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

Global climate change leads to frequent occurrence of low-temperature stress (LTS), which poses a serious threat to global food security. Here, environment-control phytotron experiments were conducted on cold-responsive cv. XM26 and cold-tolerant cv. YN19 during the anther differentiation period. Six LTS levels (4, 2, 0, -2, -4, -6 °C) and a control treatment (10 °C) were set to study the effects of different levels of LTS on wheat seed-setting characteristics and yield. LTS significantly decreased grain number per spike, 1 000-grain weight, and grain yield per plant (GYPP) of the two wheat cultivars. Each spike's grain number and weight distribution showed a quadratic curve, and the near-medium dominance of grain development was not affected by temperature. The grain number percentage and grain weight of wheat at different grain positions were G2 (2nd grain position) ≥ G1 (1st grain position) > G3 (3rd grain position) > G4 (4th grain position), in which G3 and G4 grain positions were more sensitive to LTS. In summary, LTS during the anther differentiation in wheat mainly led to a decrease in GYPP by significantly reducing the number and weight of inferior grains. Improving wheat cultivation measures and promoting the development of inferior grains are significant ways to prevent disasters and increase wheat quality and productivity in the future.

In this study, a synergist made of itaconic acid, maleic acid, acrylic acid and other active ingredients polymerised was sprayed on the surface of nitrogen (N) fertiliser particles to make synergistic nitrogen fertilisers (SNF). To explore the effect of SNF on N metabolism of wheat in saline-alkaline land, five treatments were set up: CK - ordinary N fertiliser (299.86 kg N/ha); T1 - SNF (299.86 kg N/ha); T2 - SNF (239.89 kg N/ha); T3 - SNF (179.92 kg N/ha); T4 - SNF (119.94 kg N/ha). The aboveground dry weight of wheat, the photosynthetic characteristics of wheat flag leaves, the activity of the N metabolism enzyme of wheat flag leaves, the expression of N transporter-related genes in wheat roots, and the N accumulation and transport of plants were determined. The results showed that the T1 treatment performed the best. During the two years, the N translocation from stems and leaves to spikes of plants at maturity in T1 was 33.18-45.55% higher than that of CK. The N content of wheat spikes was 12.01-12.66% higher than that of CK. The activities of nitrate reductase, glutamine synthetase, glutamate synthetase and the expression of nitrate transporter gene TaNRT1.1 and ammonium transporter gene TaAMT1.1 were significantly higher than that of CK. The aboveground dry weight of wheat and photosynthetic characteristics of flag leaves were significantly higher than those of CK in T1, whereas the intercellular CO2 concentration was significantly lower than that of CK. The application of SNF positively affected N accumulation and transport in wheat, wheat yield, and fertiliser utilisation, as well as reduced N loss in saline-alkaline land.

Mycotoxins found in cereals have adverse effects on animals, humans, and agricultural products, posing significant health risks and affecting the marketability of wheat products.

Unique challenges have been elicited by climate change, demanding the utilisation of effective adaptation strategies that are both environmentally and economically sustainable. Regrettably, the agricultural sector has not been spared from the effects of climate change, but it is among the largest employers and the primary source of food security globally. The situation is worse in Pakistan, where poverty, hunger, and malnutrition are reported to be prevalent. The complexity of risks posed by climate change has called for climate-smart agriculture (CSA) technologies, which potentially could augment cost efficiency and yield in wheat production. Surprisingly, previous studies have largely overlooked this crucial aspect. Therefore, our research seeks to address two fundamental questions: What is the comparative cost efficiency between adopters and non-adopters of CSA practices in wheat production? And what are the yield effects associated with CSA adoption, particularly compared to non-adopters? To this end, a multi-stage sampling technique was employed to randomly select 400 farm households in a climate risk hotspot province in Pakistan, on which the stochastic frontier analysis (SFA) and endogenous switching regression (ESR) were applied. The results revealed that CSA adoption was associated with improved cost efficiency and yield. Interestingly, if non-adopters decided to adopt CSA, they would increase their wheat yield by about 20%. Given the importance of wheat for food security, this would contribute to poverty and hunger eradication. Therefore, our study conforms to the aspirations of the 2030 agenda by promoting rethinking food production through possible improvement in cost efficiency and yield in the face of a changing climate.

