Microwave pretreatment effects on the changes in seeds microstructure, chemical composition and oxidative stability of rapeseed oil

Oven-Roasting Effects the Fatty Acid Composition, Antioxidant Properties, and Oxidative Stability of Pomegranate (Punica granatum L.) Seed Oil

In this study, we investigated the effect of roasting conditions and time on the physicochemical properties of pomegranate seed oil. We analyzed the fatty acid, total phenolic, flavonoid, tocopherol, and phytosterol contents of pomegranate seed oil extracted under four conditions: raw, heated at 160°C for 15 min, heated at 160°C for 20 min, and heated at 180°C for 10 min, which included three that were well-established to enhance nutritional and flavor properties. Furthermore, the oxidative stability was evaluated based on the acid value, peroxide value, and induction period. Roasting significantly decreased the contents of punicic acid, polyunsaturated fatty acids, tocopherol, and phytosterol and the 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity (P<0.05) of the oil. Conversely, saturated fatty acids, monounsaturated fatty acids, acid value, peroxide value, total phenolic and flavonoid contents, and induction period were significantly increased (P<0.05). Our results suggest that the roasting conditions were nutritionally and oxidatively stable, thereby enhancing the roasting process and providing a database for essential roasting treatments for pomegranate seed oil.

Influence of microwave heating on bioactive properties, phenolic compounds and fatty acid profiles of pomegranate seed oil

In this study, the effects of different microwave powers on the bioactive properties, fatty acid and phenolic profiles of pomegranate seed oil were reported using various analytical methods, GC and HPLC. Antioxidant capacity and total phenolic values of pomegranate seed oils were established between 14.16% (control) and 19.18% (720 and 900 W) to 0.00 (900 W) and 3.61 mgGAE/100 g (control), respectively. The viscosity values of pomegranate seed oil increased with the heat treatment. But, the viscosity of the oils increased with the applied Watt increase. The p-coumaric acid amounts of the seed oils heated at 180, 720 and 900 W in the microwave were found to be statistically similar. In general, phenolic compounds of pomegranate seed oils did not show a constant increase or decrease depending on microwave power. The key fatty acid of pomegranate seed oil was punisic acid (30.49-36.10%). followed by linoleic acid (25.95-30.01%).

Innovative technologies to enhance oil recovery

The processes for extracting and refining edible oils are well-established in industry at different scales. However, these processing lines encounter inefficiencies and oil losses when recovering crude or refined oil. Palm oil and olive oil extraction methods are used mainly as a combination of physical, thermal, and centrifugal methods to recover crude oil, which results in oil losses in the olive pomace or in palm oil effluents. Seed oils generally require a seed steam conditioning, and cooking stage, followed by physical oil recovery through an inefficient expeller. Most of the crude oil remaining in the expeller cake is then recovered by hexane. Crude seed oil is further refined in stages that also undergo oil losses. This chapter provides an overview of innovative technologies using microwave, ultrasound, megasonic and pulsed electric field energies, which can be used in the above-mentioned crude and refined oil processes to improve oil recovery. This chapter describes traditional palm oil, olive oil, and seed oil processes, as well as the specific process interventions that have been tested with these technologies. The impact of such technology interventions on oil quality is also summarized.

Enzymatic Acylation of Flavonoids from Bamboo Leaves: Improved Lipophilicity and Antioxidant Activity for Oil-Based Foods

The goal of this study was to expand the applications of bamboo leaf flavonoids (BLFs) by improving their lipophilicity through enzymatic acylation with vinyl cinnamate. Characterization of the acylated BLFs using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, high-resolution electrospray ionization mass spectrometry, electrospray ionization with tandem mass spectrometry, and ¹H nuclear magnetic resonance spectroscopy indicated that acylation occurred at the C6-OH position of glucoside moieties. The highest degree of acylation (18.61%) was obtained by reacting BLFs with vinyl cinnamate (1:5, w/w) at 60 °C for 48 h. Acylation significantly improved the lipophilicity of BLFs and their capacity to inhibit lipid peroxidation, as evidenced by the reduced production of lipid hydroperoxides and malondialdehyde in rapeseed oil and rapeseed oil-in-water emulsions during storage at 37 °C for 15 days. The study findings provide important data that will enable the use of BLFs in lipid or lipophilic matrices, such as oil-based foods.

