Epsilon Open Archive

Abstract

Falcarinol type polyacetylenes (FaTP) in carrots have been assigned both positive health effects and negative effects on taste, in connection with human consumption.

The aim of this thesis was to contribute to the description of factors influencing the concentrations of FaTP in carrot. Some 465 different samples, from 77 different plots, harvested at 17 different occasions during the period 2005 – 2008 were used in the investigations. The samples were analyzed concerning their size, root morphology, concentrations of soluble sugars and concentrations of polyacetylenes. Only the three major polyacetylenes in carrots; falcarinol (FaOH), falcarindiol (FaDOH) and falcarindiol-3-acetate (FaDOAc) were considered in this thesis.

No single factor was found to explain all of the variation in the levels of FaTP. Factors such as harvesting year, location of growing site, length of the growing season, storage and soil conditions were shown to have a stronger impact on the FaTP concentrations than for example manuring strategy. Increased concentrations of FaDOH, and sometimes also of FaOH, appeared to be a reaction on stress, i.e. a way of resisting stress.

The concentration of FaTP increased until 110-115 days after sowing and then decreased during the latter part of the season. Initially the levels of FaTP increased as the roots grew larger. However, roots heavier than 70 g exhibited lower levels of FaDOH and roots heavier than 107 g were lower also in their total concentration of FaTP. It was not possible to assign a specific root shape as an indicator of the composition of FaTP in the carrot samples.

The levels of FaOH were mainly correlated to regular changes occurring during root development, but they could occasionally increase if the carrots were grown under stressful conditions. The FaDOH concentration exhibited a pattern of variation more dependent on external factors, such as annular variation and soil conditions. The concentration of FaDOAc was more dependent on factors such as the levels of hexoses and on root length or root shape.

The variation in the concentration of FaOH indicated the existence of a critical level below which the synthesis of this compound was triggered. The enzymes transforming FaOH into FaDOH appeared to be active under similar conditions as the enzymes converting sucrose to hexoses.