Show simple item record

dc.contributor.advisorDe Wit, Maryna
dc.contributor.advisorHugo, Arno
dc.contributor.advisorFouché, Herman
dc.contributor.authorDu Toit, Alba
dc.date.accessioned2017-08-07T06:22:52Z
dc.date.available2017-08-07T06:22:52Z
dc.date.issued2016-08
dc.identifier.urihttp://hdl.handle.net/11660/6514
dc.description.abstractEnglish: Cactus pear plants (Opuntia ficus-indica and Opuntia robusta) are edible plants that grow and thrive in the semi-arid area of the Free State, South Africa, yet are unknown food sources. Cactus pear cladodes could be developed into a crop that could offer solutions in terms of food security, yet are ignored and underutilized in South Africa. Extensive research done abroad on the nutritional and therapeutic properties of cladodes and mucilage verified its high potential for human consumption. The development of mucilage into a commercial nutraceutical food product offers an opportunity to add value to the crop while providing a healthy product that could significantly enhance the well-being of the South African consumer. A successful, easy, inexpensive and chemical free extraction process was developed, yet cladodes were not equal in terms of the amount of quality of mucilage. Thus, the most appropriate cultivar for optimal mucilage yield and quality from forty-two local cultivars had to be selected and cladode harvesting time established. It was found that mucilage yield was not a consequence of cladode size or moisture content, but of cultivar and viscosity. Seven cultivars were selected that proved to have the lowest viscosity while commercially viable in South Africa (O. ficus-indica cultivars namely Algerian, Meyers, Morado, Ficus-Indica, Gymno-Carpo, Tormentosa, Turpin). The eighth cultivar represented a different species (O. robusta Robusta). Further morphological and rheological investigations revealed that the dormant stage (dormant months) would be the optimal harvesting time, while the selection of cultivars were narrowed down to four (O. ficus-indica Algerian, Morado, Gymno- Carpo and O. robusta Robusta). Mucilage (native and freeze-dried powders) from all cultivars showed non-Newtonian, pseudoplastic tendencies. Higher viscosity mucilage was time dependent, rheopectic and had yield stress tendencies. Fluctuations in temperature, pH, concentration and electrolytes influenced the mucilage viscosity that could affect product texture. In the analyses of the native mucilage, lower pH during summer was correlated to higher mucilage yields. The flow properties, water- and oil- related properties showed the high potential of mucilage powders as commercial nutraceutical product. The chemical analysis of freeze-dried mucilage powders showed high fibre and minerals, yet low fat and carbohydrates. Although the protein content was low, the presence of proteins was confirmed for the protein-lipid interaction necessary in the stabilization action of emulsions. The higher organic acids in summer concurred with the lower pH (as a consequence of CAM) that in turn affected the mucilage viscosity and yield. Mucilage was successfully applied to food products and is recommended for commercialization as a nutraceutical food product. In terms of cultivar selection, ‘Robusta’ had the highest contents of protein, total fats (beneficial fatty acids), starch, potassium and phosphorous, while ‘Algerian’ mucilage had the lowest energy and insoluble fibre, but highest calcium, iron and copper contents. ‘Gymno-Carpo’ had high linoleic acid, magnesium and manganese and good fat ratios. It is recommended that cladodes be harvested in the summer months, directly after the fruit had been harvested for optimal mucilage yield and quality. ‘Robusta’ emerged as the best cultivar for higher viscosity mucilage and Algerian for lower viscosity mucilage of the best quality. However, a careful selection of the most appropriate cultivar mucilage would be paramount for specific food applications.en_ZA