Effect of some Cultivation Factors and Extraction Methods on Terminalia Catappa L. Seed Oil

Terminalia catappa L. is a common tropic tree for shade and ornament in many countries. Recently, Terminalia catappa L. seed oil has been considered as a new oleaginous seed for dietary and biofuel production. In this study, ripe Terminalia catappa L. fruits originated in Vietnam were collected and seed oil extracted. In our experiment conditions, the effect of tree location, tree age, and annual harvest time on seed weight and seed oil content was investigated. As results, the seeds at the eastern site of the ground obtained not only the biggest size (3.607 g) but also contained the highest oil mass percentage (56.38%). The suitable annual harvesting time for the good seed quality was from March to April. In addition, the Terminalia catappa L. seeds for oil extraction began being harvested in the fourth year with 55.88% oil content compared to 55.99% of the five and six-year-old and trees. After seed drying, the seed oil was extracted by five different methods including cold screw pressing, hot screw pressing, hydraulic pressing, and solvent extracting, and combining method (cold screw pressing then solvent extraction of oil cake). Among the physical methods, cold screw pressing observed the highest oil yield of 77.32%, and the good oil quality was obtained with low free fatty acid (0.550% oleic acid), low acid value (1.080 mg KOH/g oil), and low peroxide value (1.240 meq O2/kg oil). However, the combination of cold screw pressing and cake oil extracting by solvent increased the oil yield by 14.61%. The saponification values fluctuated between 196 to 197 mg KOH/g oil, while the iodine values were in the range of 77.00 and 79.89 g I2/kg oil.

Simultaneous Analysis of Free/Combined Phytosterols in Rapeseed and Their Dynamic Changes during Microwave Pretreatment and Oil Processing

Here, a simple, efficient, and rapid solid phase extraction-gas chromatography (SPE–GC) method was developed for the simultaneous analysis of free/combined phytosterols in rapeseed and their dynamic changes during microwave pretreatment and oil processing. First, by comparing different methods for extracting free/combined phytosterols from rapeseed and rapeseed cake, the Folch method was considered to be the optimal method and was selected in subsequent experiments. Subsequently, the extraction method was validated by determining the recoveries of standards (brassinosterol, campesterol, β-sitosterol and cholesteryl oleate) spiked in rapeseed and rapeseed oil samples, and the recoveries were in the range from 82.7% to 104.5% and 83.8% to 116.3%, respectively. The established method was applied to study the dynamic changes of the form and content of phytosterols in rapeseed and its products (rapeseed oil and cake) during rapeseed microwave pretreatment and the oil production process. Additionally, the results showed that more than 55% of the free/combined phytosterols in rapeseed were transferred to rapeseed oil during the oil processing, and this proportion will increase after microwave pretreatment of rapeseed. This work will provide analytical methods and data support for a comprehensive understanding of phytosterols in rapeseed and its products during oil processing.

Effect of pretreatments of camellia seeds on the quality, phenolic profile, and antioxidant capacity of camellia oil

Camellia oil is one of the four major woody oils in the world and has high nutritional value due to its richness in monounsaturated fatty acids (MUFAs) and bioactive substances. In order to compare the effects of pretreatments of camellia seeds on the quality, phenolic profile, and antioxidant capacity of camellia oil, three different pretreatment methods, i.e., hot air (HA), steam (ST) and puffing (PU), were used to treat the seed powder in the present study. All three pretreatments changed the internal structure of the camellia seeds. The oil yield was increased after all three pretreatments, with the highest oil yield increased by PU pretreatment (Based on the oil yield, we screened out the best conditions of the three pretreatments, HA pretreatment is 60°C for 40 min, ST pretreatment is 100°C for 15 min, PU pretreatment is 800 rpm). The fatty acids (FAs) of the oil were relatively stable, with no significant changes after three pretreatments. However, all three pretreatments had a significant effect on the acid value (AV), peroxide value (PV), and benzo(a)pyrene (Ba P) of the camellia oil. The PU and HA pretreatments could increase the tocopherol content and the total sterols content in the camellia oil. The ST and PU pretreatments significantly increased the free phenolics (FP) content, all three pretreatments reduced the contents of conjugated phenolics (CP) and insoluble-bound phenolics (IBP) in the camellia oil. The IBP made the most significant contribution to the antioxidant capacities of camellia oil. ST and PU prtreatments increased the antioxidant capacities of the total phenolics in the camellia oil. Eight phenolics in FP, CP, and IBP were significantly correlated with the antioxidant capacities of camellia oil. The results of the present study could provide some theoretical guidance for the pretreatment of camellia seeds for higher oil yield, phenolic content and enhanced antioxidant capacities of camellia oil.

