Something very soothing about the kitchen pantry, where jars full of beautiful red lentils, golden split peas, kidney beans and green gram are lined up. Pulses and lentils are the best staples in the diet of millions of families around the world. Being high in plant proteins, fibers, vitamins and minerals, they provide your body with all necessary nutrients.

But there must be nothing worse than finding that your lentils have been overrun by moths, become covered in fine powder at the bottom of the jar, or even that little insects have made tunnels through your lentils.

What causes this? Is there anything that can be done to prevent this from happening?

Pulses may appear to be simple to store – "put in a jar and forget about it" – but actually the process of storing dry foods is more complex and involves a delicate equilibrium of biological processes, such as moisture content, temperature, oxygen, and light. This article provides everything you need to know about the science of food preservation and tells how to store pulses and how to store lentils for the best results.

The Hidden Enemies of Stored Pulses and Lentils

Prior to the discussion on preservation methods, it is vital to consider the reasons for deterioration of pulses. In contrast to fruits and vegetables, dried pulses represent low moisture content seeds in an inactive state biologically. In order to preserve them, you need to safeguard them from four main enemies:

1. Excessive Moisture and Humidity

Moisture is considered to be the main enemy in terms of storage of dry foods. Whenever pulses start absorbing ambient moisture from the atmosphere, there appear two main issues:

Microbial Growth: Increased moisture content ($12\%$ internal moisture) provides conditions for development of mold, mildew, and fungi such as Aspergillus that can create toxic mycotoxins.

Clumping and Spoilage: Absorption of moisture results in pre-swelling of the external seed coat thus causing the process of clumping, odor formation, and quick spoilage.

2. Oxygen and Oxidation

Oxygen promotes chemical reactions inside the natural fats and proteins of the seed coat and inner cotyledon. Oxygen exposure leads to stale odor and color changes. Besides, oxygen is necessary for the development of insect eggs in storage.

3. Insects and Storage Pests

Some of the most prevalent pests associated with legume storage include the pulse beetles (Callosobruchus maculatus), pulse weevils, and Indian meal moths. The truth is that microscopic insect eggs are already present on the outer layers of raw, unpolished pulses even fresh off the farm or local market. These eggs then hatch to form larvae that eat away at the lentils from inside out, leaving behind empty husks and dust.

4. Heat and Light

Heat causes accelerated chemical reactions in which the natural oils in pulses undergo a process of spoilage referred to as becoming rancid. Sunlight and intense indoor lighting also cause bleaching of the natural colors of the pulses—taking the bright red color from masoor dal to a pale yellow hue—and breakdown of photosensitive vitamins.

Pre-Storage Preparation: Making Your Pulses Last Longer

If you're wondering how to store pulses for long time, the process actually begins before you even seal them in storage containers. Proper preparation is essential because it helps prevent moisture and pests from getting trapped inside the containers, ensuring your pulses stay fresh and safe for extended periods. 

Step 1: Examine the Batch Closely

If you have purchased fresh pulses in bulk form, spread them evenly in a shallow tray or on a plain piece of paper. Look for cracked seeds, rocks, soil, or evidence of existing infestation by way of small holes or dust. Remove these from the batch to prevent contamination of the whole lot.

Step 2: The Method of Sun Drying

Even if the store-purchased lentils feel dry in hand, there is a chance that these have accumulated hidden moisture while traveling from one place to another or when packed. Lay the pulses in a thin layer on a plain cotton sheet and let them bask in strong sunlight for about 6 to 8 hours.

• Sunlight accomplishes the following two purposes:

• It evaporates hidden moisture, resulting in decreased humidity of the seed.

• It acts as a disinfectant by UV rays that keep the adults and micro-eggs at bay.

Note: Ensure that the pulses get cooled to room temperature completely before storing them. Putting still hot pulses in an enclosed container results in steaming up, which will ensure mold formation later!

Step 3: Winnowing/Cleaning

Once the pulses have been air-dried, they should be winnowed/sieved in order to blow off the lighter dust and debris, including any dirt. Clean pulses are less likely to attract storage pests.

