Agriculture Reference
In-Depth Information
between aroma intensity and the three flavor
attributes, so that metabolites such as the
umami compounds, AMP and GMP, hexanal, and
2-
methylbutanoic acid methyl ester were strongly
correlated negatively with aroma intensity but
correlated positively with flavor intensity, flavor
creaminess, and flavor savoriness. Conversely,
metabolites associated positively with aroma in-
tensity, such as
2-
methylbutanal,
3-
methylbuta-
nal, and furan, are strongly associated negatively
with flavor intensity, flavor savoriness, and flavor
creaminess.
This study also emphasized the differ-
ences in flavor between cooked tubers from
Tuberosum and Phureja. Principal compo-
nent analysis (PCA) identified that the largest
differences in flavor were due to stronger fla-
vor intensity, flavor creaminess, and flavor sa-
voriness in the Phureja genotypes, and that
the metabolites associated most closely with
these traits were the non-volatile compounds,
AMP and GMP, and the volatiles,
2-
methylbu-
tanoic acid methylester, hexanal, and methyl-
salicylate. Previous work (Winfield
et al
.,
2005) also identified the methylester of
methylbutanoic acid and methylsalicylate as
being significantly different between Phureja
and Tuberosum genotypes, but also identified
a further ten volatiles that were different be-
tween the two potato types. Esterified branched-
chain carboxylic acids such as
2-
methylbuta-
noic acid methyl ester are derived from
branched-chain amino acids such as valine,
leucine, and isoleucine, in a reaction pathway
that is thought to involve branched-chain
amino acid aminotransferase (BCAAT; Beck,
2005), which catalyzes the rate-limiting step.
Methyl salicylate (MeSA) is a volatile com-
pound found in the floral scents of more than
100
species of
30
different families (Effmert
et al
., 2005). In some plants, MeSA acts as a
pollinator attractant, is involved in tritrophic
interactions, or is emitted in response to
herbivore damage (Effmert
et al
., 2005; Zhu
and Park, 2005). Additionally, MeSA is an
important flavor constituent of many fruits,
including strawberries and apples, as well
as processed foods such as breads, cheeses,
wines, and beer (reviewed in Goff and Klee,
2006). MeSA is formed by the action of sali-
cylic acid carboxyl methyltransferase on
salicylic acid.
19.4 Tuber Flavor: Environment
and Agronomy
Interactions between genotype, environment,
and agronomy in the development of potato
flavor can be important (Faulks and Giffiths,
1983; Arvanitoyannis
et al
., 2008; Jansky,
2008). Some potential flavor compounds are
affected significantly by growing environ-
ment. For example, the level of the volatile me-
thional, derived from the sulfur-containing
amino acid methionine, is sensitive to sulfur
application rate (Duckham
et al
., 2002). Tuber
potassium level may enhance umami taste in-
tensity, and so the effects of potassium fertil-
ization may also be important (Morris
et al
.,
2007). Tuber nitrogen content correlates with
the levels of organic acids (Cieslik, 1997), as
well as amides and amines, compounds that
can potentially give rise to off flavors (Thybo
et al
., 2006; Jansky, 2008). Several studies
have compared organic versus conventional
production systems on sensory attributes. In
one study, sensory panellists could distinguish
between boiled samples of the cultivar, Dark
Red Norland, if the samples were not peeled.
However, if the tubers were peeled prior to
boiling, the panel could not detect any signifi-
cant flavor differences (Wszelaki
et al
., 2005).
The studies of Woese
et al
. and Hajslova
et al
.
also made comparisons of cooked tuber flavor
in samples from organic and conventional
production (Woese
et al
., 1997; Hajslova
et al
.,
2005). As with the Wszelaki study, there was
no evidence that the production system gave
rise to flavor differences. Studies have been
published investigating the effects of environ-
ment on the quantitative descriptive analysis
of cooked tuber attributes (Jansky, 2008,
2010; Seefeldt
et al
., 2011). Seefeldt
et al
. com-
pared
11
potato varieties grown in two loca-
tions (one with a sandy soil type, the other
having clay soil) used for three culinary pre-
parations (Seefeldt
et al
., 2011). Attributes
related to tuber texture and yellowness were
affected most strongly by location, and there
was a relatively low variation in taste and
flavor. Environmental effects on baked tuber
flavor were reported by Jansky, with the tex-
tural attribute, mealiness, showing the most
variation (Jansky, 2008).
