Bioprocess of robusta cherry coffee with polyphenol oxidase and quality enhancement

• Published in: European food research & technology Vol. 240; no. 2; pp. 319 - 325
• Main Authors: Mathur, Ritika, Navya, P. N, Basavaraj, K, Murthy, Pushpa S
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.02.2015; Springer Berlin Heidelberg; Springer Nature B.V
• Subjects: Agricultural commodities; Agriculture; Ammonium; ammonium sulfate; Analysis; Analytical Chemistry; beans; Biochemistry; bioprocessing; Biotechnology; bitterness; Caffeine; catechol oxidase; Cellulose; chemical reactions; Chemicals; Chemistry; Chemistry and Materials Science; Chromatography; Coffea arabica; Coffea canephora; Coffee; coffee beans; consumer satisfaction; Enzymes; Extraction processes; Flavors; Food; Food processing industry; food research; Food Science; foods; Forestry; fruiting bodies; molecular weight; Mushrooms; Original Paper; Oxidation; phenolic compounds; Phenols; Pleurotus florida; Pleurotus ostreatus; polyacrylamide gel electrophoresis; Polyphenols; Proteins; Studies; temperature; Sensory profile; Phenolics; Quality; Robusta cherry coffee; Polyphenol oxidase
• ISSN: 1438-2377; 1438-2385
• DOI: 10.1007/s00217-014-2331-8

Flavor plays an important role in consumer satisfaction and influences further consumption of foods. Robusta coffee is rich in caffeine and phenolics and is undesirable for coffee connoisseurs compared to arabica coffee. The exogenous polyphenol oxidase (4,000 U/ml) was extracted from the fruiting bodies of Pleurotus florida otherwise referred as the oyster mushroom. The polyphenol oxidase (PPO) was partially purified by ammonium sulfate precipitation followed with DEAE-cellulose with a recovery yield of 51.2 %. It appeared as a single band on SDS-PAGE gel with a molecular mass of approximately 60 kDa. The PPO with specific activity of 125 U/mg proteins was active at pH 5–7 and 30–60 °C temperature. The robusta cherry coffee was treated with PPO at different intervals of time and the changes induced were evaluated. Insignificant changes were observed with respect to the visual properties of the treated beans. However, the PPO-induced biochemical reactions that resulted in the reduction of bitterness of robusta cherry coffee and also decline in caffeine and chlorogenic compositions were compared to untreated. The nonvolatile components such as phenolics of the treated samples were found to have reduced from 6.50 to 4.05 % (30 min) and 3.96 % (60 min) in the treated samples leading to elevated sensory attributes with overall rating of 8–8.5 in hedonic scale. This is the first implication of PPO on robusta cherry coffee to enhance the quality profile and are viable compared with physical and chemical methods.