Step 4: Deep Freezing Process (Deactivation of Pests)

If you need to be sure while storing pulses, you should opt for the thermal shock process. Place your dry pulses inside an airtight plastic bag, and then put it in an ultra-cold ($-18^\circ\text{C}$ or lower) freezer for 48 to 72 hours. This freezing procedure kills off any dormant insect eggs or larvae present on the grains, but the grain itself is not damaged by the freezing process. Once done, take out the pulses from the bag and allow it to come back to room temperature on your counter before moving on to storage containers.

Choosing the Appropriate Container

It should not be taken lightly when determining which type of container would work best for storing lentils. Not all plastic jars and bags are equally efficient in keeping the air and humidity away.

1. Glass Mason Jars with Airtight Lids

Glass material does not have pores and is totally impermeable to both gases and moisture. The glass jars that have heavy rubber gaskets or airtight silicone closures will block the humid air and insect pests entirely. It also gives you the chance to see what’s inside without opening the lid.

Best for: Medium-term pantry storage (up to $6$-$18$ months).

Tip: Store your glass containers in dark cabinets in order to protect your grain supply from light exposure.

2. Stainless Steel Containers

Stainless steel containers have been traditionally used in South Asian kitchens. The stainless steel blocks 100% of light and gives you an impenetrable protection from rodents' sharp teeth and beetles' burrowing. Make sure that the lids seal well; silicone rimmed steel lids are better than slide-on covers.

Best for: Short-term daily use and long-term pantry storage (up to $1$-$3$ years).

3. Mylar Bags with Oxygen Absorbers

For ultra-long term preservation (from $5$ to $20+ years), food-grade Mylar bags coupled with individually wrapped Oxygen Absorbers (iron powder packets that absorb oxygen molecules from the enclosed environment) constitute the highest standards in terms of food security.

Suitable for: Preparing for emergencies, bulk storage, and long-term pantry backups.

4. What to Avoid: Polyethylene Plastic Bags and Jute Sacks

Single use disposable plastic bags, sacks made from cloth and porous jute sacks must not be used for long-term storage purposes. They are easily chewed by pests such as pulse beetles and, in addition to this, porous sacks allow the air of monsoons to enter inside the grains.

Natural Organic Deterrents Against Bugs in Pulses

Organic deterrents against bugs in pulses are traditionally used in India long before the invention of artificial pesticides or food-grade insecticides.

1. The Edible Oil Coating Technique (Groundnut Oil, Mustard Oil, or Castor Oil)

One of the most efficient ways of storing pulses for a very long time by using traditional means is applying an edible oil coating on the outer covering of whole pulses. Unrefined groundnut oil, castor oil, or mustard oil are excellent choices.

• Process: The edible oil creates a thin and hydrophobic coating over the outer surface of the seed coat. In doing so, it acts as a barrier which does not allow the females to stick their eggs onto the smooth surface of the pulses. Even if the egg-laying takes place, this coating does not allow the eggs to breathe due to the closure of their pores.

• Ratio: Apply 1 teaspoon (5ml) of edible oil to every 1 kg of dry pulses. Pour the edible oil on your palm and rub the pulses with your hands till each and every pulse becomes slightly shiny.

• Suitable for: Whole pulses with complete skin coverings like whole moongdal, urad, chana, rajma, etc.

• Note: Before cooking, all you need to do is just rinse the coated pulses twice with warm water.

2. Dried Neem Leaves (Azadirachta indica)

Neem leaves are well-known for their natural insecticide, anti-fungal, and antibiotic properties.

• How to Apply: Gather neem leaves when they are fresh, rinse them properly, and make sure that they are thoroughly dried out in the shade before you use them. Never put the wet or moist leaves in your storing box! Lay the dried neem leaves in the bottom of your storing container, add the layer of pulses, and continue in this way.

• How It Works: There are natural substances such as azadirachtin in the leaves of neem that serve as a very good repellent for insects and inhibit their biological development process.

