Effects of microwave irradiation on the distribution of sinapic acid and its derivatives in rapeseed and the antioxidant evaluation

Effect of novel radio frequency roasting on color appearance, volatile compounds, fatty acid composition, and storage stability of peanut oil

This study investigates the influences of RF roasting on oil yield, color appearance, bioactive components, antioxidant capacity, volatile compounds, sensory and nutritional properties, and storage stability of peanut oil under different target temperatures (140-170 °C), holding times (0-22.5 min), and moisture contents (8.29 % and 20 %). With increasing target temperature and holding time, the browning degree, total phenolics, antioxidant capacity, and characteristic flavor compounds (mainly pyrazines, aldehydes, and furans) of oil were significantly increased. The light-roasted oils showed the highest sensory scores on overall acceptability, while the dark-roasted oils presented stronger roasted and burnt odors. Increasing moisture content enriched 13 species and 34.43 μg/g of volatiles by promoting the Maillard reaction. Compared with hot-air roasting, RF roasting improved the oil yield and oil quality uniformity. A quality prediction method was developed based on the browning index. These findings indicated that RF roasting is a promising technique for processing high-quality plant oils.

Comprehensive Assessment of Anti-Inflammatory, Antiproliferative and Neuroprotective Properties of Cauliflower after Dehydration by Different Drying Methods

Cauliflower (Brassica oleraceae L. var. Botrytis Linnaeus) has various health benefits due to its rich bioactive compound content. However, this fresh vegetable faces challenges related to its perishability and short shelf life. This study explores the effect of five drying methods, namely vacuum drying (VD), convective drying (CD), infrared drying (IRD), low-temperature vacuum drying (LTVD) and vacuum freeze-drying (VFD), on the bioactive compounds and health-promoting properties of cauliflower. Analyses of amino acids, hydroxycinnamic acid and its derivatives, glucosinolates, and isothiocyanates, as well as evaluations of their anti-inflammatory, antiproliferative, and neuroprotective properties, were conducted based on these five drying methods. The results revealed that samples treated with VFD and IRD had a higher content of amino acids involved in GSL anabolism. Moreover, VFD samples retained hydroxycinnamic acid derivatives and glucosinolates to a greater extent than other methods. Nonetheless, the CD and VD samples exhibited higher antiproliferative and neuroprotective effects, which were correlated with their high sulforaphane content. Overall, considering the retention of most bioactive compounds from cauliflower and the topical inflammation amelioration induced in mice, VFD emerges as a more satisfactory option.

Quality Evaluation of Walnuts from Different Regions in China

This study analyzed and evaluated the basic crude fat contents, crude protein contents, phenolic compounds, lipid compositions (fatty acids, phytosterols, and tocopherols), and amino acid compositions of 26 walnut samples from 11 walnut-growing provinces in China. The results indicate that the oil contents of the samples varied from 60.08% to 71.06%, and their protein contents ranged from 7.26 g/100 g to 19.50 g/100 g. The composition of fatty acids corresponded to palmitic acid at 4.61-8.27%, stearic acid at 1.90-3.55%, oleic acid at 15.50-32.28%, linoleic acid at 53.44-67.64%, and α-linolenic acid at 2.45-12.77%. The samples provided micronutrients in widely varying amounts, including tocopherol, phytosterol, and total phenolic content, which were found in the walnut oil samples in amounts ranging from 356.49 to 930.43 mg/kg, from 1248.61 to 2155.24 mg/kg, and from 15.85 to 68.51 mg/kg, respectively. A comprehensive evaluation of walnut oil quality in the samples from the 11 provinces using a principal component analysis was conducted. The findings revealed that the samples from Henan, Gansu, and Zhejiang had the highest composite scores among all provinces. Overall, Yunnan-produced walnuts had high levels of crude fat, polyunsaturated fatty acids, and total tocopherols, making them more suitable for producing high-quality oil, whereas Henan-produced walnuts, although lower in crude fat, had a higher crude protein content and composite score, thus showing the best walnut characteristics.

