One piece of information I was able to find is in Joe and Dennis Fisher's book, The Homebrewer's Garden. Page 91 reads, "For a long time nasturtiums have been popular in salads and teas. Homebrewers are increasingly dropping the edible leaves and flowers into their brew kettles to add a unique, peppery aroma and taste to their beer. Use 5 - 10 cups (1.2 to 2.4 L) of the fresh flowers and leaves late in the boil".
I picked 40 grams (just under 1.5 ounces) of fresh nasturtium flowers from my backyard and the park at the end of my street. I opted to use only the flowers and to not use any of the leaves, which are also edible, in order to reduce the possibility of extracting a lot of tannins. In addition to the nasturtiums I also bought 5 valencia oranges and two lemons, which were zested on a cheese grater about 15 minutes before the end of the boil.
The Recipe:
Grain Bill:
5 lbs. Belgian Pilsner Malt
3 lbs. Flaked Wheat
2 lbs. Wheat Malt
1 lbs. Flaked Oats
.25 lbs. Munich Malt
.125 lbs. Acidulated Malt
Hop & Spice Bill:
1 oz Saaz (6.8 %AA) @ 60 minutes
40 grams Nasturtium Flowers @ 5 minutes
Zest of 5 oranges and 2 lemons @ 5 minutes
Yeast:
White Labs Wit II (WLP410)
OG: 1.05
FG: 1.012
ABV: 5.1%
Tasting Notes:
Appearance:
Foggy cloud of flaked grain, pale orange in color, thin white head
Aroma:
Nose is spicy yeast phenolics, tangy citrus rind, pear
Flavor:
Soft bitters, earthy spiciness (nasturtiums), tangy citrus rind (the acid malt / wheat really helps make the zest flavors pop), orange wheat spritz, black pepper wit yeast phenolics match up nicely with earthy flower spice
Palate:
Feels like I'm drinking an oatmeal stout, though light in color and flavor this ale feels very thick and heavy, which makes it less refreshing than it could be
Overall / Changes for next time:
I would cut the oatmeal down to a half pound and might replace one pound of flaked wheat with an additional pound of wheat malt, because of how thick and filling this beer drinks. I would brew this recipe with as much as 2-2.5 ounces of nasturtiums next time in order to really taste them in the final product and fully understand what they bring to the table, though the balance of flower / phenolics is nice with current weight of flowers. An additional spice might help round off this ale and add a touch of complexity, either a pinch of cinnamon or a pinch of coriander
The Verdict:
I would certainly encourage using nasturtiums in your next wit, if not to define the ale, at least to add a bit of earthy complexity to the final product. I would think that the nasturtium flavors would also work well in a Saison or other Belgian styles (Abbey Dubbel?).
When ingested fresh and directly the flowers can have an extremely hot-spicy, pepper flavor. This flavor profile however, seems to escape the flavors of this recipe. I'm not sure if it is the result of the amount (small?) being used or a chemical reaction that occurs during boil / fermentation, but the flavors I associate with the flowers in the beer are earthy, mildly vegetal spice that melds well with the phenolics of the WLP410 yeast strain.
