Nazanin Maryam Mohseni; Habibollah Mirzaee; Masoumeh Moghimi
Abstract
Introduction: Niger seed with scientific name of Guizotia abyssinica Cass from Asteraceae family is a dicotyledonous and one year plant that is one of the main and most important oil sources in Ethiopia and India. In different researches the amount of extracted oil from the seed of this plant has been ...
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Introduction: Niger seed with scientific name of Guizotia abyssinica Cass from Asteraceae family is a dicotyledonous and one year plant that is one of the main and most important oil sources in Ethiopia and India. In different researches the amount of extracted oil from the seed of this plant has been mentioned about 37 to 50 percent. The composition of fatty acid in this plant is similar to safflower and sunflower seed oil (of course with high percentage of Linoleic acid that may reach more than 85 percent). Generally, the mechanical press is one of the most popular methods for extracting oil from vegetable oil seeds all over the world. Increase in temperature will lead to more and faster extraction of oil from seeds and will increase the extraction efficiency. Microwave, is the non-ionized electromagnetic wave with frequency between 300 MHz to 300 GHz and are placed between the radio and infrared waves in the electromagnetic spectrum, consumers’ increasing demand for higher quality products and with minimized waste of nutrients in comparison with conventional thermal methods, caused an increase in use of non-thermal methods such as pulsed electric field methods. In current research it is tried to study the influence of pulsed electric fields and microwave pre-treatments on some characteristics of oil and meals obtained from Niger seed. Materials and methods: To perform this research, the Niger seeds (contain 40% oil) was prepared from local market of Fars Province (Iran). Then the external materials such as weed seeds, sand and stones were separated and removed manually and the seeds were treated with microwave pre-treatment with power of 900W and different procedure times (100 and 200 seconds), and pulsed electric field with two levels of electric field intensities of (250 and 500 kV/cm with 30 pulses). After performing these treatments, the seeds oil was extracted with screw press at the speed of 34 rpm then various experiments, such as the efficiency amount of oil extraction, refractive index, total phenolic compounds, oxidative stability, protein and ash of meals, were performed on the oil in a complete random model with three repetitions. Results and discussions: The comparing group mean test with Duncan’s method indicated that applying pulsed electric fields and microwave pre-treatments in lower times and intensities caused an increase in extraction efficiency. But with increase in the microwave time and also increase in the intensity of pulsed electric field, the efficiency of oil extraction was decreased in such a manner that when a pulsed electric field with intensity of 500 kV/m was used, the oil extraction had the lowest extraction efficiency. The increase of oil extraction efficiency using microwave can be related to more fracture or disintegration of cells which contain oil during treating with microwave. The reason for increase in the efficiency of oil extraction using the pulsed electric fields can be attributed to the electrical decomposition of cells and more permeability of them. A decrease in the oil extraction efficiency with excessive increase in the microwave time and intensity of electric field is probably attributed to more degradation of seeds internal structure and closure of oil outlet duct. Analysis of data obtained from oils refractive index indicated that the pre-treatment type didn’t have any significant influence on the oils refractive index (P>0.05) and the amount of refractive index was 1.478 for all of the measured samples (figure 2). Applying various pre-treatments, caused an increase in the amount of total phenol and oxidative stability of oils in the manner that the maximum amount of total phenol and oxidative stability was obtained from pulsed electric field pre-treatment with the intensity of 500 kV/m. The amount of tocopherol and antioxidant compounds can be the reason for this observation because of applying these pre-treatments. Variance analysis of data obtained from performing tests and experiments indicated that the influence of pre-treatment type on the amount of protein and meals ash was completely significant (P<0.01). Comparison of the means in data obtained from experiments showed that the maximum and minimum amount of protein and meals ash in the treated sample was obtained with 100 seconds microwave and the pulsed electric fields with 500 kV/m intensity, respectively, in other words, applying various treatments (in low times and electric field intensities of microwave and pulsed electric fields) in oil extraction led to an increase in the amount of protein and ash in comparison with non-treated sample and the reason of this fact can be attributed to the more extraction of oil from seeds and consequently an increase in the % protein and ash remained in the meals. Finally, the results of this research indicated that applying microwave (for 100 seconds) and pulsed electric field (with electric field intensity of 250 kV/m) can be very useful in extracting oil from Niger seed because of increase in the extraction efficiency and also increase of useful compounds in oil.
Hamid Bakhshabadi; Habibollah Mirzaee; Alireza Ghodsvali; Seyed Mahdi Jafari; Aman Mohammad Ziaiifar
Abstract
Introduction: Black Cumin seed (Nigella sativa L.) as one of the novel edible oil resources used commonly nowadays as seasoning in food product industries due to considerable medicinal properties and high nutritional impacts. Oil extraction by pressing method as an approach compared to other methods ...
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Introduction: Black Cumin seed (Nigella sativa L.) as one of the novel edible oil resources used commonly nowadays as seasoning in food product industries due to considerable medicinal properties and high nutritional impacts. Oil extraction by pressing method as an approach compared to other methods including solvent extraction is faster, safer and cheaper. In the oil extraction process, the preparation of the seeds is a substantial stage for obtaining oil with high quality and efficiency. Microwaves are electromagnetic waves that have a frequency ranged from 300 MHz to 300 GHz with corresponding wave lengths ranged from 1 mm to 1 m. On the other hand the artificial neural network as a powerful predictive tool in a wide scale of process parameters has been studied on an industrial scale in this research in order to achieve a simple, rapid, precise as well as effective model in the oil extraction of Nigella sativa L seed.