High-oleic rapeseed oil quality indicators and endogenous antioxidant substances under different processing methods

This study exposed high-oleic rapeseed oil (HORO) to different pretreatment (microwave or roasting) and processing methods to investigate (cold pressing, hexane extraction, subcritical butane extraction, and aqueous enzymatic extraction) the effects of processing technologies on HORO parameters associated with its physicochemical properties, endogenous antioxidant substances, and antioxidant capacity. The oil yield of various processing technologies was between 35.4% and 59.7%, and the fatty acid composition did not significantly differ. Hierarchical clustering and principal component analyses were used for evaluation. The results revealed that the microwave pretreatment-hexane extraction (M-HE) method resulted in significantly higher levels of tocopherols (688.4 mg/kg), polyphenols (1007.76 mg/kg), and phytosterols (1810.6 mg/kg) in HORO, implying strong free radical scavenging capacity (DPPH-oil: 79.63, DPPH-nonpolar: 71.42, DPPH-polar: 6.65, FRAP: 55.4, ABTS: 3043.7 μmol TE/kg). Hence, M-HE is a promising method for producing HORO with a higher stability and nutritional value.

Optimization of Canolol Production from Canola Meal Using Microwave Digestion as a Pre-Treatment Method

Canola meal, the by-product of canola oil refining, is a rich source of phenolic compounds and protein. The meal, however, is primarily utilized as animal feed but represents an invaluable source of nutraceuticals. Of particular interest are the sinapates, sinapine and sinapic acid, with the decarboxylation of the latter to form canolol. Extracting these phenolics has been carried out using a variety of different methods, although there is an urgent need for environmentally safe and sustainable methods. Microwave-assisted solvent extraction (MAE), as a green extraction method, is receiving considerable interest. Its ease of use makes MAE one of the best methods for studying multiple solvents. The formation of canolol, from sinapine and sinapic acid, is primarily dependent on temperature, which favors the decarboxylation reaction. The application of MAE, using the MultiwaveTM 500 microwave system with green extractants, was undertaken to assess its ability to enhance the yield of sinapates and canolol. This study examined the effects of different pre-treatment temperature-time combinations of 140, 150, 160, and 170 °C for 5, 10, 15, 20, and 30 min on the extraction of canolol and other canola endogenous phenolic compounds. Total phenolic content (TPC), total flavonoid content (TFC), as well as metal ion chelation (MIC) and DPPH radical activity of the different extracts were assessed. The results confirmed that extractability of canolol was optimized with methanol at 151 °C and with ethanol at 170 °C with pre-treatment times of 15.43 min and 19.31 min, respectively. Furthermore, there was a strong positive correlation between TPC and TFC (p < 0.05) and a negative correlation between TFC and DPPH radical activity. Interestingly, no significant correlation was observed between MIC and DPPH. These results confirmed the effectiveness of MAE, using the novel MultiwaveTM 500 microwave instrument, to enhance the yield of canolol. This was accompanied by substantial improvements in the antioxidant activity of the different extracts and further established the efficacy of the current MAE method for isolating important natural phenolic derivatives for utilization by the nutraceutical industry.

Effect of Adsorption Deacidification on the Quality of Peony Seed Oil

To overcome the issues in the traditional deacidification processes of peony seed oil (PSO), such as losses of neutral oil and trace nutrients, waste discharge, and high energy consumption, adsorption deacidification was developed. The acid removal capacity of adsorbent-alkali microcrystalline cellulose was evaluated using the isothermal adsorption equilibrium and the pseudo-first-order rate equation. The optimized adsorption deacidification conditions included adsorbent-alkali microcrystalline cellulose at 3%, a heating temperature of 50 °C, and a holding time of 60 min. The physicochemical, bioactive properties, antioxidant capacities, and oxidative stabilities of PSO processed by alkali refining and oil-hexane miscella deacidification were compared under the same operating conditions. Fatty acid content was not significantly different across all three methods. The deacidification rates were 88.29%, 98.11%, and 97.76%, respectively, for adsorption deacidification, alkali refining, and oil-hexane miscella deacidification. Among the three deacidification samples, adsorption deacidification showed the highest retention of tocopherols (92.66%), phytosterols (91.96%), and polyphenols (70.64%). Additionally, the obtained extract preserved about 67.32% of the total antioxidant activity. The oil stability index was increased 1.35 times by adsorption deacidification. Overall, adsorption deacidification can be considered a promising extraction technology in terms of quality as compared to alkali refining and oil-hexane miscella deacidification.

