Date of Award

5-2019

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Education and Human Services

Department/Program

Nutrition and Food Studies

Thesis Sponsor/Dissertation Chair/Project Chair

Adrian Kerrihard

Committee Member

John Specchio

Committee Member

Kristin Truglio

Abstract

Coffee is one of the most widely consumed beverages in the world. Cold brew coffee has grown in popularity among the recent years. PURPOSE: To determine the effects of grind size and extraction time on the antioxidant potential, sensory profile, and consumer likability of cold brew coffee. MATERIALS AND METHODS: 138 adults participated in randomized sample consumer assessment of the likeability of 18 different cold brew coffee samples based on appearance, aroma, flavor, and overall. The samples were made with 2 different types of beans, 3 different grind sizes (0.65mm, 1.15mm, and 1.65mm), and 3 different brewing times (18h, 24h, and 30h). Additionally, twelve trained panelists participated in a descriptive analysis of these 18 cold brew coffee samples. These samples were assessed on 19 selected attributes. Antioxidant potential was also assessed using Trolox Equivalent Antioxidant Capacity (TEAC) assay for 9 samples (1 bean type: Los Santos, 3 grind sizes (0.65mm, 1.15mm, and 1.65mm), and 3 brew times (18h, 24h, 30h)). Multivariable modeling was performed to quantify the effects of the processing factors on each of the assessment outcomes. RESULTS: For Consumer Assessment, samples brewed at 24 hours consistently scored lower than 18 and 30 hours. The sample with a grind size of 1.65 mm brewed for 30 hours scored the highest. For Descriptive Analysis, 24 hours consistently produced the lowest scores across all attributes. For grind size, it was found that 0.65mm had significantly higher antioxidant potential than 1.15mm and 1.65mm (p<.001 and p<.001). For brew time, 24 hours had the lowest antioxidant potential of 0.81. 18 hours had an antioxidant potential of 1.4. 30 hours had the highest antioxidant potential of 2.86. CONCLUSIONS: Cold brew coffee brewed for 18 or 30 hours had higher magnitudes of descriptive traits, higher acceptability and antioxidant potential than 24 hours. Further research into the compounds that are dissolving between the hours of 18 and 24 would be warranted to identify what is mitigating flavor attributes and perceived quality as well as the antioxidant potential. To produce cold brew coffee considering its overall flavor, likability and antioxidant potential, it is recommended to brew cold brew coffee for 30 hours with a coarser grind size (1.65mm).

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