When to add 'rice hulls' to the mash

Have you ever had a stuck sparge when there's simply no wort exiting the tun? 

What a way to slow down your brew day! 

Sure, you can give your mash grain a bit of stir and try and remove the blockage and get going again but what if you could add something to the mash to prevent another stuck sparge?

Enter the use of rice hulls to prevent a stuck mash.

Rice hulls are the exterior layers of grains of rice.

When rice is harvested, the hulls are cast off because they are not for eating.

Once the hulls have been washed and dried (which removes flavor and color) they can be used as a filtration agent for getting the wort out of the mash.

They work by creating some space around the gritty and grisly mash particles so the wort can flow out of the mash tun. Given they do not add any flavour to the wort and are pretty cheap to buy, rice hulls are an excellent solution to a brewer's need to prevent a stuck sparge or lautering process.

Rice hulls offer a natural, easy way to help prevent a stuck mash!

Use rice hulls when sparging a high gravity beer

High gravity beers are beers with a higher concentration of fermentable sugars in the wort, which results in a higher alcohol content in the finished beer. These beers require a larger amount of grains to produce the desired gravity, which can lead to a thicker mash that is more difficult to filter.

Specialty malts, wheat, and rye are commonly used in high gravity beers to add complexity and flavor to the finished product. However, these grains also have higher levels of protein and beta-glucan than compared with barley grains. Beta-glucans are long-chain polysaccharides that contribute to the viscosity of the wort, which can make it difficult to filter.

Rice hulls, being an inert material, can be added to the mash to help prevent the grains from clumping together, thereby improving the filterability of the wort. Rice hulls act as a filter bed, creating channels through which the wort can flow freely. This helps to reduce the viscosity of the wort, making it easier to filter, while also ensuring that the wort is well-aerated during the lautering process.

How much rice hulls should I add to the mash?

Many brewers seem to use hulls at a percentage no greater than 5 per cent of the total grain bill. In reality, a common measure is 1/2 lb per 5 gallon batch.

When do I add the rice hulls to the mash?

When using rice hulls in brewing, it is important to add them at the appropriate time in the brewing process to ensure maximum effectiveness. Generally, rice hulls are added to the mash before the hot water infusion, along with the dry grains.

As the dry grains and rice hulls are mixed together, the rice hulls will help to create channels within the mash bed, which will improve the flow of water through the grains during the infusion process. 

This will help to prevent clumping and ensure that the water is distributed evenly throughout the mash, allowing for proper conversion of the grain starches into fermentable sugars.

Adding the rice hulls before the infusion also ensures that they are evenly distributed throughout the mash, which will improve filtration efficiency during lautering. 

This is because the rice hulls will create a filter bed at the bottom of the mash tun, which will help to prevent the grains from compacting together and creating a stuck mash.

Therefore, when brewing a high gravity beer with a big grist, it is recommended to add rice hulls to the dry grains before the infusion with hot water. This will help to ensure a smooth and efficient brewing process, as well as improve the quality of the finished beer.

Can I sparge with oat hulls instead of rice?

You sure can. 

Like rice hulls, oat hulls are the shell of the oat grain. 

Given they are pretty much inedible and no good for making porridge with, they have found other uses as filters. They act in just the same manner as rice hulls and do not any impart anything into the wort.

They are commonly used when brewing rye or wheat beers, the same as rice hulls.

Do I have to worry about rice hulls absorbing water?

Worry? 

Perhaps that's the wrong word but if you are the kind of brewer who likes their beer exactly as the recipe demands, then yes, the hulls can absorb water. 

So, what do to? Soak them in water prior to use so you don't have to even think about it.

Given there can be the odd bit of dust in them, give them a rinse in a colander before soaking.

Do I need to sterilize the rice or oat hulls before adding to the mash?

Some people do but I really can't see the point as the wort is about to be boiled within an inch of its life in the brewing kettle on top of a gas burner with masses of BTU which should kill any bugs that were hiding on the grains or hulls. 

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