Tuber glucose and French fry reflectance of Elk River Russet, a new potato variety from the University of Minnesota (P-19)

Elk River Russet is a new potato cultivar from the University of Minnesota suitable for French fry processing or the fresh market. It typically produces a lower total yield than Russet Burbank, but more of its total yield is of marketable size ( > 4 oz.), and less of its marketable yield is represented by U.S. No. 2 tubers. We evaluated both cultivars for the storage characteristics of tubers grown under low (80 lbs/ac) and high nitrogen (200 lbs/ac) fertilizer regimes in 2023 and 2024 and stored at 40, 46, and 48°F with and without chlorpropham (CIPC). At harvest, Russet Burbank tubers had higher glucose concentrations than Elk River Russet tubers, especially when grown at 80 lbs/ac N in 2023. French fry reflectance values were higher at the stem end in both cultivars, but more so in Russet Burbank. The use of CIPC significantly decreased tuber sucrose concentration and increased French fry reflectance values for tubers stored at 40°F for three or six months, but even with CIPC, French fry reflectance values after storage at this temperature were too low to be marketable. CIPC did not have a consistent effect on glucose concentrations in tubers stored at 46 or 48°F. After three or six months’ storage at 46 or 48°F without CIPC, the two cultivars had similar tuber glucose concentrations. Stored at 46 or 48°F, Russet Burbank fries were darker at the bud end and lighter at the stem end than Elk River Russet fries. Based on these results, Elk River Russet’s potential for long-term storage and French fry processing is similar to that of Russet Burbank. Both cultivars are susceptible to cold-induced sweetening, and while CIPC reduces this effect, it does not do so sufficiently to produce marketable French fries from tubers stored at 40°F.