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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. [ABSTRACT FROM AUTHOR]

In this study, flaxseed was pretreated by steam explosion technology and subsequently pressed to prepare flaxseed oil. GC, UPLC, HPLC, and GC‐MS techniques were used to analyze the quality characteristics of the prepared flaxseed oil. These included the food safety risk indices, micronutrient components, and oxidative stability. The effects of different steam explosion pressures on the quality characteristics and relative volatile components of flaxseed oil were also investigated. The results revealed that steam explosion pretreatment technology could significantly increase the oil yield, improve micronutrient content, and strengthen the oxidation stability of the product. Moreover, the food safety risk indices (e.g., benzopyrene) were controlled within a reasonable range, while the fatty acid content remained almost unchanged. Notably, the relative pyrazine content in the total volatile components of flaxseed oil was 68.25% when the steam explosion pressure reached 1.2 MPa. This was considered as the main factor that contributed to the unique concentrated fragrance of the produced flaxseed oil. To prove the superiority of the steam explosion pretreatment, we compared this technique with traditional high‐temperature roasting and popular microwave pretreatment techniques. The results revealed that flaxseed oil prepared by steam explosion pretreatment displayed the best quality characteristics and most concentrated fragrance. Thus, steam explosion technology shows great potential for application to produce high‐quality concentrated fragrance flaxseed oil. This study provides significant reference and guidance for the preparation process of flaxseed oil. [ABSTRACT FROM AUTHOR]

In the present, oil pressing is still the main process for extracting oil from flaxseed in China, but it cannot achieve efficient utilization of functional materials in flaxseed, such as flaxseed gum and lignin secoisolariciresinol diglycoside (SDG). So a comprehensive process that produces multiple products from flaxseed needs to be developed. On the basis of the structural characteristics that the flaxseed gum is in the outermost layer of flaxseeds, the grinding degumming technology using high-speed rotating sand roller grind flaxseed surface is studied before in our laboratory. Model 150 flaxseed degumming machine was designed and manufactured according to this technology, it is composes of motor, sand roller, sieve, gum powder collector etc. Electronic motor is used in the machine to drive the sand roller with high-speed rotation inner the sieve to grind flaxseed, the gum powder flow out the sieve and is collected, the sand roller length and diameter is 800 and 146 mm, the cylindrical sieve diameter is 158 mm with uniform distribution of F1.5 mm sieve size. In this paper, the feasibility of Model 150 flaxseed degumming machine was studied. Based on that, the research work of flaxseed degumming and oil pressing co-process was carried out with the commodity flaxseed from Gansu as the research material. The results showed that: the machine was able to obtain flaxseed gum-powder successfully when flaxseed flow rate was controlled at 40 to 220 kg/h. The rate of gum-powder grinded from flaxseed was 6.5%±0.3%. The viscosity of the defatted gum-powder was (5100 ± 520) mPaos. The oil contents of flaxseed and the degummed flaxseed were 39.30%±0.25% and 41.62%±0.22%, respectively. By using the method of adding 30% flaxseed cake to degummed flaxseed, the oil of degummed flaxseed can be screw pressed successfully. The oil yield pressed from degummed flaxseed was 34.65%±0.43%, higher than that pressed twice from flaxseed (33.94% ± 0.43%)when the flaxseed was pressed with the screw pressing machine without degumming. By the combination of degumming and screw-pressing for flaxseed processing, two benefits were achieved, they were: increase number of products and high pressed oil yield. The research results can provide reference for flaxseed processing. [ABSTRACT FROM AUTHOR]