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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Physico-chemical, nutritional and functional properties of defatted marama bean flour

Maruatona, Gaamangwe Nehemiah 11 June 2009 (has links)
Marama bean (Tylosema esculentum (Burch) A. Schreib) is an underutilised, drought-tolerant legume native to the drier parts of Botswana, Namibia and South Africa. The bean is comparable to soya beans in protein content and quality whereas its oil content is comparable to that of peanuts. By adding value to the marama bean through processing into protein-rich flours, its utilisation may be increased. Therefore, one of the objectives of this study was to adopt suitable low-cost processing technologies used for soya processing to produce protein-rich marama bean flours. The effect of dry heating of whole marama beans on lipoxygenase enzymes of its defatted flour was determined since oxidative rancidity catalysed mainly by lipoxygenase enzymes can reduce the shelf-life of the flour. The presence of trypsin inhibitors can affect the protein digestibility of the marama bean flour adversely. The effect of dry heating of whole marama beans on in-vitro protein digestibility and amino acid content of its defatted flour was determined. Lastly, the effect of dry heating of whole marama beans on the protein-related functional properties of the resultant defatted flour was determined. The presence of lipoxygenase iso-enzymes (L-1 and L-2) activity in marama beans was determined by a visual and spectrophotometeric method using unheated soya beans as reference. Lipoxygenase iso-enzymes (L-1 and L-2) activity was not detected in marama beans. This may possibly suggest that these lipoxygenase iso-enzymes are absent or possibly inhibited in marama beans. In an attempt to optimise dry heating to inactivate trypsin inhibitors in marama beans, whole marama beans were dry heated at 100°C, 120°C and 150°C, respectively for 20 min. Defatted flours prepared from the heated marama beans (HMF’s) were analysed for their trypsin inhibitor activity using defatted flours from unheated marama beans (UMF) and soya beans (USF) as control and reference samples, respectively. Trypsin inhibitor activity in UMF was almost four and half times higher than in USF. Dry heating of whole marama beans at 150°C/20 min significantly reduced the trypsin inhibitor activity in its defatted flour to almost zero probably due to inactivation of the trypsin inhibitor. The effect of dry heating of whole marama beans at 150°C/20 min on the physico-chemical, nutritional and protein-related functional properties of defatted marama bean flour was determined. UMF was used as a control while USF and HSF were used as reference samples. HMF had higher protein content but lower fat content than UMF. It is suggested that dry heating disrupted the lipid bodies of the marama beans allowing more oil to be expelled during coarse milling of the flour. Heating significantly reduced the L* values of marama and soya bean flours possibly due to Maillard browning reactions. Heating significantly increased in-vitro protein digestibility of marama and soya bean flours probably due to protein denaturation and inactivation of trypsin inhibitors. Heating generally decreased the amino acid contents of marama and soya bean flours possibly due to chemical modification of the amino acids. UMF and HMF can potentially be used to improve protein quality in marama-cereal composite flours, porridges and breads. Heating significantly decreased the nitrogen solubility index (NSI) and emulsifying capacity (EC) of marama and soya bean flours possibly due to protein denaturation and/or cross-linking. This may make HMF and HSF not suitable for applications in emulsion type meat products such as sausages because emulsion formation is critical during processing of sausages. Heating significantly decreased the foaming capacity of soya flour but did not have an effect on that of marama bean flour probably due to their high residual fat content which may have disrupted protein films during foam formation. UMF has a potential to be used in comminuted meat products because of its relatively high NSI, EC and OAC. The laboratory process used in this study can be modified and adopted by SME’s to produce defatted marama bean flours with potential applications in bakery and meat products and as a protein supplement in composite marama-cereal products. / Dissertation (MSc)--University of Pretoria, 2011. / Food Science / unrestricted
2

Assessment Of Consumer Perceptions About Food Processing Technologies For Cooperative Extension Educational Initiatives

