Turnip

In the present millennium, plant-based functional foods have received substantial attention due to their
potential nutritional profile, presumed safety and therapeutic effects. Due to these functional foods, plants
provide numerous opportunities for cancer therapy. A wide range of horticultural crops are included in the
Brassicaceae family, and some are extensively used in the diet due to their economic significance throughout
the world. Various common vegetables are included in the genus Brassica, such as Bassical Rapa L. (turnip)
also known as Shaljam in Pakistan (Mourato et al., 2015). Since prehistoric times, the turnip has been used
for human consumption and is the oldest cultivated vegetable (Kaveh & Chayjan, 2017). This specie is
particularly famous in Europe and grows in temperate climates.
Across Eastern America, Asia and European regions, the turnip is considered as a famous nutritious root
vegetable, and in ancient Roman and Greek times, it was cultivated as a staple food (Lo Scalzo et al., 2008).
Baby turnips, also known as young turnips, are eaten raw in salads. Mature turnips have a stronger taste and
their texture becomes firmer and woody as compared to baby turnips, which have a sweeter taste and delicate
texture.
There are various varieties of turnips, of which Bavarian turnips are considered the best variety in terms
of yield. The leaves of a few B. rapa (Bavarian turnip) varieties are also used, and are known as Chinese
cabbage. Both the roots and leaves have a pungent flavour and the edible portions of the turnip are used as
an ingredient in stews and soups. Similarly, turnip tops and turnip greens have been used as vegetable
products in some parts of the globe. A bitter taste, particular sulphurous aroma and pungent flavour are the
characteristics of turnips. Likewise, numerous secondary metabolites such as phenolic acid in turnip tops and
glucosinolates in turnip greens have been significantly correlating with the flavour and texture. The amount
and pattern of the glucosinolates and volatiles in Brassica plants vary according to the plant species, cultivar
and vegetable part, as well as to the developmental stage of the plant (Kessler & Baldwin, 2002). When the
glucosinolates come into contact with myrosinases in the presence of water (during processing, cutting, tissue
chewing or when injured), they give rise to breakdown products (isothiocyanates, thiocyanates, nitriles,
epithionitriles and oxazolidines). Both glucosinolates and its derivatives are known to have a wide range of
important biological activities (Padilla et al., 2007). Some have been shown to be beneficial (such as the
chemoprotective effect against certain cancers in humans), while others are detrimental for human and animal
consumption (potentially goitrogenic) (Padilla et al., 2007; Taveira et al., 2009). The persistent bitter taste
and aftertaste of turnips are due to the progoitrin and gluconapin present in both turnip greens and tops
(Francisco et al., 2011a).

Morphological attributes
Turnip grow well in territories in cold environments and may be stored for months after harvest. The leaves
are usually light green, thin and sparsely downy. The turnip plant has a white-fleshed edible part, and the
large sphered root develops underneath the flowering stems and leaf petioles. The flowers form a bunch at
the top of the raceme and are usually raised above the terminal buds. Bolting of turnip plants occurs in late
winter, followed by the formation of flower buds, which are also consumed before opening, while still green.