3. Whole Dry Red Chilies and Garlic Cloves

Putting 4-6 whole and unbroken red dried chilies with their stalks into a lentil jar will form a habitat that the pests try to avoid. The capsaicin content and the volatile nature of the pungent substances serve as a good natural repellant. The same way whole garlic cloves which are fully dried and unpeeled put in the lentil jars prevent pests from coming inside. It is necessary to replace the dried garlic cloves every two months once their smell is gone.

4. Tejpatta and Cloves

Tejpatta is full of eugenol, which is aromatic essential oil that repels flour moth, weevils, and ants. Putting 3-4 dry bay leaves and a few whole cloves in your lentil jars will make the air inside pleasantly fragrant for humans and at the same time repulsive for pests.

5. Organic Turmeric Powder

Mixing pure turmeric powder with your raw, unprocessed and split lentils makes a natural dust barrier on the surface of the lentils, which prevents the development of fungi and discourages crawling pests.

Food Storage Environments: Temperature, Humidity and Positioning

Regardless of the quality of the container itself and its repellent qualities, storage in a wrong environment is a recipe for disaster. The position in which you store your food jars is as important as the packaging itself.

Deep Dark and Cool Storage Environment

Pulse containers should be kept in a cool and dry pantry or lower kitchen cabinet. The optimal temperature for storage should be within the defined limits. Food jars must not be stored in close proximity to your stoves or oven where extreme heating occurs.

Storage Containers Should Not Be Stored Directly on Concrete Floor and Exposed to the External Wall

Concrete floor and exposed external walls absorb moisture from the air and pass it onto food jars. You should always store your storage containers on elevated wooden or plastic shelving.

“Hard-To-Cook” Problem (HTC)

Is there any time that you have cooked aged split chickpeas or whole kidney beans for 2 hours but they were still hard, chalky, and rubbery? Well, this annoying problem has a scientific name – the Hard-to-Cook (HTC) problem.

The HTC problem occurs due to improper storage of the pulses where high temperature and high humidity are present together for long periods. Under such extreme conditions:

Insoluble complexes are formed by pectin molecules along with calcium and magnesium ions within the cell walls.

The outer seed coat lignifies and becomes impermeable to boiling water.

Proteins within the cotyledon cross-link and make it impossible for the starch granules to gelatinize properly while cooking.

How to Avoid HTC and How to Remedy It:

Prevention: Adherence to appropriate storage methods (low humidity, low temperatures, and air-tight containers) ensures that HTC does not occur.

Solution to Existing Problem with Older Stock: When cooking old stock of lentils that have hardened, include a small amount (one-quarter teaspoon) of baking soda in the soaking water. This baking soda increases the pH level, thereby disintegrating insoluble pectin complexes and making the hardened seed coats tender in the process of pressure cooking.

Storage Scenarios That You Might Find Yourself In:

These scenarios call for different ways of storing lentils effectively:

Scenario A: Coastal Areas of High Humidity (Managing Monsoons)

• If you happen to live in a coastal area where you have humid climates and humidity levels going above 80% during monsoon seasons:

• Add the silica gel packets (desiccant food-grade pouches) to the upper part of the lid of your glass jars to actively absorb any extra moisture from the air inside the jars.

• Make use of small batch refrigeration; storing dried pulses in air-tight containers inside your refrigerator stops all developmental processes of insects and prevents moisture issues.

Scenario B: Bulk Purchase (between 10 kg and 25 kg)

• Do not keep the bulk bag of your pulses open on the pantry floor.

• Split the purchase up right away: pour 1 or 2 kilograms into a jar that is easily available to you every day for cooking, and put the rest in heavy-duty stainless steel tubs or Mylar bags with oxygen absorbers.

• When you open your main storage container every day, you expose your whole bulk to fresh air, moisture, and atmospheric dust. Seal your bulk storage away!

Fill Your Storage with Only the Best From Vanatva

Food that can be stored for a long time is best done with natural and unprocessed grains that come directly from Mother Nature. If you need your pantry to be stocked up with healthy grains which have not been processed by any chemicals, then visit the collection of natural foods from Vanatva. The store will offer you all the natural kitchen necessities such as fresh pulses, cold pressed oil, and more.