Arnold, Nicole Leanne 25 September 2019 (has links)
New food processing technologies are needed to create safe, high-quality food products that are still considered "fresh" by consumers. Despite the numerous benefits attributed to 'food processing', consumers continue to perceive the term negatively. Consumer acceptance of foods processed with different technologies generally increases when factual information is provided to the consumer. Educators working within Cooperative Extension are a resource for public dissemination of food information. By working directly in the community, Extension educators often cultivate positive relationships with local clientele. Therefore, Extension educators can dispel myths related to food processing technologies and deliver science-supported information to the general public. Consumer knowledge, perceptions, and purchasing intentions associated with both conventional and emerging food processing technologies were assessed through a nationwide telephone survey administered by Virginia Tech's Center for Survey Research Center. A similar version of the telephone survey was disseminated in an online format to Virginia Extension agents. An additional section of the online survey served as a needs assessment for educational materials related to food processing technologies. A grounded theory methodology was used for qualitative coding in both surveys. Approximately 67% of consumers expressed concerns towards the term "processed foods." The majority of Extension agents (67.4%) expressed concerns about foods that had been processed, citing additional ingredients, preservatives, and additives; safety; and health implications. Both the consumer and Extension agent groups were more likely to be supportive of light-exposed foods to enhance food safety and quality, in comparison to gas-exposed foods. Although agents may be familiar with some food processing technologies, they may not have the resources to understand the scientific mechanisms for which a technology is able to increase food safety. Consumer education regarding emerging technologies is necessary to anticipate potential consumer concerns; however, agents still lack resources and information about existing and frequently used food processing technologies. Educational interventions are needed to provide information to consumers and increase their acceptance of new and currently used processing technologies so that the food industry can effectively target emerging issues related to food. / Doctor of Philosophy
3

Sustainable food packaging based on polyhydroxyalkanoate / Hållbara livsmedelsförpackningar baserade på polyhydroxialkanoat

Al-Ashor, Safana January 2024 (has links)
The Norwegian Food Research Institute (Nofima) and the University of Borås worked together to develop this project. The commonly used packaging materials pose a serious threat to the environment, as they are produced from nonrenewable crude oil and cannot decompose naturally. Despite some manufacturers' claims of their products being eco-friendly or sustainable, they are not entirely made from renewable resources and are not biodegradable. Nevertheless, some bio-based materials have emerged as a viable alternative that can naturally break down and safely decompose in the environment. Despite many studies, biopolymers possess limited mechanical and barrier properties, which restricts their potential for use in products. To overcome this limitation, polymer blending can be employed to enhance their final properties and make them more suitable for various applications. The objective of this project was to design sustainable food packaging using biopolymers. PHBV, one of the PHA’s bio-based polymers, was blended with other polymers to enhance its properties as a sustainable food packaging material. Through blending, PHAs'physical, chemical, and thermal properties can be enhanced to obtain exceptional films for food packaging purposes. Finally, in this work, a bio-based polymer, polyhydroxyalkanoate, was used to producea biodegradable packaging system for potential food packaging applications. The effect of the physical modification of PHBV on mechanical and barrier properties was studied by blending it with biodegradable polymers such as PLA and PBAT. Thermal properties were analyzed using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and FourierIItransform infrared spectroscopy (FTIR) while the mechanical properties were evaluated by tensile test. Barrier properties were characterized using water vapor transmission rate (WVTR). The mechanical performance of PHBV 50%: PBAT 50% blend has been significantly improved, leading to better tensile properties. The high crystallinity of the PHBV 50%: PBAT 50% blend than other blends have been found to enhance the barrier properties of the polymer film, according to DSC analysis. FTIR investigations have suggested no difference in absorption peaks between the blends and the neat material. Furthermore, WVTR investigations have shown that PHBV50%: PBAT50% exhibits excellent barrier properties against water vapor, making it a highly promising material.
4