Polyphenolic compounds from rapeseeds (Brassica napus L.): The major types, biofunctional roles, bioavailability, and the influences of rapeseed oil processing technologies on the content

The rapeseed (Brassica napus L.) are the important oil bearing material worldwide, which contain wide variety of bioactive components with polyphenolic compounds considered the most typical. The rapeseed polyphenols encompass different structural variants, and have been considered to have many bioactive functions, which are beneficial for the human health. Whereas, the rapeseed oil processing technologies affect their content and the biofunctional activities. The present review of the literature highlighted the major types of the rapeseed polyphenols, and summarized their biofunctional roles. The influences of rapeseed oil processing technologies on these polyphenols were also elucidated. Furthermore, the directions of the future studies for producing nutritional rapeseed oils preserved higher level of polyphenols were prospected. The rapeseed polyphenols are divided into the phenolic acids and polyphenolic tannins, both of which contained different subtypes. They are reported to have multiple biofunctional roles, thus showing outstanding health improvement effects. The rapeseed oil processing technologies have significant effects on both of the polyphenol content and activity. Some novel processing technologies, such as aqueous enzymatic extraction (AEE), subcritical or supercritical extraction showed advantages for producing rapeseed oil with higher level of polyphenols. The oil refining process involved heat or strong acid and alkali conditions affected their stability and activity, leading to the loss of polyphenols of the final products. Future efforts are encouraged to provide more clinic evidence for the practical applications of the rapeseed polyphenols, as well as optimizing the processing technologies for the green manufacturing of rapeseed oils.

Comprehensive review of composition distribution and advances in profiling of phenolic compounds in oilseeds

A wide range of phenolic compounds participate in oilseed growth, regulate oxidative stability of corresponding vegetable oil, and serve as important minor food components with health-promoting effects. Composition distribution of phenolic compounds varied in oilseeds. Isoflavones, sinapic acid derivatives, catechin and epicatechin, phenolic alcohols, chlorogenic acid, and lignans were the main phenolic compounds in soybean, rapeseed, peanut skin, olive, sunflower seed, sesame and flaxseed, respectively. Among which, the total isoflavones content in soybean seeds reached from 1,431 to 2,130 mg/100 g; the main phenolic compound in rapeseed was sinapine, representing 70–90%; chlorogenic acid as the predominant phenolic compound in sunflower kernels, represented around 77% of the total phenolic content. With the rapid development of analytical techniques, it is becoming possible for the comprehensive profiling of these phenolic compounds from oilseeds. This review aims to provide recently developments about the composition distribution of phenolic compounds in common oilseeds, advanced technologies for profiling of phenolic compounds by the metabolomics approaches based on mass spectrometry. As there is still limited research focused on the comprehensive extraction and determination of phenolics with different bound-forms, future efforts should take into account the non-targeted, pseudo-targeted, and spatial metabolomic profiling of phenolic compounds, and the construction of phenolic compound database for identifying and quantifying new types of phenolic compounds in oilseeds and their derived products.

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.

