Lipids characterization of ultrasound and microwave processed germinated sorghum
Lipids in Health and Diseasevolume 16, Article number: 125 (2017)
Cereal crops and oilseeds provide diverse pool of fatty acids with characteristic properties. Sorghum (Sorghum bicolor (L.) Moench) provides the staple food with serving as main source of energy and protein. Germination of sorghum generally increases the nutritive value of seeds and the effects of germination on lipids composition of seeds vary greatly with processing conditions. Therefore, the current study was conducted to compare the effect of emerging processing techniques such as ultrasound (US) and microwave (MW) on fatty acids composition and oil yield of sorghum seeds before and after germination.
Initially sorghum grains were soaked with 5% NaOCl (sodium hypochlorite) for surface sterilization. Afterwards, grains were soaked in excess water for 22 h at room temperature and were divided into four portions. The first portion (100 g grains) was subjected to germination without applying any microwave and ultrasonic treatment (T0). Second portion was further divided into four groups (T1, T2, T3, T4) (100 g of each group) and grains were subjected to ultrasonic treatments using two different ultrasonic intensities (US1: 40%; US2: 60%) within range of 0–100% and with two different time durations (tUS1: 5 min; tUS2: 10 min) at constant temperature. Third portion was also divided into four groups (T1, T2, T3, T4) (100 g of each group) and exposed to microwave treatments at two different power levels (MW1: 450 watt; MW2: 700 watt) within the range of 100-900 W for two different time durations (tMW1: 15 s; tMW2: 30s). Similarly, fourth portion was divided into four groups (T1, T2, T3, T4) (100 g of each group). Each group was exposed to both MW (MW1, MW2) (100–900 watt power) & US (US1, US2) (0–100% intensity) treatments at two different time levels (tUS, tMW). Then, germination was carried out and pre-treated raw and pre-treated germinated sorghum grains were analyzed for total oil yield, fatty acid composition and unsaturated fatty acids (Un-SFA)/saturated fatty acids (SFA) ratio by gas chromatography.
The results revealed that oil yield in sorghum before and after germination ranged from 6.55 to 7.84% and 6.28 to 7.57%, respectively. All the microwave and ultrasound processed samples showed significant difference in oil yield than the raw sorghum grains. The highest tested yield was 7.84 ± 0.31% when combination of microwave power (700 W) and ultrasound intensity (60%) was applied for 30s and 10 min, respectively. The results further demonstrate that the raw sorghum contained palmitic (13.73 ± 0.10%), palmitoleic (0.43 ± 0.02%), stearic (1.07 ± 0.04%), oleic (37.15 ± 0.10%), linoleic (43.33 ± 0.21%), linolenic (1.55 ± 0.04%), arachidic acid (0.13 ± 0.01%) and eicosenoic acid (0.37 ± 0.02%), respectively. The highest fatty acid percentage for palmitic, stearic and arachidic acid was 13.75 ± 0.07%, 1.11 ± 0.09% and 0.15 ± 0.03% at 60% US intensity for 10 min (T4), respectively. Maximum amount observed was 1.60 ± 0.09% of linolenic acid while amount of eicosenoic acid decreased from 0.37 ± 0.02% to 0.31 ± 0.01% after processing. In case of applying combination of microwave and sonication treatments, the change in eicosenoic acid increased from 0.35 ± 0.02% to 0.40 ± 0.04% while there was no significant change in other fatty acids. The ungerminated sorghum oil possessed 14.93–15.05% and 82.83–83.12% of SFA and Un-SFA, respectively. After germination, percentage of saturated fatty acids increased (16.4–16.55%) while decreased for unsaturated fatty acids (80.13–80.56%) were noted.
The results of the present study conclude that the yield of oil from sorghum grains increased by emerging processing. Fatty acid analysis of sorghum oil suggested that pre-treatment strategies will not affect the quality of the oil with respect to essential fatty acids content. Overall, the composition of saturated fatty acid in germinated grain is improved than ungerminated grains after processing.
