Employees

Potato is the third most important crop worldwide and its post-harvest management is an important challenge for the value chain. Various chemicals that are used to reduce sprouting during storage are associated with a risk of toxicity for the consumer. Less harmful molecules that have been recently commercialized hold some promises but their costs remain high. Other alternatives exist to avoid relying on anti-sprouting agents during storage such as: (1) the use of varieties with long dormancy, or (2) storage at low temperature to delay sprouting. However storage at low temperature is often constrained by the susceptibility of potato varieties to cold induced sweetening (CIS). CIS alters the potato product quality (sweet taste, browning and increased acrylamide content after frying). The sweetening is an important issue for industrial varieties because frying of potato with high free sugar contents triggers a darkening that is commercially unacceptable. The main objective of the present study is to identify varieties adapted to storage at low temperatures. Six varieties (Lady-Claire, Kiebitz, Verdi, Agria, Markies and Pirol) were planted, harvested and stored at 4 and 8°C and 85% RH during 3 seasons (2015, 2016 and 2017). After 3 months of storage, the potato quality was assessed as follows: (1) frying test with color evaluation of 10 crisps per sample (2015, 2016 and 2017), we use a scale ranging from 1 (=crisps fully dark) to 9 (=crisps clear), a score above 7 is considered as an acceptable result by the industry, and (2) glucose titer measurement in potatoes using a glucometer (Accu-Check® glucometer) (2016 and 2017). The results revealed that all factors (varieties, temperature of storage and interaction between variety and temperature) showed significant differences of the crisps color (ANOVA, p < 0.001). Among the six varieties and the two temperature of storage tested, the varieties Pirol, Markies and Agria stored at 4°C showed a color quality of crisps lower than the other varieties stored at the same temperature. At 4°C, we obtained less than 4 crisps out of 10 with acceptable color (score > 7) instead of 7 crisps and more for the potatoes stored at 8°C. All varieties stored at 8°C showed no significant differences for the color score after frying. The glucose content was higher for the varieties stored at 4°C with an average of 94 mg/dl as compared to an average of 11 mg/dl for the same varieties stored at 8°C (ANOVA, p < 0.05). An higher glucose content was measured in the varieties Pirol, Markies and Agria stored at 4°C with an average of 168 mg/dl instead of 12 mg/dl for the same varieties stored at 8°C but this effect was not significant (ANOVA, p > 0.05). In summary, our study allowed the identification of 3 varieties with limited CIS that are suitable for storage at cold temperature (Lady-Claire, Kiebitz, Verdi). Future research activities will aim at characterizing genetic and enzymatic mechanisms involved in CIS in the selected varieties.