A comprehensive review on different classes of polyphenolic compounds present in edible oils

Edible oils are used as a frying medium and in the preparation of several food products. They are mainly constituting triacylglycerols as major components, while other compounds are classified as minor constituents, which include polyphenols. This class of compounds plays an important role in the thermal stability and quality attributes of the finished industrial food products. In addition to other antioxidants, the desired thermal stability of edible is achieved by either fortification or mixing of edible oils. This comprehensive review was therefore aimed to review the different classes of polyphenolic compounds present in commonly consumed edible oils. The edible oils reviewed include soybean, olive, rapeseed, canola, sunflower, flaxseed, sesame, cottonseed, palm, almond, peanut, chestnut, coconut, and hazelnut oils. The identified classes of polyphenolic compounds such as simple phenols, hydroxybenzoic acids, phenylethanoids, hydroxycinnamic acid, esters of hydroxycinnamic acids, coumarins & chromans, stilbenes, flavonoids, anthocyanins, and lignans were discussed. It was observed that a single edible from different origins showed the varied composition of the different classes of phenolic compounds. Among the oils, soybean, sunflower, olive, and brassica oils received higher attention in terms of polyphenol composition. Some classes of phenolic compounds were either not reported or absent in one edible oil, while present in others. Among the different classes of phenolics, hydroxybenzoic acids, hydroxycinnamic acid and flavonoids were the most widely present compounds. Phenolic compounds in edible oils possess several health benefits such as antioxidant, antibacterial, anti-viral, anti-inflammatory, anti-tumour, antioxidants, cardioprotective, neuroprotective, anti-diabetic properties and anti-obesity.

Effects of microwave heat treatment on fungal growth, functional properties, total phenolic content, and antioxidant activity of sorghum (Sorghum bicolor L.) grain

Sorghum grains were subjected to microwave heating at different power levels 350 and 500 W for application times of 15, 30, and 45 s. The effect of microwave heating on fungal growth, protein content, in vitro digestibility, protein solubility, and functional and antioxidant properties of sorghum grain was investigated. The microwave heating at 350 and 500 W significantly reduced fungal incidence in the grain up to 26.2 and 33.4%. No significant changes were found in the crude protein and digestibility of protein, water holding capacity, and oil holding capacity of sorghum. However, application of microwave energy at 500 W for 30 & 45 s caused a sharp reduction on the protein solubility (8.2-7.6%), foaming capacity (6.47-0.98%), emulsion capacity (0.43-0.32 mL/g) and the emulsion stability (2.2-1.6%) of sorghum grain, respectively. Conversely, a significant increment of grain total phenolic content up to 47.1 and 50.8 mg GAE/g and the antioxidant activity up to 40.9 and 59.1% after microwave heat treatment at 350 and 500 W for 45 s, respectively, was observed. These findings revealed that sorghum grain should be treated with microwave at 350 and 500 W for 45 and 15 s, respectively, in order to maintained and enhanced its functional and nutritional properties. Accordingly, microwave heating, particularly at low power, may be an effective emerging method for improving the physicochemical and nutritional properties of sorghum grain.

Microwave pre-treatment of canola seeds and flaked seeds for increased hot expeller oil yield

Microwave (MW) pre-treatment of canola seeds or flaked seeds was found to be a superior alternative to the conventional thermal pre-treatment (steam). Flaked seeds were "cooked" (heat-treated) with steam or using microwave treatments in the temperature range of 62-130 °C prior to expeller pressing. Microwave cooking at 100 °C resulted in the highest increase in the pressed oil yield, which is an increase of 3.7% (w/w) on a pressed oil basis or 9.0% (oil in seed basis) compared with steam cooking. Whole canola seeds conditioning was conducted with microwaves or steam, in the temperature range of 40-75 °C, followed by microwave or steam cooking at 100 °C to evaluate the effect of MW treatment during conditioning on the expeller oil yield. The use of a continuous microwave process for combined conditioning of whole seeds at 55 °C and subsequent cooking of flaked seeds at 100 °C resulted in a 4.0% increase in expeller oil yield, compared with steam conditioning and cooking. The influence of dry basis (db %) moisture contents of 5%, 11.5%, and 16.5% on oil yield after steam or MW treatments of seeds and flaked seeds was also studied. The moisture content of 11.5% (db %) yielded the highest net oil yield for both MW and steam at best conditioning and cooking temperatures of 55 °C and 100 °C, respectively. No significant impact of MW cooking was seen on oil quality compared with conventional steam cooking.

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.