Lipids as constituent of diet and may perform essential role regarding human health and disease prevention . They perform a variety of functions in a biological system as source of energy, essential fatty acids, sterols, structural components of membranes, transport medium of metabolic fuel, provide protective covering and carriers of lipophilic vitamins. Dietary lipids perform regulatory actions in nutrient metabolism and cell functions through controlling gene expression . Such regulatory lipids have been categorized as “functional lipids” including omega-3 and omega-6 fatty acids, conjugated linoleic acids, medium chain triglycerides and phytosterols. These lipids have many beneficial effects on human health such as in obesity, bone health, managing depression, blood pressure and cardiovascular health .
Cereal grains such as wheat, rice, maize, sorghum, millet, barley and rye in their natural form (as whole grain) are rich source of vitamins, minerals, carbohydrates, fats, oils and protein . Whole grain cereals containing nutrients and bioactive substances have health-promoting effects and the evidence for this association is largely supported by observational studies . The consumption of three or more servings of whole grains is associated with a positive impact on body mass index (BMI), abdominal obesity, cardiovascular disease risk reduction and glucose homeostasis . For centuries, germination process has been used for the purpose to soften the grain structure, improvement in nutritional value, anti-nutritional compounds reduction and enhancement in functionality of seed components [6, 7]. Seed germination causes different biochemical activities thus resulting in chemical composition changes . In the last decades, experts dealing with the healthy nutrition turned their attention towards the determination of the biological value of the nutritional sprouts . The improved food value of sprouting grains has been used for human consumption in Asian countries . Besides the nutrients, sprouts are also considered as the source of phytochemicals, vitamins, minerals, amino acids and enzymes for contribution in improved human health .
To improve bioevaluation and bioavailability performance, seed pretreatments including physical and chemical treatments are widely used. Physical treatments such as irradiation and electrical are known to improve seed performance and germination . During germination, lipids, carbohydrates and proteins within the seed are broken down into essential compounds while some nutrients also transform to bioactive components . However, among the different emerging novel techniques of pre-treatment gaining interest such as ultrasound (US) and microwave (MW) assisted processes are playing the leading role. The use of US and MW assisted process reduces energy consumption and also favors safe, robust and controlled processes . Therefore, the main mandate of the research was to determine the effect of US and MW processing conditions on fatty acids composition and oil yield of sorghum seeds before and after germination.
Sorghum (Sorghum bicolor (L.) Moench) grains selected for this study were purchased from a local grain market of Faisalabad (Pakistan). Sorghum grains were cleaned to remove stones, dust glumes, stalks, light materials, broken, undersized and immature grains. Cleaning was done by hand sorting and winnowing. Sorted and cleaned grains were kept in high density polyethylene to avoid moisture uptake and contamination before use.
Grains were soaked with 5% NaOCl (sodium hypochlorite) for surface sterilization upto 5 min to avoid fungal invasion, followed by washing with distilled water until they reached neutral pH . Afterwards, grains were soaked in excess water for 22 h at room temperature. The steeping water was drained off and the soaked sorghum grains were washed twice using distilled water. The soaked sorghum grains were divided into four portions.
The first portion (100 g grains) was subjected to germination without applying any microwave and ultrasonic treatment (served as control: T0).
Ultrasonic (US) treatment
Second portion was further divided into four groups (T1, T2, T3, T4) (100 g of each group) and grains were subjected to ultrasonic treatments using two different ultrasonic intensities (US1: 40%; US2: 60%) within range of 0–100% and with two different time durations (tUS1: 5 min; tUS2: 10 min) at constant temperature . All ultrasonic treatments were carried out through ultrasonic processor of SONICS & MATERIALS. INC (model: VCX750) having power of 750 W, frequency 20 kHz and volts 230 VAC ~ 50/60 Hz NOM.
Microwave (MW) treatment
Third portion was also divided into four groups (T1, T2, T3, T4) (100 g of each group) and exposed to microwave treatments at two different power levels (MW1: 450 watt; MW2: 700 watt) within the range of 100-900 W for two different time durations (tMW1: 15 s; tMW2: 30s) . All microwave treatments were carried out with HOMAGE microwave oven (model: HDSO234S) having capacity of 23 L with rated voltage of 230 V~, rated frequency 50 Hz, rated input 1250 W, rated output 800 W and microwave frequency of 2450 MHz.
US & MW treatment
Similarly fourth portion was also divided into four groups (T1, T2, T3, T4) (100 g of each group). Each group was exposed to both MW (MW1, MW2) (100-900 W power) & US (US1, US2) (0–100% intensity) treatments at two different time levels (tUS, tMW).