Characterizing the Bioactive Ingredients in Sesame Oil Affected by Multiple Roasting Methods

Roasting is an important step in sesame (Sesamum indicum L.) processing. The current research was undertaken to evaluate the oil content, fatty acid (FA) profiles, and physicochemical characteristics of oil recovered from sesame roasted by different methods (cooker oven, stovetop pan, microwave, and electric frying pan). Roasting sesame seeds changed their oil content according to the roasting method used, with content ranging from 49.83% in control to 59.85% in the roasting by microwave. In oils recovered from raw or roasted seeds, seven fatty acids were obtained through gas chromatography. Changes in the fatty acid profiles occurred in all the treatments, and the total unsaturated fatty acid content was higher than that of saturated fatty acids. The obtained peroxide number of sesame oils was inside the rate of 3.90 meq/kg oil for microwave treatment versus 1.59 meq/kg oil for unroasted. The highest acid value was with the stovetop pan treatment at 3.78 mg/g, followed by the microwave treatment at 3.24 mg/g; the oven treatment gave the lowest value at 1.66 mg/g. The lowest iodine value was observed with the electric frying pan treatment (102.30/100 g oil), and phytosterols were most abundant with the microwave treatment. Moreover, the phenolic and flavonoid contents and antioxidant activity were the highest with the microwave roasting. The FTIR spectrum illustrated slight differences in peaks intensity (1738, 1454, 1151, 710 cm⁻¹) between the roasting methods used. The finding of the current investigation of roasting methods was that the fatty acid profiles were across methods. As is clear from the obtained results, the microwave roasting treatment is the favoured roasting method for the healthiest sesame seed oil contents. Sesame seeds are considered a significant and abundant resource with numerous beneficial nutrients that positively affect human health.

Canolol and its derivatives: A novel bioactive with antioxidant and anticancer properties

The health and safety concerns associated with synthetic antioxidants has resulted in an urgent search for natural sources of antioxidants. Such antioxidants are not only convenient but may also have important therapeutic properties. Oilseed crops, for example, are rich in phenolic compounds some of which exhibit powerful antioxidant properties that have broad applications in both the food and feed industry. Often, the concentration of these phenolic compounds is affected by many processing conditions including temperature, pressure, pH, and extracting solvents. Hence it is important to optimize processing conditions to obtain maximum levels of those antioxidants with superior antioxidant activity. Oilseeds, such as canola and mustard, are rich sources of sinapates and kaempferol derivatives. When subjected to different processing conditions, including pressurized temperature, sinapates are converted to vinyl phenol derivatives, of which the major one is canolol. This chapter will focus on the nature of canolol and its applications in food and medicine.

Effect of Microwave Treatment on Adzuki Beans (Vigna angularis L.) under Dry State—Analyzing Microstructure, Water Absorption, and Antioxidant Properties

In this study, a microwave was used on adzuki beans (Arari and Geomguseul) without water, in order to investigate their changes in microstructure, water absorption, and antioxidative properties. As the microwave treatment time increased (2450 MHz, 0 to 60 s), the lightness, redness, and yellowness were reduced, and moisture content significantly decreased in both varieties. The microstructure space between the seed coat, cotyledon, and pores within the cotyledon were observed, due to the loss of moisture. Regardless of microwave treatment, the water absorption behavior of the adzuki beans was sigmoidal. However, the water absorption kinetics of Arari increased after microwave treatment, whereas with microwave-treated Geomguseul, the water absorption rate decreased, compared to the control, except for the sample treated for 30 s. During soaking, the water absorption and softening rates in the microwave-treated adzuki bean were twice as fast as the untreated beans. Antioxidant activity, total phenolic compounds, and total flavonoid compounds were greatly improved by microwave treatment. These results indicate that microwave treatment affects the color, hydration, and bioactive compounds, and it can be used as a pretreatment method before processing adzuki beans.