Pressure assisted thermal sterilization: a novel means of processing foods

Wimalaratne, Sajith Kanchana January 2009 (has links)
This thesis investigates a newly developed and patented technology for its ability to inactivate spore- forming bacteria and non-spore-forming microorganisms. This new technology “Pressure Assisted Thermal Sterilization©” (PATS) is based on the theory of the thermal expansion of liquids. The efficiency of inactivating spore-forming and non-spore-forming microorganisms by PATS was compared with the thermal treatment alone. A combination treatment consisting of high pressure processing and gaseous carbon dioxide was also investigated for its ability to inactivate bacterial spores in model and real food matrices. The structural damage caused by treatments to the spores and non-spore-forming bacteria was assessed by scanning electron microscopy. Geobacillus stearothermophilus spores suspended in Milli-Q water, UHT milk and pumpkin soup, treated by PATS were found to have significantly lower decimal reduction times (D values) compared with the thermal treatment alone. Spores suspended in UHT milk were more heat resistant compared with those in Milli-Q water and pumpkin soup. Bacillus cereus spores suspended in Milli-Q water and pumpkin soup treated with PATS were more effectively inactivated compared with spores treated by the thermal treatment alone. Clostridium botulinum spores in saline buffer subjected to PATS treatment were inactivated more effectively compared with the thermal treatment alone. Overall, the results show that PATS was a better processing technique for inactivation of bacterial spores compared with thermal treatment alone. However, PATS had no added benefit in inactivating the non-spore-forming bacteria Escherichia coli and Saccharomyces cerevisiae cells compared with the thermal treatment. A shelf life study showed that B. cereus spores in pumpkin soup retained a low spore count (<5 LogCFU/mL) for approximately 40 days in 30oC storage after treatment with PATS. No additional degradation of colour pigments of pumpkin soup and model pumpkin juice was observed following PATS compared with the thermal treatment. Spore-forming microorganisms can be resistant to pressure treatment alone, which limits the application of high pressure processing (HPP). Therefore, a combination approach was investigated. The mechanism of inactivating spores by combining HPP with other treatments is that the pressure assists in spore germination. Then a secondary treatment (thermal or CO2 gas) can be used to inactivate the germinated spores. A combined application of HPP and a consecutive CO2 treatment was investigated for the efficiency of spore inactivation. Results showed that HPP (200 MPa for 30 min) followed by a CO2 treatment inactivated Bacillus subtilis 168 in nutrient broth, tomato juice and liquid whole egg by 2.5, 1.0 and 1.5 LogCFU/mL respectively. These results indicated that this technique is inadequate for practical use. Scanning electron micrographs showed that pressure processing of B. subtilis 168 and B. subtilis natto spores resulted in deformation of the spore structure. This structural deformation of spores may have been due to water absorption during HPP and subsequent release upon decompression. PATS treated G. stearothermophilus and B. cereus spores were more severely damaged compared with the same spores which underwent thermal treatment alone. However, the extent to which E. coli and S. cerevisiae cells were damaged by both PATS and thermal treatment was similar.
5

