The author of the post, Matt Del Fiacco, not only talks about how to toast the wood, but a number of other related topics like the different "toast levels" of wood and how they impact the flavors, and the kinds of flavors you can expect from using different types of wood in your brewing.
If you don't feel like reading the entire post (but I recommend it), here's the important detail:
- Lightly toasted woods have fewer tannins and impart more of a vanilla and wood flavor
- Medium toasted woods produce toasty, sweet, caramel, maple, and vanilla flavors
- Heavily toasted wood tends to provide smoky, roasty, coffee like flavors balanced with some of the flavors seen in a medium toast
The temperature used to toast wood chips tends to affect the flavor as well. With oak, for example, here's how the roasting temperature affects the flavor imparted to beer:
- 200-280 F: Primarily oaky, with sweetness beginning to show at the upper range
- 280-360 F: Oaky and sweet, turning vanilla and sweet toward the upper range of temps
- 360-500 F: Vanilla at the low end, toasty flavors coming in around 400, and almond in the 500-520F range. Beyond about 490F some acrid flavors appear
The above should be treated as "rule of thumb" info as one tree may vary from another somewhat and react differently to toasting.
The different types of wood affect beer flavor as noted here:
- Cherry: dried cherry, earthy, sweet finish, light vanilla, fried bread
- Hickory: Light woodsy character, hay-like aroma, slight honey-sweetness
- Hard Maple: Woody aroma, maple-syrup character in finish, light nutmeg
- Soft Maple: Caramel, yellow cake, pear-like esters, maple sap flavor
- Red Oak: Red berries, woodsy, peppery, resinous, very dominating
- White Oak: Soft esters of orange and pear, chardonnay-like, light earth and spice
- White Ash: Light dried plum and pear, bready, lingering sweetness at finish
- Yellow Birch: Toasted marshmallow, caramel, wood aromatics, more aroma than flavor
To toast wood, spread it out on a foil lined cookie sheet. Preheat the oven to the desired temperature, using the temperature guidelines shown earlier. When the oven is at the right temp, put the wood in and set a timer for an hour. Check it about every 15 minutes until it hits the toast level you want, then remove it.
There are different ways wood chips can be used in brewing. The author of the post suggested that you boil them for about 10 minutes to sterilize them a bit and remove some astringency, drain them, then put about a half-ounce of them in the fermenter for a week before removing them.
I've personally used sterilized wood chunks (from Kentucky Bourbon barrels) and added them during the boil. This delivered quite a bit of flavor and I didn't have to fish them out of the fermenter later on. I'm told you can also boil the wood separately to make a "tea" and add this tea to the wort instead of the chips.
Another method is to soak the chips in liquor (bourbon or vodka) and add this liquor to the beer at bottling. An advantage here is that you can control the level of wood flavor by controlling the amount of the liquor you add to the beer.