Project Sustainability: Green Malt Project pt.2

 

The first scale-up trial utilized 400 kg of barley, which was weighed and divided into four separate drums, 100 kg each. The grains were washed with soft water before being immersed in water for the first steeping, drained, and allowed to air rest overnight, followed by a second steeping and germination period (Table 3).

Table 3. Steeping/germination protocol for scale-up trial.

 

Special attention was given to mixing the grain bed to avoid overheating due to the exothermic activity of the respiring grains and prevent the rootlets from tangling together. This further helped dispel any built-up CO2 and keep the grains oxygenated. Temperature was controlled and monitored throughout using a long thermometer capable of reaching deep into the grain bed. 

 

The entire “malting” period of Green Malt took approximately 48 hours. Germination was deemed finished when the rootlets had grown considerably outside the grain, confirming that the endosperm was well modified. The production of brewing-relevant enzymes (ɑ-amylase and β-amylase) during the steeping and germination steps was determined (Table 4). The production of ɑ-amylase increased significantly over the germination process and reached values higher than the lab-scale tests at 24 hours (Table 4).  Once the grains were deemed sufficiently germinated, around 24 hours, they were transferred to a mash tun and subjected to continuous steep milling (or wet milling) (Fig.4).

      

Figure 4: Green malt being transferred to mash tun.
 

 

To test the suitability of Green Malt for brewing applications and assess its flavor and aroma contribution to a distilled product, the Empirical team designed a brewing and fermentation schedule that would maximize the contribution of the freshly malted grain. The 400 kg of grains and 1000L of water were mixed, ground through a wet hammer mill, and sent back into the mash tun in one continuous stream. After mashing (Fig. 5, left), the wort was sent through a mesh filter press to remove the grain solids, then a chiller to cool it down and transferred to a fermentation vessel, ready to be pitched with White Labs Belgian Saison II Ale Yeast (WLP566).

Fermentation commenced at room temperature. Fermentation was monitored daily, noting temperature, pH, and °Plato (Fig. 5, right). After 12 days, the fermented wash of 1000L was transferred to a vacuum still and distilled at 70 mbar between 24°C and 40°C for 24 hours. Low wine was collected and distilled again 70 mbar between 24°C and 42°C for approximately 24 hours, yielding a spirit. The collected tails from this spirit run were further distilled under the same conditions, yielding more than 100L of spirit (>50% ABV). 

The trial process efficiency showed great potential for Green Malt utilization, with a margin for significant time savings on the mashing and fermentation steps in follow-up trials.

Figure 5. Brewing schedule (left) and fermentation curve of the Green Malt wort (right).
 

 

 

 

 

 

The Green Malt trials at White Labs started more than 10 years ago, and we learned many valuable lessons during the initial trials, but it took the concerted efforts of different partners to source the grains, implement a new process, and develop a brand new product that highlights the uniqueness of the process (Fig. 6). In any industry, looking at current processes or methods and challenging them is the first step to make advances. Process improvements might range from increased efficiency (time and energy savings) and lower process footprint (water and CO₂) to complete re-thinking of the supply chain, as in this Green Malt project. However, testing and implementing innovations, especially when involving sustainability, is a long process that requires the right partners and resources.

Figure 6. The final product of the Green Malt process, a clean and unique spirit that can be used for different applications.