Thesis (PhDFoodSc)--Stellenbosch University, 2024. | ENGLISH ABSTRACT: Dry thermal treatment techniques as a pre-processing method for whole wheat or flour are gaining popularity for enhancing wheat properties. The effect of heat treatment on flour functionality is of critical importance for achieving the desired outcome. This study aimed to investigate the effect of forced convection roasting on the physicochemical, functional and structural properties of whole wheat kernels, flour and starch. Firstly, chemical-structural changes in whole wheat and flour, due to roasting, were investigated by determining the effect of roasting conditions and wheat types on shortwave infrared (SWIR) spectral data using ANOVA simultaneous component analysis (ASCA). Secondly, optimum roasting conditions were determined to (1) enhance flour viscosifying properties and (2) maintain protein integrity of the produced flour. Finally, ¹H time domain (TD) nuclear magnetic resonance (NMR) was used to investigate the molecular dynamics of the starch-water systems during heating and to differentiate between starch isolated from roasted and unroasted wheat as well as maize starch. Changes in whole wheat and flour due to roasting were characterised by determining the effect of roasting temperature, roasting frequency and wheat types on SWIR spectral data by applying ASCA. Roasting at different conditions significantly affected the chemical-structural properties of moisture, protein, starch, lipids and enzymes in wheat and/or flour as observed by the main variations in the loading line plots. Wheat roasting at 115 ºC and 140 ºC significantly affected protein stability in the white flour as well as in the whole wheat flour and kernel, respectively. Milling as well as roasting at 115 ºC and 140 ºC were responsible for starch damage observed in the white and whole wheat flour, respectively. Significant differences between hard and soft wheats were also indicated. Wheat roasting at 115 ºC and 65 Hz was predicted, by response surface methodology (RSM), to be the optimum conditions that would improve flour viscosifying properties. Optimally roasted wheat showed grain puffing, slight damage to the starch granule surface and destruction of the protein matrix. Compared to an unroasted sample, lowered relative crystallinity along with formation of amylose-lipid complexes were observed. Increased viscosities, compared to the control, were attributed to the combined effect of starch and protein properties affected by heat treatment. RSM predicted 108 ºC and 80 Hz as the optimum wheat roasting conditions that would maintain protein integrity. Increased viscosities, compared to the control, were ascribed to conformational changes in protein structures. Proteins were observed to be more heat sensitive than starch. At these optimum conditions, the starch granule structure and relative crystallinity remained relatively unaffected. TD-NMR experiments accurately demonstrated the interaction between starch and water, and the distribution of hydrogen atoms in the starch-water systems. The change in relaxation times enabled differentiation between unroasted, optimally roasted wheat starches and maize starch. Results obtained by TD-NMR, thermal and rheological analysis methods were comparable. The pulse sequences and signal processing methods used identified key characteristics associated with the structural (crystallinity), thermal (onset of gelatinisation) and rheological (maximum stiffness) properties of different starches. TD-NMR was shown in this study to be an effective and simple method to perform crystallinity measurements and study starch gelatinisation. | AFRIKAANSE OPSOMMING: Droë termiese behandelingstegnieke as 'n voorverwerkingsmetode vir volkoring of meel neem toe in gewildheid vir die verbetering van koring eienskappe. Die effek van hittebehandeling op meelfunksionaliteit is van kritieke belang om die gewenste uitkoms te bereik. Die studie het ten doel gehad om die effek van geforseerde konveksie rooster metode op die fisies- chemiese, funksionele en strukturele eienskappe van volkoringpitte, meel en stysel te identifiseer. Eerstens was die chemiese-strukturele veranderinge, as gevolg van rooster, in volkoring en meel ondersoek deur die effek van rooster toestande en koringtipes op kortgolf infrarooi (KGIR) spektrale data te bepaal deur gebruik te maak van ANOVA gelyktydig komponentanalise (ASCA). Tweedens, die optimale roostertoestande wat (1) die meel viskosifiseerende eienskappe verbeter en (2) die proteïenintegriteit van die geproduseerde meel behou is bepaal. Laastens was ¹H tyddomein (TD) kernmagnetiese resonansie (KMR) gebruik om die molekulêre dinamika van die stysel-water mengsels tydens verhitting te ondersoek, asook om te onderskei tussen stysel geïsoleer vanaf geroosterde en ongeroosterde koring, sowel as mieliestysel. Veranderinge in volkoring