The detailed treatment plan has been presented in Table 1.
Germination and fat extraction
To conduct germination all the untreated (control sample) and treated grains (100 seeds of each group) were subjected to germination. Grains were placed on moist paper towel sheet and covered with another sheet of paper towel. The germination trays were placed in an incubator at 25 ± 2 °C, germinated for 48 h and watered 2–3 times a day to enhance the germination process . The seed was considered to have germinated when both the plumule and radicle had emerged >0.5 cm .
After germination, raw seed, control germinated sample and all treated samples were washed using running distilled water and dried in a drying oven at 55 °C for 24 h then pulverized into a fine powder by using a stainless steel blender. The oil was removed from the sample using a Soxhlet apparatus (hexane 8 h). Two different treatments were used to extract the fat: in the first, the fat was extracted directly from the powder, while in the second the powder was hydrolyzed using an aqueous solution of HCL 6 N in reflux during 8 h before the extraction with the hexane . The oil samples were stored at 4 °C in an amber bottle. Percentage of seed oil yield was calculated as follows.
Yield of seed extract (%) = (Oil extract from seeds (g) / Initial weight of seeds (g)) × 100.
Total fatty acid analysis
The fatty acids profile of extracted oil samples was determined by the method Ce 1f–96 given in AOCS . The oil sample (50 μL) was methyated in the presence of 4 mL KOH (1 M) at room temperature for 1 h in order to convert fatty acids into their respective methyl esters. The resultant fatty acid methyl esters (FAMEs) were extracted with GC grade n–hexane and analyzed by Gas Chromatograph apparatus equipped with an auto sampler, flame–ionization detector (FID) and supelco wax column. The samples (1 μL) were injected with Helium (1 mL/min) as a carrier gas onto the column, which was programmed for operating conditions such as column oven temperature 160 °C at 0 min with subsequent increase of 3 °C/min until 180 °C. The column oven temperature was increased from 180 °C to 220 °C at 1 °C/min and was held for 7.5 min at 220 °C. Split ratio was 50% with injector 240 °C and detector 250 °C temperatures. The peak areas and total fatty acids composition were calculated for each sample by retention time using Varian Chem Station software. The standards of fatty acids methyl esters purchased from Sigma-Aldrich were also run under the same conditions for comparison with experimental samples.
The data of oil yield and fatty acids composition obtained for each treatment was subjected to statistical analysis to determine the level of significance by using the software package (Statistic 8.1) according to the method described . The average of the three runs was reported as the measured value with standard deviation. The Duncan’s multiple range (DMR) test was used to estimate the level of significance that existed between the mean values at a probability level of 5%.
The average oil content in raw sorghum was found 6.55 ± 0.25%. The oil extraction yield before and after germination by applying different processing pre-treatments have been presented in Table 2. It was found that oil extraction yield was increased slightly when microwave pretreatment power level and time was increased. The optimum condition for microwave pretreatment was 450 W (T3) and 700 W (T4) which resulted in the highest oil yield 7.54 ± 0.31% and 7.79 ± 0.32%, respectively (p ≤ 0.05). Ultrasonic intensity 40% (T3) and 60% (T4) showed highest oil yield 7.39 ± 0.21% and 7.58 ± 0.28% for samples, respectively (p ≤ 0.05). Both intensity and pretreatment time had a positive effect on extraction oil yield from sorghum grains. The combination of microwave and ultrasound pretreatments showed significant difference in oil yield than the raw sorghum grains. The highest oil yield 7.84 ± 0.31% was observed when combination of microwave power (700 W) and ultrasound intensity (60%) was applied for 30s and 10 min, respectively (p ≤ 0.05).
