Date of Award
Master of Science
Food Science and Technology
John R. Mount
Svetlana Zivanovic, David A. Golden
Roasting is an important processing step for developing cocoa flavor, color, and aroma. Cocoa beans contain polyphenolic compounds, which can be desirable antioxidants. Oxygen Radical Absorbance Capacity (ORAC) values can be used as an indicator of health benefits of antioxidants in foods. ORAC values measure total antioxidant capacity of different foods by measuring antioxidant scavenging activity against peroxyl radical induced by 2,2’-azobis (2-amidinopropane) dihydrochloride (AAPH). This measurement of total antioxidant capacity gives a complete assessment during which the inhibition time and inhibition degree are measured as the reaction comes to a completion. ORAC values were determined as Trolox Equivalents (TE). Cocoa beans were also measured for antioxidants using Total Phenolics assay and DPPH assay and measured as gallic acid equivalents (GAE). Cocoa beans from the Ivory Coast were roasted at varying times (10-40 minutes) and temperatures (100ºC -190ºC). It was determined that cocoa beans from the Ivory Coast, roasted at 130ºC for 30 minutes resulted in an ORAC value of 522,789 μmol (micromoles) TE/g, GAE value of 2.46 mg/L as determined by Total Phenolics, and GAE value of 1.48 mg/L as determined by DPPH assay. The analyzed values tended to decrease at the highest temperatures and times of roasting. Cocoa beans from different countries were roasted at 130ºC for 30 minutes and antioxidants were analyzed. It was determined that Dominican Republic and Ecuador had the highest TE values (487,913 and 463958 μmol (micromoles) TE/g respectively). GAE differed and Total Phenolic assay found Haiti had the highest GAE (3.26 mg/L) and DPPH assay found Ivory Coast and Dominican Republic had the highest (0.623 and 0.610 mg/L respectively). If an acceptable flavor, color, and aroma of cocoa can be developed at a roasting temperature closer to 130ºC than to 160ºC, then a greater antioxidant content should occur in dry cocoa powder.
Harrington, Whitney Leigh, "The Effects of Roasting Time and Temperature on the Antioxidant Capacity of Cocoa Beans from Dominican Republic, Ecuador, Haiti, Indonesia, and Ivory Coast. " Master's Thesis, University of Tennessee, 2011.