Pressure assisted thermal sterilization: a novel means of processing foods

Wimalaratne, Sajith Kanchana January 2009 (has links)
This thesis investigates a newly developed and patented technology for its ability to inactivate spore- forming bacteria and non-spore-forming microorganisms. This new technology “Pressure Assisted Thermal Sterilization©” (PATS) is based on the theory of the thermal expansion of liquids. The efficiency of inactivating spore-forming and non-spore-forming microorganisms by PATS was compared with the thermal treatment alone. A combination treatment consisting of high pressure processing and gaseous carbon dioxide was also investigated for its ability to inactivate bacterial spores in model and real food matrices. The structural damage caused by treatments to the spores and non-spore-forming bacteria was assessed by scanning electron microscopy. Geobacillus stearothermophilus spores suspended in Milli-Q water, UHT milk and pumpkin soup, treated by PATS were found to have significantly lower decimal reduction times (D values) compared with the thermal treatment alone. Spores suspended in UHT milk were more heat resistant compared with those in Milli-Q water and pumpkin soup. Bacillus cereus spores suspended in Milli-Q water and pumpkin soup treated with PATS were more effectively inactivated compared with spores treated by the thermal treatment alone. Clostridium botulinum spores in saline buffer subjected to PATS treatment were inactivated more effectively compared with the thermal treatment alone. Overall, the results show that PATS was a better processing technique for inactivation of bacterial spores compared with thermal treatment alone. However, PATS had no added benefit in inactivating the non-spore-forming bacteria Escherichia coli and Saccharomyces cerevisiae cells compared with the thermal treatment. A shelf life study showed that B. cereus spores in pumpkin soup retained a low spore count (<5 LogCFU/mL) for approximately 40 days in 30oC storage after treatment with PATS. No additional degradation of colour pigments of pumpkin soup and model pumpkin juice was observed following PATS compared with the thermal treatment. Spore-forming microorganisms can be resistant to pressure treatment alone, which limits the application of high pressure processing (HPP). Therefore, a combination approach was investigated. The mechanism of inactivating spores by combining HPP with other treatments is that the pressure assists in spore germination. Then a secondary treatment (thermal or CO2 gas) can be used to inactivate the germinated spores. A combined application of HPP and a consecutive CO2 treatment was investigated for the efficiency of spore inactivation. Results showed that HPP (200 MPa for 30 min) followed by a CO2 treatment inactivated Bacillus subtilis 168 in nutrient broth, tomato juice and liquid whole egg by 2.5, 1.0 and 1.5 LogCFU/mL respectively. These results indicated that this technique is inadequate for practical use. Scanning electron micrographs showed that pressure processing of B. subtilis 168 and B. subtilis natto spores resulted in deformation of the spore structure. This structural deformation of spores may have been due to water absorption during HPP and subsequent release upon decompression. PATS treated G. stearothermophilus and B. cereus spores were more severely damaged compared with the same spores which underwent thermal treatment alone. However, the extent to which E. coli and S. cerevisiae cells were damaged by both PATS and thermal treatment was similar.
6

Pressure assisted thermal sterilization: a novel means of processing foods

Wimalaratne, Sajith Kanchana January 2009 (has links)
This thesis investigates a newly developed and patented technology for its ability to inactivate spore- forming bacteria and non-spore-forming microorganisms. This new technology “Pressure Assisted Thermal Sterilization©” (PATS) is based on the theory of the thermal expansion of liquids. The efficiency of inactivating spore-forming and non-spore-forming microorganisms by PATS was compared with the thermal treatment alone. A combination treatment consisting of high pressure processing and gaseous carbon dioxide was also investigated for its ability to inactivate bacterial spores in model and real food matrices. The structural damage caused by treatments to the spores and non-spore-forming bacteria was assessed by scanning electron microscopy. Geobacillus stearothermophilus spores suspended in Milli-Q water, UHT milk and pumpkin soup, treated by PATS were found to have significantly lower decimal reduction times (D values) compared with the thermal treatment alone. Spores suspended in UHT milk were more heat resistant compared with those in Milli-Q water and pumpkin soup. Bacillus cereus spores suspended in Milli-Q water and pumpkin soup treated with PATS were more effectively inactivated compared with spores treated by the thermal treatment alone. Clostridium botulinum spores in saline buffer subjected to PATS treatment were inactivated more effectively compared with the thermal treatment alone. Overall, the results show that PATS was a better processing technique for inactivation of bacterial spores compared with thermal treatment alone. However, PATS had no added benefit in inactivating the non-spore-forming bacteria Escherichia coli and Saccharomyces cerevisiae cells compared with the thermal treatment. A shelf life study showed that B. cereus spores in pumpkin soup retained a low spore count (<5 LogCFU/mL) for approximately 40 days in 30oC storage after treatment with PATS. No additional degradation of colour pigments of pumpkin soup and model pumpkin juice was observed following PATS compared with the thermal treatment. Spore-forming microorganisms can be resistant to pressure treatment alone, which limits the application of high pressure processing (HPP). Therefore, a combination approach was investigated. The mechanism of inactivating spores by combining HPP with other treatments is that the pressure assists in spore germination. Then a secondary treatment (thermal or CO2 gas) can be used to inactivate the germinated spores. A combined application of HPP and a consecutive CO2 treatment was investigated for the efficiency of spore inactivation. Results showed that HPP (200 MPa for 30 min) followed by a CO2 treatment inactivated Bacillus subtilis 168 in nutrient broth, tomato juice and liquid whole egg by 2.5, 1.0 and 1.5 LogCFU/mL respectively. These results indicated that this technique is inadequate for practical use. Scanning electron micrographs showed that pressure processing of B. subtilis 168 and B. subtilis natto spores resulted in deformation of the spore structure. This structural deformation of spores may have been due to water absorption during HPP and subsequent release upon decompression. PATS treated G. stearothermophilus and B. cereus spores were more severely damaged compared with the same spores which underwent thermal treatment alone. However, the extent to which E. coli and S. cerevisiae cells were damaged by both PATS and thermal treatment was similar.
7

