Start Date
2019
Description
Much of the world's coffee is grown on soils that have developed from the chemical and physical weathering of basalt, a volcanic rock with relatively high iron content. Volcanic rocks vary in composition depending on the relative amounts of major elements that produce minerals such as plagioclase, pyroxene and olivine. The breakdown of these minerals is dependent on climate and slope as well as the initial composition. Chemical weathering associated with climate, eventually leads to the development of clay minerals, oxides, and hydroxides that are key components of the soil chemistry. The soil transfers elements to the coffee plant through soil moisture as ions in solution and may be stored in the coffee bean. The purpose of this project has been to examine the characteristics of the Kona region as well as determine the chemical connection between the volcanic rocks, soil, and coffee. A major goal was to develop a method to tracking elements, specifically those found in the coffee to examine the possibility of inferring connections between those elements and the volcanic soils. Our initial literature review focused on three areas: composition of basaltic flows in Hawaii, soil development in Hawaii, and chemical profiling of coffee to determine geographic locations. The composition of the lava flows provides a chemical backdrop for understanding the availability of ions in the region. Extensive geochemical data sets are available as well as mineralogical modes. Certain minerals break down faster and influence the resulting soil composition. Studies of the soils provide insight to the secondary minerals such as goethite, calcite, and others. Because each volcanic region has a slightly different chemical signature, the resulting coffee takes on some component of that chemical signature. Our review also included geographic information systems of volcanic flows, soil classification, and large coffee farms in the Kona region. In addition to reviewing relevant literature and published data, we also developed a method for analyzing the dry coffee. We used XRF – X-ray fluorescence – a technology to measure the trace metals with atomic masses greater than Mg. The primary chemistry of coffee is organic in nature and dominated by C, H, and O; all of which are not detectable by the XRF. So, we used a technique that combined the coffee with a known mineral or “spike” and modeled the elements as oxides. The coffee that we used was purchased at Greenwell farms during the January 2019 Interim and represented a 100% Kona variety from this known location at different roasting levels. We started by grinding the coffees – medium roast, dark roast and full city roast – and the minerals which we would be mixing with each. After grinding and mixing the testing samples, we analyzed each mixture as a compound, collecting data for a series of oxides. Over 120 analyses were conducted during this project. This data was processed and reduced to determine the elemental signatures associated with the coffee.
Recommended Citation
Mollison, Kathryn; Bos, Nathaniel; and Sparks, C. Renee, "Trace elements of volcanic soils and coffee – Kona" (2019). Summer Research. 31.
https://digitalcommons.calvin.edu/summer_research/2019/Posters/31
Included in
Trace elements of volcanic soils and coffee – Kona
Much of the world's coffee is grown on soils that have developed from the chemical and physical weathering of basalt, a volcanic rock with relatively high iron content. Volcanic rocks vary in composition depending on the relative amounts of major elements that produce minerals such as plagioclase, pyroxene and olivine. The breakdown of these minerals is dependent on climate and slope as well as the initial composition. Chemical weathering associated with climate, eventually leads to the development of clay minerals, oxides, and hydroxides that are key components of the soil chemistry. The soil transfers elements to the coffee plant through soil moisture as ions in solution and may be stored in the coffee bean. The purpose of this project has been to examine the characteristics of the Kona region as well as determine the chemical connection between the volcanic rocks, soil, and coffee. A major goal was to develop a method to tracking elements, specifically those found in the coffee to examine the possibility of inferring connections between those elements and the volcanic soils. Our initial literature review focused on three areas: composition of basaltic flows in Hawaii, soil development in Hawaii, and chemical profiling of coffee to determine geographic locations. The composition of the lava flows provides a chemical backdrop for understanding the availability of ions in the region. Extensive geochemical data sets are available as well as mineralogical modes. Certain minerals break down faster and influence the resulting soil composition. Studies of the soils provide insight to the secondary minerals such as goethite, calcite, and others. Because each volcanic region has a slightly different chemical signature, the resulting coffee takes on some component of that chemical signature. Our review also included geographic information systems of volcanic flows, soil classification, and large coffee farms in the Kona region. In addition to reviewing relevant literature and published data, we also developed a method for analyzing the dry coffee. We used XRF – X-ray fluorescence – a technology to measure the trace metals with atomic masses greater than Mg. The primary chemistry of coffee is organic in nature and dominated by C, H, and O; all of which are not detectable by the XRF. So, we used a technique that combined the coffee with a known mineral or “spike” and modeled the elements as oxides. The coffee that we used was purchased at Greenwell farms during the January 2019 Interim and represented a 100% Kona variety from this known location at different roasting levels. We started by grinding the coffees – medium roast, dark roast and full city roast – and the minerals which we would be mixing with each. After grinding and mixing the testing samples, we analyzed each mixture as a compound, collecting data for a series of oxides. Over 120 analyses were conducted during this project. This data was processed and reduced to determine the elemental signatures associated with the coffee.