I’m very surprised and excited about the results of this experiment. If you’ve read my past experiments with malting oats then you’ll know the trouble I’ve had with it. Even though I’ve tried different brands and hulless vs. with hulls I’ve always noticed a grassy flavour to it, and by grassy I mean like freshly cut lawn clippings or even green corn husks. I still do not know what causes this but it seems to appear only 1 or two days after steeping. It has been suggested in this article by E. Hosseini, M. Kadivar and M. Shahedi that rancid bitter flavours are due to the oxidization of free fatty acids and they show that increasing the pH of the steep water has a positive effect on enzyme activity which may have an affect on the development of rancid flavours. Though, I’ll admit I found this article confusing, maybe you guys can make better sense of it. The folks from Breiss malting suggest in this podcast that bacteria present on the oat husk is what caused off flavours to emerge in their trials.
Germination was not great at about 70% for all three batches
Steeped for only 4 hours to achieve a 42% moisture content.
So whatever the reason, I wanted to see if adjusting the pH of the steep water would have any effect on flavour. The first batch of malt would be my control using regular filtered water. The second batch had the steep water adjusted to a pH of 9.5 (only because I couldn’t hit 8 due to the small amount of Sodium Hydroxide used). The third batch was subjected to a 1 hour steep in a .2% lye solution which had a pH of around 13 in order to disinfect the grain from any mold or bacteria. Then it was rinsed and steeped for another three hours in regular filtered water.
0.4 grams of lye was added to 4 Litres of water to change the pH from 6.3 to 9.5
8 grams of Lye per 4 Litres was used for the third batch.
And the winner is … the 9.5 pH batch. Within a few days of steeping I noticed that it was not developing as much grassy aroma as the other two. Even after mashing this malt it’s tasting much more like a bowl of oatmeal than a bowl of cut grass. I still have to brew with it as a final test to see if this is actually working but I’m very optimistic. Also the brix of the 9.5 batch after mashing small 4 oz. samples was 13, both the normal batch and the disinfected batch were just 10. Of course these mash results could have been different had I adjusted the pH of the mashes.
All three batches were steeped at 12C 54F and germinated for 5 days at 16C 61F.
All three batches were also dried and kilned the same; 12 hours at 21C 70F with fan. 8 hours at 30C 86F with fan. 8 hours at 50C 122F no fan. 4 hours in the oven at 185F
Tomorrow I’ll start to malt another 10 lbs. in order to make another attempt at a 100% oat malt beer.
Mini-mashing 4 oz. batches.
After mashing for two hours it still did not pass the iodine test.
After mashing, before boiling. The 9.5 pH batch in the center had a brix of 13, the other two 10
Brewing Beer The Hard Way 