Plasma coffee: Exploring the use of PS-pulsed lasers as a way to expedite coffee extraction in cold brew

Abstract

This thesis builds on existing research into applications of laser synthesis and processing of colloids (LSPC) as a way to decrease the total extraction time in cold brew coffee. In this thesis, the irradiation of a water-coffee colloid using an 800 nm pulsed pico-second laser successfully reduced the time of extraction from 2 hrs 45 min (1.18 TDS +/- 0.06) to 20 minutes (1.05 TDS +/- 0.18) which represents an 8.25x decrease or 87.8% time savings. The laser system was configured to a 1K Hz repetition rate, 100 ps pulse rate, and 1 cm 2 focal spot area. The coffee-water ratio was 1:18.5 using 20g of Guatemala Arabica Coffee grown at 1600m and 350g of deionized water. The colloid was mixed at 2,120 RPM using a stirring magnet to ensure consistent irradiation. This work is coupled with informal industry interviews and a brief market estimate to assess the viability of using laser systems for commercial cold brew production in US coffee shops. It was determined that within as little as 6 days, a large coffee could break even on investment for such a system.