Impact of variety, ripeness and harvest date on the colour stability of strawberry nectar made from puree

Impact of variety, ripeness and harvest date on the colour stability of strawberry nectar made from puree. 10 local strawberry varieties were tested for their ability to produce nectars made from puree with a high colour stability. Firmness, respiration rate, fruit weight, colour values and protein content of the fruit were measured. The pH-value, titratable acidity and degrees Brix-value of the puree were measured and the contents of anthocyanins (pelargonidin-3-glucoside, cyanidin-3-glucoside) and flavonols (kaempferol-3-glucoside, quercetin-3-glucoside) of the nectars were analysed. Fruit of the variety 'Mars' were harvested at two different harvest dates (beginning and end of harvest) and each lot was divided into "ripe" and "fully ripe" fruits. Nectars made from puree were processed and their colour values were measured during storage. Results show, that there are some differences between the measured values of the different varieties, but most of them showed no significant effect on the colour stability. The contents of anthocyanins, cyanidin-3-glucoside and protein had a significant effect on the colour stability of the nectars. Moreover the stage of ripeness and the harvest date had a significant effect on colour stability as well. The colour stability of varieties which were harvested later was better than from varieties which were harvested earlier (with some exceptions). Nectars from "fully ripe" and later harvested strawberries showed the best colour stability. These fruit had the lowest protein contents.