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FLHGSRAC
FLHGSRAC

Physiology

Polyphenol oxidase activity and levels of total phenolics positively correlate with enzymatic browning after storage of russet-type potato cultivars

Tuesday, July 29, 2025
10:45 AM - 11:00 AM CDT
Location: Hall of Ideas EH
FLHGSRAC
Enzymatic browning is a postharvest issue affecting the quality and marketability of fresh and processed potatoes. Storage induces physiological changes in tubers that might affect polyphenol content, antioxidant compounds, and PPO activity. This study aimed to evaluate the browning susceptibility and biochemical profile of russet-type potatoes at the beginning and the end of the storage season. Clearwater Russet (CR), Russet Norkotah (RN), Russet Burbank (RB), and Ranger Russet (RR) tubers were cured at 12.8 °C and 95% RH for 14 days, then stored at 7.2 °C and 95% RH for one and seven months. Tubers stored for one month were washed, and central slices from six tubers were treated with 0.01 M catechol solution, compared to untreated controls, with five replications. Slices were exposed to air (22°C and 15% RH) for 6 hours. Colorimetric changes (L, ΔL) were monitored at 0, 2, 4, and 6 h. Samples were collected for biochemical profiles and PPO activity. CR exhibited significantly lower browning with ΔL of 5.62, followed by RN and RR, while RB showed the highest discoloration ΔL (7.23). CR had significantly lower phenolic content (3.36 mg/g) and PPO activity (8.44 U/g), indicating less susceptibility to browning, followed by RN and RR. Russet Burbank had the highest phenolic content (5.02 mg/g) and PPO activity (12.60 U/g), contributing to higher browning susceptibility. CR showed the lowest level of precursor amino acids (tyrosine, phenylalanine, and tryptophan), followed by RN, RR, and RB. Pearson correlation showed ΔL was positively correlated to PPO activity, total phenolics, and amino acids, but negatively correlated to chlorogenic and ascorbic acid. Clearwater Russet may be suitable for fresh-cut products due to its low phenolic content. This study was repeated with tubers stored for seven months, and analyses are ongoing. It will provide insights into potato browning susceptibility during storage.