Blueberry Season – Blueberry Cake and An Easy Blueberry Lacto-Ferment

Blueberry season is here. Saw the first tableful pop up at the market a couple of weeks ago and was excited for them. One of the easiest ferments in the Noma guide to fermentation is blueberries. All of the lacto-ferments in it are pretty easy (like those mushrooms) but I think these blueberries turn out really well and are an even better gateway to home-fermenting.

When blueberry season hits I try to get as much as I can out of it every week buying blueberries and fermenting. The lacto-ferment turns them into salty, funky, sweet berries and I’ll freeze a few batches for use them later in the year.

Having prepared blueberries like this for over a year now I can tell you the fresher the better. A recent batch I did from the new berries fermented a little differently than usual. I’ve always washed them before weighing and salting but this time I didn’t wash the berries, wanted to see what the effects of leaving residual microbes on the really fresh berries would be and was rewarded for this little experiment.

Salted and sealed

There was waaaaaay more gas action in the bag than usual. Most of the time, especially if I’m using grocery store blueberries and have washed them, the bag will puff up very little. These fresh-from-the-farm, eco-organic berries on the other hand were quite the hive of lacto-ferment activity. I was totally surprised when I went to check on them at the end of the week and saw the bag was fully puffed up with gas. Never seen that before. This batch is definitely more on the acidic side than salty/sweet side and have a more sour, tingly sensation in the tongue to them.

7 days later. Lots of gas with the batch. Probably due to the freshness of the berries and the fact I didn’t rinse before salting and sealing.

I like the results of both. Now I’m starting to wonder about leaving the fresh-from-the-farm berries in longer while releasing some of the gas and resealing to see how long it takes to mellow out the acid. What is one of the rules about proving hypotheses and scientific experiments…can you replicate it? We’ll see.

Side Roam: I split the latest batch from the farmers market. One washed, one not. We’ll see next week if there’s a difference. UPDATE: …not much of a difference in washing vs not washing. The washed bag had a little less gas and had some give to it but just as puffed up. When I checked midweek the unwashed bag was more expanded but the washed caught up. So I’m going to go with the fresher the berries the better fermenting reaction.

Fermented blueberries, yogurt, honey. Salty, sweet, sour. Hits a lot of notes here.

What do you do with these fermented berries? Kind of like the pickled rhubarb you can do pretty much anything you’d do with regular blueberries. I’ll puree them and make a blueberry sauce for grilled or roasted meats, (for example a rack of lamb) they make a delicious breakfast in yogurt and honey with some granola, and will add another dimension to your blueberry muffins or cake.

Blueberry sauce on lamb chops (trust me there’s a sauce on there!), blueberries with greens

For a decent sized batch you’ll need 500gr of blueberries (a farmers market quart container will do), 10 gr Kosher salt (or 2% of the weight of your blueberries), jar or ziploc bag or vacuum sealer. That’s it.

Combine the salt with the blueberries and mix. Place in a vacuum bag in a single layer. Seal bag. Let bag sit on counter (or in your fermentation chamber) for 1 week.

Put the blueberries into a vacuum bag and seal. Don’t have that? If you have fermentation weights you can use a jar. You can also use a ziploc bag and squeeze out as much air as possible. (There’s a technique of partially sealing the bag closed then submerging the bag in water which forces air out then finish sealing. I’ve never done it as I have the vacuum sealer. Mason jar & weights is my second go-to for these ferments, especially ones which release a lot of water/juice like tomatoes. Don’t worry we’ll get to those when the season rolls around.)

Seal up the bag/jar and let it sit for a week or 10 days. It’s fine on the counter but if you’ve made a fermentation chamber then put it in there set for 80F.

According to the Noma book you should ‘burp’ the bag/jar occasionally but until the last batch I’ve never experienced a build-up of gas large enough to necessitate this. It’s easy with a jar, just open it then put lid back on.

Fermented Blueberry Loaf using a quick muffin batter ratio 2 parts flour : 2 parts liquid : 1 part egg : 1 part butter

Dry – 8 oz flour, 4 oz sugar, 2tsp baking powder, Wet – 8 oz milk, 2 large eggs, 4 oz melted butter. 1/2 – 1 C fermented blueberries (or boring old plain if you want), Tbs butter

Pre-heat your oven to 350F. Mix the dry ingredients in one bowl and the wet ingredients in another whisking the eggs in. Combine the two, whisking to a uniform consistency, add the blueberries. Butter a loaf pan and pour the batter into the pan. Depending on your oven it should take 50-mins to an hour, maybe a little longer. Start checking the loaf around 50 minutes with skewer into the middle to see if it comes out clean. If it doesn’t bake some more and check again in 5-10mins. Allow to cool on a rack then pop it out of the pan.


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