Oxidative Stability and Antioxidant Activity of Selected Cold-Pressed Oils and Oils Mixtures

The aim of the study was to analyse the chemical composition and oxidation stability of selected cold-pressed oils and oil mixtures. The oils were tested for their initial quality, fatty acid composition, total phenolic compounds, DPPH, and ABTS free radical scavenging activity. The Rancimat method was used to assess oxidative stability. The obtained results were subjected to principal component analysis (PCA) to determine the influence of selected chemical properties on the oxidative stability of the oil. It has been found that different factors of oil quality influence the stability of cold-pressed oils. The highest correlation coefficient was noted between the induction time, peroxide value, and TOTOX indicator (r = 0.89). Fatty acid composition, including the percentage of SFA, MUFA, PUFA, and the ability to scavenge ABTS captions radicals, did not significantly affect the oxidative stability of the oils. Black cumin seed oil was the most resistant to the oxidation processes in the Rancimat apparatus, mainly due to the high content of phenolic compounds (384.66 mg GAE/100 g). On the other hand, linseed oil and its mixtures were the least stable. Their fatty acid composition was dominated by a polyunsaturated α-linolenic fatty acid, significantly reducing the antioxidant resistance.

Using Box–Behnken Design Coupled with Response Surface Methodology for Optimizing Rapeseed Oil Expression Parameters under Heating and Freezing Conditions

The effect of heating and freezing pretreatments on rapeseed oil yield and the volume of oil energy under uniaxial compression loading was investigated. Four separate experiments were carried out to achieve the study objective. The first and second experiments were performed to determine the compression parameters (deformation, mass of oil, oil yield, oil expression efficiency, energy, volume of oil and volume of oil energy). The third and fourth experiments identified the optimal factors (heating temperatures: 40, 60 and 80 °C, freezing temperatures: −2, −22 and −36 °C, heating times: 15, 30 and 45 min and speeds: 5, 10 and 15 mm/min) using the Box–Behnken design via the response surface methodology where the oil yield and volume of oil energy were the main responses. The optimal operating factors for obtaining a volume of oil energy of 0.0443 kJ/mL were a heating temperature of 40 °C, heating time of 45 min and speed of 15 mm/min. The volume of oil energy of 0.169 kJ/mL was reached at the optimal conditions of a freezing temperature of −36 °C, freezing time of 37.5 min and speed of 15 mm/min. The regression model established was adequate for predicting the volume of oil energy only under heating conditions.

Influence of dry air and infrared pre-treatments on oxidative stability, Maillard reaction products and other chemical properties of linseed (Linum usitatissimum L.) oil

In this study, the influence of dry air and infrared pre-treatments on linseed oil (LO) yield, chemical properties, colour, pigment content, total phenolic content (TPC), Maillard reaction products (MRPs), fatty acid composition (FAC), radical scavenging activity (RSA), and oxidative stability index (OSI) were investigated. An increase in dry air and infrared roasting temperature had increased the LO yield, pigment content, a* value, TPC, RSA, OSI, and browning index (BI) while lowered the L* and b* values of LO. Higher OSI (2.24 h), chlorophylls (2.29 mg/kg), carotenoids (3.87 mg/kg), TPC (63.67 mg GAE/100 g), RSA (62.53%), BI (0.330), and MRPs (2.10 mg/kg) were detected in LO by dry air roasting at 180°C for 10 min. Dry air and infrared roasting had slightly affected the FAC of LO. Both dry air and infrared pre-treatments had influenced the LO quality characteristics. However, dry air roasting of linseed at 180°C for 10 min proved more effective in improving oxidative stability, antioxidant activity and other quality characteristics of LO.

SUPPLEMENTARY INFORMATION

The online version of this article at 10.1007/s13197-021-05023-6.

Effects of Radio Frequency Pretreatment on Quality of Tree Peony Seed Oils: Process Optimization and Comparison with Microwave and Roasting

In this study, we explored the technical parameters of tree peony seeds oil (TPSO) after their treatment with radio frequency (RF) at 0 °C-140 °C, and compared the results with microwave (MW) and roasted (RT) pretreatment in terms of their physicochemical properties, bioactivity (fatty acid tocopherols and phytosterols), volatile compounds and antioxidant activity of TPSO. RF (140 °C) pretreatment can effectively destroy the cell structure, substantially increasing oil yield by 15.23%. Tocopherols and phytosterols were enhanced in oil to 51.45 mg/kg and 341.35 mg/kg, respectively. In addition, antioxidant activities for 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric-reducing antioxidant power (FRAP) were significantly improved by 33.26 μmol TE/100 g and 65.84 μmol TE/100 g, respectively (p < 0.05). The induction period (IP) value increased by 4.04 times. These results are similar to those of the MW pretreatment. The contents of aromatic compounds were significantly increased, resulting in improved flavors and aromas (roasted, nutty), by RF, MW and RT pretreatments. The three pretreatments significantly enhanced the antioxidant capacities and oxidative stabilities (p < 0.05). The current findings reveal RF to be a potential pretreatment for application in the industrial production of TPSO.

