| 1. |
- Castro Alves, Victor Costas, 1986-, et al.
(författare)
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Speeding up the extraction of mushroom polysaccharides
- 2016
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Ingår i: Food Analytical Methods. - New York : Springer. - 1936-9751 .- 1936-976X. ; 9:9, s. 2429-2433
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Tidskriftsartikel (refereegranskat)abstract
- Non-digestible polysaccharides from edible mush-rooms may have immunomodulatory properties. Therefore,the availability of mushroom polysaccharides is relevant for research or industrial purposes, as polysaccharides may be used as functional food ingredients. Recently, a method using successive extractions to obtain mushroom polysaccharides was developed, but it is time-consuming. As a way to enablea fast and efficient extraction, a set of improvements was proposed, allowing for obtaining water-soluble polysaccha-rides in half the time of the original method. Similar yield, composition, molecular weight, homogeneity and conforma-tion of polysaccharides obtained demonstrated that the optimised method could be explored as a fast and efficient way to obtain water-soluble non-digestible polysaccharides from mushrooms.
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| 2. |
- Castro Alves, Victor, 1986-, et al.
(författare)
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Total Soluble Phenolic Compounds Quantification Is Not As Simple As It Seems
- 2015
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Ingår i: Food Analytical Methods. - New York : Springer. - 1936-9751 .- 1936-976X. ; 8:4, s. 873-884
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Tidskriftsartikel (refereegranskat)abstract
- Despite the important role of total soluble phenoliccompounds (TSPC) in plant and human health, a large numberof studies that have evaluated the TSPC in food matrices didnot consider possible interfering compounds such as solublesugars, ascorbic acid (AA), and other reducing compounds inthe Folin-Ciocalteu (F-C) quantification method. Thus, thepresent study describes steps for the optimization of a meth-odology to extract the TSPC using banana leaves as an exam-ple. In addition, the method was tested using ascorbate oxi-dase (AOX) as a tool to determine and emphasize the impor-tance of the evaluation of AA interference in food productsusing orange juice as an example. The results showed that twoextraction cycles with 80 % acetone and a posterior hexaneextraction cycle to remove the excess of chlorophylls wereable to obtain a good TSPC extraction yield from bananaleaves without extracting compounds that may interfere withthe F-C method. The methodology has proven to be accurate,precise, simple, rapid, and inexpensive. Additionally, an over-estimation of the TSPC levels in AA-rich matrices was provenusing orange juice as an example. Finally, it was demonstratedthat the use of AOX could be a useful and simple tool to verifyand reduce the AA interference. This work proves and em-phasizes the importance of evaluating the yield of the extrac-tion and interferences in the quantification of the TSPC invegetal-derived foods, which are complex matrices thatshould be cautiously evaluated.
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| 3. |
- Dutta, Paresh
(författare)
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Analytical Methods for Quantification of Modified Fatty Acids and Sterols Formed as a Result of Processing
- 2009
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Ingår i: Food Analytical Methods. - : Springer Science and Business Media LLC. - 1936-9751 .- 1936-976X. ; 2, s. 30-40
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Tidskriftsartikel (refereegranskat)abstract
- Fats and oils are often submitted to technological treatments before being consumed. Some treatments like refining, hydrogenation, and frying often lead to the formation of modified fatty acids such as cyclic fatty acid monomers (CFAM), geometrical fatty acid isomers, and/or oxidized fatty acids and sterols (cholesterol and phytosterols). Both cholesterol oxidation products (COP) and phytosterol oxidation products (POP), may be present in foods. As some of the newly formed components may present some adverse effects upon consumption, methods have been developed to analyze these compounds in food products and biological samples. Gas liquid chromatography (GC) on long polar columns (100m) is a good choice to quantify trans mono- and poly-unsaturated fatty acids. In some cases a pre-fractionation step using silver nitrate thin layer chromatography (AgNO3-TLC) may be necessary to avoid GC overlapping of cis and trans isomers. Analysis of CFAM usually involves transformation of the sample in fatty acid methyl esters (FAME) which after addition of an internal standard (IS) are further hydrogenated. An enrichment step using reverse phase high performance liquid chromatography (RP-HPLC) permits to obtain a fraction which consists of a mixture of CFAM and the IS. This fraction is further analyzed by GC on a polar column. The analysis of oxidized triacylglycerol monomers (oxTG) as a group was feasible by a combination of adsorption and size-exclusion chromatography. Quantification in used frying fats and oils around the limit of rejection for human consumption (25% polar compounds) has shown that the amount of oxTG range 5.9-9.4% expressed on fat or oil weight. In foods and biological tissues, the level of oxidized sterols (SOP) is often a very small fraction of their unoxidized forms. Analysis of SOP involved extraction of lipids, saponification or transesterification, enrichment, and subsequent qualitative and quantitative determination by GC and GC-MS, or HPLC and HPLC-MS. In addition, enrichment of SOP requires complete separation from the unoxidized sterols in order to separate these compounds even by high resolution GC capillary columns.
