Hydrothermal process in the Collab article was interesting from the point of eliminating "bitterness" of proso. It implies bitterness comes from residual hulls after dehulling and from oils of the hull. The Milling and Grain article states: - Polishing: At this stage, any residual hull fragments containing natural oils that can cause bitterness are additionally removed. This significantly improves the taste profile and eliminates unpleasant aftertaste. Unfortunately, the promotion article does not address the hidden issues of quantity of residual hulls removed, original tannin levels, fiber, ash, and micronutrient changes in hydrothermal processing. 1.) *Hulling* is a slow process with the faster millet seeds pass through huller the more unhulled seed remains intact affecting cooked flavor. Curious, in the hulling stage how many seeds per thousand retained hulls before the hydrothermal process? 2.) *Seedcoat color*: What was the original hull color? Proso hulls vary from black to white with red, brown, gray, silver, yellow, green and miscellaneous shades in historic varieties. Each likely carry different tannin levels which can influence bitterness (e.g. like the difference between white and red sorghum seed). Soaking and processing may also decrease tannin levels. 3.) *Nutrient profile*: What is the optimum processing of millets? Processing affects the nutrient profile. Seedcoat (hull) of millets and other grains carry valuable nutrients. What was the dietary fiber and micronutrient profile of whole and dehulled millets before and after the hydrothermal process? 4.) *Minute millet*? To speed rice cooking, General Foods developed Minute Rice to help working moms speed rice cooking. Is cooking time slowing or preventing the adoption of proso as a food? I am not surprised that hydrothermal processing proso improves purity, speeds cooking, improves shelf life, and likely reduces ash content, but I want to know what is gained and given up during the process? Proso is relished for its beneficial nutrient profile. High in dietary fiber, B vitamins (i.e. thiamin, niacin, riboflavin) and nutrients (i.e. iron, potassium, magnesium, phosphorus, manganese). Whereas like hydrothermal millet, Minute Rice maintains protein and carbohydrate levels but supposedly has less (labeled and unlabeled) thiamin and niacin (B vitamins) and less iron and potassium. See Is Minute Rice Different? Uncovering the Truth Behind the Convenience - ShortFoodBlog <https://shortfoodblog.com/is-minute-rice-different/>. Many of the questions I raised above are addressed in this 2025 proso study of various processing and cooking methods. Change in nutrient profile is important with the potential of increasing bioavailability of nutrients, like iron. See Impact of hydrothermal processing on the mineral, antinutritional, antioxidant and functional characteristics of proso millet (Panicum miliaceum) | Food, Nutrition and Health | Springer Nature Link <https://link.springer.com/article/10.1007/s44403-025-00027-y>....Gary Wietgrefe On Mon, Jun 8, 2026 at 8:50 AM Don Osborn via Collab < collab@lists.millets2023.space> wrote:
"Innovations in Hulled Millet Processing, Impact of Hydrothermal Treatment" (24 Mar. 2026) is a feature article on the India-based Milling and Grain website.
https://millingandgrain.com/innovations-in-hulled-millet-processingimpact-of...
It discusses implementation of a hydrothermal treatment of "millet" by Agrofirma Pole LLC (Ukraine). Based on the latter's location, I'm assuming this is proso millet.
"Hydrothermal treatment is an advanced processing technology that uses steam and precisely controlled temperature to treat the grain (hulled millet) before further processing (e.g., milling into flour). This method is applied immediately after the initial cleaning stages – specifically after dehulling (removal of the flower hull), calibration, impurity removal, sorting and metal detection."
I don't know how this method differs from what may already is done to treat various millets for shelf longevity. In any event, the article gives a thorough description of processing that incorporates hydrothermal treatment.
Don Osborn, PhD (East Lansing, MI, US) North American Millets Alliance
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