This 2019 study investigated oat sprout parameters:
“Huskless oat ‘Gehl’ cultivated in 2016 in Canada, was used throughout the study. Grains (500 g) were sprouted at different temperatures (10, 14, 20, 25, and 30°C) and for different times (1, 2, and 3 days). Changes in vitamin C, β‐glucan, and reducing sugar were monitored, and α‐amylase activity was studied as a marker for total enzyme activity.
Mass fraction of radicle [root] and coleoptile [shoot] in grain correlated very well with β‐glucan level. A similarly good correlation was found for the much easier applicable degree of sprouting, visual assessment of coleoptile length set into relation to grain size.
Germinability after 3 days was about 99% at all temperatures. Temperatures between 20° and 25°C yielded the most dramatic changes in properties of sprouted oats.
- At 3 days, α‐amylase activities at 20° and 25°C increased significantly to values one order of magnitude larger than those for other temperatures.
- β‐glucan content was decreased after 3 days at all temperatures. Degradation was most pronounced at 20°C, almost halving initial β‐glucan content to 3.9%.
- No ascorbic acid was present in native grain. Upon sprouting, a significant increase in ascorbic acid content was found – except at 30°C – with highest levels at 20°C.
Ascorbic acid content in radicles and coleoptile was four times higher than that in grain without radicles and coleoptile. Oat grains sprouted for 3 days at 20°C had an average degree of sprouting of 3; hence, radicles and coleoptile contributed about 8% of mass. These findings indicate that a fast visual determination of degree of sprouting allows to estimate, for example, ascorbic acid content without doing expensive experiments.
Around 20% of grains sprouted at 20° and 25°C had a coleoptile longer than a full grain length (degree of sprouting 5). Less long coleoptiles developed at other temperatures.
- For the 3‐day sprouting period, the longest coleoptile was observed for sprouting at 25°C.
- At 30°C average degree of sprouting was 1.4, and grains showed no practical radicle growth.
Coleoptile and radicle growth (input parameters for the degree of sprouting) and reducing sugars and α‐amylase activity are interdependent. Degree of sprouting could develop into a reliable characterization method for sprouted grains, usable for predicting compositional and nutritional changes of oats during sprouting.”
https://onlinelibrary.wiley.com/doi/full/10.1002/cche.10203 “Sprouting of oats: A new approach to quantify compositional changes”
Relative humidity wasn’t mentioned in this study. I asked the corresponding coauthor about it, since two Sprouting oats studies stated relative humidity as a factor for sprouting oats.
I also asked them to explain their “4.5‐hr wet steeping, 19‐hr air rest, and 4‐hr steeping, all at 20°C” procedures to start germination, since I didn’t have access to the cited study. No reply yet.
This was my model study for Sprouting hulled oats.