ศูนย์นวัตกรรมเทคโนโลยีหลังการเก็บเกี่ยว

Effects of transitory water stress on potato tuber stem-end reducing sugar and fry color.

Eldredge, E. P.; Holmes, Z. A.; Mosley, A. R.; Shock, C. C.; Stieber, T. D.;

American Potato Journal Year: 1996 Vol: 73 Issue: 11 Pages: 517-530 Ref: 18 ref

1996

บทคัดย่อ

Potatoes grown for processing in irrigated regions of the Pacific Northwest of USA sometimes develop undesirably high concentrations of reducing sugars in tuber stem ends due to hot weather and water stress during tuber development. Such tubers usually produce French fries with dark stem ends or sugar ends. In order to better quantify the relationship between water stress and stem-end sugar levels for potatoes cv. Russet Burbank, single episodes of transitory water stress were established by delaying irrigations until soil water potentials ranging from -32 to -107 kPa were reached during early tuber bulking. Tubers were sampled before transitory stress, at maximum stress, after stress was relieved with sprinkler irrigation, and postharvest. Reducing sugar concentrations did not increase in tuber stem ends until two weeks or longer after the plant water stress was relieved. Increased reducing sugar concentrations were positively associated with decreased soil water potential (drier soil). Tubers

were sliced and fried at harvest and six weeks postharvest. Decreasing soil water potential was associated with progressively darker fry colours at harvest and postharvest. Significant darkening in the average stem-end fry colour light reflectance of tubers at harvest was observed at -80 kPa in 1988 and -69 kPa in 1989. The effect of imposed water stress on tuber stem-end reducing sugar concentrations was most pronounced postharvest.