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Lösel H, Arndt M, Wenck S, Hansen L, Oberpottkamp M, Seifert S, Fischer M. Exploring the potential of high-resolution LC-MS in combination with ion mobility separation and surrogate minimal depth for enhanced almond origin authentication. Talanta 2024; 271:125598. [PMID: 38224656 DOI: 10.1016/j.talanta.2023.125598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 12/20/2023] [Accepted: 12/22/2023] [Indexed: 01/17/2024]
Abstract
Almonds (Prunus dulcisMill.) are consumed worldwide and their geographical origin plays a crucial role in determining their market value. In the present study, a total of 250 almond reference samples from six countries (Australia, Spain, Iran, Italy, Morocco, and the USA) were non-polar extracted and analyzed by UPLC-ESI-IM-qToF-MS. Four harvest periods, more than 30 different varieties, including both sweet and bitter almonds, were considered in the method development. Principal component analysis showed that there are three groups of samples with similarities: Australia/USA, Spain/Italy and Iran/Morocco. For origin determination, a random forest achieved an accuracy of 88.8 %. Misclassifications occurred mainly between almonds from the USA and Australia, due to similar varieties and similar external influences such as climate conditions. Metabolites relevant for classification were selected using Surrogate Minimal Depth, with triacylglycerides containing oxidized, odd chained or short chained fatty acids and some phospholipids proven to be the most suitable marker substances. Our results show that focusing on the identified lipids (e. g., using a QqQ-MS instrument) is a promising approach to transfer the origin determination of almonds to routine analysis.
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Affiliation(s)
- Henri Lösel
- Hamburg School of Food Science - Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146, Hamburg, Germany
| | - Maike Arndt
- Hamburg School of Food Science - Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146, Hamburg, Germany
| | - Soeren Wenck
- Hamburg School of Food Science - Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146, Hamburg, Germany
| | - Lasse Hansen
- Hamburg School of Food Science - Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146, Hamburg, Germany
| | - Marie Oberpottkamp
- Hamburg School of Food Science - Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146, Hamburg, Germany
| | - Stephan Seifert
- Hamburg School of Food Science - Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146, Hamburg, Germany
| | - Markus Fischer
- Hamburg School of Food Science - Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146, Hamburg, Germany.
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Wenck S, Mix T, Fischer M, Hackl T, Seifert S. Opening the Random Forest Black Box of 1H NMR Metabolomics Data by the Exploitation of Surrogate Variables. Metabolites 2023; 13:1075. [PMID: 37887402 PMCID: PMC10608983 DOI: 10.3390/metabo13101075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 10/05/2023] [Accepted: 10/10/2023] [Indexed: 10/28/2023] Open
Abstract
The untargeted metabolomics analysis of biological samples with nuclear magnetic resonance (NMR) provides highly complex data containing various signals from different molecules. To use these data for classification, e.g., in the context of food authentication, machine learning methods are used. These methods are usually applied as a black box, which means that no information about the complex relationships between the variables and the outcome is obtained. In this study, we show that the random forest-based approach surrogate minimal depth (SMD) can be applied for a comprehensive analysis of class-specific differences by selecting relevant variables and analyzing their mutual impact on the classification model of different truffle species. SMD allows the assignment of variables from the same metabolites as well as the detection of interactions between different metabolites that can be attributed to known biological relationships.
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Affiliation(s)
- Soeren Wenck
- Institute of Food Chemistry, Hamburg School of Food Science, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany (M.F.); (T.H.)
| | - Thorsten Mix
- Institute of Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany;
| | - Markus Fischer
- Institute of Food Chemistry, Hamburg School of Food Science, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany (M.F.); (T.H.)
| | - Thomas Hackl
- Institute of Food Chemistry, Hamburg School of Food Science, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany (M.F.); (T.H.)
- Institute of Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany;
| | - Stephan Seifert
- Institute of Food Chemistry, Hamburg School of Food Science, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany (M.F.); (T.H.)
