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The use of near infrared spectroscopy for the analysis of fumonisins
Thesis (PhDFoodSc)--Stellenbosch University, 2025.
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613898648059904 |
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| access_status_str | Open Access |
| author | Laubscher, Anja |
| author2 | Williams, Paul James |
| author_browse | Laubscher, Anja Williams, Paul James |
| author_facet | Williams, Paul James Laubscher, Anja |
| author_sort | Laubscher, Anja |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhDFoodSc)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132615 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:43:27.297Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132615 The use of near infrared spectroscopy for the analysis of fumonisins Laubscher, Anja Williams, Paul James Rose, Lindy Joy Stellenbosch University. Faculty of Agrisciences. Dept. of Food Science. Fumonisins -- Analysis Food contamination Infrared spectroscopy -- Analysis Mycotoxins Plants -- Effect of mycotoxins on Fungal diseases of plants Fusarium Corn -- Diseases and pests Maize industry UCTD Thesis (PhDFoodSc)--Stellenbosch University, 2025. Laubscher, A. 2025. The use of near infrared spectroscopy for the analysis of fumonisins. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/5eaeba57-68c8-42d9-8cd5-6b5c1a1dc60d ENGLISH ABSTRACT: Fumonisins are mycotoxins produced by Fusarium fungi, which regularly contaminate maize, a staple food in Africa. Their dietary intake has resulted in nephrotoxic, hepatotoxic, immunosuppressive, and carcinogenic effects in both humans and animals. Mycotoxin surveillance is critical in limiting consumer exposure and requires rapid, accurate, and cost-effective analysis techniques. Near-infrared (NIR) spectroscopy has, therefore, gained considerable interest. However, its potential to analyse fumonisins has been associated with detecting spectral changes caused by indirect factors such as the mycotoxigenic fungi and their effects on maize, which may reduce sensitivity to the toxin. This study explores the feasibility of using NIR spectroscopy (1000 – 2500 nm) for the direct analysis of fumonisins. To establish the potential fumonisin absorbance bands and whether they can be detected at mg.kg-1 concentrations, fumonisin B1 (FB1) was first analysed in methanol. Partial least squares discriminant analysis (PLS-DA) detected 100 mg.kg-1 FB1 dissolved in methanol with a perfect classification accuracy, and potential FB1 absorbance bands were identified from the regression coefficients. The concentrations at which FB1 can be detected were further explored by analysing 1 - 100 mg.kg-1 FB1 dilutions in water. Similar bands were identified as meaningful, confirming their association with FB1, and the PLS-DA models indicated that FB1 detection above 4 mg.kg-1 in water was possible, with accuracies exceeding 72%. To confirm whether direct FB1 analysis in maize at these low concentrations is feasible, the spectra of whole (intact) and ground maize artificially contaminated with 0.5 – 10 mg.kg-1 FB1 were analysed. The whole maize samples yielded poor results and were unsuitable for fumonisin analysis. However, the partial least squares (PLS) regression model developed for the ground maize samples, initially scanned in order of increasing FB1 concentrations, achieved excellent results with a coefficient of determination (R2p) of 0.98 for validation. However, when the maize samples were randomly scanned, the model performance drastically decreased (R2p = 0.03). This discrepancy was attributed to the effects of systematic noise that, even under controlled conditions, interfered with the analysis of FB1 in artificially contaminated maize. Finally, to confirm the potential of NIR spectroscopy for the direct analysis of FB1, whole and ground maize inoculated with Fusarium verticillioides were analysed. Whole maize again yielded performances unsuitable for fumonisins analysis. However, the PLS model of ground maize achieved good and reliable results (R2p = 0.77). Furthermore, PLS-DA could classify the samples with 100% accuracy at the 2 mg.kg-1 maximum levels legislated in South Africa. Wavelengths similar to those previously determined as potential FB1 absorbance bands were identified, and the performance of the model reconstructed on them (R2p = 0.80) indicated that they contain valuable information for FB1 prediction. However, it was determined that the mycotoxigenic fungi also influenced these bands. Additionally, NIR spectroscopy obtained better results in analysing maize contaminated with Fusarium compared to artificially FB1-contaminated samples. These results confirmed the value of NIR spectroscopy as an indirect fumonisin analysis method. This study demonstrates NIR spectroscopy’s effectiveness as a fumonisins screening method in maize, providing valuable insights for its implementation in the maize industry. AFRIKAANSE OPSOMMING: Fumonisiene is mikotoksiene wat deur Fusarium swamme geproduseer word en gereeld mielies, ‘n stapelvoedsel in Afrika, kontamineer. Hul dieet-inname het