Glucosinolates or erucic acid, which one contributes more to volatile flavor of fragrant rapeseed oil?

This study aims to investigate the effect of three rapeseed varieties with different erucic acid (EA) and glucosinolates (GLSs) content, and different degumming methods on the volatile flavor profiles of fragrant rapeseed oil (FRO). A total of 171 volatile compounds were identified by headspace solid-phase microextraction combine with gas chromatography-mass spectrometry (HS-SPME/GC-MS), and 87 compounds were identified as key odorants owing to their relative odor activity values (ROAV) ≥ 1. Methyl furfuryl disulfide was identified in rapeseed oil for the first time, with highest ROAVs (up to 26805.46). The volatile flavor profile of rapeseed oil was affected by GLSs content to a certain extent rather than EA content. Rapeseed varieties with low-EA and high-GLSs are suitable to produce FRO. Silicon dioxide adsorbing was an effective alternative method to water degumming in FRO. This work provided a new idea for selection of raw materials and degumming methods in FRO production.

Remove Non-hydrated Phospholipids in Okra Seed Oil by Silicon Dioxide.

Water degumming, mainly removes hydrated phospholipids, is the most common method applying in traditional edible oil production. Silicon dioxide (SiO2) adsorption has been proved as a green and efficient method for removing phospholipids from rapeseed oil. But both methods exhibited poor effect on okra seed oil. Based on a hypothesis that SiO2 can adsorb non-hydrated phospholipids, removal effect of non-hydrated phospholipids in okra seed oil was studied. Single factor test and response surface design were used to optimize the SiO2 adsorbing process in water-degummed oil. Meanwhile, the qualities and flavor changes of okra seed oil before and after degumming were compared and analyzed. The results showed that the optimized degumming procedure was: 1.43% (w/w) of SiO2 added into the water-degummed oil, and the mixture was stirred at 33.52℃ for 30.47 min. The maximum non-hydrated phospholipids removal rate reached 43.3%. Comparing with crude okra seed oil, the optimal degumming method resulted in the increase of peroxide value and the decrease of induction period (IP) of the oil. However, it had the same safety as the water and the SiO2 degumming methods. It could retain 62% of total phenols, which was less than the water and the SiO2 degumming methods (both about 79%). The differences of E-nose sensors among oils were most likely caused by the pyrazines. It is necessary to study the composition and properties of phospholipids and develop new methods to further improve the phospholipids removal rate of okra seed oil.

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.

Fermentation process improvement of a Chinese traditional food: soybean residue cake.

UNLABELLED: Fermentation process improvement of soybean residue cake, a Chinese traditional fermented food, and its physicochemical analysis during fermentation were studied. One of the dominant strains in the fermentation was isolated and identified as Mucor racemosus Fresenius. The fermentation process was improved by subsection fermentation. The crude protein content decreased from 19.95 ± 0.03% in the raw soybean residue to 16.85 ± 0.10% in the fermented products, and the formaldehyde nitrogen content increased from 0.068 ± 0.004% to 0.461 ± 0.022% in final fermented cakes. Hardness of samples significantly (P < 0.05) increased whereas springiness, cohesiveness, and resilience significantly (P < 0.05) decreased with increasing fermentation time, respectively. Microstructure observations showed obvious change of the surface of cake samples during the fermentation process. PRACTICAL APPLICATION: During the soybean processing, it will produce plenty of by-products, and the most part of them is soybean residue. The discarded soybean residue causes economic loss. Fortunately, we can obtain nutritious and delicious fermented soybean residue cakes by fermenting soybean residue as raw material.

Use of luminescence probing for the study of the interaction of polytitanasiloxane with trivalent rare earth ions.

Luminescent probing methods were employed to investigate the interaction of the Ti-O chains of polytitanasiloxane with europium ions in the mixture of ethanol and water. The UV-vis absorption, the luminescence intensity, and the luminescence lifetimes of the Eu3+ ions in PTS solutions were all found to increase with the increase of TBT/TEOS molar ratio. The results indicated that the incorporation of TBT can result in the increase of absorption energy of the Ti-O group by near-UV excitation and in the increase of energy transfer to the metal ion, and that the Ti-O chains due to the site binding of Eu3+ ions can expel six to nine solvent molecules from the first coordination solvation shell of the ion. The investigation of the energy transfer from europium to neodymium ions in polytitanasiloxane solutions revealed the formation of aggregates consisting of seven rare earth ions (together with the polytitanasiloxane countercharges).