The raw sorghum contained palmitic (13.73 ± 0.10%), stearic (1.07 ± 0.04%) and arachidic acid (0.13 ± 0.01%) (Table 3). The difference in the fatty acid composition of sorghum oil was observed between an untreated sample and a MW-treated sample. Palmitic, stearic and arachidic acids were found 13.76 ± 0.08%, 1.11 ± 0.11% and 0.15 ± 0.03% for MW pretreatment seeds (T4), respectively (p ≤ 0.05). Similarly, the ultrasonic intensity and pretreatment time also showed effect on the fatty acid percentage. The highest fatty acid % for palmitic, stearic and arachidic acid was 13.75 ± 0.07%, 1.11 ± 0.09% and 0.15 ± 0.03% at 60% US intensity for 10 min (T4), respectively (p ≤ 0.05). The increase in pretreatment time improved fatty acid composition, however, pretreatment time of 5 min did not significantly affect. The change of 1.13 ± 0.10% in stearic acid was observed in case of applying combination of microwave and sonication treatments while there was no significant change in palmitic and arachidic acid. The result showed that the composition of saturated fatty acid in germinated grain was improved than ungerminated grains. The germinated grains (T4) showed high results of palmitic, stearic and arachidic acids. For the saturated fatty acids (SFA), palmitic acid was the most dominant fatty acids (14.56 ± 0.12%), while arachidic acid was the least (0.21 ± 0.01%) (p ≤ 0.05).
Table 4 presents sorghum unsaturated fatty acid before and after germination by applying different pretreatments. The results indicated that raw sorghum contained palmitoleic (0.43 ± 0.02%), oleic (37.15 ± 0.10%), linoleic (43.33 ± 0.21%), linolenic (1.55 ± 0.04%) and eicosenoic acid (0.37 ± 0.02%), respectively. Fatty acid compositions of oils did not change much with microwave and ultrasound treatment. The results show that the major fatty acids in sorghum seed oils were linoleic acid (43.53 ± 0.30%) and oleic acid (37.17 ± 0.15%) for microwave treatments, respectively. The ultrasound processed sorghum samples contained maximum amount of linolenic acid 1.60 ± 0.09% while amount of eicosenoic acid decreased from 0.37 ± 0.02% to 0.31 ± 0.01%, respectively (p ≤ 0.05). The eicosenoic acid increased from 0.35 ± 0.02% to 0.40 ± 0.04% as a result of applying microwave and sonication combined treatments while there was no significant change in other fatty acids (p ≥ 0.05). The germination caused marked changes in the percentage of palmitoleic acid (0.49 ± 0.05%), linolenic acid (1.96 ± 0.12%) and eicosenoic acid (0.39 ± 0.04%), respectively (Table 4). While the maximum decrease in unsaturated fatty acid was observed in oleic acid (34.04 ± 0.10%) (p ≤ 0.05) which may be due to its decomposition by the lipolytic enzymes.
Table 5 shows percentage of saturated fatty acids (SFA), unsaturated fatty acids (Un-SFA) and Un-SFA/SFA ratio before and after germination by applying different pre-treatments. The results indicated that ungerminated sorghum oil contained 14.93–15.05% and 82.83–83.12% of SFA and Un-SFA, respectively. After germination, the percentage of saturated fatty acids increased 16.4–16.55% while decreased for unsaturated fatty acids 80.13–80.56% was observed (p ≤ 0.05).
Oils contents of sorghum grains before and after germination
The results of oil extraction yield are in agreement with previous findings [23,24,25]. By using microwave radiation in oil seeds, a higher extraction yield and an increase in mass transfer coefficients can be obtained because the cell membrane is more severely ruptured. Apart from this, permanent pores are generated as accordingly and this enables the oil to move through permeable cell walls . Similarly, different research studies found increased in oil yield with high ultrasound amplitude level [27, 28]. This increase in yield for ultrasound treatment has been proposed due to the effect of ultrasonic cavitation. The physical effects of cavitation immediately disrupt intact biological cells in the hot spots by rupturing biological membranes and cell walls. Thus, cellular material pours out into the liquid medium made up of the solvent and lipids are selectively dissolved in it. This process forms the basis for ultrasound-assisted solvent extraction and is responsible for the much higher oil yields from ultrasonic treatment in comparison with other methods [29, 30]. The combination of ultrasound pretreatment with other physical methods could weaken the particle surface bonds and enhance the extraction yield effectively . In the present study, germination significantly decreased crude oil content of raw and pretreated sorghum flours, which was in agreement with results of previous investigation [18, 32, 33]. The reduction may be due to the fact that biochemical and physiological changes occurred during germination and such changes required energy to proceed and therefore part of the seed oil was utilized for the production of this energy. The observed decrease in fat content of sorghum flour during germination might be attributed to the increased activities of the lipolytic enzymes during germination, which hydrolyze fats to fatty acids and glycerol [18, 33]. From a nutritional point of view, food-grade sorghum flour turns out to be a very interesting product. In fact, its nutritional value is comparable to those belonging to the ordinary flours obtained from the noble cereals [34, 35].