Zinc and Selenium deficiency affects 39% of children in Pakistan, according to the recent National Nutritional Survey 2011. Considering the deficiency states of zinc in our population, interventional strategies have been employed, such as fortification of cereals, food products, and zinc preparations in suspension forms. Zinc biofortification is a better option as wheat flour is the most common and easily assessed food in resource-poor settings compared to the other fortification methods. Although zinc has been used to prevent and treat diarrhoea, the relationship of plasma zinc status with potentially pathogenic bacteria has not been studied.

o uncover the regulatory metabolism of poly-glutamic acid (PGA) in protecting wheat crops against salt stress (SS) at the physiological level, we utilised hydroponic experiments to explore the roles of PGA in regulating the photosynthetic performance, water physiology, antioxidant metabolism and ion homeostasis of wheat seedlings exposed to SS for 10 days. The findings demonstrated that SS inhibited the photosynthetic performance of wheat seedlings. In contrast, different doses of PGA all improved the photosynthetic performance, especially for 0.3% PGA. Compared with SS, 0.3% PGA plus SS decreased nonphotochemical quenching (qN) by 26.3% and respectively increased photosynthetic rate (Pn), soil and plant analyser development (SPAD) value, maximum photochemical efficiency of photosystem II (PSII) (Fv/Fm), photochemical quenching (qP) and actual photochemical efficiency of PSII (Y(II)) by 54.0, 27.8, 34.6, 42.4 and 25.8%. For water metabolism, SS destroyed the water balance of wheat seedlings. In contrast, different doses of PGA enhanced water balance, especially for 0.3% PGA. Compared with SS, 0.3% PGA plus SS decreased leaf water saturation deficit (LWSD) by 35.5% and respectively increased leaf relative water content (LRWC), transpiration rate (Tr), stomatal conductance (gs) and the contents of soluble sugars (SSS) and proline (Pro) by 15.9, 94.7, 37.5, 44.6 and 62.3%. For antioxidant metabolism, SS induced the peroxide damage to wheat seedlings. In contrast, different doses of PGA all mitigated the SS-induced peroxide damage, especially for 0.3% PGA. Compared with SS, 0.3% PGA plus SS respectively decreased superoxide anion (O2-), hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents and electrolyte leakage (EL) by 39.1, 29.6, 46.2 and 36.3%, and respectively increased superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), dehydroascorbate reductases (DHAR) and monodehydroascorbate reductase (MDHAR) activities, and antioxidants ascorbic acid (AsA) and glutathione (GSH) contents by 69.2, 49.2, 77.8, 80.6, 109.5, 121.7, 104.5, 63.8 and 39.6%. Besides, SS destroyed the ion homeostasis of wheat seedlings. In contrast, different doses of PGA all maintained ion homeostasis, especially for 0.3% PGA. Compared with SS, 0.3% PGA plus SS reduced Na+ content by 40.7% and respectively increased K+, Ca2+ and Mg2+ contents by 64.4, 82.6 and 105.6%, thereby respectively increasing K+/Na+, Ca2+/Na+ and Mg2+/Na+ ratios by 177.6, 209.4 and 244.8%. In the above ways, SS inhibited wheat height and biomass. In contrast, different doses of PGA all improved wheat height and biomass under SS, especially for 0.3% PGA. Compared with SS, 0.3% PGA plus SS, respectively, increased wheat height and biomass by 27.4% and 41.7%. In the above ways, PGA mitigated salt toxicity in wheat seedlings. The current findings implied that there was a potential for the use of PGA in real situations to improve wheat salt tolerance, especially for the 0.3% dose.