Effect of oilseed roasting on the quality, flavor and safety of oil: A comprehensive review

Roasting is widely applied in oil processing and employs high temperatures (90-260 °C) to heat oilseeds evenly. Roasting improves the extraction yield of oil by the generation of pores in the oilseed cell walls, which facilitates the movement of oil from oilseed during subsequent extraction. It also affects the nutritional value and palatability of the prepared oil, which has attracted consumers' attention. An appropriate roasting process contributes to better extraction of bioactive compounds, particularly increasing the total polyphenol content in the oil. Correspondingly, extracted oil exhibits higher antioxidant capacity and oxidative stability after roasting the oilseeds due to better extraction of endogenous antioxidants and the generation of Maillard reaction products. Furthermore, roasting process is critical for the formation of aroma-active volatiles and the improvement of desired sensory characteristics, so it is indispensable for the production of fragrant oil. However, some harmful components are inevitably generated during roasting, including oxidation products, polycyclic aromatic hydrocarbons, and acrylamide. Monitoring and controlling the concentrations of harmful compounds in the oil during the roasting process is important. Therefore, this review updates how roasting affect the quality and safety of oils and provides useful insight into regulation of the roasting process based on bioactive compounds, sensory characteristics, and safety of oils. Further research is required to assess the nutritional value and safety of roasted oils in vivo and to develop a customized roasting process for various oilseeds to produce good-quality oils.

Novel seeds pretreatment techniques: effect on oil quality and antioxidant properties: a review

Seed oil quality is a function of several attributes which include its bioactive compounds, physicochemical and functional properties. These quality attributes are important in seed oil processing as they determine the oil palatability, nutritional and market value. Besides the health, environmental and economic issues related to seed oil extraction using organic solvents such as hexane, other conventional seed oil extraction techniques such as supercritical fluid extraction, enzyme digestion and cold pressing are associated with low recovery of oil and bioactive compounds. Application of novel seeds pretreatments techniques such as microwaving, enzymatic digestion, pulsed electric field and ultrasonication do not only improve the oil yield and quality attributes, but also reduces seed oil extraction time, solvent and energy consumption. Higher phenolic compounds, carotenoids, tocopherols, phytosterols and antioxidant properties in oil from pretreated seeds offer health benefits related to the prevention of cancer, diabetes, obesity, inflammatory and cardiovascular diseases. Increased consumer interest in functional foods and the potential of seeds pretreatments in enhancing the extractability of bioactive compounds from plant material has increased the application of novel pretreatment techniques on diverse oilseeds. This review describes the commonly studied novel seeds pretreatment techniques and critically discusses their influence on the oil physicochemical attributes, oxidation indices, bioactive compounds and antioxidant properties.

Preliminary Characterisation of Wastes Generated from the Rapeseed and Sunflower Protein Isolation Process and Their Valorisation in Delaying Oil Oxidation

Since rapeseed and sunflower meals are two of the most representative oilseed crops in the world, this study was focused on ethanol-wash solutes (EWS) obtained as wastes from the protein isolation process of rapeseed and sunflower meals. These meals have been previously valorised; however, the use of the EWS is unexplored. The present study is aimed at the characterisation of their phenolic profile, and antioxidant capacity for preventing lipid oxidation in rapeseed, sunflower, and soybean oil, which has been used as a reference oil. The sunflower EWS exhibited more total phenolic compounds (TPC) and antioxidant activity (119.39 ± 1.13 mg GA/g and 193.97 ± 9.77 mg TE/g, respectively) than the rapeseed one (103.44 ± 5.94 mg GA/g and 89.51 ± 3.17 mg TE/g). The phenolic identification showed hydroxybenzoic and protocatechuic acid in the rapeseed EWS, and pyrogallol and caffeic acid in the sunflower EWS, as the main representative phenols. Both EWS at 15% increased significantly (p < 0.05) the oxidative stability of the oils in the Rancimat equipment with values of antioxidant activity index (AAI) from 1.01 to 1.20, depending on the type of oil employed. In conclusion, the rapeseed and sunflower EWS showed great potential, and they could be used as a source of natural antioxidants within the food industry, replacing the synthetic ones, and promoting the circular economy since they are agro-food wastes.

