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11.
The high density steam flash-explosion (HDSFE) was used to extract protein from soybean meal. Soybean meal samples were treated at 1.3 MPa and 1.8 MPa for 60 s, 120 s and 180 s, respectively. After HDSFE treatment at 1.8 MPa for 180 s, the extraction yield of protein was increased from 50.50% to 65.66% compared with untreated soybean meal. The emulsification properties and fat-binding capacity of soy protein isolate (SPI) extracted from soybean meal treated by HDSFE were all improved compared with SPI extracted from untreated soybean meal and white flakes. Molecular weight distribution analysis of SPI showed that after HDSFE treatment the peak with molecular weight about 504 kDa and 43.3 kDa disappeared and the peak with molecular weight about 669 kDa increased indicating protein aggregation. Gel electrophoresis showed that high molecular weight aggregates of protein have been formed by covalent bond. 相似文献
12.
An LC-ESI-MS/MS method was developed for the quantitative detection of postharvest fungicide residues in citrus juices and reported in this paper. The analyses of thiabendazole (TBZ), carbendazim (MBC), thiophanate methyl (TPM), imazalil (IMZ) and prochloraz (PCZ) residues were performed by using a gradient elution in conjunction with positive ionization mode electrospray ionization tandem mass spectrometry. Fungicides were extracted from citrus juices with recoveries ranging from 79.8 to 101.2% and relative standard deviation better than 15%. The quantification limits ranged from 0.01 μg/kg IMZ to 0.06 μg/kg for MBC. The LC-MS-MS method was applied to commercial citrus juices, detecting MBC, TBZ and IMZ residues in the 90% of the samples. Prochloraz residues were detected only in one of the multifruit juice (orange, lemon and carrot) samples. 相似文献
13.
From ‘green’ technologies to ‘red’ antioxidant compounds extraction of purple corn: a combined ultrasound–ultrafiltration–purification approach
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14.
Comparison and Characterization of Compounds with Antioxidant Activity in Lycium barbarum Using High‐Performance Thin Layer Chromatography Coupled with DPPH Bioautography and Tandem Mass Spectrometry
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Shing‐Chung Lam Zhen Luo Ding‐Tao Wu Kit‐Leong Cheong De‐Jun Hu Zu‐Meng Xia Jing Zhao Shao‐Ping Li 《Journal of food science》2016,81(6):C1378-C1384
Methanol extracts from 50 batches of Lycium barbarum (L. barbarum, wolfberry) in China were compared and characterized using high‐performance thin‐layer chromatography coupled with 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) bioautography (HPTLC‐DPPH) and electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry (ESI‐Q‐TOF‐MS/MS), respectively. Results showed that similar components occupying the major antioxidant activity existed in L. barbarum collected from different origins. However, the average antioxidant capacities of methanol extracts of L. barbarum collected in Ningxia were significantly higher than those of Qinghai, Xinjiang, Inner Mongolia, and Gansu, which may contribute to rational use of L. barbarum in China. Furthermore, the chemical structure of compound with the highest antioxidant capacity was tentatively identified as 2‐O‐β‐d ‐glucopyranosyl‐l ‐ascorbic acid using ESI‐Q‐TOF‐MS/MS analysis, which possessed high potentials to be used as an antioxidant biomarker for the quality control of L. barbarum. Results are helpful for the bioactivity‐based quality control of L. barbarum, and beneficial for the improvement of their performance in functional/health foods area, suggesting that HPTLC‐DPPH bioautography with ESI‐Q‐TOF‐MS/MS could be used as a routine approach for quality control of antioxidant components in L. barbarum. 相似文献
15.
16.
Maria Grazia Calabrese Gianfranco Mamone Simonetta Caira Pasquale Ferranti Francesco Addeo 《Food chemistry》2009
The unnatural amino acid lysinoalanine (LAL) has been identified in milk and cheese products by liquid chromatography mass spectrometry (LC/ESI/MS) with selective ion monitoring (SIM) of the 9-fluorenyl-methylchloro-formate (FMOC) derivative. LAL is not present in raw milk or derived from Mozzarella cheese; however, high amounts of LAL are found in calcium caseinate and milk powder. As expected, milk fortified with caseinate or whey protein powder produces cheese with higher LAL content. Our analytical procedure is based on the simultaneous detection of specific ion masses of the FMOC–LAL derivative and the N-ε-methyl-lysine internal standard. A linear relationship was observed within the 0.2–20 ppm concentration range, in addition to a high correlation coefficient and ∼3% relative standard deviation. 相似文献
17.