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Loesel H, Shakiba N, Wenck S, Le Tan P, Karstens TO, Creydt M, Seifert S, Hackl T, Fischer M. Food Monitoring: Limitations of Accelerated Storage to Predict Molecular Changes in Hazelnuts ( Corylus avellana L.) under Realistic Conditions Using UPLC-ESI-IM-QTOF-MS. Metabolites 2023; 13:1031. [PMID: 37887356 PMCID: PMC10608644 DOI: 10.3390/metabo13101031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Revised: 09/13/2023] [Accepted: 09/22/2023] [Indexed: 10/28/2023] Open
Abstract
Accelerated storage is routinely used with pharmaceuticals to predict stability and degradation patterns over time. The aim of this is to assess the shelf life and quality under harsher conditions, providing crucial insights into their long-term stability and potential storage issues. This study explores the potential of transferring this approach to food matrices for shelf-life estimation. Therefore, hazelnuts were stored under accelerated short-term and realistic long-term conditions. Subsequently, they were analyzed with high resolution mass spectrometry, focusing on the lipid profile. LC-MS analysis has shown that many unique processes take place under accelerated conditions that do not occur or occur much more slowly under realistic conditions. This mainly involved the degradation of membrane lipids such as phospholipids, ceramides, and digalactosyldiacylglycerides, while oxidation processes occurred at different rates in both conditions. It can be concluded that a food matrix is far too complex and heterogeneous compared to pharmaceuticals, so that many more processes take place during accelerated storage, which is why the results cannot be used to predict molecular changes in hazelnuts stored under realistic conditions.
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Affiliation(s)
- Henri Loesel
- Hamburg School of Food Science, Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany; (H.L.); (N.S.); (S.W.); (P.L.T.); (T.-O.K.); (M.C.); (S.S.); (T.H.)
| | - Navid Shakiba
- Hamburg School of Food Science, Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany; (H.L.); (N.S.); (S.W.); (P.L.T.); (T.-O.K.); (M.C.); (S.S.); (T.H.)
- Institute of Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - Soeren Wenck
- Hamburg School of Food Science, Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany; (H.L.); (N.S.); (S.W.); (P.L.T.); (T.-O.K.); (M.C.); (S.S.); (T.H.)
| | - Phat Le Tan
- Hamburg School of Food Science, Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany; (H.L.); (N.S.); (S.W.); (P.L.T.); (T.-O.K.); (M.C.); (S.S.); (T.H.)
| | - Tim-Oliver Karstens
- Hamburg School of Food Science, Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany; (H.L.); (N.S.); (S.W.); (P.L.T.); (T.-O.K.); (M.C.); (S.S.); (T.H.)
| | - Marina Creydt
- Hamburg School of Food Science, Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany; (H.L.); (N.S.); (S.W.); (P.L.T.); (T.-O.K.); (M.C.); (S.S.); (T.H.)
| | - Stephan Seifert
- Hamburg School of Food Science, Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany; (H.L.); (N.S.); (S.W.); (P.L.T.); (T.-O.K.); (M.C.); (S.S.); (T.H.)
| | - Thomas Hackl
- Hamburg School of Food Science, Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany; (H.L.); (N.S.); (S.W.); (P.L.T.); (T.-O.K.); (M.C.); (S.S.); (T.H.)
- Institute of Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - Markus Fischer
- Hamburg School of Food Science, Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany; (H.L.); (N.S.); (S.W.); (P.L.T.); (T.-O.K.); (M.C.); (S.S.); (T.H.)
