Abstract
Corn grits are commonly used adjuncts in the brewing industry in the United States, especially for lager beers. The major challenge of using a high amount of adjuncts in the brewing process is reduced levels of nutrients available to yeast during fermentation, which negatively affects the growth and functioning of yeast, and results in sluggish fermentation. The problem is usually addressed by adding external nutrition. The objective of this work was to assess the suitability of corn components other than brewer’s grits to improve the fermentation rates. Water obtained after soaking of corn germ, a vital source of lipids and soluble proteins, was investigated as a source of nutrient during brewing of 40:60 (w/w) corn grits and malt mixture. Performance of water-soluble nutrients from germ of two corn verities, yellow dent corn and flint corn, was investigated. Germ soak water was added during corn grits slurry formation before mashing. The addition of germ water increased the free amino nitrogen levels by 37% and Zn concentrations by 3.6 times in the wort, which resulted in up to a 28% higher fermentation rate (between 48 to 72 h of fermentation) and shortened the fermentation time from 120 to 96 h. The use of water obtained from the soaking of flint corn germ resulted in a similar shortening of fermentation time. In another approach, nutrient-rich concentrated germ soak water was directly added into the wort, which also resulted in similar improvements in the fermentation rate as those from adding germ soak water during slurry formation. Due to leaching of micronutrients and soluble proteins, the oil concentrations in the germ increased by more than 30%, enhancing its economic value.
Highlights
IntroductionBarley has been the most common raw material used for beer brewing
Beer is the oldest and the most popular alcoholic beverage in the world
The fermentation rate was 30% higher than the control between 48 and 72 h of fermentation. These results indicate that germ water can be concentrated and added to the wort to fasten the fermentation
Summary
Barley has been the most common raw material used for beer brewing. The use of barley provides advantages of easy germination, high starch content, moderate protein content, high amylolytic activity, and wort filtration assistance from husk [1,2]. Due to increasing demands of sensory modification and specialty beers, and cost optimization, brewing industries are increasing the use of locally available less expensive unmalted grains, known as adjunct grains, in the beer brewing process [3,4,5]. The use of locally available grains as adjuncts in the brewing process reduces the need for importing malt, provides tax benefits (avoidance of malt tax in some countries), reduces the carbon footprint, and supports local farmers [6]. Wheat, rice, unmalted barley, oats, and sorghum are some of the major adjunct grains used.
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