Sorghum saturated fatty acids (SFA) before and after germination
The fatty acid composition of sorghum seed is very similar to previous reported composition [36, 37]. Yoshida et al. , Anjum et al.  and Yoshida et al.  studied the effect of microwave treatment on peanut seeds (Arachis hypogaea L.), sunflower seed (Heliantus annuus L.) and pumpkin seeds (Cucurbita spp.), respectively. These authors reported a change in the fatty acid composition of vegetable oils through the effect of microwave treatment. Changes in the fatty acid composition after MW pretreatment of oilseeds have been reported by Yoshida et al. . The findings of US treatments were in agreement with those reported by Luque–Garcia and Luque de Castro . The slight increase might be due to non-conversion of free fatty acids to carbohydrates which may lead to increase in fat composition during germination . The increased intake of saturated fatty acids leads towards the risks of cardiovascular diseases, cancer and autoimmune disorders . Palmitic acid and stearic acids are some of the main fatty acids present in animals, vegetables and human milk fats. Several controversies are there about health and adverse impact of palmitic and stearic acid on human health, particularly about role of palmitic acid in cardiovascular disease and carcinogenicity [45, 46].
Sorghum unsaturated fatty acid (un-SFA) before and after germination
The results for unsaturated fatty acids present in sorghum grains are well correlated with previous investigations [36, 37]. Seed oils undergo changes in terms of chemical and physical properties when they interact with the food or the atmosphere. The fatty acid composition of oil can be an indicator of its stability, physical properties and nutritional value. Some food processing techniques can affect fatty acid composition of oils when hardly subjected to successive heating [42, 47, 48]. Cravotto et al.  reported the non-significant changes in polyunsaturated fatty acids of seaweed oil obtained under conventional and ultrasonic conditions. Kang et al.  mentioned that oleic acid was decreased by 50%, whereas those of linoleic and linolenic acid were increased by 1.3 and 5.4 times, respectively after 7 days of germination. Hahm et al.  reported the germinated derooted sesame rich in linolenic acid. Some studies suggested that linolenic acid intakes reduce the risk of cardiovascular diseases [52, 53]. An interaction between dietary linolenic acid intake and cardiovascular health in humans was reviewed [54, 55].
Percentage of saturated fatty acids (SFA), unsaturated fatty acids (un-SFA) and un-SFA/SFA ratio
The polyunsaturated fatty acids in most of sorghum varieties were found higher than monounsaturated fatty acids . The white sorghum oil contained 12.40% total saturated fatty acid and 87.60% total unsaturated fatty acid, respectively . The unsaturated fatty acids level of sorghum decreased on germination. The observed decrease might be due to the increased activities of the lipolytic enzymes during germination, which hydrolyze oils to fatty acids and glycerol . The simpler products can be used for synthesis of carbohydrate and protein or as a source of energy for developing embryo. Similar observation was made by other researchers . Oils being source of lipids, are of more nutritional value if they have more unsaturated to saturated fatty acid ratio .
Lipids composition due to their pharmacological significance has caught the attention of both consumer and industries. The presence of all saturated and unsaturated fatty acids essential for human health in sorghum oil could be alternative source of edible oil. It can be concluded that the germination of sorghum grains caused marked reduction in oil content. Moreover, also showed a decrease in total unsaturated fatty acids while the total saturated fatty acids increased by germination of seeds. Fatty acid analysis of sorghum oil suggested that pre-treatment strategies will not affect the quality of the oil with respect to essential fatty acid content. Every pre-treatment has some positive and negative impact on the quality and character of the extracted oils. Thus, selection of appropriate pre-treatment strategies will help to achieve enhanced seed oil with desired quality. The results of present study suggested that combination of microwave and ultrasonic treatment was best method for extracting high quality sorghum oil.
Alabdulkarim B, Bakeet ZAN, Arzoo S. Role of some functional lipids in preventing diseases and promoting health. J King Saud Univ Sci. 2012;24:319–29.
Nagao K, Yanagita T. Bioactive lipids in metabolic syndrome. Prog Lipid Res. 2008;47:127–46.
