Antioxidant content and potential of fresh and processed cladodes and fruit from different coloured cactus pear (Opuntia ficus-indica and Opuntia robusta) cultivars
| dc.contributor.advisor | De Wit, M. | |
| dc.contributor.advisor | Osthoff, G. | |
| dc.contributor.author | Du Toit, Alba | |
| dc.date.accessioned | 2018-04-03T10:11:05Z | |
| dc.date.available | 2018-04-03T10:11:05Z | |
| dc.date.issued | 2013-02 | |
| dc.description.abstract | English: Different coloured cactus fruit, peel, seeds and cladodes were studied for antioxidant content and -capacity in fresh products. Fruit and cladodes from seven different cultivars from the O.ficus-indica spp. and one of O. robusta spp. were collected representing the four colours of fruit available namely, green, pink, orange and purple. It was found that fresh cactus pear fruit and cladodes contained exceptionally high levels of Ascorbic acid, Total Phenolics and Betalains and modest amounts of Carotene. Antioxidant potential remained at very high levels regardless of the specific antioxidant content. The highest antioxidant content and -capacity were found in purple (O.robusta Robusta) fruit and cladodes, attributed to the high levels of Betalains. Ascorbic acid, working synergistically with Phenolics, was found to provide almost as much antioxidant capacity to orange fruit coloured cultivars. It was thus found that cultivars with purple and orange fruit and cladodes were the best in regards to antioxidant content as well as -potential. Five cultivars, representing the four colours were further investigated by processing into different products in order to determine the influence that preservation techniques had on the antioxidant content and potential in the fruit, peel and cladodes. Juice, dried products, chutneys, whole preserves and pickles were prepared from the fruit (pulp), peel and cladodes of the five different coloured cultivars that attained the highest values in the fresh study. Betalains were retained in processed products; Ascorbic acid was mostly preserved in the processed products that involved minimal heat treatments, while Carotene and Phenolics increased after processing. Processed cladodes, more than fresh cladodes, from all the cultivars, were concluded to provide an excellent source of antioxidants and could be suggested for products such as cladode flour and pickles. The peel in general was found to contain very similar antioxidant content and potential as the fruit and should be included in products when possible. In fruit, the purple fruit is highly recommended for processing, as it displayed the highest antioxidant potential in its fresh form and maintained these levels in processed product. Dried fruit is the product with the highest source of antioxidants to the consumer. Juice and chutney from pink or orange fruit would also provide products that the South African consumer is accustomed to with exceptionally high antioxidant potential. The study brings to light the potential that cactus pear products have for the food industry. It could be developed into a profitable industry if the public could be made aware of the health benefits that they provide. | en_ZA |
| dc.description.abstract | Afrikaans: Verskillende kleure turksvy vrugte, skille, sade en kladodés was bestudeer In hierdie studie vir antioksidant inhoud en -kapasiteit. Vrugte en kladodes van sewe verskillende Opuntia ficusindica kultivars en een O. robusta kultivar, wat die vier vrug kleure (groen, pienk, oranje en pers) insluit, is gebruik. Die bevindinge dui daarop dat vars turksvy vrugte en kladodes, baie hoë vlakke van askorbiensuur, fenole en betalaiene asook laer karoteen vlakke bevat, maar die antioksidant potensiaal bly hoog ongeag die spesifieke antioksidant waardes. Die heel hoogste antioksidant inhoud en -potensiaal vlakke is gevind in die pers (0. robusta Robusta) kultivar, in die vrugte sowel as die kladodes. Hierdie hoë vlakke is toegeskryf aan die hoë betalaien inhoud. Askorbiensuur, in samewerking met fenole, het die antioksidant potensiaal vlakke aan die ander kleure en veral aan oranje vrugte verskaf. Daar is dus gevind dat pers en oranje kultivars die beste keuse is vir antioksidant inhoud en -waarde. In die verdere studie is vyf kultivars, wat steeds die vier turksvy kleure verteenwoordig, verwerk in verskillende produkte sodat bepaal kan word of die antioksidante steeds teenwoordig sal wees na prosessering in die vrugte, skille en kladodes. Sap, gedroogde produkte, blatjang, heel ingelegde produkte en piekels (suurtjies) was voorberei van die vrugte, skille en kladodes van die vyf kultivars wat die beste resultate gelewer het in die eerste deel van die studie. Daar is gevind dat betalaiene behoue gebly het, askorbiensuur was meestal behou in die prosesse waar minder hitte toegevoeg is, terwyl karoteen en fenole toegeneem het tydens prosessering. Geprosesseerde kladodes, eerder as vars kladodes, van enige kultivar is 'n uitstekende bron van antioksidante en daarom word dit hoogs aanbeveel vir die gebruik in produkte soos turskvy kladode meel en piekels. Die skil, oor die algemeen, het dieselfde hoë antioksidant inhoud as die vrug en behoort ingesluit te word in produkte waar moontlik. Veral die pers vrug word aanbeveel aangesien dit die hoogste antioksidant inhoud gehad het en die inhoud het hoog gebly na prosessering. Gedroogte vrugte is 'n uitstekende bron van antioksidante aan die verbruiker. Turksy vrugtesap en blatjang het ook hoë potensiaal as produkte wat die Suid Afrikaanse verbruiker ken. Hierdie studie het die hoë potensiaal wat turksvy produkte aan die voedsel industrie kan lewer uitgelig. Dit kan ontwikkel word tot 'n winsgewende industrie as die publiek bewus gemaak kan word van die gesondheidsvoordele wat dit inhou. | af |
| dc.identifier.uri | http://hdl.handle.net/11660/8083 | |
| dc.language.iso | en | en_ZA |
| dc.publisher | University of the Free State | en_ZA |
| dc.rights.holder | University of the Free State | en_ZA |
| dc.subject | Cactaceae | en_ZA |
| dc.subject | Semiarid plants | en_ZA |
| dc.subject | Opuntia | en_ZA |
| dc.subject | Opuntia ficus-indica | en_ZA |
| dc.subject | Opuntia robusta | en_ZA |
| dc.subject | Cactus pear | en_ZA |
| dc.subject | Prickley pear | en_ZA |
| dc.subject | Cactus fruit | en_ZA |
| dc.subject | Cladodes | en_ZA |
| dc.subject | Cactus pads | en_ZA |
| dc.subject | Natural antioxidants | en_ZA |
| dc.subject | Antioxidant content | en_ZA |
| dc.subject | Antioxidant capacity | en_ZA |
| dc.subject | Chelating activity | en_ZA |
| dc.subject | Betalains | en_ZA |
| dc.subject | Ascorbic acid | en_ZA |
| dc.subject | Phenolics | en_ZA |
| dc.subject | Carotenes | en_ZA |
| dc.subject | Trolox equivalent antioxidant capacity (TEAC) | en_ZA |
| dc.subject | Processing | en_ZA |
| dc.subject | Preserved fruit | en_ZA |
| dc.subject | Antioxidants | en_ZA |
| dc.subject | Prickly pears -- Processing | en_ZA |
| dc.subject | Dissertation (M.Sc.Home Ec. (Consumer Science))--University of the Free State, 2013 | en_ZA |
| dc.title | Antioxidant content and potential of fresh and processed cladodes and fruit from different coloured cactus pear (Opuntia ficus-indica and Opuntia robusta) cultivars | en_ZA |
| dc.type | Dissertation | en_ZA |