Honey authentication: effect of irradiation and ageing on near-infrared (NIR) spectroscopy classification models
| dc.contributor.advisor | Manley, Marena | en_ZA |
| dc.contributor.advisor | Williams, Paul James | en_ZA |
| dc.contributor.advisor | Allsopp, Mike | en_ZA |
| dc.contributor.author | Rust, Alexandra Elizabeth | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of AgriSciences. Dept. of Food Science. | en_ZA |
| dc.date.accessioned | 2020-02-26T07:39:05Z | |
| dc.date.accessioned | 2020-04-28T15:15:45Z | |
| dc.date.available | 2020-02-26T07:39:05Z | |
| dc.date.available | 2020-04-28T15:15:45Z | |
| dc.date.issued | 2020-03 | |
| dc.description | Thesis (MScFoodSc)--Stellenbosch University, 2020. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: Near-infrared (NIR) spectroscopy was used to investigate the effects of syrup dilution, ageing, storage temperature and irradiation treatment on the NIR spectra of honey. Additionally, NIR spectroscopy and partial least squares discriminant analysis (PLS-DA) were employed to develop a classification model for the rapid screening of high-fructose corn syrup (HFCS) and invert cane sugar syrup (ICSS) diluted honey. Detection of irradiation treatment was also investigated, to assess NIR spectroscopy-based models as a potential screening tool for detecting mislabelled honey. Unfiltered and unheated honey samples (n = 17) obtained from South African beekeepers were uniformly strained and subjected to treatment combinations of 10 kGy gamma irradiation and dilution with 0, 10 or 20% (w/w) ICSS or HFCS to create sub-samples (n = 174) which were stored at 25°C. Another three undiluted subsets were stored at 4°C, 40°C and in uncontrolled ambient conditions (n = 51). A benchtop BÜCHI Fourier transform-near infrared (FT-NIR) spectrometer and a portable MicroNIR NIR spectrometer, with ranges of 1000–2500 nm and 908-1676 nm respectively, were used to acquire triplicate spectral measurements, over a period of 9 months. ANOVA-simultaneous component analysis (ASCA) indicated that honey type, diluent type, storage temperature and age had significant (p > 0.05) effects on the spectral dataset, while diluent level and irradiation treatment did not. Despite this, irradiation treatment was found to reduce the validation accuracy and efficacy of authentication models, by 5.82% and 7.19% respectively, when PLS-DA models based on only irradiated and only non-irradiated spectral data were compared, suggesting that authentication may be impeded by irradiation treatment to some degree. However, a PLS-DA model discriminating on the basis of irradiation treatment obtained an unsuccessful validation classification of 59.7%, suggesting that there is little or no utilisable effect of irradiation on the spectral data. The best-performing authentication solutions were individual two-class PLS-DA models for detecting ICSS (75.95% accuracy, 86.31% sensitivity) and HFCS (73.95% accuracy, 82.14% sensitivity) dilution, which demonstrated predictive power adequate for screening purposes. PLS-DA models based on spectral data acquired with the benchtop BÜCHI instrument performed best when compared with the portable MicroNIR instrument and its two sample presentation formats. Despite this, the MicroNIR with Teflon cup sample presentation was shown to be a feasible and cost-effective alternative, demonstrating similar accuracies (70.0-75.47%) and efficiencies (68.22-74.51%). In addition, quantification of the level of diluent with partial least squares regression (PLSR) was poor for both ICSS (R2 Pred = 0.118, RMSEP = 6.795%) and HFCS (R2 Pred = 0.147, RMSEP = 6.596%) dilutions. This was attributed to an inadequate range of dilution levels in the reference data, as well as the insignificant effect (p < 0.05) of diluent level on the overall variation in the spectral data. The findings of this study highlighted the potential shortcomings of NIR spectroscopy models in providing definite authentication, while demonstrating the capabilities of this technique for authenticity screening. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Naby-infrarooi (NIR) spekroskopie is gebruik om die effekte van stroop verdunning, veroudering, stoortemperatuur en bestraling behandeling op heuning se NIR spektra te ondersoek. NIR spekroskopie, gekombineer met parsiёle kleinste kwadrate diskriminantanalise (PLS-DA), is ook aangewend om ’n klassifikasie model te ontwikkel wat kan onderskei tussen outentieke heuning en heuning wat met hoё- fruktose mieliestroop (HFCS) of omgekeerde suikerriet stroop (ICSS) verdun is. Bepaling van vorige bestraling behandeling is ook ondersoek, om NIR spekroskopie-gebasseerde modelle te assesseer as ‘n moontlike hulpmiddel vir die identifisering van bedrieglik-geetiketteerde heuning. Rou, ongefiltreerde heuningmonsters (n = 17) verkry van Suid-Afrikaanse byeboere is eenvormig gesyg en met behandelingskombinasies van 10 kGy bestraling en verdunning met 0, 10 en 20% (w/w) ICSS en HFCS onderverdeel (n = 174). Nog drie outentiek en onverdunde deelversamelings is by 4°C, 40°C en in onbeheerde omringende toestande gebêre (n = 51). ’n Laboratorium BÜCHI Fourier-transformasie nabyinfrarooi (FT-NIR) spekrofotometer en ‘n draagbare MicroNIR NIR spekrofotometer, met golflengte reekse van 1000–2500 nm en 908-1676 nm, onderskeidelik, is gebruik om spektra in triplikaat te versamel, oor ’n tydperk van 9 maande. ANOVA-gelyktydige komponentanalise (ASCA) het aangedui dat heuningtipe, verdunningsmiddeltipe, stoortemperatuur en ouderdom beduidende (p > 0.05) effekte op die spektrale datastel het, terwyl verdunningsvlak en bestraling geen beduidende effek het nie. Ten spyte hiervan, is bestraling verantwoordelik vir ‘n 5.82% en 7.19% vermindering van validasie akkuraatheid en doeltreffenheid, onderskeidelik, wanneer PLS-DA modelle wat op bestraalde en onbestraalde spektrale data gebou is, vergelyk is. Dit dui daaraan dat bestraling behandeling, heuning egtheid verifikasie tot ’n mate kan belemmer. Egter kon PLS-DA onderskeiding van bestraling behandeling ’n onsuksesvolle validasie akkuraatheid van slegs 59.7% behaal. Dié resultaat stel voor dat bestraling geen bruikbare effek op die spektrale data het nie. Afsonderlike twee-klas PLS-DA modelle vir ICSS (75.95% akkuraatheid, 86.31% sensitiwiteit) en HFCS (73.95% akkuraatheid, 82.14% sensitiwiteit) verdunningbepaling is as die mees effektiewe verifikasieoplossing bevind, en het voldoende voorspellingskrag vir keuring gedemonstreer. PLS-DA modelle wat op die BÜCHI laboratorium spekrofotometer data gebou is, het beter opgetree as dié wat op die draagbare MicroNIR spekrofotometer, en albei die MicroNIR se monsterhouers, gebaseer is. Ten spyte hiervan, bied die MicroNIR, met die Teflonhouer, soortgelyke akkuraatheid (70.0-75.47%) en doeltreffenheid (68.22- 74.51%) aan, en is dus bewys as ’n haalbare en koste-effektiewe alternatief. Kwantifisering van verdunningsvlak met parsiёle kleinste kwadrate regressie (PLSR) het swak vertoning gewys vir beide ICSS (R2 Pred = 0.118, RMSEP = 6.795%) en HFCS (R2 Pred = 0.147, RMSEP = 6.596%) verdunnings. Hierdie resultaat is toegeskryf aan die onvoldoende verskeidenheid van verdunningsvlakke in die verwysingsdata, asook die onbeduidende (p < 0.05) effek van verdunningsvlak op die algehele variasie van die spektrale data. Die resultate van hierdie studie beklemtoon NIR spekroskopie se moontlike tekortkominge vir die doeleindes van heuning egtheid verifikasie, maar demonstreer ook die geskiktheid van hierdie tegniek vir heuning egtheid keuring. | af_ZA |
| dc.description.version | Masters | en_ZA |
| dc.format.extent | xii, 123 pages : illustrations (some color) | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/108482 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | Near-infrared spectroscopy | en_ZA |
| dc.subject | Syrup dilution | en_ZA |
| dc.subject | Storage temperature | en_ZA |
| dc.subject | Honey -- Africa, Southern | en_ZA |
| dc.subject | Beekeepers -- South Africa | en_ZA |
| dc.subject | Honey -- Storage | en_ZA |
| dc.subject | Bee culture | en_ZA |
| dc.subject | Honey -- Flavor and odor | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.title | Honey authentication: effect of irradiation and ageing on near-infrared (NIR) spectroscopy classification models | en_ZA |
| dc.type | Thesis | en_ZA |