Air frying pretreatment and the recovery of lipophilic sinapates from the oil fraction of mustard samples

Roasting of mustard seeds prior to oil extraction is a well-documented unit operation essential to produce canolol and other lipophilic sinapates. This study investigated the effectiveness of air frying as a seed roasting treatment operation for enhancing the recovery of lipophilic sinapates from various mustard samples and fractions/products. Air frying of seeds, powder, cake, bran, and flour from different mustard varieties was carried out at temperature-time combinations of 160, 170, and 180°C for 5, 10, 15, and 20 min, respectively. Oil was extracted using the Soxtec method. Lipophilic sinapates were extracted from the oil using equal volumes of hexane to methanol 70% (v/v) and quantified by high performance liquid chromatography-diode array detection (HPLC-DAD). The total phenolic content (TPC) and antioxidant activity of the oils were also evaluated. The results showed a time-temperature dependency for the recovery of major oil-soluble sinapates in all mustard samples and fractions. The optimum air frying condition 180°C for 15 min produced the maximum yield of canolol as well as other unidentified oil-soluble sinapates (retention time (RT)-7.7, RT-11.50, RT-14.95, and RT-16.24 min). The oil from lower grade yellow mustard seeds (LGYMS) roasted at 180°C for 20 mins specifically had the highest TPC (3402.22 ± 58.79 mg GAE/g oil), while LGYMS oils generally showed better antioxidant activities (2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric ion reducing antioxidant power (FRAP), and inhibition of linoleic acid oxidation) but were lower in metal ion chelating capacity. This information would be beneficial to the oil industry because air frying generated valuable canolol and other antioxidant lipophilic sinapates from mustard varieties and their fractions. PRACTICAL APPLICATION: A major limitation in the application of natural extracts in vegetable oils is the poor lipophilic nature of phenolic compounds. This study employed a new thermal treatment (air frying) in the recovery of canolol and other lipophilic antioxidants. Such treatments can enrich mustard-based ingredients with canolol and other lipophilic antioxidants for domestic and industrial applications.

Effect of infrared ray roasting on oxidation stability and flavor of virgin rapeseed oils

Effects of infrared ray roasting (IRR) on the oxidation stability and flavors of virgin rapeseed oil (VROs) at 110-170°C were investigated and compared with traditional roller roasting (TRR). Results showed that IRR samples showed lower acid and peroxides values, higher oxidation stability index, and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity than TRR ones. IRR samples displayed better thermal expansion of rapeseed for internal fragmentation from microstructures, which facilitated the release of tocophenols (652.63-748.78 mg/kg) and 4-vinylsyringol (7.54-678.19 mg/kg), compared with TRR ones with tocophenols (652.63-689.28 mg/kg) and 4-vinylsyringol (7.54-524.18 mg/kg) contributing to better oxidation stability. Moreover, important volatile compounds, including pyrazines, isothiocyanates, nitriles and aldehydes, were formed quantitatively more in IRR than TRR samples, which was attributed to better heat transfer efficiency and internal fragmentation promoting complex reactions inside rapeseed. Therefore, IRR has more positive roasting effects on VROs than TRR. PRACTICAL APPLICATION: Virgin rapeseed oil is a massively consumed flavor vegetable oil, but the traditional high-temperature roller seed roasting process can cause serious quality problems. Our work applied a novel roasting technology, infrared ray roasting to rapeseed pretreatment. The results show that this new type of roasting technology is more efficient and stable and has important applications in the production of virgin rapeseed oil with better oxidative stability and flavor.

