Agronomic performance, consumer acceptability and nutrient content of new sweet potato varieties in South Africa
| dc.contributor.advisor | Labuschagne, M. T. | |
| dc.contributor.author | Laurie, Sunette Marlize | |
| dc.contributor.other | Faber, Mieke | |
| dc.contributor.other | Van Jaarsveld, Paul | |
| dc.date.accessioned | 2015-09-02T10:21:56Z | |
| dc.date.available | 2015-09-02T10:21:56Z | |
| dc.date.copyright | 2010-05 | |
| dc.date.issued | 2010-05 | |
| dc.date.submitted | 2010-05 | |
| dc.description.abstract | English: Malnutrition, including vitamin A deficiency, and food insecurity are national priorities in South Africa. Sweet potato has several agronomic advantages giving it potential to address both priorities. The crop is popular amongst resource-poor farmers as it is easy-to-grow and hardy. Orange-fleshed genotypes (β-carotene-rich) are used internationally in crop-based approaches to address vitamin A deficiency. Due to a shortage of varieties with desirable traits for resourcepoor farmers, several new varieties have been developed. The overall objective of this study was to evaluate the agronomic performance, sensory quality and nutrient content of new South African varieties. The ANOVA of new varieties in MET, indicated significant differences in dry matter content, marketable yield, number of marketable roots and total yield. AMMI and GGE biplot analysis showed that cream-fleshed varieties Ndou and Lethlabula produced yields comparable to the commercial variety Blesbok. Ndou (unstable high yield), Mokone and Monate (stable, average yields) and Amasi (moderately unstable, average yield) had dry matter content similar to the control variety Mafutha (known for sweet and dry taste). Recommending these new varieties will have a considerable yield advantage over Mafutha, with a possible impact on food security. From MET with nine orange-fleshed varieties the ANOVA and GGE SREG analysis indicated that Impilo produced stable, high yield and 2001-5-2 unstable, high yield. Both had average dry matter content. The two varieties offer a significant yield advantage above USA imports, previously recommended to address vitamin A deficiency. Orange-fleshed varieties produced significantly lower yield than cream-fleshed ones. Raw roots of nine orange-fleshed varieties, harvested from MET at four agro-geographical production sites, had an overall mean trans-β-carotene content of 5091 to 16456 μg/100 g. Resisto, Khano, 2001-5-2, W-119, Beauregard and 1999-1-7 exceeded 5500 μg/100 g β-carotene (breeding target). Dry matter content ranged from 23.1% (Impilo) to 28.7% (W-119). The content of six minerals was determined. Consumption of a boiled portion of 100 g raw root of all nine varieties can potentially contribute to ≥100% of the recommended intake for vitamin A, 21% of magnesium, 12% of zinc and 9% of iron for 4 to 8 year old children. CIE L* and a* color measurement of nine varieties with varying orange flesh color had the best correlations with total β-carotene content, and is a faster selection method. A mathematical function with natural logarithm (ln) transformation derived to predict total β-carotene content from color L*, predicted 91% of the values with >75% accuracy. The color and taste acceptability of boiled sweet potato of new varieties were evaluated in two experiments by grade 1 – 7 learners and adults in a BIBD using a 5-point hedonic scale. A trained panel found clear differences in the sensory attributes of the varieties. Cream to yelloworange varieties, Mafutha, Lethlabula and Phala had the highest consumer panel (n=190) scores, associated most with wateriness, discolor, graininess, gumminess, sweet potato-like flavor and instronforce. Orange-fleshed varieties Impilo, Excel, Resisto, 2001-5-2, Serolane and W-119, and cream-fleshed varieties Monate and Ndou were acceptable to the second consumer panel (n=216), mostly related to dry matter content, maltose content, sweet flavor, wateriness, discoloration and dark edges. High maltose and starch content were found in Ndou, Serolane, Resisto and Monate; while Blesbok, Impilo and 2001-5-2 had high fructose and glucose content. Orange-fleshed varieties were as acceptable as cream-fleshed varieties. The present study provides novel results on G x E analysis, comprehensive and systematic determination of nutrient content, consumer and sensory assessment of a considerable number of new cream to orange-flesh sweet potato varieties promoted in South Africa. Varieties Ndou, Mokone, Monate and Amasi were recommended to address food security; and Impilo and 2001- 5-2 to address vitamin A deficiency. | en_ZA |