Turnip greens have an intense aroma, the colour of the leaves and a salty taste, while the tops are unique for
their colour, moistness, fibrosity in the mouth and bitter taste (Lim, 2015). Two turnip varieties are grown,
small, tender ones and large sized ones, the small ones being grown for human consumption and the larger
ones for the purpose of livestock feed.
3 Nutritional profile
The nutritional assessment of turnips shows various valuable moieties. 100 grams of turnip roots provides
2-grams dietary fibre, 0.1 gram fat, 6.7 grams carbohydrate, 0.6 gram protein, 1.1 milligrams riboflavin,
0.4 milligram thiamine, 0.08 milligram Vit. B6, 16 milligrams Vit. C, 20 micrograms folate, 50 milligrams
calcium, phosphorous and iron, 8 milligrams magnesium, 280 milligrams potassium and 18 milligrams
sodium (Lo Scalzo et al., 2008). Thus, turnip root is low calorie (28 calories/100 gram) although it is a good
storehouse of minerals, vitamins, dietary fibre and antioxidants.
Many essential nutrients are present in the turnip greens which are not present in the turnip roots. Turnip
greens are not only abundant in antioxidants such as carotenoids, xanthins, lutein, vitamin A and vitamin C,
but are also an excellent source of vitamin K. Cartea et al. (2010) reported that the vitamin B complex i.e.
riboflavin; pantothenic acid and thiamine are abundantly present in the top greens of the turnip. Likewise,
calcium, iron, copper and manganese are important mineral sources present in the fresh turnip greens.
4 Phenolic compounds & organic acids
The literature suggests that a diet rich in fruits and vegetables can lessen the appearance of various ailments
such as diabetes, cancer, CVD and other diseases (Christensen, 2009). Compounds associated with the health
endorsing effects of vegetables are the organosulphur compounds, glucosinolates and other secondary
metabolites i.e. carotenoids, phytosterols, (Ferreres et al., 2005). Witman (2011) reported that the focus has
recently been diverted towards other potential health endorsing compounds found in different natural
vegetable products, partly explaining the health effects of, as an example, carrots and other related vegetables,
which contain polyacetylenes of the falcarinol-type, which show numerous biological activities including
anti-inflammatory and anti-cancer effects.
A diet containing vegetables is the chief source of the flavonoid compounds (Haytowitz et al., 2002).
Heimler et al. (2013) analysed various flavonoid and hydroxycinnamic derivatives present in aqueous turnip
extracts by HPLC, as shown in Table 1. Flavonoids may reduce the potential risk of cardiovascular, cancer
and inflammatory ailments in humans. Sinapic, ferulic and caffeic acids, kaempferol 3-O-sophoroside-7-Osophoroside, kaempferol 3,7-O-diglucoside, isorhamnetin 3,7-O-diglucoside, kaempferol 3-O-
(feruloyl/caffeoyl)-sophoroside-7-O-glucoside, kaempferol 3-O-sophoroside, 1,20-disinapoyl-2-feruloyl
gentiobiose, kaempferol 3-O-sophoro-side-7-O-glucoside, 3-p-coumaroylquinic, 1,2-disin-apoylgentiobiose,
isorhamnetin 3-O-glucoside and kaempferol 3-O-glucoside are the phenolic compounds found in the stem,
leaves and flower buds of the turnip. Likewise, Sinapic and ferulic acids and their by-products were present
in vestigial amounts in the analysis of turnip roots. Isorhamnetin 3-O-glucoside, 1,20-disinapoyl-2-feruloyl
gentiobiose, kaempferol 3,7-O-diglucoside, kaempferol 3-O-sophoroside, 1,2-disinapoylgentiobiose,
kaempferol 3-O-glucoside and isorhamnetin 3,7-O-diglucoside were the compounds in common when
compared with the results obtained for the B. rapa variety (Kumar & Andy, 2012; Romani et al., 2006a).
These phenolic moieties were found in various turnip extracts, with 10 to 19g/kg and 8 to 13g/kg on a dry
weight basis in the flower buds and leaves and stems, respectively (Ludwig et al., 2011). The leaves and
stems exhibited similar profiles, with kaempferol 3-O-sophoroside-7-O- glucoside, kaempferol 3-O-
(feruloyl/caffeoyl)-sophoroside-7-O-glucoside, isorhamnetin 3,7-O- diglucoside and isorhamnetin 3-Oglucoside present in larger amounts, whereas 3-p- coumaroylquinic acid, 1,2-disin-apoylgentiobiose and
1,20-disinapoyl-2-feruloylgentiobiose were present in minor quantities (Rafatullah et al., 2016). Likewise,

sinapic acid and kaempferol 3-O-glucoside were present in larger amounts, whereas caffeic acid and
kaempferol 3-O-sophoroside-7-O-sophoroside were found in smaller amounts in the turnip flower buds.
However, turnip flower buds showed significantly lower amounts of the pair kaempferol 3-O-sophoroside7-O-sophoroside plus caffeic acid, and presented significantly larger amounts of sinapic acid, 1,20-disinapoyl-2- feruloylgentiobiose and kaempferol 3-O-glucoside than the leaves and stems (Christensen, 2009).
Similarly, despite quantitative differences noticed in the organic acid contents of different extracts from the
same plant material, ketoglutaric, shikimic, citric, aconitic, malic and fumaric acids were found in almost all
the turnip portions (Francisco et al., 2011b). However, the leaves, stems and flower buds contained
significantly higher contents of organic acids (36 to 51 g/kg) than the roots (Fernandes et al., 2007). A smaller
amount of aconitic acid was found in the stem, roots and leaves, and shikimic acid was a minor compound
in the flower buds (Daryoush et al., 2011). Similarly, ketoglutaric and citric acid showed higher
concentrations in the flower buds, while malic acid was a major acid in all the edible portions of the turnip.
Turnip root showed higher concentrations of malic acid (81%), followed by the leaves and stems (65%) and
the flower buds (44%). Aconitic acid was higher in the flower buds (14%) and relatively lower in the roots
(2%). It has been reported in the literature that shikimic, citric, aconitic, malic and fumaric acids show
positive activity against gram negative bacteria (Sousa et al., 2008). On the other hand, shikimic acid is
generally used as the starting material for the industrial synthesis of the antiviral drug Oseltamivir (this drug
is effective against the H5N1 influenza virus and is administered to treat and prevent all known strains of the
influenza virus) (Bradley, 2005; Bochkov et al., 2012). In addition, a Chinese research team has synthesized
a shikimic acid derivative, triacetylshikimic acid, which exhibits anticoagulant and antithrombotic activities
(Huang et al., 2002). In another study, citric acid showed antioxidant and anti-inflammatory effects when
administered orally at 1–2 g/kg in brain tissue. Similarly, citric acid also demonstrated a beneficial hepatic
protective effect when administered in the same dose range (Abdel-Salam et al., 2014).