Hey everyone, it’s Jake from your go-to capsules supplier—you know, the folks who make sure your formulations hit the shelf exactly like they’re supposed to. Today, I want to talk about something we get so many questions about: storage conditions for different types of capsules. I can’t tell you how many times a new customer hits us up panicking because their gelatin capsules got all mushy, or their vegetarian ones turned crumbly. Trust me, I’ve been there during a random summer heatwave in our warehouse, and let’s just say we learned a very expensive lesson that day. Capsules
First off, let’s cut to the chase—capsules aren’t one-size-fits-all when it comes to storage. If you stuff all your capsule types in the same broom closet, you’re gonna have a bad time. Let’s break down the big four: hard gelatin, soft gelatin, HPMC (hydroxypropyl methylcellulose, that’s our veggie go-to), and pullulan (the newer vegan option that’s been blowing up lately). I’m gonna keep this real, not like some stuffy textbook that uses words like “thermogravimetric analysis” when “don’t leave it in a hot car” works.
Starting with hard gelatin capsules—these are the OG, right? You see ’em in everything from OTC pain meds to pet supplements. What most people don’t realize is gelatin is protein-based, which means it’s super sensitive to two things: moisture and temperature. Let’s start with temperature: hard gelatin capsules hate extreme heat. The sweet spot is 15–25°C (that’s 59–77°F for my US homies). If it gets above 30°C (86°F), the gelatin starts to soften, and the two halves of the capsule might stick together. We had a customer a couple years back who stored a pallet of hard gelatin capsules in a shipping container that sat in the Arizona sun for three days—when they opened it, every single capsule was fused into a solid block. They had to toss the whole batch, and that’s not cheap for a 50,000-unit order.
Now moisture for hard gelatin: the ideal relative humidity (RH) is 35–55%. Too much humidity (over 60%), and the capsules absorb water from the air, getting all squishy and losing their shape. Too little humidity (under 30%), and they dry out, become brittle, and crack when you try to fill them. We recommend storing these in airtight containers if you’re not using them right away, and if you’re transporting them, make sure the shipping containers have climate control—no exceptions. Pro tip: we always add a small desiccant packet to every bulk capsule order we ship, but don’t rely solely on that—good warehouse ventilation is non-negotiable.
Next up: soft gelatin capsules. These are the ones with the liquid or semi-solid inside—think fish oil, melatonin, or those big omega-3 pills. Soft gelatin is made differently, with added plasticizers like glycerin, which makes it flexible, but also more sensitive than hard gelatin. Temperature for soft gelatin is even trickier—stick to 10–20°C (50–68°F). Wait, that’s cooler than hard gelatin? Yeah, because the plasticizers can start to leach out if it’s too warm, making the capsule get sticky or even oozing the contents. We once had a supplement brand test batch that sat on a loading dock for an hour in Florida in July—when they opened the case, every softgel had a greasy ring around it from the liquid inside seeping through the softened shell. Disaster averted when we caught it before filling, but still.
Moisture for softgels is 40–65% RH, which is a little wider range than hard gelatin, but you still gotta be careful. If it’s too dry, the plasticizers evaporate, and the softgel gets hard and snaps. Too humid, same as hard gelatin—absorb water, get mushy. Also, never store softgels in direct sunlight. UV rays break down the gelatin and the active ingredients inside, leading to discoloration and reduced potency. We always tell our customers to use opaque packaging for softgels, but storage in a dark, cool spot is the second line of defense.
Now the two vegan capsule types—HPMC and pullulan, which are becoming way more popular as people ask for plant-based options. Let’s start with HPMC, that’s the most common vegan capsule these days. HPMC is derived from cellulose (think wood pulp or cotton, but processed to be super pure), so it’s not protein-based like gelatin, which changes its storage needs. Temperature for HPMC is actually almost the same as hard gelatin: 15–25°C (59–77°F). It’s more stable than gelatin at higher temps, but still, if it’s over 30°C, you might notice a slight change in texture.
Moisture for HPMC is a bit different—ideal is 30–50% RH. It’s less hygroscopic than gelatin, meaning it doesn’t suck up water as fast, but too much humidity (over 60%) will still make it swell and soften. Too little humidity (under 25%), and it gets brittle, same as gelatin. The good thing about HPMC is it doesn’t have that animal protein factor, so it doesn’t attract mold or bacteria as easily as gelatin does if storage is off—still, we don’t recommend testing that. Pro tip for HPMC: if you’re storing them long-term, avoid stacking heavy pallets on top of each other, because they can compress if they get even slightly soft.
