Browsing by Author "Mustanoja, Ella"

The literature review was concerned with colourful vegetables and the most common pigments in vegetables: carotenoids, anthocyanins, betalaines and chlorophyll. In addition, how thermal treatments affect these pigments and the structure of vegetable was reviewed. The aim of the experimental work was to investigate the effect of thermal treatments on the colour, pigments and texture of carrots and beet-roots. Seven coloured carrot cultivars and four coloured beet-root cultivars were examined. Three different kinds of thermal treatments were applied to the samples: blanching, boiling and steaming. Orange and purple carrots contained the highest amounts of carotenoids. The total carotenoid content of the carrots increased due to the thermal treatments. Purple carrots were the only carrots which contained anthocyanins. Anthocyanin stability is pH dependent: boiling in slightly acidic water had a minor impact on anthocyanin content than boiling in pure water. Red beet was the most betalain-rich beet-root. Other cultivars contained remarkably less betalaines. Betalain content decreased due to the thermal treatments. Betalain degradation due to the thermal treatments was detected as the pigment content and colour changed. Thermal treatments softened the vegetable structure. Thermal treatment improves the extraction of the pigments from the vegetable structure, which was detected as the increase in pigment concentration, leading to an enhancement of bioavailability of pigments. However, long thermal treatments cause pigment degradation and reduce the nutritional value of the vegetables.