432
Á. Farkas et al.
nine conjugated double bonds) is esterified with two molecules of the disaccharide
gentiobiose.
Crocetin glycosides are water-soluble, slightly soluble in absolute alcohol, and
insoluble in vegetable oils (Rodriguez-Amaya 2003; Kirk-Othmer 2007). Picrocrocin is a β-D-glucoside of safranal, and this molecule is responsible for the bitter
taste of saffron (Alonso et al. 2001). Safranal (2,6,6-trimethyl-1,3-cyclohexadiene1-carboxaldehyde), a terpene aldehyde, is the major volatile oil component (60–
70%) of the essential oil in the stigma. It is responsible for the distinctive flavour
of saffron (it is characterized as floral with a fatty herbaceous undertone), and it
is produced by dehydration of picrocrocin during the drying process (Dris and Jain
2004). Protocrocin (a combination of two molecules of picrocrocin and one molecule
of crocin) has also been found in saffron (deMan et al. 2018). Cis- and trans-isomers
of crocetin glycosides carrying 1–5 glucose moieties have also been found in saffron
(Tarantalis et al. 1994).
Saffron and saffron extracts have a high tinctorial strength: besides crocin, they
also contain zeaxanthin and β-carotene (NIIR Board 2017). Saffron is typically used
at levels of 1-260 ppm in culinary (e.g. rice dishes, soups, cheese, meat dishes),
bakery, sugar confectionery products, alcoholic and non-alcoholic beverages (Maga
1994). The amounts generally needed are extremely low (1–10 mg/kg) except for
alcoholic drinks and meats (20–200 mg/kg). It exhibits moderately good resistance
to heat (NIIR Board 2017). The production of saffron is very labour-intensive (about
165,000 flowers are needed for 1 kg of saffron stigmas containing about 50 g of
the pigment, Kirk-Othmer 2007), therefore the extremely high cost severely limits
its use as a food colourant, and it is rather considered as a spice within the EU. In
the United States, crocetin is listed as a colour additive exempt from certification.
The less expensive Gardenia species grow in the Far East, and here they are used
to colour sugar and flour confectionery, dairy products, jams, preserves, rice, pasta,
ices, noodles, cakes, beans, smoked white fish (such as cod and haddock, where it
binds to the flesh) and other dishes. They do not have the same flavour as saffron,
only their colour is similar (Maga 1994). Gardenia yellow is a colourant produced
by extraction of the fruits of the mentioned Gardenia species with ethanol or water;
it is an approved food colourant in Japan and China, but not in the United States and
the EU (Solymosi et al. 2015).
The LD 50 value of saffron was 4120 ± 556 mg/kg after oral administration in
BALB/c mice and that of crocetin was 1–5 g/kg IP for male Razi mice and Wistar
rats. After intraperitoneal administration, the LD 50 values of safranal were 1.48,
1.88 and 1.50 ml/kg in male mice, female mice and male Wistar rats, respectively
(Hosseinzadeh et al. 2010, 2013; Bostan et al. 2017).
To the best of our knowledge, crocin itself has not been found in any microalgae.
But some microalgae may contain carotenoid glycosides (e.g. (2
S)-2-hydroxymyxol
2
-α-L-fucoside was found in the freshwater cyanobacterium Cylindrospermopsis
raciborskii; Nagy et al. 2018), and therefore may be able to be used for microalgal
production of carotenoid glycosides, such as crocin.
Á. Farkas et al.
nine conjugated double bonds) is esterified with two molecules of the disaccharide
gentiobiose.
Crocetin glycosides are water-soluble, slightly soluble in absolute alcohol, and
insoluble in vegetable oils (Rodriguez-Amaya 2003; Kirk-Othmer 2007). Picrocrocin is a β-D-glucoside of safranal, and this molecule is responsible for the bitter
taste of saffron (Alonso et al. 2001). Safranal (2,6,6-trimethyl-1,3-cyclohexadiene1-carboxaldehyde), a terpene aldehyde, is the major volatile oil component (60–
70%) of the essential oil in the stigma. It is responsible for the distinctive flavour
of saffron (it is characterized as floral with a fatty herbaceous undertone), and it
is produced by dehydration of picrocrocin during the drying process (Dris and Jain
2004). Protocrocin (a combination of two molecules of picrocrocin and one molecule
of crocin) has also been found in saffron (deMan et al. 2018). Cis- and trans-isomers
of crocetin glycosides carrying 1–5 glucose moieties have also been found in saffron
(Tarantalis et al. 1994).
Saffron and saffron extracts have a high tinctorial strength: besides crocin, they
also contain zeaxanthin and β-carotene (NIIR Board 2017). Saffron is typically used
at levels of 1-260 ppm in culinary (e.g. rice dishes, soups, cheese, meat dishes),
bakery, sugar confectionery products, alcoholic and non-alcoholic beverages (Maga
1994). The amounts generally needed are extremely low (1–10 mg/kg) except for
alcoholic drinks and meats (20–200 mg/kg). It exhibits moderately good resistance
to heat (NIIR Board 2017). The production of saffron is very labour-intensive (about
165,000 flowers are needed for 1 kg of saffron stigmas containing about 50 g of
the pigment, Kirk-Othmer 2007), therefore the extremely high cost severely limits
its use as a food colourant, and it is rather considered as a spice within the EU. In
the United States, crocetin is listed as a colour additive exempt from certification.
The less expensive Gardenia species grow in the Far East, and here they are used
to colour sugar and flour confectionery, dairy products, jams, preserves, rice, pasta,
ices, noodles, cakes, beans, smoked white fish (such as cod and haddock, where it
binds to the flesh) and other dishes. They do not have the same flavour as saffron,
only their colour is similar (Maga 1994). Gardenia yellow is a colourant produced
by extraction of the fruits of the mentioned Gardenia species with ethanol or water;
it is an approved food colourant in Japan and China, but not in the United States and
the EU (Solymosi et al. 2015).
The LD 50 value of saffron was 4120 ± 556 mg/kg after oral administration in
BALB/c mice and that of crocetin was 1–5 g/kg IP for male Razi mice and Wistar
rats. After intraperitoneal administration, the LD 50 values of safranal were 1.48,
1.88 and 1.50 ml/kg in male mice, female mice and male Wistar rats, respectively
(Hosseinzadeh et al. 2010, 2013; Bostan et al. 2017).
To the best of our knowledge, crocin itself has not been found in any microalgae.
But some microalgae may contain carotenoid glycosides (e.g. (2
S)-2-hydroxymyxol
2
-α-L-fucoside was found in the freshwater cyanobacterium Cylindrospermopsis
raciborskii; Nagy et al. 2018), and therefore may be able to be used for microalgal
production of carotenoid glycosides, such as crocin.