gelei tot nefrotoksiese, hepatotoksiese, immuunonderdrukkende en kankerverwekkende effekte in beide mense en diere. Mikotoksien-toesig is van kritieke belang om verbruikersblootstelling te beperk en vereis vinnige, akkurate en koste-effektiewe ontledingstegnieke. Naby infrarooi (NIR) spektroskopie het dus aansienlike belangstelling verwerf. Die potensiaal daarvan om fumonisiene te ontleed is egter geassosieer met die opsporing van spektrale veranderinge wat veroorsaak word deur indirekte faktore soos die mikotoksiese swamme en hul uitwerking op mielies, wat sensitiwiteit vir die toksien kan verminder. Hierdie studie ondersoek die uitvoerbaarheid van die gebruik van NIR spektroskopie (1000 – 2500 nm) vir die direkte ontleding van fumonisiene. Om die potensiële fumonisien absorpsiebande vas te stel en of dit by mg.kg⁻¹ konsentrasies opgespoor kan word, is fumonisien B1 (FB1) eers in metanol geanaliseer. Gedeeltelike kleinste kwadrate diskriminant analise (PLS-DA) het 100 mg.kg⁻¹ FB1 opgelos in metanol met 'n perfekte klassifikasie akkuraatheid opgespoor, en potensiële FB1 absorpsiebande is geïdentifiseer vanaf die regressiekoëffisiënte. Die konsentrasies waarteen FB1 opgespoor kan word, is verder ondersoek deur 1 - 100 mg.kg⁻¹ FB1 verdunnings in water te ontleed. Soortgelyke bande is as betekenisvol geïdentifiseer, wat hul assosiasie met FB1 bevestig, en die PLS-DA modelle het aangedui dat FB1 deteksie bo 4 mg.kg⁻¹ in water moontlik was, met akkuraathede van meer as 72%. Om te bevestig of direkte FB1 analise in mielies by hierdie lae konsentrasies uitvoerbaar is, is die spektra van heel (intakte) en gemaalde mielies, wat kunsmatig met 0.5 – 10 mg.kg⁻¹ FB1 besmet is, geanaliseer. Die heel mieliemonsters het swak resultate opgelewer en was ongeskik vir fumonisien analise. In kontras, het die gedeeltelike kleinste kwadrate (PLS) regressiemodel wat ontwikkel is vir die gemaalde mieliemonsters, wat aanvanklik in volgorde van toenemende FB1 konsentrasies geskandeer is, uitstekende resultate behaal met ’n bepalingskoëffisiënt (R²p) van 0.98 vir validering. Wanneer die mieliemonsters egter willekeurig geskandeer was, het die model se werkverrigting drasties afgeneem (R²p = 0.03). Hierdie teenstrydigheid is toegeskryf aan die uitwerking van sistematiese geraas wat, selfs onder beheerde toestande, die analise van FB1 in kunsmatig besmette mielies geafekteer het. Laastens, om die potensiaal van NIR spektroskopie vir die direkte analise van FB1 te bevestig, is heel en gemaalde mielies, geïnnokuleer met Fusarium verticillioides, geanaliseer. Heel mielies het weer prestasies opgelewer wat ongeskik was vir fumonisien analise. Die PLS-model van gemaalde mielies het egter goeie en betroubare resultate behaal (R²p = 0.77). Verder kon PLS-DA die monsters met 100% akkuraatheid klassifiseer by die 2 mg.kg⁻¹ maksimum vlakke wat in die Suid-Afrikaanse wetgewing gestipuleer is. Golflengtes soortgelyk aan dié wat vroeër bepaal is as potensiële FB1 absorpsiebande, is geïdentifiseer, en die prestasie van die model wat op hierdie golflengtes herbou is (R²p = 0.80) het aangedui dat dit waardevolle inligting vir FB1 voorspelling bevat. Dit is egter bepaal dat die mikotoksiese swamme ook hierdie bande beïnvloed het. Boonop die bevinding, het NIR spektroskopie beter resultate behaal vir die analise van Fusarium besmette mielies in vergelyking met mielies kunsmatig besmet met FB1. Hierdie resultate het die waarde van NIR spektroskopie as 'n indirekte fumonisien analise metode bevestig. Die studie demonstreer NIR spektroskopie se doeltreffendheid as 'n “screening” metode vir fumonisiene in mielies en bied waardevolle insigte vir die implementering daarvan in die mieliebedryf. Doctoral 2025-06-11T14:02:06Z 2025-06-11T14:02:06Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132615 Stellenbosch University xv, 10 unnumbered pages, 141 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Fumonisins -- Analysis Food contamination Infrared spectroscopy -- Analysis Mycotoxins Plants -- Effect of mycotoxins on Fungal diseases of plants Fusarium Corn -- Diseases and pests Maize industry UCTD Laubscher, Anja The use of near infrared spectroscopy for the analysis of fumonisins |
| title | The use of near infrared spectroscopy for the analysis of fumonisins |
| title_full | The use of near infrared spectroscopy for the analysis of fumonisins |
| title_fullStr | The use of near infrared spectroscopy for the analysis of fumonisins |
| title_full_unstemmed | The use of near infrared spectroscopy for the analysis of fumonisins |
| title_short | The use of near infrared spectroscopy for the analysis of fumonisins |
| title_sort | use of near infrared spectroscopy for the analysis of fumonisins |
| topic | Fumonisins -- Analysis Food contamination Infrared spectroscopy -- Analysis Mycotoxins Plants -- Effect of mycotoxins on Fungal diseases of plants Fusarium Corn -- Diseases and pests Maize industry UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132615 |
| work_keys_str_mv | AT laubscheranja theuseofnearinfraredspectroscopyfortheanalysisoffumonisins AT laubscheranja useofnearinfraredspectroscopyfortheanalysisoffumonisins |