Pressure assisted thermal sterilization: a novel means of processing foods

Wimalaratne, Sajith Kanchana January 2009 (has links)
This thesis investigates a newly developed and patented technology for its ability to inactivate spore- forming bacteria and non-spore-forming microorganisms. This new technology “Pressure Assisted Thermal Sterilization©” (PATS) is based on the theory of the thermal expansion of liquids. The efficiency of inactivating spore-forming and non-spore-forming microorganisms by PATS was compared with the thermal treatment alone. A combination treatment consisting of high pressure processing and gaseous carbon dioxide was also investigated for its ability to inactivate bacterial spores in model and real food matrices. The structural damage caused by treatments to the spores and non-spore-forming bacteria was assessed by scanning electron microscopy. Geobacillus stearothermophilus spores suspended in Milli-Q water, UHT milk and pumpkin soup, treated by PATS were found to have significantly lower decimal reduction times (D values) compared with the thermal treatment alone. Spores suspended in UHT milk were more heat resistant compared with those in Milli-Q water and pumpkin soup. Bacillus cereus spores suspended in Milli-Q water and pumpkin soup treated with PATS were more effectively inactivated compared with spores treated by the thermal treatment alone. Clostridium botulinum spores in saline buffer subjected to PATS treatment were inactivated more effectively compared with the thermal treatment alone. Overall, the results show that PATS was a better processing technique for inactivation of bacterial spores compared with thermal treatment alone. However, PATS had no added benefit in inactivating the non-spore-forming bacteria Escherichia coli and Saccharomyces cerevisiae cells compared with the thermal treatment. A shelf life study showed that B. cereus spores in pumpkin soup retained a low spore count (<5 LogCFU/mL) for approximately 40 days in 30oC storage after treatment with PATS. No additional degradation of colour pigments of pumpkin soup and model pumpkin juice was observed following PATS compared with the thermal treatment. Spore-forming microorganisms can be resistant to pressure treatment alone, which limits the application of high pressure processing (HPP). Therefore, a combination approach was investigated. The mechanism of inactivating spores by combining HPP with other treatments is that the pressure assists in spore germination. Then a secondary treatment (thermal or CO2 gas) can be used to inactivate the germinated spores. A combined application of HPP and a consecutive CO2 treatment was investigated for the efficiency of spore inactivation. Results showed that HPP (200 MPa for 30 min) followed by a CO2 treatment inactivated Bacillus subtilis 168 in nutrient broth, tomato juice and liquid whole egg by 2.5, 1.0 and 1.5 LogCFU/mL respectively. These results indicated that this technique is inadequate for practical use. Scanning electron micrographs showed that pressure processing of B. subtilis 168 and B. subtilis natto spores resulted in deformation of the spore structure. This structural deformation of spores may have been due to water absorption during HPP and subsequent release upon decompression. PATS treated G. stearothermophilus and B. cereus spores were more severely damaged compared with the same spores which underwent thermal treatment alone. However, the extent to which E. coli and S. cerevisiae cells were damaged by both PATS and thermal treatment was similar.
8

