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Kinetics of volatile generation during coffee roasting and analysis using Selected Ion Flow Tube-Mass Spectrometry

Krishnaswamy, Sangeetha
http://rave.ohiolink.edu/etdc/view?acc_num=osu1492506642418004

Abstract Details

2017, Master of Science, Ohio State University, Food Science and Technology.
Roasting is a critical step comprising of a series of complex reactions that are responsible for flavor generation in coffee. This study presents a real-time analytical technique that predicts the mechanism of volatile generations during different roasting conditions which could be ultimately used for online process control to deliver a more consistent target roast profile. The objectives of this research were to 1) To monitor the volatile compound generation during coffee roasting in real-time using online SIFT-MS 2) To investigate the influence of the time-temperature process during coffee roasting on the kinetics of volatiles generated and develop predictive models to determine kinetic parameters of volatile compounds and 3) predict temperature distribution histories within the coffee bean at different roasting conditions. Colombian Arabica coffee beans were roasted in a horizontal drum roaster at 210, 220 and 230 °C for 10, 15 and 20 minutes respectively. The concentrations of 7 volatile organic compounds (VOC’s), with impact on coffee flavor, were measured in the gas stream at the exit from the roaster using online Selected Ion Flow Mass Spectrometry (SIFT-MS) and were compared to the amounts retained in the final coffee extract. Modified Gompertz and Logistic models were used to describe the rate of volatile generation and estimate the kinetic parameters for the Volatile Organic Compounds (VOC’s) during different roasting conditions. The activation energy coefficients were calculated using the Arrhenius relationship. A transient heat conduction model for unsteady state heat transfer was used to determine the temperature distribution within the coffee bean. A synergy existed between the VOC release pattern in the roaster gas and the VOC formation/retention trend in the coffee extract. Excessive roasting (230 °C beyond 15 minutes), led to lower VOC concentrations in the roaster gas and the coffee extract. The modified Logistic models provided good statistical fit to the experimental data and precise estimation of kinetic parameters based on low NRMSE and SEE%. The changes in the temperature influenced the kinetics of volatile generation during the roasting process. The rate constant and peak concentration increased significantly with increase in temperature for all VOC’s. The range of activation energy coefficient for volatile compounds indicates a very high temperature sensitivity for the volatile compounds. The mass average temperature was predicted considering the mass contribution of different regions within the coffee bean using transient heat conduction model. Model validation was performed by combining the reference kinetics parameters of volatile compounds with the predicted mass average temperature. A correlation between the rate of volatile generation and the mass average temperature within the coffee bean was evident. The results showed that the predicted VOC concentration was in good agreement with the experimental values. The simulation can be useful for predicting VOC release for different roaster types and optimizing the roasting conditions.
Dennis Heldman, PhD (Advisor)
Sudhir Sastry, PhD (Committee Member)
Simons Christopher, PhD (Committee Member)
155 p.
Food Science
Coffee Roasting, On-line Selected Ion Flow Tube Mass Spectrometry, Kinetics of VOC generation, Coffee Bean Temperature Distribution

Recommended Citations

Citations

  • Krishnaswamy, S. (2017). Kinetics of volatile generation during coffee roasting and analysis using Selected Ion Flow Tube-Mass Spectrometry [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492506642418004

    APA Style (7th edition)

  • Krishnaswamy, Sangeetha. Kinetics of volatile generation during coffee roasting and analysis using Selected Ion Flow Tube-Mass Spectrometry . 2017. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1492506642418004.

    MLA Style (8th edition)

  • Krishnaswamy, Sangeetha. "Kinetics of volatile generation during coffee roasting and analysis using Selected Ion Flow Tube-Mass Spectrometry ." Master's thesis, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492506642418004

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.