Malting - ‘the middle parts of fortune’ - a history of innovation and the enduring quest for efficiency

Abstract

Why was the work done: The malting process has long been a target for innovation to improve malt quality.  The efficiency of utilisation of labour, capital, water and energy, particularly the energy intensive kilning process is a key target for maltsters to reduce the environmental footprint and costs. Similarly, water use during steeping is a priority due to scarcity of water and regulations regarding the disposal of wastewater. How was the work done: A comprehensive review of the literature was undertaken to identify prospects for improving the efficiency of the malting process. What are the main findings: The malting process involves: (i) selection of barley variety of suitable quality (protein, microbiologically sound); (ii) cleaning and grading; (iii) steeping in water with dry rests over one to two days, moisture increases from 10-13 to >40% (ideally 42-45%); (iv) germination at 12-16°C in a flow of humid air to maintain malt moisture at 42-46%; (v) kilning at between 50-85°C with hot dry air and (vi) storage and blending of malt to specification. Analysis of these steps shows that there is potential to reduce water use and discharge by ~40% with the Optisteep® system. In terms of energy, kilning uses 80-90% of all malting energy (conventionally gas), which makes kilning attractive for energy savings. Marginal energy savings can be made by lowing malt moisture to <40% before germination/kiln transfer and reducing malt moisture to <9% rather than 4-6%. Novel solutions include using green malt and barley brewing which save energy (especially kilning). Although for brewing with unkilned green malt, significant challenges remain to be solved. However, over the past 25 years, maltsters have been successful in incrementally reducing kilning energy by 20-35% per decade. Why is the work important: Increasing malting efficiency while maintaining or improving quality has important implications for reducing costs and reducing the environmental footprint of the malting process.