Nadine Jaeckels Stefan Tenzer Susanne Rosfa Hansjoerg Schild Heinz Decker Petra Wigand 《Food chemistry》2013
Lipid transfer proteins (LTP) play a major role in plant defence and are of particular interest due to their known ability to cause allergic reactions. These proteins are expressed in grapes and also remain detectable after vinification, especially in red wine. However, it remains unknown whether the protein undergoes any changes during the vinification process. Here, we present a purification method for LTPs from Dornfelder grapes and wine. By liquid-chromatography–mass spectroscopy (LC–MS/MS) we identified LTPs from two different species (Vitis vinifera and Vitis aestivalis). Additionally, the purified LTPs were characterised using spectrometric methods, confirming their high purity and structural stability during vinification. We conclude that LTPs are resistant to the alcohol content (13.5 vol%), acidic milieu of wine and other ingredients present during the vinification process, indicating that the allergenic potential of grape LTP is not diminished by the vinification process. 相似文献
18.
Pramodkumar D. Jadhav Yang Zuo Youn Young Shim Jianheng Shen Martin J. T. Reaney Ning Zhang Yong Wang 《International Journal of Food Science & Technology》2018,53(8):1972-1982
Linusorbs (LOs; a.k.a. cyclolinopeptides) are naturally occurring orbitides derived from flaxseed. These compounds consist of 8–10 amino acid residues, which are linked via an N ‐ to C‐terminal peptide bond with molecular masses of approximately 1 kDa. The LO circular structure makes them candidates for metal binding studies. Flaxseed extracts are known to suppress Pb and Cd toxicity. Hence, four metal salts surveyed include Zn(CH3COO)2, ZnSO4, Pb(CH3COO)2 and Cd(NO3)2 with pure LOs 1–5 . Proton NMR spectra indicated interaction of LOs with metal salts in solution and were used to determine impacts of methionine oxidation on interactions with metal ions. The methyl group of methionine S,S ‐ dioxide of related LOs did not show the same shift in the presence of Zn(CH3COO)2 and Pb(CH3COO)2 observed in their methionine S ‐ oxide analogues. Metal complexes were observed forming at 10?2 m to 10?4 m but not at lower concentrations (10?5 m to 10?8 m ). Mass spectrometry data confirmed that metal binding strength varied by metal in the order Zn(CH3COO)2<Pb(CH3COO)2<ZnSO4<Cd(NO3)2. 相似文献
19.
Suzana Corte Real Maria de Nazareth Leal de Meirelles 《Microscopy research and technique》1991,18(2):192-196
Immunocytochemistry was used to investigate the localization of F1 ATPase in mitochondria of cryosections of adult mouse heart muscle cells. The initial aldehyde fixation was the only denaturation step for antigens. The fine structure was preserved with contrast enhancement as the sections were maintained hydrated, with the advantage that the entire procedure is completed in one working day. The reaction was highly specific, and entire mitochondria were labeled with the Protein A-gold complex. A new analytical technique, electron spectroscopic imaging (ESI), contributed to a better visualization of the localization of the F1 factor. 相似文献
20.
Vallverdú-Queralt A Martínez-Huélamo M Arranz-Martinez S Miralles E Lamuela-Raventós RM 《Journal of the science of food and agriculture》2012,92(10):2043-2049
BACKGROUND: Carotenoids are important antioxidant compounds in the human diet. Owing to their constrained polyene structure, carotenoids can exist in cis and trans isomeric forms that can be difficult to differentiate in natural samples. In ketchups and gazpachos, all‐trans isomeric forms are predominant. However, during thermal processing, cis isomers are formed. Therefore the determination of carotenoid isomers is required for the assessment of the nutritional value of foods. RESULTS: The main carotenoid found in ketchups was trans‐lycopene, whereas in gazpachos a higher contribution to the total carotenoid content was made by other carotenoids such as 5‐, 9‐ and 13‐cis‐lycopene, lutein, β‐carotene and α‐carotene. Ketchups exhibited the highest lipophilic antioxidant content owing to their higher content of trans‐lycopene, the main carotenoid in tomatoes. CONCLUSION: Direct analysis of carotenoids by electrospray ionisation mass spectrometry (ESI‐MS) often produces poor results requiring offline time‐ and sample‐consuming derivatisation techniques. Therefore in this work a simple ESI‐MS approach is described for the direct analysis of carotenoids in ketchups and gazpachos using the post‐column addition of lithium chloride to promote the cationisation of carotenoids. To the best of the authors' knowledge, this paper presents for the first time the identification of 5‐, 9‐ and 13‐cis‐lycopene in ketchups and gazpachos. Copyright © 2012 Society of Chemical Industry 相似文献