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Shakiba N, Lösel H, Wenck S, Kumpmann L, Bachmann R, Creydt M, Seifert S, Fischer M, Hackl T. Analysis of Hazelnuts ( Corylus avellana L.) Stored for Extended Periods by 1H NMR Spectroscopy Monitoring Storage-Induced Changes in the Polar and Nonpolar Metabolome. J Agric Food Chem 2023; 71:3093-3101. [PMID: 36720100 DOI: 10.1021/acs.jafc.2c07498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Storage is a critical step in the post-harvest processing of hazelnuts, as it can lead to mold, rancidity, and off-flavor. However, there is a lack of analytical methods to detect improper or extended storage. To comprehensively investigate the effects of hazelnut storage, samples were stored under five different conditions for up to 18 months. Subsequently, the polar and nonpolar metabolome were analyzed by 1H NMR spectroscopy and chemometric approaches for classification as well as variable selection. Increases in hexanoic, octanoic, and nonanoic acid, all products of lipid oxidation and responsible for quality defects, were found across all conditions. Furthermore, the concentration of free long-chain fatty acids increased in samples stored at high temperatures. Harsh short-term storage resulted in an increase in fumaric and lactic acid, glucose, fructose, and choline and a decrease in acetic acid.
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Affiliation(s)
- Navid Shakiba
- Institute of Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
- Hamburg School of Food Science─Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - Henri Lösel
- Hamburg School of Food Science─Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - Soeren Wenck
- Hamburg School of Food Science─Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - Leif Kumpmann
- Institute of Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - René Bachmann
- Landeslabor Schleswig-Holstein, Max-Eyth-Straße 5, 24537 Neumünster, Germany
| | - Marina Creydt
- Hamburg School of Food Science─Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - Stephan Seifert
- Hamburg School of Food Science─Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - Markus Fischer
- Hamburg School of Food Science─Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
| | - Thomas Hackl
- Institute of Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
- Hamburg School of Food Science─Institute of Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
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Lösel H, Shakiba N, Wenck S, Le Tan P, Arndt M, Seifert S, Hackl T, Fischer M. Impact of Freeze-Drying on the Determination of the Geographical Origin of Almonds (Prunus dulcis Mill.) by Near-Infrared (NIR) Spectroscopy. FOOD ANAL METHOD 2022. [DOI: 10.1007/s12161-022-02329-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractNear-infrared (NIR) spectroscopy is a proven tool for the determination of food authenticity, mainly because of good classification results and the possibility of industrial use due to its easy and fast application. Since water shows broad absorption bands, the water content of a sample should be as low as possible. Freeze-drying is a commonly used preparatory step for this to reduce the water content in the sample. However, freeze-drying, also known as lyophilization, is very time-consuming impeding the widespread usage of NIR analysis as a rapid method for incoming goods inspections. We used a sample set of 72 almond samples from six economically relevant almond-producing countries to investigate the question of how important lyophilization is to obtain a well-performing classification model. For this approach, the samples were ground and lyophilized for 3 h, 24 h, and 48 h and compared to non-freeze-dried samples. Karl-Fischer titration of non-lyophilized samples showed that water contents ranged from 3.0 to 10.5% and remained constant at 0.36 ± 0.13% after a freeze-drying period of 24 h. The non-freeze-dried samples showed a classification accuracy of 93.9 ± 6.4%, which was in the same range as the samples which were freeze-dried for 3 h (94.2 ± 7.8%), 24 h (92.5 ± 8.7%), and 48 h (95.0 ± 9.0%). Feature selection was performed using the Boruta algorithm, which showed that signals from lipids and proteins are relevant for the origin determination. The presented study showed that samples with low water content, especially nuts, can be analyzed without the time-consuming preparation step of freeze-drying to obtain robust and fast results, which are especially required for incoming goods inspection.
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Shakiba N, Gerdes A, Holz N, Wenck S, Bachmann R, Schneider T, Seifert S, Fischer M, Hackl T. Determination of the geographical origin of hazelnuts (Corylus avellana L.) by Near-Infrared spectroscopy (NIR) and a Low-Level Fusion with nuclear magnetic resonance (NMR). Microchem J 2022. [DOI: 10.1016/j.microc.2021.107066] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Wenck S, Creydt M, Hansen J, Gärber F, Fischer M, Seifert S. Opening the Random Forest Black Box of the Metabolome by the Application of Surrogate Minimal Depth. Metabolites 2021; 12:metabo12010005. [PMID: 35050127 PMCID: PMC8781913 DOI: 10.3390/metabo12010005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/16/2021] [Accepted: 12/18/2021] [Indexed: 11/16/2022] Open
Abstract
For the untargeted analysis of the metabolome of biological samples with liquid chromatography–mass spectrometry (LC-MS), high-dimensional data sets containing many different metabolites are obtained. Since the utilization of these complex data is challenging, different machine learning approaches have been developed. Those methods are usually applied as black box classification tools, and detailed information about class differences that result from the complex interplay of the metabolites are not obtained. Here, we demonstrate that this information is accessible by the application of random forest (RF) approaches and especially by surrogate minimal depth (SMD) that is applied to metabolomics data for the first time. We show this by the selection of important features and the evaluation of their mutual impact on the multi-level classification of white asparagus regarding provenance and biological identity. SMD enables the identification of multiple features from the same metabolites and reveals meaningful biological relations, proving its high potential for the comprehensive utilization of high-dimensional metabolomics data.
