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 you 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 rice hulls.

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 flavour 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 gristy 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

It is a good idea to use rice hulls when you're brewing a high gravity beer with a big grist. This applies especially to beer recipes that demand high percentages of specialty malts and for wheat and rye beers.

This is because these grains have higher levels of protein and beta-glucan than compared with barley grains and these elements cause the wort to be more viscous than other brews.

How much rice hulls should I add to the mash?

Many brewers seem to use hulls at a percentage no greater than 5 percent 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?

You can simply mix them into to your dry grains before you infuse them with the hot water.

Can I sparge with oat hulls instead of rice?

You sure can. 

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

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 burner with masses of BTU which should kill any bugs that were hiding on the grains or hulls.