nofima.no
Creating value
2013
19
Plant breeders, fruit growers, jam producers and scientists are collaborating to find the perfect berry varieties.
photo: kjell j. merok © nofima
The most promising varieties include the raspberries
‘Glen Fyne’ and ‘Cascade Delight’ and the strawberry
‘Saga’.
As well as thriving in Norwegian weather conditions,
the varieties must provide good crops, maintain high
quality and be suitable for processing.
The most important qualities of jams are colour,
taste, aroma and nutrient content. Making jams from
100 varieties of berries, and then analysing them for
both sensory qualities and chemical composition, is a
large and demanding job. All the jam producers used the
same recipe, stored the jams for up to six months and
assessed taste and colour of the jams.
Research Scientists Kjersti Aaby and Berit Karoline
Martinsen and PhD student Sebastian Mazur (Bioforsk)
analyzed the jams for compounds that contribute to
colour and healthiness. In this context, the anthocyanins
play a very important role, providing both the red colour
and promising health-beneficial properties.
Source of purple:
The scientists analysed how the
anthocyanins, and thereby colour, managed when the
berries were homogenized and heated and the jam was
stored. They also investigated how the anthocyanins
were affected by other constituents in the berries.
“For raspberries, there appears to be a correlation
between the amount of anthocyanins in the berries and
the colour stability of the jam. The more anthocyanins in
the berries, the more stable the colour was. For straw-
berries, finding correlations is harder, but it appears that
jams made from strawberries containing high concentra-
tions of vitamin C have less stable colour,” says Kjersti
Aaby.
The scientists have also studied the consequence of
making jams from berries at various stages of ripeness.
It was found that the colour changed most during stor-
age of jams made from the least ripe berries.
“So, make jam from well-ripened berries,” advises
Aaby.
About 100 varieties of strawberry and raspberry have been tested to
find those best suited for making jam. Only a few made the grade.
Hunting for the perfect berry