dc.description.abstractAfrikaans: Die turksvy (Opuntia ficus-indica en Opuntia robusta) is eetbare plante wat groei en floreer in die semi-droë area van die Vrystaat, Suid Afrika. Dit is egter ‘n onbekende voedsel bron. Turksvye kan ontwikkel as ‘n gewas waarvan die kladode ‘n oplossing kan bied in terme van voedselsekuriteit, tog word dit geïgnoreer en is onderbenut in Suid Afrika. Uitgebreide internasionale navorsing oor die voedings- en terapeutiese eienskappe van kladodes en slymgom het die potensiaal daarvan vir menslike gebruik bevestig. Die ontwikkeling van slymgom in ‘n kommersiële voedingsproduk bied ‘n geleentheid om waarde tot die gewas te voeg, terwyl dit ‘n gesonde produk kan lewer wat baie voordelig kan wees vir die welstand van die Suid-Afrikaanse verbruiker. ‘n Suksesvolle, maklike en chemies-vrye onttrekkingsproses is ontwikkel, tog het die kladodes nie dieselfde kwaliteit slymgom gelewer nie. Daarom moes vasgestel word watter kultivar die mees geskikste kultivar is in terme van die optimale slymgom opbrengs en kwaliteit uit 42 plaaslike kultivars. Die beste oestyd vir die kladodes moes ook bepaal word. Daar is bevind dat die opbrengs van slymgom nie bepaal word deur die gewig of vog inhoud van die kladodes nie, maar deur die kultivar en viskositeit van die slymgom. Sewe kultivars met die laagste viskositeit, wat nogsteeds kommersieël lewensvatbaar is in Suid Afrika, is geïdentifiseer (O. ficus-indica kultivars: Algerian, Meyers, Morado, Ficus-Indica, Gymno-Carpo, Tormentosa, Turpin). Die agtste kultivar verteenwoordig ‘n ander spesie (O. robusta ‘Robusta’). Verdere morfologiese en rheologiese ondersoeke het getoon dat die dormante groeistadium die optimale oes tyd is, en dat die vier beste kultivars O. ficus-indica: Algerian, Morado, Gymno-Carpo en O. robusta: Robusta is. Slymgom (natuurlike slymgom en gevriesdroogde slymgom) van al die kultivars het nie-Newtoniese en pseudoplastiese neigings getoon. Slymgom met’n hoër viskositeit was tyd afhanklik, rheopeuties en het vloei spanning neigings getoon. Skommelings in temperatuur, pH, konsentrasie en elektroliete het die slymgom viskositeit beïnvloed, wat weer die voedselproduk se tekstuur kan affekteer. Die lae pH-waardes van die plaaslike slymgom korreleer met die hoër slymgom opbrengste daarvan. Die vloei, water- en olie verwante eienskappe van die slymgom poeiers het potensiaal getoon as kommersiële nutraseutiese produkte. Die chemiese ontleding van die gevriesdroogde slymgom poeiers het hoë vesel en minerale inhoude getoon, maar ook lae vet en koolhidraat vlakke. Alhoewel die proteïen inhoud laag was, was die teenwoordigheid van proteïen bevestig vir die proteïen-lipied interaksie, wat nodig was vir die stabiliserende aksie van die emulsies. Die hoër organiese suur inhoud van die slymgom, wat tydens die na-oes periode versamel is (as ‘n gevolg van CAM), het die slymgom viskositeit en opbrengs beïnvloed. Slymgom was suksesvol by voedselprodukte gevoeg en word aanbeveel vir die kommersialisering van ‘n nutraseutiese voedselproduk. In terme van kultivar keuse, het ‘Robusta’ slymgom die hoogste proteïen, totale vette (voordelige vetsure), stysel, potassium en fosfor inhoude getoon, terwyl ’Algerian’ die laagste energie en onoplosbare vesel, maar die hoogste kalsium, yster en koper inhoude getoon het. ‘Gymno-Carpo’ het die hoogste linoleïensuur, magnesium, mangaan en goeie vet inhoud getoon. Vir optimale slymgom opbrengs en kwaliteit word aanbeveel dat die kladodes direk nadat die vrugte geoes is in die somer (Februarie), geoes word. ‘Robusta’ het uitgestaan as die kultivar met ‘n hoër viskositeit slymgom en ‘Algerian’ met ‘n laer viskositeit slymgom met die beste kwaliteit. Kultivar keuse vir die beste slymgom produksie is egter van kardinale belang vir spesifieke aanwendings in voedselprodukte.af
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectOpuntia ficus-indicaen_ZA
dc.subjectOpuntia robustaen_ZA
dc.subjectCactus pearen_ZA
dc.subjectPrickly pearen_ZA
dc.subjectCladodesen_ZA
dc.subjectMucilageen_ZA
dc.subjectNative mucilageen_ZA
dc.subjectFreeze-dried mucilageen_ZA
dc.subjectFood securityen_ZA
dc.subjectArid and semi-ariden_ZA
dc.subjectRheological propertiesen_ZA
dc.subjectFunctional propertiesen_ZA
dc.subjectChemical propertiesen_ZA
dc.subjectNutritional contenten_ZA
dc.subjectNutraceutical food productsen_ZA
dc.subjectSustainable food sourceen_ZA
dc.subjectThesis (Ph.D. (Consumer Science))--University of the Free State, 2016en_ZA
dc.titleSelection, extraction, characterization and application of mucilage from cactus pear (Opuntia ficus-indica and Opuntia robusta) cladodesen_ZA
dc.typeThesisen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record