CHARACTERIZATION OF POLYPHENOL OXIDASE FROM ROOSTER POTATO (SOLANUM TUBEROSUMCV ROOSTER)

Abstract

The isolation and purification of polyphenol oxidase from potatoes (Solanum tuberosum cv. Rooster) is described. A 64‐fold purified preparation has been obtained with 10% yield by a procedure involving (NH4)2SO4 precipitation, phenyl sepharose chromatography, ion exchange chromatography and hydroxyapatite chromatography. The partially purified enzyme has both cresolase and catecholase activity. Activity was lower toward monophenols than diphenols. Enzyme activity was optimal at pH 6.0–6.5 and at 30C. Greater than 50% activity was retained during storage for 72 h at pH 6.0–7.5. Residual activity was greater than 50% after incubation at 20C for 72 h, 30C for 48 h, 40C for 24 h, 50C for 2 h and 60C for 15 min. The most effective inhibitors tested were sodium metabisulfite and ascorbic acid. Sodium dodecyl sulphate appeared to activate the enzyme. The enzyme was capable of cross‐linking casein but did not increase gel‐strengths in acidified milk gels. PRACTICAL APPLICATIONS Rooster is the most important potato cultivar grown in Ireland and data on its isolation and characterization has not been reported previously. This work describes a method to isolate polyphenol oxidase and characterization of the enzyme. Information on characterization of the enzyme could be valuable in relation to control of enzymatic browning during current processing and in minimum processing. There is potential for use of the enzyme in the emerging cross‐linking area, as the results show some success and there may be potential of more cross‐linking as the field develops and as interest in natural methods of cross‐linking for food texture grows. This could lead to an important use for potato waste. Food product applications are given.

Partial purification and characterization of polyphenol oxidase from Chinese parsley (Coriandrum sativum)

“…Similar results were also reported where PPO exhibited a maximum activity at 40 o C or both 4methylcatechol and catechol (20). Despite variation of optimum PPO temperatures among sources, methods of extraction, and substrates used, PPO activity is generally the highest between 30 and 50 o C. Temperatures lower than 30 or higher than 50 o C had suggested low PPO activities from various sources such as round brinjal (11), Ankara pear (15), and Amasya apple (27). Optimum pH: Optimum enzyme pH values were 8.0 with 4methylcatechol and 7.0 with catechol.…”

“…Partial purification of PPO A crude enzyme solution of 684 mL was subjected to ammonium sulfate precipitation via slow addition of solid ammonium sulfate crystals to the solution until 50% saturation was achieved while stirring on ice (15). The mixture was allowed to homogenize for 10 min during extended stirring on a magnetic hotplate stirrer, followed by overnight incubation at 4 o C. The mixture was then subjected to centrifugation at 12,000xg for 15 min at 4 o C. The enzyme was restored via dissolution of protein pellets in 5 mL of 0.1 M phosphate buffer at pH 6.8 and supernatants were pooled and subjected to repeat precipitation at 60, 70, and 80% saturation.…”

Removal of Olive Mill Wastewater Phenolics with the Use of a Polyphenol Oxidase Homogenate from Potato Peel Waste

“…Quinones, in turn, can spontaneously polymerise to yield insoluble polymers [39]. Although the activity of potato PPO on monophenols is rather trivial [24,40], monophenolase activity could be stimulated in the presence of o-diphenols [41]. In addition, monophenols could either react with the o-quinones formed [42] or oxidised through coupling reactions [43].…”

Comparsion Between Ppo From Plant Sources and Differ-Ent Chemicals in Tattoo Dyes Decolorization

“…Polyphenol oxidases (PPOs) are a wide prevalent group of enzymes found in animals, fungi, plants, and bacteria (19). In the existence of PPO and atmospheric oxygen, monophenol is hydroxylated to o-diphenol, and diphenol can be oxidized to o-quinones, which then subject for polymerization to yield dark brown polymers (16). PPOs have different applications in industrial processes like food and medicine.…”