P 4.05 – Recap and Glossary

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  • For larger scale brewing, drawdown should occupy 25-30% of the total contact time.
  • For single cup brewing, the necessity of keeping the slurry temperature sufficiently hot to promote good extraction yields needs to take precedence over the drawdown time profiling.
  • Spray heads with insufficient streams promote wells in the coffee bed.
  • 01 sized flat-bed brewers promote even extraction but can trap grinds in the fluted edges.
  • Filter papers are fabricated with wet strength agents that create ionic bonds between the cellulose to make them stronger.   
  • Wet lay machines are used in the fabrication process to facilitate extra wet strength.
  • Creping of the paper surface promotes faster flow and helps counteract the muddying effect which can reduce flow rates.



Creping  A method of increasing the pour availability of filter papers by bunching up the paper into a creped texture.

Development time ratio  A roast profiling doctrine used to help locate the optimum position in the roast for first crack to occur

First crack  The sudden expansion of the coffee cell walls brought on by a build-up of steam pressure inside a coffee bean.

Fluted edges  The wave-shaped creases pressed into a filter paper, intended to increase the strength of the walls.

Muddying  The caking of fine particles onto the surface of a filter paper, which has the effect of reducing the flow rate of liquid through the filter.

Wet lay machine  A machine used in the fabrication of coffee filter papers


End 4.05

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