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Wagner JD, Schauwecker DS, Davidson D, Wenck S, Jung SH, Hutchins G. FDG-PET sensitivity for melanoma lymph node metastases is dependent on tumor volume. J Surg Oncol 2001; 77:237-42. [PMID: 11473371 DOI: 10.1002/jso.1102] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND AND OBJECTIVES The purpose of this study is to determine the tumor volume threshold for successful positron emission tomography (PET) imaging of melanoma nodal metastases. METHODS Review of a clinical series of patients who had FDG-PET imaging of regional lymph node basins followed by lymphadenectomy. Lymph node tumor volumes were calculated from direct measurements of metastatic nodule(s) in formalin fixed specimens. PET scan interpretations were correlated with histology to determine sensitivity. Sensitivity was correlated with the aggregate lymph node tumor volume in the nodal basin and with AJCC stage group. RESULTS Forty-five patients with 49 pathologically positive regional nodal basins comprised the study group. Median total basin tumor volume was 28.3 mm(3)(range 0.004-22,879 mm(3)). FDG-PET sensitivity for detection of all tumor volumes was 0.49. The observed 90% sensitivity threshold for detection of nodal metastases was > or = 78 mm(3). PET sensitivity was 0.14 for detection of tumor volumes < 78 mm(3). PET sensitivity differed by prescan AJCC stage: I-0.0; II-0.24; III-0.81; IV-1.0 (P < 0.001). CONCLUSIONS FDG-PET reliably detects lymph node tumor deposits greater than approximately 80 mm(3) volume, but sensitivity falls rapidly below this. This amount of tumor is most likely to occur in patients with AJCC stage III or IV disease.
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Affiliation(s)
- J D Wagner
- Indiana University School of Medicine, Department of Surgery, Indiana University-Purdue University at Indianapolis, Indianapolis, IN 46202, USA.
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Schwaibold H, Wenck S, Huland E, Huland H. Immunocytologic staining of cytokeratin in bone marrow aspirates to detect micrometastatic cells fails in patients with metastatic urologic carcinoma. Int J Oncol 1997; 11:1197-201. [PMID: 21528322 DOI: 10.3892/ijo.11.6.1197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The detection of cytokeratin-positive cells in bone marrow of patients with various carcinomas is considered an adverse marker. To establish a routine diagnostic procedure to detect these cells in patients with urologic carcinoma, we evaluated different immunocytological techniques in parallel. The study included 50 patients with urologic carcinoma (16 with metastatic disease) and 10 healthy volunteers. Bone marrow was aspirated from the iliac crest; after density centrifugation, cytocentrifuged specimens were stained according to optimized modifications of conventional immunocytologic techniques. Overall only 3% of patients with locally restricted carcinoma and only 19% with metastatic disease showed cytokeratin-positive bone marrow cells. Nonspecific labeling of bone marrow cells in the immunoglobulin isotype controls was a major problem, demonstrating the need for numerous detailed controls. If all nonspecific reactions were excluded, up to 20% of the healthy controls yielded positive results as well. The presence of cytokeratin-positive cells in bone marrow aspirates shows only slight correlation with systemic metastasis. The biologic and clinical relevance of this immunocytologic marker must be judged cautiously.
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