Concentrations of Free Amino Acids and Sugars in Nine Potato Varieties: Effects of Storage and Relationship with Acrylamide Formation

Acrylamide forms during cooking and processing predominately
from
the reaction of free asparagine and reducing sugars in the Maillard
reaction. The identification of low free asparagine and reducing sugar
varieties of crops is therefore an important target. In this study,
nine varieties of potato (French fry varieties Maris Piper (from two
suppliers), Pentland Dell, King Edward, Daisy, and Markies; and chipping
varieties Lady Claire, Lady Rosetta, Saturna, and Hermes) grown in
the United Kingdom in 2009 were analyzed at monthly intervals through
storage from November 2009 to July 2010. Acrylamide formation was
measured in heated flour and chips fried in oil. Analysis of variance
revealed significant interactions between varieties nested within
type (French fry and chipping) and storage time for most free amino
acids, glucose, fructose, and acrylamide formation. Acrylamide formed
in chips correlated significantly with acrylamide formed in flour
and with chip color. There were significant correlations between glucose
or total reducing sugar concentration and acrylamide formation in
both variety types, but with fructose the correlation was much stronger
for chipping than for French fry varieties. Conversely, there were
significant correlations with acrylamide formation for both total
free amino acid and free asparagine concentration in the French fry
but not chipping varieties. The study showed the potential of variety
selection for preventing unacceptable levels of acrylamide formation
in potato products and the variety-dependent effect of long-term storage
on acrylamide risk. It also highlighted the complex relationship between
precursor concentration and acrylamide risk in potatoes.