Sarwar MH, Sarwar MF, Sarwar M, Qadri NA, Moghal S. The importance of cereals (Poaceae: Gramineae) nutrition in human health: a review. J Cereals Oilseeds. 2013;4:32–5. doi:10.5897/JCO12.023.
Seal CJ, Brownlee IA. Whole grains and health, evidence from observational and intervention studies. Cereal Chem. 2010;87:167–74.
Jonnalagadda SS, Harnack L, Liu RH, McKeown N, Seal C, Liu S, et al. Putting the whole grain puzzle together: health benefits associated with whole grains-summary of American Society for Nutrition 2010 satellite symposium. J Nutr. 2011;141:1011S–22S.
Ijarotimi OS, Keshinro OO. Comparison between the amino acid, fatty acid, mineral and nutritional quality of raw, germinated and fermented African locust bean (Parkia biglobosa) flour. Acta Sci Pol Technol Aliment. 2012;11:151–65.
Suliburska J, Krejpcio Z, Lampart-Szczapa E, Wójciak RW. Effect of fermentation and extrusion on the release of selected minerals from lupine grain preparations. Acta Sci Pol Technol Aliment. 2009;8:87–96.
Moongngarm A, Saetung N. Studies on comparison of chemical compositions and bioactive compounds of germinated rough rice and brown rice Thailand. Food Chem. 2010;122:782–8.
Penas E, Gomez R, Frias J, Vidal-Valverde C. Application of high- pressure on alfalfa (Medigo sativa) and mung bean (Vigna radiata) seeds to enhance the microbiological safety of their sprouts. Food Control. 2008;19:698–705.
Resh HM. Hydroponic food production. 6th ed. Santa Barbara: Woodbridge Press; 2001. p. 567p.
Webb GP. Dietary supplements and functional foods. Oxford: Blackwell Publishing Ltd; 2006. p. 1–120.
Vashisth A, Nagarajan S. Exposure of seeds to static magnetic fields enhancesgermination and early growth characteristics in chickpea (Cicer arietinum L.). Bioelctromagnetics. 2008;29:571–8.
Suda CNK, Giorgini JF. Seed reserve composition and mobilization during germination and early seedling development of Euphorbia heterophylla. Braz J Plant Physiol. 2000;12:226–45.
Patil PD, Reddy H, Muppaneni T, Mannarswamy A, Schuab T, Holguin FO, et al. Power dissipation in microwave-enhanced in situ transesterification of algal biomass to biodiesel. Green Chem. 2012;14:809–18.
Hamidi R, Pirasteh-Anosheh H, Izadi M. Effect of seed halo-priming compared with hydro-priming on wheat germination and growth. Inter J Agron Plant Produc. 2013;4:1611–5.
Machikowa T, Kulrattanarak T, Wonprasaid S. Effects of ultrasonic treatment on germination of synthetic sunflower seeds. Int. J Biolog Veter Agric Food Engg. 2013;7(1):1–3.
Aladjadjiyan A. Effect of microwave irradiation on seeds of lentils (Lens culinaris, med.). Rom J Biophys. 2010;20:213–21.
Inyang CU, Zakari UM. Effect of germination and fermentation of pearl millet on proximate, chemical and sensory properties of instant “fura”- a Nigerian cereal food. Pak J Nutr. 2008;7:9–12.
Geressu K, Gezaghegne M. Response of some lowland growing sorghum (Sorghum bicolor L. Moench) accessions to salt stress during germination and seedling growth. Afr J Agric Res. 2008;3:044–8.
Hadbaoui Z, Djeridane A, Yousfi M, Saidi M, Nadjemi B. Fatty acid, tocopherol composition and the antioxidant activity of the lipid extract from the sorghum grains growing in Algeria. Mediterr J Nutr Metab. 2010;3:215–20.
AOCS. Official methods and recommended practices of AOCS. 5th ed. Champaign: American Oil Chemists Society; 1998.
Steel RGD, Torrie JH, Dickey D. Principles and procedures of statistics, a biometrical approach. 3rd ed. McGraw Hill Book Co Inc: USA; 1997.
Chung M, Kim E, Yeo M, Kim S, Seo M, Moon H. Antidiabetic effects of three Korean sorghum phenolic extracts in normal and streptozotocin-induced diabetic rats. Food Res Int. 2011;44:127–32.
