Acrylamide elution from roasted barley grains into mugicha and its formation during roasting

ABSTRACT

This paper investigated acrylamide elution from roasted barley grain into mugicha and its formation during roasting of the grain. Mugicha is an infusion of roasted barley grains. Highly water-soluble acrylamide was easily extracted to mugicha from milled roasted barley grains in teabags. On the other hand, the acrylamide concentration in mugicha prepared from loose grain increased with longer simmering and steeping times. During roasting in a drum roaster, the acrylamide concentration of the grain increased as the surface temperature rose, reaching a maximum at 180–240°C. Above this temperature, the acrylamide concentration decreased with continued roasting, exhibiting an inverted ‘U’-shaped curve. For most of the samples, the acrylamide concentration showed good correlation with the value of the colour space parameter L*. The dark-coloured roasted barley grains with lower L* values contained lower amounts of acrylamide as a result of deep roasting. The level of asparagine in barley grains was found to be a significant factor related to acrylamide formation in roasted barley products. The data are an important contribution to the mitigation of acrylamide intake from mugicha.

KEYWORDS:

• Acrylamide
• mugicha
• barley tea
• roasting
• barley grains
• colour

Acknowledgements

The authors wish to thank Mr. Yuhei Hirono (NARO Institute of Vegetable and Tea Science) for the analysis of crude protein in barley grains.

Additional information

Funding

This study was carried out as a part of a research project on the elucidation of acrylamide formation and development of practical applications for acrylamide reduction in heated foods [grant number 21049], Regulatory Research Project for Food Safety, Animal Health and Plant Protection of the Ministry of Agriculture, Forestry and Fisheries, Japan.