Some important studies:

Roasted Barley Extract (Mugicha) Containing Cyclo(D-Phe-L-Pro) Prevents a Decrease in Skin Temperature in Cold Conditions: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study.
Ashigai H, Mizutani M, Ikeshima E, Nakashima K, Taniguchi Y, Matsukura Y, Yajima H.
J Nutr Sci Vitaminol (Tokyo). 2019;65(1):90-93. doi: 10.3177/jnsv.65.90.

Roasted Barley Extract Affects Blood Flow in the Rat Tail and Increases Cutaneous Blood Flow and Skin Temperature in Humans.
Ashigai H, Taniguchi Y, Matsukura Y, Ikeshima E, Nakashima K, Mizutani M, Yajima H.
J Agric Food Chem. 2018 Feb 7;66(5):1251-1257. doi: 10.1021/acs.jafc.7b04930.

Effect of barley coffee on the adhesive properties of oral streptococci.
Papetti A, Pruzzo C, Daglia M, Grisoli P, Bacciaglia A, Repetto B, Dacarro C, Gazzani G.
J Agric Food Chem. 2007 Jan 24;55(2):278-84.

Melanoidins and carbohydrates in roasted barley.
Milić BL, Grujić-Injac B, Piletić MV, Lajsić S, Kolarov LA.
J Agric Food Chem. 1975 Sep-Oct;23(5):960-3.

Roasted barley soluble is a very common food supplement in civilized countries and is consumed with water or milk. There is also a tea of toasted barley.

It is added in the processing of beer to give it a red color and get a taste of hazelnut if you add 3%, while with a 10% you get a taste of coffee.

It comes from the common barley (Hordeum vulgare)

which is heated to a high temperature.

This product is quite interesting for its antioxidant properties. In this study, the barley was roasted in a microwave oven and the optimum temperature to maintain the oxidising power of the barley was 600W (1).

The industrial roasting process triggers the Maillard reaction and increases the antioxidant activity (2).

Roasted barley studies

References______________________________

(1) Antioxidant activity in barley (Hordeum Vulgare L.) grains roasted in a microwave oven under conditions optimized using response surface methodology. Omwamba M, Hu Q.J Food Sci. 2010 Jan-Feb;75(1):C66-73. doi: 10.1111/j.1750-3841.2009.01426.x.

(2) Isolation of an in vitro and ex vivo antiradical melanoidin from roasted barley.   Papetti A, Daglia M, Aceti C, Quaglia M, Gregotti C, Gazzani G.  J Agric Food Chem. 2006 Feb 22;54(4):1209-16.