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| 4. |
- Grønlund, H. A., et al.
(författare)
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The use of infrared thermography as a novel approach for real-time validation of PCR thermocyclers
- 2010
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Ingår i: Food Analytical Methods. - : Springer Science and Business Media LLC. - 1936-9751 .- 1936-976X. ; 3:2, s. 116-119
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Tidskriftsartikel (refereegranskat)abstract
- Validation of PCR thermocycler performance is crucial to obtain reliable results. In this study, infrared (IR) thermography was evaluated as a novel validation tool. After stabilisation, no significant difference in the temperatures recorded using thermography and a reference block-based system was found. By employing IR thermography, information about the length of the time until temperature stabilisation in the sample could be obtained. This study shows the potential of using IR thermography for validation of thermocyclers. © Springer Science + Business Media, LLC 2009.
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| 5. |
- Hefni, Mohammed E., et al.
(författare)
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A HPLC-UV Method for the Quantification of Phenolic Acids in Cereals
- 2019
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Ingår i: Food Analytical Methods. - : Springer. - 1936-9751 .- 1936-976X. ; 12:12, s. 2802-2812
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Tidskriftsartikel (refereegranskat)abstract
- Cereals are a good source of phenolic acids, most of which are present in bound form. The aim of this study was to develop a method for quantifying total phenolic acids in cereals that includes a robust step for hydrolysis of bound forms. Different hydrolysis procedures were evaluated. Acid hydrolysis, even with subsequent use of enzymes, proved unsuitable for releasing bound phenolic acids from the cereal matrix. Base hydrolysis (3 M, 90 min) resulted in the highest extractability, with average recoveries of 88-108% for cereal phenolic acids. The phenolic acid content in cereals (two cultivars each of rye, barley, and oats, and eight cultivars of wheat) varied up to 2-fold between cereal genotypes and 1.5-fold within genotypes. The highest content was found in rye, followed by wheat, barley, and oats. Ferulic acid dominated in all cereals, amounting to 48-72% of total phenolic acid content.
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| 6. |
- Hefni, Mohammed E., et al.
(författare)
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A Simple HPLC Method with Fluorescence Detection for Choline Quantification in Foods
- 2015
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Ingår i: Food Analytical Methods. - : Springer Science and Business Media LLC. - 1936-9751 .- 1936-976X. ; 8:9, s. 2401-2408
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Tidskriftsartikel (refereegranskat)abstract
- A high-performance liquid chromatography–fluorescence detection (HPLC-FLD) method was developed and validated for choline quantification in foods. Samples were extracted by homogenizing in chloroform/methanol/water and hydrolyzing in HCl-acetonitrile. Choline was derivatized using 1-naphthyl isocyanate and quantified by HPLC-fluorescence detection. Average recovery using choline iodide as the standard (n = 6) ranged from 84 ± 6 % for whole-wheat flour to 106 ± 5 % for milk. Recovery after addition of dietary lecithin to two different food matrices faba beans and for whole-wheat flour (n = 6) was 83 ± 5 %. The precision of the analysis (coefficient of variation) ranged from 2 to 13 %. Accuracy was evaluated by analyzing dietary lecithin using HPLC-FLD, liquid chromatography–mass spectrometry, and nuclear magnetic resonance, which across the different methods agreed within 15 %. This method was applied to quantify the choline content in different food matrices, and provides a simple, inexpensive method that could be widely used.
