Rapid Assessment of Quality Changes in French Fries during Deep-frying Based on FTIR Spectroscopy Combined with Artificial Neural Network.

Fourier transform infrared (FTIR) spectroscopy combined with backpropagation artificial neural network (BP-ANN) were utilized for rapid and simultaneous assessment of the lipid oxidation indices in French fries. The conventional indexes (i.e. total polar compounds, oxidized triacylglycerol polymerized products, oxidized triacylglycerol monomers, triacylglycerol hydrolysis products, and acid value), and FTIR absorbance intensity in French fries were determined during the deep-frying process, and the results showed the French fries had better quality in palm oil, followed by sunflower oil, rapeseed oil and soybean oil. The FTIR spectra of oil extracted from French fries were correlated to the reference oxidation indexes determined by AOCS standard methods. The results of BP-ANN prediction showed that the model based on FTIR fitted well (R2 > 0.926, RMSEC < 0.481) compared with partial least-squares model (R2 > 0.876). This facile strategy with excellent performance has great potential for rapid characterization quality of French fries during frying.

Transfer assessment of carbendazim residues from rapeseed to oil production determined by HPLC-MS/MS.

It is crucial to develop practical procedures for the control and reduction of pesticide residues in oil productions from farm to dining table. In this study, the dissipation behaviors of typical fungicide from rapeseed to oil production were studied to reveal relationship among spraying stage, application dosage, household oil processing stage, and pesticide residues. In the field trials, rape plants were sprayed with carbendazim at three different dosages during flowering period. Transfer assessment of carbendazim residues from rapeseed to oil production during household oil processing via different press techniques was determined using high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). The recoveries of carbendazim in rapeseed samples, meals after squeezing samples, and rapeseed oil samples ranged from 82.5% to 93.6% with relative standard deviations (RSDs) ＜5.2%. The validation results illustrated that the methods were reliable and sensitive. The average processing factor (PF) during household oil processing via hot press technique and cold press technique was 0.15 and 0.51, respectively. This study demonstrated that household oil processing could significantly reduce the pesticide residues, especially by hot press technique.

Physicochemical properties and health risk assessment of polycyclic aromatic hydrocarbons of fragrant rapeseed oils in China.

BACKGROUND: Fragrant rapeseed oil is a type of hot-pressed oil in China. In this study, physicochemical properties, oxidative stability index (OSI), tocopherols, sterols, and polycyclic aromatic hydrocarbons (PAHs) in fragrant rapeseed oils were evaluated. Additionally, the cancer risk assessment pertaining to PAHs in fragrant rapeseed oil was investigated. RESULTS: Acid values (0.64-2.68 mg potassium hydroxide per gram), peroxide values (1.58-4.86 mmol kg-1 ), and color values (R = 2.6-5.8, Y = 35) of fragrant rapeseed oils were all within codex limits. Tocopherols and sterols ranged from 559.5 to 783.7 mg kg-1 and 4412.6 to 7859.8 mg kg-1 respectively. The OSI (110 °C) was between 4.8 and 15.9 h, with an average value of 10.8 h. Mean values of benzo[a]pyrene and PAH4 (chrysene, benz[a]anthracene, benzo[b]fluroranthene, and benzo[a]pyrene) were 2.32 µg kg-1 and 8.21 µg kg-1 respectively. The 95% dietary exposure of benzo[a]pyrene equivalent (BaPeq) contents from PAH4 were 0.3474 ng kg-1 day-1 , 0.3942 ng kg-1 day-1 , 1.8293 ng kg-1 day-1 , and 0.4294 ng kg-1 day-1 for male children, adolescents, adults, and seniors respectively. For females, these values were 0.3443 ng kg-1 day-1 , 0.3228 ng kg-1 day-1 , 1.8697 ng kg-1 day-1 , and 0.4084 ng kg-1 day-1 , respectively. Moreover, incremental lifetime cancer risk values at the cumulative probabilities of 91.3% and 91.6% for male adults and female adults respectively were higher than 1 × 10-5 . CONCLUSION: The results imply that the potential risk of cancer with PAHs in fragrant rapeseed oil should be a concern, especially for the health of adults. Fragrant rapeseed oil is still a product subject to contamination by PAHs. Limits for PAH4 of fragrant rapeseed oil should be included in Chinese regulations to improve safety. © 2020 Society of Chemical Industry.

