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New Zealand Plant Protection 66 (2013): 384

Analysis of potato crisp colour topography following infection by 'Candidatus Liberibacter solanacearum'

S.L. Lewthwaite, T. Holmes and C.M. Triggs

ABSTRACT

The potato (Solanum tuberosum L.) is classified as an herbaceous perennial because of the clonal continuity provided by its primary carbohydrate storage organ, the tuber. The biochemical composition of the tuber varies throughout its development and during postharvest storage, but consists principally of water and carbohydrates. Although sugars make only a small contribution to the total carbohydrate content, they are critical to the quality of fried potato products. Increased concentrations of the reducing sugars glucose and fructose contribute to the Maillard reaction, which promotes dark colours and burnt flavours. These sugars are also key precursors for acrylamide formation, with associated consumer health concerns. The concentrations of specific sugars within a potato tuber are a function of the cultivar, tuber health and maturity, the growing environment and storage conditions. While the general colour of processed potato crisps may be readily assessed on a subjective visual scale or by reflectance spectrophotometer, infection by the bacterium 'Candidatus Liberibacter solanacearum' causes highly uneven colouration across individual crisp surfaces. This research explores the use of image analysis to define disease symptom expression in processed crisps from infected plants.

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