[6-1130-P] Postharvest/Food Technology and Process Engineering (6th)

[6-1130-P-22] Effect of roasting and storage on chemical compounds and sensory score of specialty coffee

*Yuri Koshima¹, Yutaka Kitamura¹, Mito Kokawa¹, Thais M.F.S. Vieira², Juliana Antunes Gavalão², Luis Felipe de Freitas Fabricio², Md Zohurul Islam¹ (1. University of Tsukuba(Japan), 2. University of Sao Paulo(Brazil))

Keywords: lipid oxidation, specialty coffee, coffee roasting, shelf life, sensory evaluation

Coffee is the most consumed food product in the world. Among them, coffee beans which are evaluated as 80 or more points in the sensory evaluation of Specialty Coffee Association of America (SCAA) is called specialty coffee. And specialty coffee has unique flavor characteristics and high traceability of the value chain. Specialty coffee consumption is increasing in recent years. Flavor is the most important criteria for coffee quality evaluation, and also one of the major motivations for consumer preferences. The storage period of specialty coffee is relatively short compared to commodity coffee, but some commercial products are stored for a period longer than the recommendation of specialists. Many studies have conducted on aromatic components such as phenol in coffee, but there are still few findings on lipid oxidation. Roasting induces transformation on chemical and physical composition in coffee beans. During storage, further chemical and physical changes that affect the quality of brew may occur. Along with this change, the acceptability of consumers also changes. In this experiment, the quality change of coffee due to oxidation of lipid is clarified. Catuai Amarelo coffee cultivars from Alta Mogiana, SP, Brazil was used. The sample was harvested on August 2018 then processed according to natural method. Green bean, light roasted bean, medium roasted bean and dark roasted bean were stored up to 85 days then analyzed for chemical components of lipid oxidation. Hydroperoxide content as a primary oxidation compounds evolution during storage were monitored by conjugated dienes and trienes determination by spectrophotometric method. Free fatty acids (FFA) as a secondary oxidation compounds were evaluated by American Oil Chemists’ Society (AOCS) method. The sensory evaluation was conducted according to the sensory test protocol of SCAA. The production of fatty acid, which is the final product of lipid oxidation, stabilized after transient increase. On the other hand, the sensory evaluation score decreased overall. A weak correlation was found between fatty acid content and sensory score, with a correlation coefficient of R^2=0.39.