Assessment of rapeseed oil body (oleosome) lipolytic activity as an effective predictor of emulsion purity and stability.

The lipolytic activity in oil body creams as affected by recovery and washing protocols was investigated. The effect of thermal treatment on the hydrolytic activity and physical stability of fresh and aged (up to 30 days) oil body emulsions was studied. The use of alkaline pH solutions (9.5) to soak and grind rapeseeds were more effective reducing the contamination of oil body material from seed proteins/enzymes, compared with neutral pHs. Soaking and grinding seeds with a NaHCO3 solution (0.1 M, pH 9.5) yielded oil bodies with a similar composition to those prepared in urea (9 M); however, the physical stability over storage was compromised due to the presence of hydrolytic enzymes. Heating a dispersion of oil bodies for 6 mins at 95 °C did not alter the physical properties of oil bodies and significantly reduced lipolytic activity (>90% enzyme inactivation), resulting in a stable emulsion.

Characterization of the Aroma-Active Compounds in Commercial Fragrant Rapeseed Oils via Monolithic Material Sorptive Extraction.

Commercial fragrant rapeseed oil (CFRO), from roasted and hot-pressed seeds, is enjoyed in China for its unique aroma. However, the characteristic of aroma-active compounds in CFRO is still unclear. In this study, a new odor monolithic material sorptive extraction method was established to trap volatiles from rapeseed oil. Thirty CFROs were investigated using this method coupled with gas chromatography-mass spectrometry. A total of 29 volatile compounds were identified by gas chromatography-olfactometry including pyrazines, alcohols, aldehydes, ketones, and sulfur compounds. Further, 2,5-dimethylpyrazine (peanut-like), 3-ethyl-2,5-dimethylpyrazine (roasted nut-like), dimethyl trisulfide (cabbage-like), 4-isothiocyanato-1-butene (pungent and pickle-like), butyrolactone (caramel-like), and benzyl nitrile (pungent and sulfur-like) are affirmed as the key odorants for the overall aroma of CFRO, owing to their odor activity values ≥1. This work provides a new insight on acquiring aroma-active compounds from rapeseed oil in a more time-effective process compared to conventional methods. Futhermore, this novel approach is applicable in the field of food flavor.

Assessment of contamination source and quality control approach for polycyclic aromatic hydrocarbons in wood-pressed rapeseed oil.

Contamination sources of polycyclic aromatic hydrocarbons (PAHs) in the raw material, oil production and storage processes of wood-pressed rapeseed oil were investigated in this study. The results showed that benzo[a]pyrene (BaP) and PAH4 (sum of BaP, benzo[a]fluoranthene, benzo[b]fluoranthene and chrysene) were unevenly distributed in the kernel (0.56-0.98 and 2.84-8.64 µg/kg, respectively) and hull (1.53-3.17 and 13.49-22.31 µg/kg, respectively) of the rapeseed raw materials. The contents of BaP and PAH4 continuously increased during the process of wood-pressed rapeseed oil, ranging from 2.21 to 10.93 and 9.36 to 40.03 µg/kg, thus demonstrating that a wide range of pollution sources of PAHs existed for the test wood-pressed rapeseed oils. The initial temperature and time of roasting should be controlled at <210°C and <60 min, due to the generation of PAHs in rapeseed by over-roasting. In addition, contact tools and substance such as lubricating oil (from the mill), heat-transfer oil (from roasting machine), rubber gaskets and straws should be properly screened. The BaP and PAH4 of rapeseed placed in the roasting area increased from 0.5 to 2.24 and from 2.08 to 9.03 µg/kg, respectively. Therefore, roasting fume control and treatment systems are necessary and the roasting section should be strictly isolated from the other stages. Storage can slightly lower the PAHs amounts in the rapeseed oil, which made the contents of BaP and PAH4 decrease from 27.00 to 24.70 and from 138.63 to 117.58 µg/kg, respectively. Quality control measures of PAHs in wood-pressed rapeseed oil were proposed and implemented, and the final oil products' BaP and PAH4 were kept below 2 and 10 µg/kg, respectively, which meets the European Commission Regulation No. 835/2011.