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Sensory quality of turnip greens and turnip tops grown in northwestern Spain - page 4 / 31





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are characterized by a particular sulfurous aroma, pungent flavor, and a bitter taste,

which differentiate them from other Brassica vegetables [4, 5].

Like all Brassica species, B. rapa crops contain secondary plant metabolites,

mainly glucosinolates (which are found almost exclusively in Brassicaceae family) and

phenolic compounds including flavonoids and hydroxycinnamic acids. The presence of

these compounds in the diet has increased on the last years because of their beneficial

health properties [6]. Moreover, these compounds have been related to the sensorial and

nutritional qualities of vegetables. In fact, total glucosinolate content and their

breakdown products were associated with sensory attributes in Brassica crops [7-9].

Other authors [5, 10] have reported that bitterness is considerably affected by the

gluconapin, an aliphatic glucosinolate.

The cultivation of B. rapa takes place during the winter season. In many cases,

the same variety can be exploited for several uses (turnips, turnip greens, and turnip

tops), preventing the fixing of standard morphological characteristics and allowing the

existence of local varieties with high levels of variability. A collection of 200 varieties

collected from northwestern Spain was previously evaluated for their agronomic

performance [2] as well as for their nutritional value focused on glucosinolate, fiber and

protein content [5]. Besides, a first evaluation regarding sensorial attributes (bitterness

and flavor) was carried out with the aim to discard those varieties that did not fit the

normal parameters of this crop. As result, varieties were classified based on their

morphological and agronomic attributes by using the Ward-MLM method [2]. Based on

this previous classification, some varieties, suitable for turnip tops or/and for turnip

greens fresh production were selected. Galician local varieties are maintained by local

farmers based on their agronomic behavior but sensory quality was not a criterion to

maintain them.

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