Hamad RME. Preliminary studies on the popping characteristics of sorghum grains. M.Sc. Sudan: Thesis, Sudan Academy of Science, Al-Zaiem Al-Azhari Univiversity; 2007. p. p90.
Uquiche E, Jerez M, Ortiz J. Effect of pretreatment with microwaves on mechanical extraction yield and quality of vegetable oil from Chilean hazelnuts (Gevuina avellana Mol). Innov Food Sci Emerg Technol. 2008;9:495–500.
Azadmard-Damirchi S, Alirezalu K, Fathi AB. Microwave pretreatment of seeds to extract high quality vegetable oil. World Acad Sci Eng Technol. 2011;57:72–5.
Li H, Pordesimo L, Weiss J. High intensity ultrasound-assisted extraction of oil from soybeans. Food Res Int. 2004;37:731–8.
Hashemi SMB, Michiels J, Asadi Yousefabad S. H.; Hosseini, M. Kolkhoung (Pistacia khinjuk) kernel oil quality is affected by different parameters in pulsed ultrasound-assisted solvent extraction. Ind Crop Prod. 2015;70:28–33.
Feng H, Yang W, Hielscher T. Power ultrasound. Food Sci Technol Int. 2008;14:433–6.
Wang L, Weller CL. Recent advances in extraction of nutraceuticals from plants. Trends Food Sci Tech. 2006;17:300–12.
Arabani AA, Hosseini F, Abbaspour F, Anarjan N. The effects of ultrasound pretreatment processes on oil extraction from tomato wastes. Int J Biosci. 2015;4:8–15. ISSN: 2220-6655 (Print), 2222-5234 (Online)
Okrah SG. Screening of six local sorghum varieties for their malting and brewing qualities. MSc. Ghana: Thesis, Kwame Nkrumah University Science and Technology; 2008. p. 87p.
Kikafunda JK, Abenakyo L, Lukwago FB. Nutritional and sensory properties of high energy/nutrient dense composite flour porridges from germinated maize and roasted beans for child-weaning in developing countries: a case for Uganda. Ecol Food Nutr. 2006;45:279–94.
Dicko MH, Gruppen H, Traoré AS, Voragen AGJ, van Barkel WJH. Sorghum grain as human food in Africa: relevance of content of starch and amylase activities. African J Biotechnol. 2006;5:384–95.
Taylor JRN, Schober TJ, Bean SR. Novel food and non-food uses for sorghum and millets. J Cereal Sci. 2006;44:252–71.
Mehmood S, Orhan I, Ahsan Z, Aslan S, Gulfraz M. Fatty acid composition of seed oil of different Sorghum bicolor varieties. Food Chem. 2008;109:855–9.
Pontieri P, Di Fiore R, Troisi J, Bean SR, Roemer E, Okot J, et al. Chemical composition and fatty acid content of white food sorghums grown in different environments. Maydica. 2011;56:1–7.
Yoshida H, Hirakawa Y, Tomiyama Y, Nagamizua T, Mizushina Y. Fatty acid distributions of triacylglycerols and phospholipids in peanut seeds (Arachis hypogaea L.) following microwave treatment. J Food Comp Anal. 2005;18:3–14.
Anjum F, Anwar F, Jamil A, Iqbal M. Microwave roasting effects on the physico-chemical composition and oxidative stability of sunflower seed oil. J Am Oil Chem Soc. 2006;83:777–84.
Yoshida H, Tomiyama Y, Hirakawa Y, Mizushina Y. Microwave roasting effects on the oxidative stability of oils and molecular species of triacylglycerols in the kernels of pumpkin (Cucurbita spp.) seeds. J Food Comp Anal. 2006;19:330–9.
Yoshida H, Hirakawa Y, Tomiyama Y, Mizushina Y. Effects of microwave treatment on the oxidative stability of peanut (Arachis hypogaea) oils and the molecular species of their triacylglycerols. Eur J Lipid Sci Technol. 2003;105:351–8.
Luque-Garcia JL, Luque De Castro MD. Ultrasound-assisted Soxhlet extraction, an expeditive approach for solid sample treatment, application to theextraction of total fat from oleaginous seeds. J Chromatogr A. 2004;1034:237–42.
Afam-Anene OC, Onuoha LN. Nutritional and functional properties of sesame. Nig J Nutr Sci. 2006;27:16–21.