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| 7. |
- Hefni, Mohammed E., et al.
(författare)
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Validation of HPLC-UV Methods for the Quantification of Betaine in Foods by Comparison with LC-MS
- 2016
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Ingår i: Food Analytical Methods. - : Springer Science and Business Media LLC. - 1936-9751 .- 1936-976X. ; 9:2, s. 292-299
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Tidskriftsartikel (refereegranskat)abstract
- The importance of dietary betaine is increasingly recognized. The aim of this study was to develop a simple high-performance liquid chromatography with standard ultraviolet spectrometric detection (HPLC-UV) method for betaine (N,N,N-trimethylglycine) determination in foods after derivatization. Two methods were used for betaine derivatization. Thereafter, derivatized betaine was quantified using HPLC-UV, and the results were compared with liquid chromatography mass spectrometry (LC-MS). The established derivatizing agent 2′-naphthacyl triflate and a novel derivatizing agent 2-bromo-2′-acetonaphthone produced the same cationic derivative when they react with betaine. The calibration curves were linear up to 1000 μmol/L (R 2 = 0.9974 for 2′-naphthacyl triflate and 0.9995 for 2-bromo-2′-acetonaphthone). The limit of detection was 1 μmol/L for both methods (2′-naphthacyl triflate and 2-bromo-2′-acetonaphthone), confirming sufficient sensitivity for betaine quantification in foods. The average recovery from different food matrices (wheat flour and spinach) (n = 12) was 99 ± 9 %, 95 ± 10 %, and 101 ± 8 % for LC-MS, 2′-naphthacyl triflate, and 2-bromo-2′-acetonaphthone, respectively. Inter- and intra-assay coefficients of variation (CVs) in the control samples (whole wheat flour) were below 10 %. Quantitative results for foods analyzed using 2′-naphthacyl triflate and 2-bromo-2′-acetonaphthone were comparable to LC-MS (R 2 = 0.992 and 0.990), respectively. The highest betaine content (~160 mg/100 g) was found in spinach followed by faba bean, wheat flour, and beetroot. These methods can be widely used for betaine quantification because of the simplicity of the derivatization procedures, and the commercial availability of the derivatizing reagent (2-bromo-2′-acetonaphthone) or through the relatively easy synthesis of 2-naphthacyl triflate.
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| 8. |
- Löfström, Charlotta, et al.
(författare)
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Validation of a Diagnostic PCR Method for Routine Analysis of Salmonella spp. in Animal Feed Samples
- 2008
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Ingår i: Food Analytical Methods. - : Springer Science and Business Media LLC. - 1936-9751 .- 1936-976X. ; 1:1, s. 23-27
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Tidskriftsartikel (refereegranskat)abstract
- As a part of a validation study, a comparative study of a PCR method and the standard culture-based method NMKL-71, for detection of Salmonella, was performed according to the validation protocol from the Nordic validation organ for validation of alternative microbiological methods (NordVal) on 250 artificially or naturally contaminated animal feed samples. The PCR method is based on culture enrichment in buffered peptone water followed by PCR using the DNA polymerase Tth and an internal amplification control. No significant difference was found between the two methods. The relative accuracy, relative sensitivity and relative specificity were found to be 96.0, 97.3, and 98.8%, respectively. PCR inhibition was observed for rape seed samples. For the acidified feed samples, more Salmonella-positive samples were found with the PCR method compared to the NMKL method. This study focuses on the growing demand for validated diagnostic PCR methods for routine analysis of animal feed and food samples to assure safety in the food production chain.