en meel, as gevolg van rooster, is gekenmerk deur die effek van rooster temperatuur, roosterfrekwensie en koringtipes op KGIR-spektrale data te bepaal deur ASCA toe te pas. Rooster by verskillende toestande het die chemiese-strukturele eienskappe van vog, proteïene, stysel, lipiede en ensieme in koring en/of meel beduidend geaffekteer, soos waargeneem deur die belangrikste variasies in die ladingslyn plotte. Koringrooster by 115 ºC en 140 ºC het die proteïenstabiliteit in die wit meel sowel as in die volkoring meel en pit onderskeidelik, beduidend beïnvloed. Die maal van koring sowel as rooster by 115 ºC en 140 ºC was verantwoordelik vir die styselbeskadiging waargeneem in die onderskeidelike die wit en volkoringmeel. Beduidende verskille tussen hard en sagte koring is ook waargeneem. Koringrooster by 115 ºC en 65 Hz is, volgens reaksie oppervlakmetodologie (RSM), voorspel as die optimale toestande wat meel viskosifiserende eienskappe sal verbeter. Optimaal geroosterde koring het gewys dat korrelpof, geringe skade aan die styselgranuleoppervlak en vernietiging van die proteïenmatriks na vore kom. In vergelyking met ‘n ongeroosterde monster was laer relatiewe kristalliniteit tesame met die vorming van amiloos-lipied komsplekse waargeneem. Verhoogde viskositeit, in vergelyking met die kontrole, is toegskryf aan die gekomineerde effek van stysel- en proteïeneienskappe wat deur hittebehandeling beïnvloed is. RSM het 108 ºC en 80 Hz voorspel as die optimale koringroostertoestande wat proteïen integriteit sal handhaaf. Verhoogde viskositeite, in vergelyking met die kontrole, is toegeskryf aan struktureleveranderinge in die proteïen strukture. Daar is waargeneem dat proteïene meer hitte-sensitief is as stysel. Die styselgranulestruktuur en relatiewe kristalliniteit het by hierdie optimale toestande redelik onveranderd gebly. Die interaksie tussen stysel en water, en die verspreiding van waterstof atome in die stysel-water sisteme is akkuraat met TD-KMR eksperiemente gedemonstreer. Die verandering in die ontspanningstye het dit moontlik gemaak om te onderskei tussen ongeroosterde, optimaal geroosterde koring stysels asook mieliestysel. Die resultate verkry deur TD-KMR, termiese en reologiese metodes is vergelykbaar. Die polsreeks en seinverwerkingsmethodes wat gebruik is, het kenmerke geïdentifiseer wat verband hou met die struksturele (kristalliniteit), termiese (aanvang van gelatienisering) en reologiese (maksimum styfheid) eienskappe van die verskillende stysels. In hierdie studie het TD-KMR getoon om ‘n effektiewe en eenvoudige methode te wees om krialliniteitsmetings te neem en om styselgelatiniseering te bestudeer. | Doctorate

Thesis (M.Sc.Agric.) -- University of Stellenbosch, 1999. | ENGLISH ABSTRACT: Knowledge of the growth, yield and quality response of spring wheat cultivars to high temperatures is important to minimise variation that often exists in yield and breadbaking quality of wheat produced in warmer regions. To achieve this, four South African spring wheat cultivars Kariega, Palmiet, SST 55 and SST 57 were grown under controlled conditions at the University of Stellenbosch during 1998 at temperature regimes of 15/10, 20/15, 25/20 and 30/25°C during grain filling. From seeding till anthesis, plants were grown at a temperature of 15/10°C. In this study,. the highest temperature regime of 30/25°C affected all parameters tested, while at lower temperature regimes cultivars responded differently. The 30/25°C temperature regime caused premature senescence of the leaf area which was attributed to a decrease in relative leaf water content. Increased senescence of leaves at this temperature regime, reduced photosynthesis during grain filling, with the result that shriveled kernels with a lower mass kernel -1 were produced and yield plant -1 was reduced by almost 50% compared to that of the control (15/100 C). Other yield components such as kernels ear -1 were less reduced and Kariega was less affected in comparison with the other cultivars. High temperature regimes of 30/25°C during grain filling resulted in increased flour protein content. Mixogram peak heights increased as post-anthesis temperature regimes increased, while Palmiet also showed an increase in dough development time with increasing temperatures. At the highest temperature regime (30/25°C), the respective dough development times for SST 55 and SST 57 were well below the optimum mixing time of 2.5 to 3 minutes set by the baking industry, while the mixograph band widths of Kariega were the narrowest at all temperature regimes tested. This tendency indicated good water absorption properties. These results indicate that quality parameters of Kariega and Palmiet are less sensitive to high post-anthesis temperatures in comparison with SST 55 and SST 57. In general, it is concluded that although this study showed small differences between cultivars, Kariega