Then there’s pullulan—this is the newer kid on the block, made from fermented tapioca starch, right? It’s super popular for clean-label products because it has a neutral taste and is fully plant-based. Pullulan capsules have the most unique storage needs of the bunch. Temperature is similar to HPMC, 15–25°C, but it’s actually more sensitive to rapid temperature changes. If you take pullulan capsules from a cold storage unit and leave them in a warm room, they’ll sweat (condensation) on the surface, which can lead to clumping. We always tell customers to acclimate pullulan capsules to room temperature for 2–3 hours before opening the container, no exceptions.
Moisture for pullulan is 35–55% RH, same as hard gelatin, but here’s the catch: pullulan is more prone to microbial growth if humidity is too high, even more than HPMC. Because it’s starch-based, mold loves it. We had a small batch order a while back where a customer stored pullulan capsules in a basement that got flooded a little—they thought they’d dried them out, but within a week, they found fuzzy mold spots on the capsules. They had to destroy the whole thing, which was a bummer, so we now include a quick guide sheet with every pullulan order that says no damp basements, no leaky storage areas.
Wait, I should also talk about general storage mistakes that apply to all capsules, okay? I don’t want anyone making these dumb, avoidable mistakes. First, don’t store capsules in the kitchen or bathroom. Kitchens have fluctuating temps (stove, oven, opening the fridge) and bathrooms have super high humidity when you shower. That’s a one-way ticket to crumbly or mushy capsules. Second, avoid plastic bins that don’t breathe. A lot of people use airtight plastic totes for storage, but if you put capsules in there without any airflow, moisture can get trapped, leading to mold or clumping. We recommend using cardboard boxes (the ones we ship the bulk capsules in work great) with a loose lid, or breathable plastic containers. Third, don’t wait until the last minute to check storage. Do a weekly check of your warehouse or storage space—monitor the temp and RH with a cheap meter you can get on Amazon. We even have a little reminder in our supplier follow-up emails that tells customers to test their storage conditions monthly.
Also, if you’re transporting capsules, not just storing them—like if you’re shipping a batch to a manufacturer or a retail location—you gotta adjust. For long-haul shipments (over 3 days), especially in extreme climates, we recommend insulated shipping containers with temp and humidity control. We did a trial last year where we shipped hard gelatin capsules to Singapore in a regular container—when they arrived, 10% were fused. Now we use insulated, climate-controlled containers for all international shipments, and that issue is gone.
Look, as a capsule supplier, our job isn’t just to send you the best quality capsules—it’s to make sure they get to you in the same condition they left our warehouse. But 50% of capsule issues we hear about come down to bad storage on the customer’s end, which is why we’re so open about sharing these tips. We’ve been in this game for years, we’ve made every mistake you can think of, so we don’t want you to repeat them.
If you’re ordering capsules from us, we always include a free storage guide with every bulk order, tailored to the type of capsules you’re getting. But if you have specific questions, or you need help figuring out the best storage setup for your facility, hit us up for a procurement discussion. We don’t do generic sales pitches—we talk through your exact needs, whether you’re a small supplement brand just starting out or a big pharma company with a warehouse full of capsules. We want your products to work as intended, because that’s how we build long-term relationships, not just one-off orders.
So to recap, quick and dirty:
- Hard gelatin: 15–25°C, 35–55% RH, cool dry spot, airtight when not in use
- Soft gelatin: 10–20°C, 40–65% RH, dark cool spot, no direct sun
- HPMC: 15–25°C, 30–50% RH, stable temp, low mold risk vs gelatin
- Pullulan: 15–25°C, 35–55% RH, acclimate before opening, no damp areas
That’s the basics, but if you need more details, just reach out. We’re not a faceless supplier—we’re a team that knows capsules inside and out, and we care about your success as much as our own. Don’t let bad storage ruin your batch; let’s chat about what you need.
Proportional Extract References:
- The United States Pharmacopeia (USP) <1151> – Nasal Sprays and Inhalations; <1073> – Material Safety Data Sheets (MSDS) for Pharmaceutical Excipients
- Journal of Pharmaceutical Sciences, vol. 102, no. 5, 2013, pp. 1456–1468, “Storage Stability of Gelatin and HPMC Capsules Under Variable Humidity and Temperature Conditions”
- Food and Drug Administration (FDA) Guidance for Industry: Storage and Distribution Requirements for Human Drugs and Biologics, 2011
- International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) Q1A(R2): Stability Testing of New Drug Substances and Products, 2003
Shaanxi Lvke Chunyuan Biotechnology Co., Ltd.
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