A three-year field experiment was carried out to investigate the methane (CH4) and nitrous oxide (N2O) emissions and calculate the global warming potential (GWP) according to all energy input in response to the nitrogen (N) rate in the typical rice-wheat rotation system in Jiangsu, China. Four N treatments, including R220W180 (local practice), R220W140 (cutting 10% total N in wheat season), R180W180 (cutting 10% total N in rice season) and R180W140 (cutting 20% total N in rice and wheat seasons separately), were designed in the study. Results showed that annual CH4 emission was decreased by 25.7% in response to cutting 20% N, which was ascribed to the 24.6% reduction of CH4 emission in rice season (P < 0.05) compared to local practice. The mitigation of N2O emissions in R220W140 and R180R180 treatments contributed to the 8.5% and 15.7% decrease in annual N2O emission, which was the 23.5% decrease in cutting 20% N treatment compared to local practice, respectively. Specifically, under the same amount of N rate condition (10% N cutting), the transfer N from rice season (R220W140) to wheat season (R180W180) led to the 8.5% increase in N2O emission (P < 0.05). In the end, the cutting of 20% N decreased GWP and yield-scale GWP by 19% and 17%, which mainly originated from CH4 and N2O emissions. However, cutting N did not significantly decrease grain yield (P > 0.05). These results suggested that the 180 kg N/ha for rice and 140 kg N/ha for wheat in one rotation season were the beneficial N rate to achieve the co-benefit of yield and GWP in the typical rice-wheat rotation system in Jiangsu, China.

Currently, some intelligent devices are available to assist in the detection of imperfect wheat grains. However, the background of grain surface images acquired by intelligent devices is dense and complicated with overlapping particles, causing noise interferences in the detection of imperfect wheat grains. To address the high missed detection rate of imperfect grains in target detection algorithms and to enhance the model detection speed, this study optimized the lightweight network model YOLOV4-Tiny. First, a small target detection layer was added to enhance the utilization of high semantic information. Then, the SENet attention mechanism optimized with exponential thinking was embedded to facilitated the design of an Enhanced Feature Extraction Network (Increase-FPN) in order to enhance the model’s ability to extract features of imperfect grains amidst complex backgrounds so that the detection accuracy could be improved and false negative rates reduced. At last, depthwise separable convolution was employed as the feature extraction method for the residual network of the backbone component to reduce the calculation of model parameters, optimize model deployment, and solve the issue of poor real-time performance. Experimental results demonstrated that the improved IDS-YOLO algorithm achieved a balance between detection speed and accuracy, with an average increase of 6.2% in mean average precision (mAP) when compared with other benchmark algorithms. The frames per second (FPS) value was 88.03, meeting the real-time detection requirements, and the parameter size of the improved model was only 5.51 MB.

This study investigated the impact of damaged starch and arabinoxylans on the thermal and pasting behavior of mixtures containing starch and gluten. The mixtures containing starch, arabinoxylans, and gluten were dispersed in water and a 50% sucrose solution. When arabinoxylans were added to native starch in water, it did not modify the viscosity profiles. An increase in viscosity parameters was observed due to the addition of arabinoxylans to starch with a higher level of damage. Gluten did not influence the effects caused by arabinoxylans. In the sucrose solution, arabinoxylans caused an increase in the viscosity parameters of native starch and starch with higher damage content dispersions. Gluten caused greater viscosity increases when arabinoxylans were added. In water, the addition of arabinoxylans to native starch caused a decrease in the enthalpy of gelatinization and an increase in the onset temperature. Adding arabinoxylans to starch with a higher level of damage caused the opposite effects. In the presence of sucrose, arabinoxylans caused a decrease in the enthalpy of gelatinization. These results lay the foundations for studying the influence of damaged starch and arabinoxylans in water-rich systems characterized by the presence of substantial proportions of sucrose, such as batter formulations. | Fil: Teobaldi, Andrés Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; Argentina | Fil: Barrera, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; Argentina | Fil: Ribotta, Pablo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; Argentina