was consistently different from other cultivars, indicating possible adaptation to hotter environments. However, more cultivars need to be screened before recommendations for such areas can be made. | AFRIKAANSE OPSOMMING: Kennis aangaande die groei-, opbrengs- en kwaliteisreaksie van lente koringcultivars teenoor hoe temperature is belangrik. Dit mag help om jaar tot variase ten opsigte van opbrengs en bakkwaliteit wat dikwels in warmer produksiegebiede voorkom, te verminder. In hierdie studie is die invloed van vier dag/nagtemperatuur-behandelings wat gedurende korrelvulling op die Suid-Afrikaanse lente koringcultivars, Karige, Palmiet, SST 55 en SST 57 toegepas is, ondersoek. Die ondersoek is gedurende 1998 onder gekontroleerde groeitoestande by die Universiteit van Stellenbosch uitgevoer. Vanaf planttyd tot antese is aile plante gegroei by 'n dag/nagtemperature van 15/10oC. Vanaf antese tot oes is die kontrole plante steeds aan hierdie temperatuur blootgestel, terwyl die ander plante aan dag/nagtemperature van onderskeidelik 20/15°C, 25/200C en 30/25°C blootgestel is. In hierdie studie is aile gemete eienskappe deur die hoogste dag/nag tempertaure beinvloed en het cultivars nie grooteliks verskil in hul reaksie nie. Verskille in cultivarreaksie het wei by die laer dag/nagtemperature voorgekom. Die 30/25°C temperatuurbehandeling het blaarafsterwing versnel weens 'n verlaging in die relatiewe water inhoud van die blare. Dit het blaaroppervlakte-duurte en dus ook fotosintese gedurende korrelvulling benadeel met die gevolg dat verkrimpte, maer korrels geproduseer en opbrengs plant-1, in vergelyking--met die kontrole plante, met byna 50% verlaag is. Ander opbrengskomponente soos korrels aar -1 is minder ernstig benadeel en Kariega was ietwat meer tolerant as die ander cultivars. Hoe dag/nagtemperatuurgedurende korrelvulling het tot 'n toename in meelproteieninhoud aanleiding gegee. Mixogram-piekhoogtes het ook toegeneem met toenemende temperature. In teenstelling met ander cultivars het Palmiet ook 'n toename in deegontwikkelingstyd getoon. By die hoogste dag/nagtemperatuur (30/25°C) was deegontwikkelingstye van die cultivars SST 55 en SST 57 betekenisvol laer as die optimum tye van 2.5 - 3.0 minute wat deur die bakbedryf vereis word. Waardes vir Kariega was meer aanvaarbaar en mixogram bandbreedtes vir kariega was ook by aile temperatuurbehandelings die smalste. Dit is 'n aanduiding van goeie waterabsorpsie-einskappe. Hierdie resultate toon dat die bakkwaliteit van Kariega en Palmiet minder gevoelig is vir hoe temperature gedurende korrlevulling in vergelyking met SST 55 en SST 57. In hierdie studie is gevind dat hoewel verskille in cultivareaksie oor die algemeen klein was, Kariega ietwat beter aanpassing by die hoe temperature getoon het. Meer cultivars sal egter getoets moet word alvorens aanbevelings in die warmer produksiegebiede gemaak kan word. | Master

Dissertation (M Inst Agrar (Weed Science))--University of Pretoria, 2006. | Please read the abstract in the section 00front of this document | Microbiology and Plant Pathology | unrestricted

The analysis of prices on wheat in Germany from the point of view of the theory of expectations is given. For this purpose, the authors propose their own method of data processing which is called the method of sliding expectations. Different variants of its application were tested for the prognosis of the future meanings of the dynamic line. The conclusion is made as to the proposed methodology that permits to increase the prognosis authenticity. The treatment of the primary data of dynamic lines by sliding expectations allows to make their character closer to the stationary ones and to use it in the future analysis.

This study reports the effect of different levels of wheat/cassava composite flour on liver architecture of wistar rat. The cassava variety- TMS 98/419 and Twenty (20) male wistar rats were used for the study. The ages of the wistar rats ranged between 10-12 weeks and weighed 90-100 g. After one (1) week period of adaptation, the rats were divided randomly into five groups (A, B, C, D and E) of four (4) rats per group. Group A served as the control while groups B, C, D and E were the experimental groups. The blood glucose levels and body weight of the animals were monitored. The result showed that among the different rat groups, their body weights increased from week 2 of the study while their blood glucose levels significantly decreased (P<0.05) with increase in the quantity of cassava flour. The histo-pathological analysis showed that from 20 % cassava flour substitution, significant distortion of the liver architecture of the wistar rats were observed resulting in intra-hepatic haemorrhage as well as necrosis. The result revealed that 10 % cassava flour substitution is adequate as this has no effect on the liver architecture of the wistar rat.