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| 9. |
- Merino, Leonardo
(författare)
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Development and Validation of a Method for Determination of Residual Nitrite/Nitrate in Foodstuffs and Water After Zinc Reduction
- 2009
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Ingår i: Food Analytical Methods. - : Springer Science and Business Media LLC. - 1936-9751 .- 1936-976X. ; 2, s. 212-220
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Tidskriftsartikel (refereegranskat)abstract
- An environmentally friendly and cost-effective spectrophotometric method to analyze nitrate and/or nitrite was developed. The method is based on reduction of nitrate with zinc powder (instead of the cadmium or enzymes used in the standard methods approved by ISO/CEN). The initial nitrite concentration and total nitrite after reduction are determined by the very sensitive and widely used diazotization-coupling Griess reaction. A single-laboratory validation was applied in five different matrices (vegetable, meat product, baby food, dairy product, and surface water). The results show that the new method fulfills the international criteria for precision and recovery. The limit of detection for several matrices, calculated using fortified samples, ranged from 3 to 5 mg/kg for both nitrite and nitrate. Furthermore, the results obtained were in good agreement with those obtained using the CEN method (HPLC) and the ISO method (Cd reduction).
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| 10. |
- Nyström, Josefina, et al.
(författare)
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Solvent and Rotating Bed Reactor Extraction with One- and Two-Phase Solvents Applied to Bilberries (Vaccinium myrtillus) for Isolating Valuable Antioxidants
- 2020
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Ingår i: Food Analytical Methods. - : Springer Science and Business Media LLC. - 1936-9751 .- 1936-976X. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Extraction of antioxidants from bilberries using solvent extraction and the novel rotating bed reactor (RBR) both with one-phase (ethanol and water) and two-phase (ethanol and water +salt) solvents was studied. Solids, ethanol, and temperature settings in an experimental design were monitored for 1 h. The measured responses were (1) polyphenol concentration, (2) visible-near infrared spectra, and (3) HPLC measurement. The (1) responses were used for making response surfaces in time and the spectra (2) could confirm these results. The HPLC results (3) confirmed the results of 1 and 2 but were found unsuitable for online monitoring. The RBR was better than traditional extraction and 16 min sufficed. The response surfaces showed an optimal concentration of ethanol, temperatures above 50 degrees C gave the best results, and high loads of solid were beneficial. Two-phase extraction was less efficient. The methodology could be transferred to larger scale extraction systems to improve yield and save on reagents/energy cost.
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| 11. |
- Plaza, Merichel, et al.
(författare)
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Green and Efficient Extraction Method to Determine Polyphenols in Cocoa and Cocoa Products
- 2017
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Ingår i: Food Analytical Methods. - : Springer Science and Business Media LLC. - 1936-9751 .- 1936-976X. ; 10:8, s. 2677-2691
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Tidskriftsartikel (refereegranskat)abstract
- Cocoa and cocoa products have broad and well-proven health benefits, most of which are associated with the high antioxidant capacity of cocoa flavonoids. Most extraction methods for flavonoids in cocoa products use several steps including a defatting step and large amount of organic solvents. Moreover, they are labor-intensive and time-consuming. In this work, a pressurized hot water extraction (PHWE) method has been compared to conventional sonication extraction (CSE) method. The contribution of individual compounds to the total antioxidant capacity of the extracts was evaluated by developing an analytical technique consisting of high-performance liquid chromatography (HPLC) with photodiode array coupled to electrochemical and to charged aerosol detectors and HPLC-mass spectrometry for the confirmation of the identity of compounds present. Additionally, procyanidins were analyzed by fluorescence detection. PHWE turned out to be more efficient in extracting phenolics and methylxanthines, as compared to the conventional method, in addition to being more “green” in terms of using less organic solvents.
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