Studium reakční syntézy intermetalických materiálů z depozitů kinetického naprašování binárních systémů obsahujících železo / Reaction synthesis of bulk intermetallic materials from cold spray deposits from binary powders containing iron

Dyčková, Lucie January 2015 (has links)
This thesis deals with reaction synthesis of materials Fe–Al, Fe–Cu and Fe–Ni from cold spray. In literature analysis are introduced these systems and for each system there is brief description of binary equilibrium diagram. Furthermore here are some short explanations of diffusion, Kirkendall effect and other possible processing technologies of intermetallic materials. In experimental part, samples of sprayed materials were annealed and then microstructural changes were investigated. This thesis contains photographs of microstructure, results from scanning electron microscopy, X-ray, and measurements of microhardness.
9

Intelligent Energy-Savings and Process Improvement Strategies in Energy-Intensive Industries / Intelligent Energy-Savings and Process Improvement Strategies in Energy-Intensive Industries

Teng, Sin Yong January 2020 (has links)
S tím, jak se neustále vyvíjejí nové technologie pro energeticky náročná průmyslová odvětví, stávající zařízení postupně zaostávají v efektivitě a produktivitě. Tvrdá konkurence na trhu a legislativa v oblasti životního prostředí nutí tato tradiční zařízení k ukončení provozu a k odstavení. Zlepšování procesu a projekty modernizace jsou zásadní v udržování provozních výkonů těchto zařízení. Současné přístupy pro zlepšování procesů jsou hlavně: integrace procesů, optimalizace procesů a intenzifikace procesů. Obecně se v těchto oblastech využívá matematické optimalizace, zkušeností řešitele a provozní heuristiky. Tyto přístupy slouží jako základ pro zlepšování procesů. Avšak, jejich výkon lze dále zlepšit pomocí moderní výpočtové inteligence. Účelem této práce je tudíž aplikace pokročilých technik umělé inteligence a strojového učení za účelem zlepšování procesů v energeticky náročných průmyslových procesech. V této práci je využit přístup, který řeší tento problém simulací průmyslových systémů a přispívá následujícím: (i)Aplikace techniky strojového učení, která zahrnuje jednorázové učení a neuro-evoluci pro modelování a optimalizaci jednotlivých jednotek na základě dat. (ii) Aplikace redukce dimenze (např. Analýza hlavních komponent, autoendkodér) pro vícekriteriální optimalizaci procesu s více jednotkami. (iii) Návrh nového nástroje pro analýzu problematických částí systému za účelem jejich odstranění (bottleneck tree analysis – BOTA). Bylo také navrženo rozšíření nástroje, které umožňuje řešit vícerozměrné problémy pomocí přístupu založeného na datech. (iv) Prokázání účinnosti simulací Monte-Carlo, neuronové sítě a rozhodovacích stromů pro rozhodování při integraci nové technologie procesu do stávajících procesů. (v) Porovnání techniky HTM (Hierarchical Temporal Memory) a duální optimalizace s několika prediktivními nástroji pro podporu managementu provozu v reálném čase. (vi) Implementace umělé neuronové sítě v rámci rozhraní pro konvenční procesní graf (P-graf). (vii) Zdůraznění budoucnosti umělé inteligence a procesního inženýrství v biosystémech prostřednictvím komerčně založeného paradigmatu multi-omics.

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