Wheat grain obtained from agricultural overproduction is stored for a long time in grain warehouses, which reduces its baking value. The aim of this study was to use barley and wheat malt flours as additives to flours obtained from grain of different wheat varieties stored for 12 months under optimal conditions, to improve their baking properties. The addition of barley malt flour at a mean rate of 0.5% or wheat malt flour at a mean rate of 0.7% reduced the time needed for the wheat gel to reach its maximum viscosity by 67.2%, compared to the control sample (without malt flour added). Bread made of flour blends with malt flours added was characterised by a higher loaf volume and specific volume as well as darker crust and crumb. The addition of malt flours also led to significantly reduced hardness, gumminess, and chewiness of bread crumb. The study demonstrated that it is possible to effectively use long-stored wheat grains for bread making applying wheat malt flour or barley malt flour as enhancers.

Thesis (MScAgric)--Stellenbosch University, 1990. | ENGLISH ABSTRACT: Wheat (Triticum aestivum) is grown in monoculture in much of the winter rainfall region of the Western Cape Province of South Africa. This has led to a dramatic increase in the incidence of take-all (caused by Gaeumannomyces graminis var. tritici). In a tillage experiment on the Langgewens research farm of the Department of Agricultural Development, a close correlation was found between disease incidence following cultivation with a chisel plough, a mouldboard plough or no tillage. Cultivation with a mouldboard plough, or no tillage resulted in a low disease incidence and higher yields. | AFRIKAANSE OPSOMMING: In 'n groot gedeelte van die Winterreënstreek van Wes-Kaapland word koring (Triticum aestivum) onder monokultuurtoestande verbou. Hierdie praktyk het tot gevolg gehad dat vrotpootjie (veroorsaak deur Gaeumannomyces graminis var. tritici) die afgelope paar jaar dramaties toegeneem het. In 'n bewerkingsproef op die Langgewens-proefplaas van die Departement Landbou-Ontwikkeling is daar 'n noue verwantskap aangetref tussen vrotpootjie-voorkoms en die plasing van die vorige jaar se vrotpootjie-geïnfekteerde wortelkrone en wortels deur bewerking. Bewerking met 'n scarifier het aanleiding gegee tot betekenisvol meer vrotpootjie as in gevalle waar beitelploeg-, skaarploeg-, of geen-bewerking gedoen is. Waar skaarploeg- of geen-bewerking onder monokultuurtoestande toegepas is, is 'n lae vrotpootjie-voorkoms, met gepaardgaande goeie opbrengste, waargeneem. | Masters

Thesis (MScAgric)--Stellenbosch University, 2019. | ENGLISH ABSTRACT: Wheat, the main cereal crop and canola, the main oilseed crop are the two most prominent crops established in the Western Cape under dryland conditions. Tine openers are most commonly used to establish these crops, but disc – and double chute openers are emerging as viable alternatives. The suitable planting depth for each opener has not yet been evaluated in the Western Cape. These openers place nitrogen (N) fertiliser at different depth in soil. Tine openers place N below the seed and disc openers mix N with seed and place it at the same depth. The double chute places N fertilser in between two twin rows of seed. The aim of the study was to determine the efficiency of establishment of wheat and canola using a tine, disc, and double chute openers, with different fertiliser placement.This study was divided into three trials, each with a specific objective: i) The first trial was conducted in a growth room to determine the effect of N rate on wheat and canola sown at different depths (1, 2, 4, and 8 cm) and in different soil types. ii) The second trial was conducted in the field to evaluate the effectiveness of a tine or disc opener to establish canola and wheat at different depths. iii) The third was another field trial to evaluate the efficiency of tine, disc, and double chute openers on wheat and canola establishment. There was no clear effect of N rate in almost all soil types for wheat and canola, but planting depth had an effect (Objective i). Most established well when sown at depths of 1 or 2 cm. Though overall canola seed establishment was poor in most soils, it is possible that the canola seeds or seedlings were damaged by coming into contact with the N fertiliser since it was previously observed that canola seeds are sensitive to N fertiliser. The tine opener planted the seed acurate at a deeper depth (Objective ii), while the disc opener planted the seed well at a shallower depth, particularly for wheat. In contrast, for canola, planting depth was not successfully controlled by either tine or disc opener. Wheat and canola seeds were