precisely phenanthrene; and volatile compounds composition was also affected,
whereas at low temperatures aldehydes and alcohols were observed. Pyrazines
formed during roasting are thought to be responsible for the aroma which differs
from fresh to roasted depending on the degree of roasting (Potočnik and Košir 2016).
Procida et al. (2012) conducted a study to analyze the fatty acid, carotenoid namely
zeaxanthine, lutein, α- and γ-tocopherol concentrations in commercially available
pumpkin seed oil samples and to determine the effect of roasting prior to oil pressing
on volatile fractions. The study showed that the aroma of the commercial oils was in
proportion to the thermal treatment. Also, the volatile compounds formed during
chemical reactions from lipid peroxidation, Strecker degradation and Maillard reactions and their formation are affected by temperature used for roasting. Roasting at
higher temperatures resulted in the strong aroma. On the other hand, lower temperatures enhanced the therapeutic quality (α- and γ-tocopherol and carotenoids profile)
of oils. Siegmund and Murkovic (2004) noted that in order to derive typical nutty
roasted aroma of pumpkin seed oil, prior roasting at a temperature of at least 90
C is
essential. For commercial production of oil, seeds are roasted up to 130
C.
Murkovic et al. (2004) demonstrated an increase in total sterol content in pumpkin
seed after roasting from 1710 to 1930 mg/kg. Van Hoed et al. (2017) suggested that
roasting of seeds prior to oil extraction not only enhanced the oil appearance and
flavor but also resulted in higher tocopherol and phenolic compounds without
significant formation of polycyclic aromatic hydrocarbons (PAH).
The germination of pumpkin seeds resulted in elevated moisture content, crude
ether extract, crude protein, and total ash contents by 0.05, 0.37, 0.78, and 0.18 folds,
respectively. It also resulted in increased crude fiber content, mineral content
specifically iron, zinc, and manganese. Among vitamins, germination resulted in a
marked increase in β-carotene and riboflavin (vitamin B 2 ) contents (Moustafa 2013).
The effects of variation in particle size, meal to solvent ratio, and contact time on oil
extraction method using n-hexane were studied using response surface methodology. The oil yield negatively correlated with particle size. The optimum yield of
422 g/kg was obtained at 0 h contact time, with particle size of 0.59 mm and
pumpkin seed meal to solvent ratio of 1:20 (w/v). A short heat treatment at 60
C
for 10 min reduced oil extraction time and saved energy as well as operation cost
without affecting oil quality. Fatty acid composition of extracted pumpkin seed oil
was found to be 755 g/kg of unsaturated fatty acids with 431 g/kg of linoleic acid and
324 g/kg of oleic acid. With its high linoleic-oleic acids oil, pumpkin seed oil can be
a good alternative to other edible oils like corn, sesame, sunflower, soybean, or
cotton (Rodríguez-Miranda et al. 2013).
In a study conducted by Vujasinovic et al. (2012) on chemical composition and
oxidative stability of the extracted oil, de-hulled pumpkin seeds post roasting with
variation in time (30 and 60 min) and temperatures (90–130
C) before oil extraction
resulted in enhanced concentrations of phospholipids (from 0.005 to 0.463%), total
phenolic compounds (from 4.63 to 19.60 mg/kg), and total tocopherols (from 265.79
to 350.98 mg/kg) in oil. Although the presence of these functional compounds
improved the oxidative stability of the oil, it lowered the quality of oil owing to
484
S. Adsul and V. Madkaikar
whereas at low temperatures aldehydes and alcohols were observed. Pyrazines
formed during roasting are thought to be responsible for the aroma which differs
from fresh to roasted depending on the degree of roasting (Potočnik and Košir 2016).
Procida et al. (2012) conducted a study to analyze the fatty acid, carotenoid namely
zeaxanthine, lutein, α- and γ-tocopherol concentrations in commercially available
pumpkin seed oil samples and to determine the effect of roasting prior to oil pressing
on volatile fractions. The study showed that the aroma of the commercial oils was in
proportion to the thermal treatment. Also, the volatile compounds formed during
chemical reactions from lipid peroxidation, Strecker degradation and Maillard reactions and their formation are affected by temperature used for roasting. Roasting at
higher temperatures resulted in the strong aroma. On the other hand, lower temperatures enhanced the therapeutic quality (α- and γ-tocopherol and carotenoids profile)
of oils. Siegmund and Murkovic (2004) noted that in order to derive typical nutty
roasted aroma of pumpkin seed oil, prior roasting at a temperature of at least 90
C is
essential. For commercial production of oil, seeds are roasted up to 130
C.
Murkovic et al. (2004) demonstrated an increase in total sterol content in pumpkin
seed after roasting from 1710 to 1930 mg/kg. Van Hoed et al. (2017) suggested that
roasting of seeds prior to oil extraction not only enhanced the oil appearance and
flavor but also resulted in higher tocopherol and phenolic compounds without
significant formation of polycyclic aromatic hydrocarbons (PAH).
The germination of pumpkin seeds resulted in elevated moisture content, crude
ether extract, crude protein, and total ash contents by 0.05, 0.37, 0.78, and 0.18 folds,
respectively. It also resulted in increased crude fiber content, mineral content
specifically iron, zinc, and manganese. Among vitamins, germination resulted in a
marked increase in β-carotene and riboflavin (vitamin B 2 ) contents (Moustafa 2013).
The effects of variation in particle size, meal to solvent ratio, and contact time on oil
extraction method using n-hexane were studied using response surface methodology. The oil yield negatively correlated with particle size. The optimum yield of
422 g/kg was obtained at 0 h contact time, with particle size of 0.59 mm and
pumpkin seed meal to solvent ratio of 1:20 (w/v). A short heat treatment at 60
C
for 10 min reduced oil extraction time and saved energy as well as operation cost
without affecting oil quality. Fatty acid composition of extracted pumpkin seed oil
was found to be 755 g/kg of unsaturated fatty acids with 431 g/kg of linoleic acid and
324 g/kg of oleic acid. With its high linoleic-oleic acids oil, pumpkin seed oil can be
a good alternative to other edible oils like corn, sesame, sunflower, soybean, or
cotton (Rodríguez-Miranda et al. 2013).
In a study conducted by Vujasinovic et al. (2012) on chemical composition and
oxidative stability of the extracted oil, de-hulled pumpkin seeds post roasting with
variation in time (30 and 60 min) and temperatures (90–130
C) before oil extraction
resulted in enhanced concentrations of phospholipids (from 0.005 to 0.463%), total
phenolic compounds (from 4.63 to 19.60 mg/kg), and total tocopherols (from 265.79
to 350.98 mg/kg) in oil. Although the presence of these functional compounds
improved the oxidative stability of the oil, it lowered the quality of oil owing to
484
S. Adsul and V. Madkaikar