Iso H, Sato S, Umemura U, Kudo M, Koike K, Kitamura A, et al. Linoleic acid, other fatty acids, and the risk of stroke. Stroke. 2002;33:2086–93.
Hunter JE, Zhang J, Kris-Etherton PM. Cardiovascular disease risk of dietary stearic acid compared with trans, other saturated, and unsaturated fatty acids: a systematic review. Am J Clin Nutr. 2010;91:46–63.
Fattore E, Fanelli R. Palm oil and palmitic acid: a review on cardio-vascular effects and carcinogenicity. Int J Food Sci Nutr. 2013;64:648–59.
Lee Y, Oh S, Chang J, Kim I. Chemical composition and oxidative stability of saffl ower oil prepared from saffl ower seed roasted with different temperatures. Food Chem. 2004;84:1–6.
Hiromi Y, Yuki H, Yuka T, Tsugumi N, Yoshiyuki M. Fatty acids distributions of triacylglycerols and phospholipids in peanut seeds (Arachis hypogaea L.) following microwave treatment. J Food Comp Anal. 2005;18:3–14.
Cravotto G, Boffa L, Mantegna S, Perego P, Avogadro M, Cintas P. Improved extraction of vegetable oils under high-intensity ultrasound and/or microwaves. Ultrason Sonochem. 2008;15:898–902.
Kang IJ, Chung CK, Kim YS, Chun HN, Kim ER. Effect of germination on the nutritional value of buckwheat seed. IFT Annual Meeting Chicago, Session. 2003;451–6. (http://archive.is/JPOia).
Hahm TS, Park SJ, Martin LY. Effects of germination on chemical composition and functional properties of sesame (Sesamum indicum L.) seeds. Bioresour Technol. 2009;100:1643–7.
Harris WS. Cardiovascular risk and alpha-linolenic acid: can Costa Rica clarify. Circulation. 2008;118:323–4.
Wang C, Harris WS, Chung M, Lichtenstein AH, Balk EM, Kupelnick B, et al. ω-3 fatty acids from fish or fish-oil supplements, but not alpha-linolenic acid, benefit cardiovascular disease outcomes in primary- and secondary- prevention studies: a systematic review. Am J Clin Nutr. 2006;84:5–17.
Geleijnse JM, Goede JD, Brouwer IA. Alpha-Linolenic acid: is it essential to cardiovascular health. Curr Atheroscler Rep. 2010;12:359–67.
Djousse L, Pankow JS, Eckfeldt JH, Folsom AR, Hopkins PN, Province MA, et al. Relation between dietary linolenic acid and coronary artery disease in the National Heart, Lung, and Blood Institute family heart study. Am J Clin Nutr. 2001;74:612–9.
Hadbaoui Z, Djeridane A, Yousfi M, Saidi M, Nadjemi B. Fatty acid, tocopherol composition and the antioxidant activity of the lipid extract from the sorghum grains growing in Algeria. MJNM. 2010;3:215–20.
Raham EH, Aal MH. Changes in gross chemical composition with emphasis on lipid and protein fractions during germination of fenugreek seeds. Food Chem. 1986;22:193–8.
Nnam NM. Evaluation of effect of sprouting on the viscosity, proximate composition and mineral content of hungary rice, acha (Digiteria exilis) flours. Nig Food J. 2000;18:57–62.
Aronson WJ, Glaspy JA, Reddy ST, Reese D, Heber D, Bagga J. Modulation of omega-3/omega-6 polyunsaturated ratios with dietary fish oils in men with prostate cancer. Urology. 2001;58:283–8.
The authors are highly obliged to the Library Department, Government College University Faisalabad (GCUF) and IT Department, Higher Education Commission (HEC, Islamabad) for access to journals, books and valuable database.
The first author is grateful to Higher Education Commission (HEC, Islamabad), Pakistan for financial support to carry out the present research.
Availability of data and materials
The dataset supporting the conclusions of this article is included within the article.
SH conceptualized and performed the study. NA analyzed the data. MKK provided the technical assistance and guided in the data collection. MI helped for drafting the manuscript. “It’s also confirmed that all the authors read and approved the final manuscript”.
The authors declare that they have no competing interests.
Consent for publication
Ethics approval and consent to participate
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.