Quality and Antioxidant Properties of Cold-Pressed Oil from Blanched and Microwave-Pretreated Pomegranate Seed

The present research studied the influence of blanching and microwave pretreatment of seeds on the quality of pomegranate seed oil (PSO) extracted by cold pressing. Pomegranate seeds (cv. Acco) were independently blanched (95 ± 2 °C/3 min) and microwave heated (261 W/102 s) before cold pressing. The quality of the extracted oil was evaluated with respect to oxidation indices, refractive index, yellowness index, total carotenoids content, total phenolic content, flavor compounds, fatty acid composition, and 2.2-diphenyl-1-picryl hydrazyl (DPPH) and 2.2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging capacity. Blanching and microwave pretreatments of seeds before pressing enhanced oil yield, total phenolic content, flavor compounds, and DPPH and ABTS radical scavenging capacity. Although the levels of oxidation indices, including the peroxide value, free fatty acids, acid value, ρ-anisidine value, and total oxidation value, also increased, and the oil quality conformed to the requirements of the Codex Alimentarius Commission (CODEX STAN 19-1981) standard for cold-pressed vegetable oils. On the other hand, blanching and microwave heating of seeds decreased the pomegranate seed oil’s yellowness index, whilst the refractive index was not significantly (p > 0.05) affected. Even though both blanching and microwave pretreatment of seeds added value to the cold-pressed PSO, the oil extracted from blanched seeds exhibited lower oxidation indices. Regarding fatty acids, microwave pretreatment of seeds before cold pressing significantly increased palmitic acid, oleic acid, and linoleic acid, whilst it decreased the level of punicic acid. On the contrary, blanching of seeds did not significantly affect the fatty acid composition of PSO, indicating that the nutritional quality of the oil was not significantly affected. Therefore, blanching of seeds is an appropriate and valuable step that could be incorporated into the mechanical processing of PSO.

The Effect of Roasting on the Protein Profile and Antiradical Capacity of Flaxseed Meal

Roasting is more and more often used as a pre-treatment of flaxseeds. However, the process can influence flaxseed proteins that may be crucial for their properties. The aim of this research was to study changes in the electrophoretic protein profile (SDS-PAGE) and the antiradical capacity of flaxseed meals after roasting. The roasting temperature (160, 180, and 200 °C) and flaxseed cultivars (golden and brown seed) were factors including in the study. The free (F-MRP) and bound-to-protein (B-MRP) Maillard reaction products were also analyzed. The most significant changes in the SDS-PAGE protein profiles of roasted seeds of each of the tested flax cultivars were observed for the 13 kDa protein fraction (decrease) and for the 19 kDa and 17 kDa fractions (increase). The research revealed a significant correlation between the roasting temperature and B-MRP content, and changes in the percentage share of those three protein fractions. The antiradical capacity of roasted flaxseeds decreased, as compared with untreated seeds. After roasting at 200 °C the antiradical capacity of flaxseeds improved slightly, probably due to the MRP formation, but it was still significantly lower than that of the raw seeds. The research provides novel information about key protein fractions that seem to be important changing during heat treatment.

Effect of Microwave Pretreatment of Seeds on the Quality and Antioxidant Capacity of Pomegranate Seed Oil

Microwave pretreatment of oilseeds is a novel technique used to enhance oil nutraceutical properties. In this study, the effect of microwave pretreatment of seeds was investigated on pomegranate seed oil quality attributes including oil yield, yellowness index, refractive index, peroxide value, ρ-anisidine value, total oxidation value, conjugated dienes, total phenolic content, total carotenoids content, phytosterol composition, fatty acid composition, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, and ferric reducing antioxidant power (FRAP). The seeds of three different pomegranate cultivars ('Acco', 'Herskawitz', and 'Wonderful') were microwave heated at 261 W for 102 s. Pomegranate seeds microwave pretreatment enhanced oil yield, yellowness index, total carotenoids content, total phenolic content, FRAP and DPPH radical scavenging capacity, despite an increase in conjugated dienes, and peroxide value. Palmitic acid, oleic acid, linoleic acid, saturated, and monosaturated fatty acids were increased after pomegranate seeds microwave pretreatment, whilst the levels of punicic acid and β-sitosterol were reduced. Nevertheless, the refractive index, the ratio of unsaturated to saturated fatty acid of the extracted oil were not significantly (p > 0.05) affected by pomegranate seeds microwave pretreatment. Principal component analysis and agglomerative hierarchical clustering established that 'Acco' and 'Wonderful' oil extracts from microwave pretreated PS exhibited better oil yield, whilst 'Herskawitz' oil extracts showed higher total carotenoids content, total phenolic content, and antioxidant capacity.

