Near infrared spectroscopy as a new tool to determine cocoa fermentation levels through ammonia nitrogen quantification.

Fermentation is a key step in obtaining fine cocoa through the formation of potent aroma precursors. The fermentation level of cocoa beans is traditionally assessed by measuring the amount of ammonia nitrogen (NH₃) using the time-consuming Conway technique. Near infrared spectroscopy (NIRS), a rapid and efficient tool, was used to analyze NH₃ levels in several hundred cocoa samples at different fermentation levels from six geographical origins. Fermentation levels were expressed as the number of fermentation days and sum of temperatures. The correlation between Conway results and NIRS spectra enabled the development of a reliable and accurate NIRS calibration to determine NH₃ content. We confirm that NH₃ is produced during fermentation and its amount depends on the fermentation time, sum of temperatures and geographical origin. NIRS could be used by chocolate manufacturers as a routine method to sort cocoa samples according to their level of fermentation.

[1]  M. Barel.  Première transformation du cacao , 1998 .

[2]  C. Pasquini.  Near Infrared Spectroscopy: fundamentals, practical aspects and analytical applications , 2003 .

[3]  H. Wells.  Food of the Gods , 1978 .

[4]  R. Boulanger,et al.  The Use of near Infrared Spectroscopy to Determine the Fat, Caffeine, Theobromine and (−)-Epicatechin Contents in Unfermented and Sun-Dried Beans of Criollo Cocoa , 2012 .

[5]  S. Wold.  Cross-Validatory Estimation of the Number of Components in Factor and Principal Components Models , 1978 .

[6]  T. Guehi,et al.  Performance of different drying methods and their effects on the chemical quality attributes of raw cocoa material. , 2010 .

[7]  A. Wheals,et al.  The Microbiology of Cocoa Fermentation and its Role in Chocolate Quality , 2004, Critical reviews in food science and nutrition.

[8]  B. Biehl,et al.  Peculiarity of the accumulation of free amino acids during cocoa fermentation , 1989 .

[9]  Pedro Fevereiro,et al.  Structural and chemical changes in cocoa (Theobroma cacao L) during fermentation, drying and roasting , 2001 .

[10]  E J Conway,et al.  An absorption apparatus for the micro-determination of certain volatile substances: The micro-determination of ammonia. , 1933, The Biochemical journal.

[11]  V. C. Quesnel.  Agents inducing the death of cacao seeds during fermentation , 1965 .

[12]  A. Fae,et al.  Effect of Drying Methods on the Chemical Quality Traits of Cocoa Raw Material , 2010 .

[13]  D. Bertrand,et al.  Sensory and instrumental characterisation of Cabernet Franc grapes according to ripening stages and growing location , 2008 .

[14]  S. Anderson,et al.  Fluorescence anisotropy decay demonstrates calcium-dependent shape changes in photo-cross-linked calmodulin. , 1988, Biochemistry.

[15]  J. S. Ribeiro,et al.  Chemometric models for the quantitative descriptive sensory analysis of Arabica coffee beverages using near infrared spectroscopy. , 2011, Talanta.

[16]  R. Barnes,et al.  Standard Normal Variate Transformation and De-Trending of Near-Infrared Diffuse Reflectance Spectra , 1989 .

[17]  Ernestina Casiraghi,et al.  NIR and MIR spectroscopy as rapid methods to monitor red wine fermentation , 2010 .

[18]  J. Vincent,et al.  Influence de différents traitements technologiques sur la fermentation du cacao et le gout du chocolat , 1970 .

[19]  W. G. Forsyth.  Cacao polyphenolic substances. II. Changes during fermentation. , 1952, The Biochemical journal.

[20]  C. Hansen,et al.  Enzyme activities in cocoa beans during fermentation , 1998 .

[21]  B. Biehl,et al.  Cocoa-specific aroma precursors are generated by proteolytic digestion of the vicilin-like globulin of cocoa seeds , 1994 .

[22]  M. Barel.  La première transformation du cacao , 1998 .

[23]  S. Dabonné,et al.  Performance of different fermentation methods and the effect of their duration on the quality of raw cocoa beans , 2010 .

[24]  K. Buckle,et al.  Effect of Different Mixing Intervals on the Fermentation of Cocoa Beans , 1997 .

[25]  Fabrice Davrieux,et al.  Near infrared spectroscopy for high-throughput characterization of Shea tree (Vitellaria paradoxa) nut fat profiles. , 2010, Journal of agricultural and food chemistry.

[26]  D. Butler,et al.  The use of an optimised organoleptic assessment protocol to describe and quantify different flavour attributes of cocoa liquors made from Ghana and Trinitario beans , 2008 .

[27]  M. Petersen,et al.  Ghanaian cocoa bean fermentation characterized by spectroscopic and chromatographic methods and chemometrics. , 2010, Journal of food science.

[28]  A. Savitzky,et al.  Smoothing and Differentiation of Data by Simplified Least Squares Procedures. , 1964 .

[29]  D. Crouzillat,et al.  Evolution of cacao bean proteins during fermentation : a study by two-dimensional electrophoresis , 1999 .

[30]  John S. Shenk,et al.  Population Definition, Sample Selection, and Calibration Procedures for Near Infrared Reflectance Spectroscopy , 1991 .

[31]  S. Kochhar,et al.  Characterization of peptides formed during fermentation of cocoa bean. , 2001, Journal of agricultural and food chemistry.

[32]  Yong He,et al.  Theory and application of near infrared reflectance spectroscopy in determination of food quality , 2007 .

[33]  M. Nout,et al.  Theobroma cacao L., “The Food of the Gods”: Quality Determinants of Commercial Cocoa Beans, with Particular Reference to the Impact of Fermentation , 2011, Critical reviews in food science and nutrition.

[34]  Emil W. Ciurczak,et al.  Handbook of Near-Infrared Analysis , 1992 .