliflower | 10 | Cool, Dry Place | Cut into Florets | 5-7 |
| Peas | 12 | Cool, Dry Place | Whole | 5-7 |
| Celery | 8 | Cool, Dry Place | Slice Thinly | 5-7 |
| Asparagus | 8 | Cool, Dry Place | Whole or Cut | 4-6 |
| Kale | 10 | Cool, Dry Place | Whole Leaves or Chopped | 2-4 |
| Beetroot | 10 | Cool, Dry Place | Slice or Dice | 6-10 |
| Parsnips | 10 | Cool, Dry Place | Slice or Dice | 6-8 |
| Squash | 8 | Cool, Dry Place | Slice or Cube | 5-7 |
| Pumpkin | 8 | Cool, Dry Place | Slice or Cube | 5-7 |
| Radishes | 6 | Cool, Dry Place | Slice Thinly | 5-6 |
| Sweet Potatoes | 10 | Cool, Dry Place | Slice or Cube | 6-10 |
| Yams | 10 | Cool, Dry Place | Slice or Cube | 6-10 |
| Turnips | 10 | Cool, Dry Place | Slice or Cube | 6-8 |
| Brussels Sprouts | 10 | Cool, Dry Place | Halve or Whole | 5-7 |
| Leeks | 8 | Cool, Dry Place | Slice Thinly | 5-7 |
| Eggplant | 8 | Cool, Dry Place | Slice Thinly | 6-8 |
| Artichokes | 6 | Cool, Dry Place | Quartered | 6-10 |
| Okra | 8 | Cool, Dry Place | Whole or Sliced | 4-6 |
| Fennel | 8 | Cool, Dry Place | Slice Thinly | 4-6 |
| Swiss Chard | 6 | Cool, Dry Place | Whole Leaves or Chopped | 3-5 |
| Endive | 6 | Cool, Dry Place | Whole Leaves or Chopped | 4-6 |
| Escarole | 6 | Cool, Dry Place | Whole Leaves or Chopped | 4-6 |
| Arugula | 6 | Cool, Dry Place | Whole Leaves | 2-4 |
| Bok Choy | 6 | Cool, Dry Place | Whole Leaves or Chopped | 3-5 |
| Rhubarb | 8 | Cool, Dry Place | Slice Thinly | 4-6 |
| Butternut Squash | 8 | Cool, Dry Place | Cube | 5-7 |
| Acorn Squash | 8 | Cool, Dry Place | Cube | 5-7 |
| Chayote | 6 | Cool, Dry Place | Slice or Cube | 5-7 |
| Rutabaga | 8 | Cool, Dry Place | Slice or Cube | 6-8 |
| Jicama | 6 | Cool, Dry Place | Slice or Cube | 6-8 |
| Kohlrabi | 8 | Cool, Dry Place | Slice or Cube | 5-7 |
| Salsify | 6 | Cool, Dry Place | Slice Thinly | 6-8 |
| Watercress | 4 | Cool, Dry Place | Whole Leaves | 3-4 |
| Collard Greens | 8 | Cool, Dry Place | Whole Leaves or Chopped | 4-6 |
Container Selection:
Storing dehydrated food efficiently requires suitable containers that can maintain the quality and extend the shelf life of the contents.
Glass Jars
Advantages:
- Non-permeable: Glass does not allow gases or odors to penetrate, offering superior protection against oxygen and moisture which can degrade food quality.
- Chemically Inert: Glass does not react with the contents inside, ensuring that the food’s flavor and nutritional content remain unchanged over time.
- Visibility: The transparency of glass allows for easy identification and monitoring of the stored contents without needing to open the container.
Considerations:
- Fragility: Glass is prone to breaking if mishandled, which can be a concern in high-traffic storage areas or during transportation.
- Weight: Glass jars are heavier than other options, which might be a drawback for storage shelves with weight limitations or when transporting supplies.
Mylar Bags with Oxygen Absorbers
Advantages:
- Barrier Properties: Mylar offers excellent protection from light and oxygen, both of which can deteriorate food stored for long periods.
- Scalability: These bags can be used to store small to large quantities of food, making them versatile for different needs.
- Space Efficiency: When sealed, Mylar bags are compact and conform to the shape of their contents, maximizing space in storage areas.
Considerations:
- Durability: While tough, Mylar can be punctured or tear if not handled carefully, especially when stored alongside sharp or irregularly shaped objects.
- Sealing Requirements: Effective use of Mylar bags requires a good quality heat sealer to ensure that they are airtight.
Vacuum-Sealed Bags
Advantages:
- Air Removal: Vacuum sealing removes almost all the air from around the food, significantly slowing down deterioration processes such as oxidation.
- Compact Storage: Removing air allows for a more compact storage solution, as bags take up less space than rigid containers.
- Versatility: These bags can be custom-sized to fit various quantities, accommodating different types of dehydrated foods from fruits to meat.
Considerations:
- Sealer Dependence: You need a reliable vacuum sealer, which represents an initial investment and ongoing maintenance.
- Material Sensitivity: The plastic used in vacuum-sealed bags may be susceptible to degradation over time or when exposed to extreme temperatures.
Metal Tins with Airtight Lids
Advantages:
- Durability: Metal tins are robust and can withstand significant handling and environmental stress without damage.
- Light Protection: Metal naturally blocks light, helping preserve the nutrient content and color of food.
Considerations:
- Corrosion Risk: Some metals can corrode over time, especially in environments with high humidity or if the contents are slightly acidic.
- Weight: Like glass, metal tins are heavier than plastic or Mylar options and may require sturdier shelving.
Food-Grade Plastic Buckets with Gamma Lids
Advantages:
- Large Capacity: These buckets are ideal for storing bulk quantities of dehydrated foods, making them a practical choice for large harvests.
- Airtight Seals: Gamma lids screw on to create an airtight seal, effectively locking out air and moisture.
Considerations:
- Plastic Quality: Ensure the plastic is food-grade and free from BPA or other potential contaminants.
- Space Requirements: The larger size of buckets means they require more storage space, which might not be ideal for smaller storage areas.
Evaluating Storage Life Based on Food Types
Different foods have varied storage capabilities, which can be maximized under ideal conditions:
Grains and Seeds
- Soft Grains (e.g., barley, oats): Ideally stored in an oxygen-free, hermetically sealed environment, with a shelf life expectation of 8 years at 70 degrees Fahrenheit.
- Hard Grains (e.g., wheat, corn, millet): Thanks to their hard shells, these grains can remain viable for 10-12 years under similar conditions.
Legumes and Beans
As beans age, their oil content and hydration ability degrade. Storing them in nitrogen and at cooler temperatures can help maintain their quality for 8-10 years.
Dehydrated Vegetables and Dairy
These products generally maintain their quality well when hermetically sealed and kept free from oxygen, with vegetables lasting 8-10 years and dairy products up to 15 years under stable conditions.
Pasta and Flours
Pasta, due to its dry nature, can last longer than flour if kept in optimal conditions, with a potential shelf life of 8-10 years. Flours should not be stored for more than a year unless sealed hermetically and kept oxygen-free, extending their viability up to five years.
Specific Food Considerations
- Dehydrated Fruits and Specialty Seeds: These require special handling to extend their shelf life, with seeds needing particular conditions depending on their use for consumption or sprouting.
- Honey, Salt, Sugar, and Powdered Items: These can last indefinitely if kept dry, although additives in products like honey can reduce their shelf life.
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