affected by the N fertiliser placement (Objective iii). When the double chute and tine openers were used in placing N fertiliser, the differences were significant in comparison to when N was broadcasted or placed using the disc opener. Plant population and biomass production was determined after 30, 60, 90 and 120 days of plant emergence, while the leaf area index (LAI) was only determinedafter 30, 60 and 90 days of plant emergence. Yield was also quantified. In most cases there were no differences between broadcasted N (control) and the disc opener for plant population, biomass production and LAI; yet, there were noticeable differences to double chute and tine opener with regard to plant population, biomass production and LAI. No yield differences were observed between the various openers. | AFRIKAANSE OPSOMMING: Koring, die hoof graangewas, en canola, die hoof oliesaadgewas, is die twee meer prominente gewasse wat onder droëlandtoestande in die Wes-Kaap gevestig word. Tandoopmakers word algemeen gebruik om die gewasse te vestig, maar skyf- en dubbelsaadskut-oopmakers word toenemend beskikbaar as alternatiewe opsies. Die optimale plantdiepte vir elke oopmaker is nog nie in die Wes-Kaap evalueer nie. Die oopmakers plaas stikstof-(N)-bemesting op verskillende dieptes in die grond. Tandoopmakers plaas N onder die saad, terwyl skyfoopmakers N op die selfde diepte as saad plaas. Die dubbelsaadskut plaas N tussen twee treinspoorrytjies saad in die middel van die ry. Die doel van die studie was op die effektiwiteit van vestiging van koring en canola te bepaal, deur van tand, skyf en dubbelsaadskut-oopmakers gebruik te maak, met verskillende plasing van N. Die studie was in drie gedeeltes verdeel, elk met sy eie objektief: i) Die eerste proef was in ‘n groeikamer uitgevoer om die effek van N-peil op koring en canola wat op verskillende dieptes (1, 2, 4, en 8 cm) en in verskillende gronde gevestig is, te bepaal. ii) Die tweede proef was uigevoer onder veldtoestande om die effektiwiteit van tand en skyfoopmakers om koring en canola te vestig op verskillende dieptes te bepaal. iii) Die derde proef was ook ‘n veldproef om die effektiwiteit van tand, skyf en dubbelsaadskut oopmakers op koring en canola te bepaal, met ‘n fokus op N. Daar was geen defnitiewe effek van N-peil in byna alle grondtipes vir koring en canola nie, maar plantdiepte het wel ‘n effek gehad (objektief 1). Die meeste saad het gevestig teen dieptes van 1 of 2 cm. Alhoewel canola-vestiging oor die algemeen swak was, was dit moontlik dat canolasaailinge deur kontak met N-bemesting beskadig was. Die tandoopmaker het saad op ‘n akkurate diepte geplaas, terwyl die skyfoopmaker saad vlakker geplaas het, veral koring. Teenstaande, vir canola was plantdiepte nie suksesvol deur die tand of skyfoopmaker beheer nie. Koring en canola was wel deur N-plasing beinvloed (objektief iii).Wanneer dubbelsaadskut- en tandoopmakers gebruik was om N te plaas, was daar betekenisvolle verskille vergeleke met wanneer N breedwerpig toegedien of met ‘n skyf geplaas was. Oor die algemeen was daar geen verskille tussen N wat breedwerpig toegedien was en die skyfoopmaker i.t.v. planpopulasie, biomassaproduksie en BOI nie, alhoewel daar wel verskille tussen die dubbelsaadskut en tandoopmaker was. Geen opbrengsverskille was waargeneem nie.

Ozone, as a strong oxidative agent, is used to eradicate microbial, but this treatment affects also the quality of grain. The objective of this study was to evaluate the effect of ozonation of winter wheat grain harvested in different cropping and tillage systems on the number and composition of fungi colonizing grain surface and on the contents of total-phosphorus (P), phytate-P and phenolic acids. Wheat was sown in a two-factor experiment established with the method of randomized sub-blocks. The first order factor included cropping systems: (a) crop rotation and (b) monoculture, whereas the second order factor included tillage systems: (1) conventional (CT); (2) reduced (RT); and (3) herbicide. Ozonation significantly reduced the count of fungi on the surface of grain, especially on the grain harvested from wheat monoculture. In addition, it increased the content of phytate-P but decreased the content of total-P. A higher total-P content was determined in the grain harvested from monoculture than from crop rotation, whereas phytate-P content in the grain from crop rotation was higher than from monoculture. The ozonated grain harvested from CT plots was characterized by a higher content of phytate-P and a lower content of total-P, compared to the non-ozonated grain. Ozonation also increased the content of phenolic acids in the grain, especially in that harvested from the RT system.