Storing malt sacks safely through a humid Indian monsoon
Malt is hygroscopic and the monsoon is relentless. A store that works in February can quietly spoil stock by August. Here is how a brewery sets up malt storage to come through the wet season with its extract and flavour intact.
What humidity does to malt
Malt typically leaves the maltings at around 4% to 5% moisture, which is what keeps it stable. It pulls water from the air until it reaches a balance with the surroundings. In monsoon conditions, with relative humidity often well above 80%, that balance sits far higher than the maltster intended.
As moisture climbs, three things happen. Extract per kilo falls, because you are paying for water. The grain turns slack and chewy, so it mills poorly, which hits lautering and brewhouse yield. At the extreme, moulds grow, bringing musty flavours and a risk of mycotoxins. Insects also breed faster in warm, damp grain.
Where to put the store
- Away from steam and wet areas. Not next to the kettle stack, the CIP station or the floor drains.
- Off the floor and away from walls. Sacks on pallets, with a gap from the walls so air moves and you can inspect for pests and damp.
- Dry and as cool as practical. Shaded, with no leaks. Check the roof before the rains, not during them.
- Closed to pests. Screened vents, door seals and no gaps where rodents can get in.
For a small brewpub, a dedicated dry room with a dehumidifier is often the single best investment. A cheap digital hygrometer on the wall tells you whether it is working.
Monitor moisture, do not guess
Log temperature and relative humidity in the store daily during the monsoon. A dehumidifier set to keep the room around 50% to 60% relative humidity is a sensible target for dry goods.
Test the malt itself too. A grain moisture meter gives a quick reading. A lab drying test is more accurate. Compare each reading with the moisture on the certificate of analysis for that lot. A creep of more than a percentage point or so tells you the store is losing the fight.
Opened sacks and silos
An opened sack is the most vulnerable. Fold and clip it shut at the end of each brew day, or decant into sealed food-grade bins with tight lids. Never leave a half-used sack open on the brewhouse floor overnight in July.
Breweries with silos should check seals and vents before the rains and look for condensation inside. Silo walls exposed to sun and cool nights can sweat, wetting the malt in contact with them.
Pests in a warm, wet season
Weevils, grain borers and moths thrive in monsoon warmth. Signs include webbing, holes in kernels, dust trails and live insects in the bags. Inspect each delivery before it enters the store and set a regular check through the season.
Use a professional pest control contractor who understands food premises. Fumigation of food stocks is a specialist and regulated job. Do not improvise with household insecticides anywhere near malt, brewing water or equipment. Infested lots go to quarantine, away from clean stock, until the head brewer decides what to do with them.
Plan stock for the season
The simplest defence is to hold less malt through the wettest months. Agree a delivery schedule with your supplier that brings smaller, more frequent lots in the monsoon. Use strict first-in-first-out and mark the receipt date on every pallet. Imported malt with long resupply times needs the most thought, since the temptation is to stock up just before the season in which storage is hardest. Our guide to sourcing malt and hops in India covers supply planning.
Count the losses
Malt that goes slack or mouldy is a direct loss. It rarely shows up as a line item. It appears instead as lower brewhouse yield, a few batches that need more malt to hit gravity, or sacks written off quietly. Track malt use per hectolitre and write-offs month by month. A brewery loss audit will usually show whether the monsoon is costing you more than a dehumidifier would.
A monsoon checklist
- Roof, vents and door seals checked before the rains.
- Hygrometer on the wall and humidity logged daily.
- All sacks on pallets, away from walls.
- Opened sacks sealed or decanted at the end of every brew day.
- Moisture tested on each lot at intervals and compared with its certificate.
- Pest checks scheduled with a contractor and recorded.
- Smaller, more frequent deliveries agreed with suppliers.
None of this is complicated. What makes it work is turning it into a routine someone owns, with a record that shows it was done.
Common questions
What moisture should malt be?
Malt usually leaves the maltings around 4% to 5% moisture. A noticeable rise in your store means it is absorbing humidity.
What humidity should a malt store be?
Aim to keep a dry goods store around 50% to 60% relative humidity with a dehumidifier. Log it daily in the monsoon.
Can I use malt that has gone slightly soft?
Slack malt usually brews, with lower extract and poorer milling. Malt with mould or insect damage should not be used.
Should I stock up on malt before the monsoon?
Usually the opposite. Hold less through the wettest months and arrange smaller, more frequent deliveries.