Materials and Methods: In the present study Black Cumin seeds after preparation including cleaning and passing resistance of the samples in front of air and moisture were stored in a plastic bag until the day of experiments. Then, they have been pre-treated with microwave within different processing times (90, 180 and 270 S) and powers (180, 540, and 900 W). Afterwards, seeds’ oil was extracted by screw rotational speed levels approach (11, 34 and 57 rpm). Different selected parameters including extraction efficiency, oil acidity value, color and oxidative stability were determined. To predict the alterations trend, the artificial neural network (ANN) design in MATLAB R2013a software was used.
Results and Discussion: According to MSE and R2 values obtained in this study, feed forward neural network with transfer function sigmoid hyperbolic tangent and Levenberg- Marquardt learning algorithm with topology of 3-10-5 (input layer with 3 neurons– a hidden layer with 10 neurons – output layer with 5 neurons) were selected as the optimal neural network with R2 more than 0.995 and MSE equal to 0.0005. Also, the results of the optimized and selected models were evaluated and these models with high correlation coefficients (over 0.949), were able to predict the changes' trend. According to the complexity and multiplicity of the effective factors in food industry processes and the results of this research, the neural network can be introduced as an acceptable model for modeling these processes. By determining the activation function in neural networks which was a function of sigmoid hyperbolic tangent in this study and also, with having the amounts of weight and bias, the connections created by the neuro-fuzzy model can be extracted. By defining this simple created mathematical equation, in computer software such as Excel, we can have a useful, simple and accurate program for predicting the desired parameters in the process of oil extraction by using microwave pre-treatment. Due to high accuracy of neural model we can trust the prediction of these models with high confidence, and this model can be used to optimize and control the process, which can lead to saving in energy and time, and on the other hand, can create a better final product.
Afsaneh Sadeghi; Ahmad Ghazanfari; Hassan Hashemipoor Rafsenjani; Hamidreza Akhavan
Abstract
Introduction: Moringa is a tree that grows in hot and humid regions and produces oil seeds that contain about 33% edible oil. The tree is native to the south-west regions of Asia and it is cultivated in Hormozgan and in Sistan and Bluchestan provinces of Iran. The oil extracted from these seeds is edible ...
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Introduction: Moringa is a tree that grows in hot and humid regions and produces oil seeds that contain about 33% edible oil. The tree is native to the south-west regions of Asia and it is cultivated in Hormozgan and in Sistan and Bluchestan provinces of Iran. The oil extracted from these seeds is edible and has some various industrial applications. The extracted oil usually contains considerable amount of dissolved impurities which must be removed prior to industrial usages. Major part of impurities is removed by settling or filtering process. The fine impurities are removed through a degumming process using water, acids or enzymes. The degumming process affects the physco-chemical characteristics of the oil. In this research, various physco-chemical and heating properties of Moringa oil was measured and the stability of the oil under elevated temperatures were investigated
Material and methods: The Moringa seeds were collected from the wild trees that grow in Hormazgan province. The seeds were manually cleaned and ground to mean diameter of less than 1 mm and then were placed in an oven at 65°C for 24 h to reduce their moisture. Samples of 50 g ground seeds were placed insoxhelt and n-hexane was used as the solvent. The oil extraction experiments were conducted at 60°C for 7 h retention time. The raw obtained oil was divided into two parts and one part was degummed. The degumming of the oil was performed by adding distilled water to it and raising the temperature to 80°C. Then, phosphoric acid was added to the mixture and stirred for 20 min at the same temperature and the mixture was centrifuged and the oil was separated from water and wax. Some characteristics of the raw and the degummed oils including: fatty acids, ion value, peroxide value, chemical, color, saponification value, ignition and clouding points, density and viscosity were measured and compared. The stabilities of the viscosity of the two oils were investigated under different temperatures ranging from 3 to 120°C. The oxidative stability of oils was determined against temperature, light and air exposure. In these experiments temperature ranged from 20 to 120°C, light and air exposure time were 10 days, each. High temperature stability of the oils was also verified using a Rancimat instrument.
Results and discussion: The results of fatty acids analysis indicated that the Moringa oil is generally unsaturated oil containing a total of 76% pulmonic and oleic acids. The major saturated oil content of Moringa oil was plasmatic acids which accounted for 14.3% of the total fatty acids. High amount of unsaturated acids indicates that this oil is good for cooking purposes. The degumming process caused a significant decrease in peroxide value, saponification number and total fatty acids but the viscosity and the pH of the oil increased which all indicates that the degummed oil should be more stable than the raw oil. All heating properties of the degummed oil such as melting, combustion, pour, and cloudy points of the degummed oil increased which indicates that the degummed oil is more suitable for heating foods. In investigating the stability of the oil, the viscosity of the Moringa oil was decreased as the temperature of the oil was increased however, the viscosity increased with the holding time. The increase of the viscosity was more significant at higher temperatures due to the oxidation and degradation of the oil. Generally, increase in the viscosity of the degummed oil occurred at with lower rates. The peroxide value of the raw and the degummed oil was increased as the temperature of them was increased. The increase had higher rates when temperature of the oil exceeded 60C. The peroxide value was also increased with the holding time. The change was not significant for the first four days but it rapidly increased after that. The peroxide value of the oil that kept away from the sunlight remained unchanged for the 10 days test period. The value of peroxide was also affected by aerating the oil. Degradation was initiated immediately as aeration was started but a steep increase was noticed after the second day. The highest peak was reached on the sixth days and after that the oil was completely degraded. A Racncimat test on the raw and degummed oil indicated that with increase in the oil temperature the stability of the oil decreased and when temperature was at 110°C the stability of the raw and the degummed oils were 19 and 31 hours. In general, all the tests indicted that the degummed Moringa oil had higher stability than the raw oil.