Extraction, purification and antioxidant activity of polysaccharide from cold pressed oil cake of 'Tengjiao' seed

Tengjiao (Zanthoxylum armatum DC.) seed cold pressed oil cake (CPC), the main by-product of the cold-pressed oil process, is mainly used for animal feed or crop fertilizer, resulting in a great waste of resources. To improve the added value, the CPC polysaccharide (CPCP) was extracted and purified, and its antioxidant activity was studied. The extraction conditions by microwave assisted extraction, and purification conditions by trichloroacetic acid and polyamide column chromatography treatment were optimized. High performance liquid chromatography and Fourier transforms infrared were applied to characterize the primary structural features. And the antioxidant activity was analyzed by detecting the reducing power, and scavenging activity on radical of superoxide anion, DPPH and ABTS. The results showed that, under the optimal extraction conditions (liquid-to-solid ratio 44 mL/g, processing time 16 min, microwave power 500 W and extraction temperature 80 °C), and the optimal purification conditions, the extract rate of crude CPCP reached 4.76 ± 0.07%, and the purity increased from 48.52 ± 2.76% to 93.76 ± 2.06%. CPCP was mainly water-soluble pyranose with α-configuration, and composed of five kinds of monosaccharides including L-Rhamnose, D-Glucuronic acid, d-Glucose, D-Galactose and D-(-)-Arabinose. CPCP displayed certain degree of antioxidant activity, revealing the potential development and utilization value as antioxidants.

Effect of Blanching Pomegranate Seeds on Physicochemical Attributes, Bioactive Compounds and Antioxidant Activity of Extracted Oil

This study investigated the effect of blanching pomegranate seeds (PS) on oil yield, refractive index (RI), yellowness index (YI), conjugated dienes (K232), conjugated trienes (K270), total carotenoid content (TCC), total phenolic compounds (TPC) and DPPH radical scavenging of the extracted oil. Furthermore, phytosterol and fatty acid compositions of the oil extracted under optimum blanching conditions were compared with those from the oil extracted from unblanched PS. Three different blanching temperature levels (80, 90, and 100 °C) were studied at a constant blanching time of 3 min. The blanching time was then increased to 5 min at the established optimum blanching temperature (90 °C). Blanching PS increased oil yield, K232, K270, stigmasterol, punicic acid, TPC and DPPH radical scavenging, whereas YI, β-sitosterol, palmitic acid and linoleic acid were decreased. The RI, TCC, brassicasterol, stearic acid, oleic acid and arachidic acid of the extracted oil were not significantly (p > 0.05) affected by blanching. Blanching PS at 90 °C for 3 to 5 min was associated with oil yield, TPC and DPPH. Blanching PS at 90 °C for 3 to 5 min will not only increase oil yield but could also improve functional properties such as antioxidant activity, which are desirable in the cosmetic, pharmaceutical, nutraceutical and food industries.

Preparation of rapeseed oil with superhigh canolol content and superior quality characteristics by steam explosion pretreatment technology

In this study, rapeseed was pretreated by steam explosion pretreatment technology and subsequently pressed to prepare rapeseed oil. GC, UPLC, and HPLC techniques were employed to analyze the quality characteristics of the rapeseed oil, including the canolol content and other quality characteristics. Additionally, the effect of steam explosion pretreatment technology on the canolol content of rapeseed oil was studied and the formation mechanism of canolol elucidated. The results revealed that when the steam explosion pressure reached 1.0 MPa, the canolol content of the tested oil increased from 41.21 to 2,168.69 mg/kg (52.63-fold increase) and that sinapic acid played a significant role in the conversion of canolol. Thus, the sinapine was converted into the intermediate (sinapic acid) by hydrolysis, which in turn was transformed into canolol through decarboxylation. The instantaneous high-energy environment generated by steam explosion pretreatment could intensify the hydrolysis and decarboxylation reactions of sinapine and sinapinic acid, thereby significantly increasing the canolol content of the oil. To prove the superiority of steam explosion pretreatment, we compared it with other pretreatment technologies, including traditional high-temperature roasting and popular microwave pretreatment. The results revealed that rapeseed oil prepared by steam explosion pretreatment displayed the best quality characteristics. This study can be a reference for the preparation process of rapeseed oil with superhigh canolol content and superior quality characteristics using steam explosion pretreatment.