Storage stresses such as handling, cold temperatures, high carbon dioxide, sprout inhibitor application, and aging can increase sugars especially in tubers which were chemically immature at harvest. Cool growing seasons that delay plant growth, excess nitrogen, and stresses such as heat or low temperatures can cause elevated sugars at harvest and dark fry colour. Analysis of the sucrose and glucose contents of tubers along with a standard frying test provides useful information in assessing the chemical maturity of the crop and the effect of various management practices on crop quality. Sucrose content gives a good estimate of potential processing quality before harvest while glucose content, when measured during storage, gives the best estimate of processing quality. Sucrose monitoring can be used to determine which fields are nearing maturity and glucose monitoring can be used to determine when they have reached a stage of chemical maturity that will ensure optimum quality out of long term storage.
Different varieties vary in the amount of sugar that is acceptable for processing.
Varieties for chipping for example must have lower reducing sugar content than those used for french fries. Sucrose and glucose monitoring can be used to determine which fields are nearing maturity and when they have reached a stage of chemical maturity that will ensure optimum quality out of long term storage. Potato vine killing either with a desiccant or by mechanical means is not commonly practised in the production of Russet Burbank potatoes french fry processing in Manitoba. Both chemical and mechanical methods can be used for vine killing. Other desiccants are currently under evaluation and may be registered in the near future.