| dc.description.abstract | Afrikaans: Wanvoeding, insluitend vitamien A tekorte, en voedselsekuriteit is van nasionale belang in Suid- Africa. Patats het potensiaal om beide prioriteite aan te spreek aangesien die gewas verskeie agronomiese voordele het. So bv. is patats gewild onder kleinboere omdat dit maklik groei en gehard is. Oranje patats (ryk aan β-karoteen) word internasionaal gebruik in gewasgebasseerde pogings om vitamien A tekorte aan te spreek. Daar was ‘n tekort aan variëteite met geskikte eienskappe vir kleinboere, sodoende is verskeie nuwe variëteite ontwikkel. Die doel van die studie was om nuwe Suid-Afrikaanse variëteite vir agronomiese prestasie, smaak en voedingswaarde te evalueer. Analise van variansie van resultate oor verskeie lokaliteite het gewys dat nuwe variëteite betekenisvol verskil in droëmassa, bemarkbare opbrengs, aantal bemarkbare stoorwortels en totale opbrengs. Volgens AMMI en GGE biplot analises is die opbrengste van roomvleis variëteite Ndou en Lethlabula (met stabiele hoë opbrengs) vergelykbaar met dié van Blesbok (kommersiële variëteit). Mokone en Monate (beide met stabiele, medium opbrengs) en Amasi (medium onstabiel, medium opbrengs) se droëmassa-inhoud was soortgelyk aan dié van Mafutha, die kontrole vir soet en droë smaak. Aanbeveling van die nuwe variëteite kan aansienlike opbrengsverhogings en impak op voedselsekuriteit teweegbring. Uit proewe met nege oranje variëteite wys ANOVA en GGE SREG analise dat Impilo ’n hoë, stabiele en 2001-5- 2 onstabiele, hoë opbrengs het. Beide het ‘n gemiddelde droëmassa-inhoud. Dié variëteite bied betekenisvolle opbrengsverhogings bo variëteite vanaf die VSA, wat voorheen aanbeveel is om vitamien A tekorte aan te spreek. Die opbrengs van orange variëteite is steeds betekenisvol laer as roomvleis variëteite. Rou stoorwortels van nege oranje variëteite, vanaf proewe by vier agro-geografiese areas, het ‘n gemiddelde trans-β-karoteen inhoud van 5091 tot 16456 μg/100 g gehad. Resisto, Khano, 2001- 5-2, W-119, Beauregard en 1999-1-7 het die teeldoelwit van 5500 μg/100 g β-karoteen oortref. Droëmassa-inhoud het gewissel van 23.1% (Impilo) tot 28.7% (W-119). Ses minerale se inhoud is ook bepaal. Wanneer ‘n gekookte porsie van 100 g rou patat van enige hierdie variëteit geëet word, is die potensiële inname ≥100% van die aanbevole inname van vitamien A, 21% van magnesium, 12% van sink en 9% van yster vir die ouderdomsgroep 4 tot 8 jaar. CIE L* en a* kleurmetings van nege oranje variëtiete, met ‘n variasie in vleiskleur, het die beste gekorreleer met β-karoteen inhoud, en is ’n vinniger seleksiemetode. ‘n Wiskundige vergelyking met ‘n natuurlike logaritmiese (ln) transformasie afgelei om totale β-karotene te skat uit L*- waardes, het 91% van die waardes met >75% akkuraatheid voorspel. Die kleur- en smaakaanvaarbaarheid van die nuwe variëteite is getoets deur Graad 1 – 7 leerders en volwassenes in ‘n BIBD uitleg d.m.v. ‘n 5-punt hedoniese skaal. ’n Opgeleide proepaneel het duidelike verskille in die sensoriese eienskappe van die variëtiete gevind. Die verbruikerspaneel (n=190) het die hoogste punte toegeken vir die room en geel-oranje variëteite Mafutha, Lethlabula en Phala. Dit was geassosieër met waterigheid, verkleuring, instrumentele fermheid, korrelrigheid en patatsmaak. Oranjevleis variëteite Impilo, Excel, Resisto, 2001-5-2, Serolane en W-119, sowel as die roomvleis variëteite Monate en Ndou was aanvaarbaar vir die tweede verbruikerspaneel (n=216). Dit was geassosieer met droëmassa-inhoud, maltose-inhoud, soetsmaak, waterigheid, verkleuring en donker rante. ‘n Hoë maltose- en styselinhoud is in Ndou, Serolane, Resisto en Monate gemeet, terwyl Blesbok, Impilo en 2001-5-2 hoog was in fruktose en glukose. Oranjevleis variëteite was net so aanvaarbaar soos roomvleis variëteite. Hierdie studie het nuwe resultate gelewer oor genotipe by omgewing interaksie, het omvattende bepaling van die inhoud van sekere nutriënte gedoen, asook verbruikersevaluasie en sensoriese beskrywing van nuwe room- tot oranjevleis patatvariëteite wat in Suid-Afrika bevorder word. Ndou, Mokone, Monate en Amasi word aanbeveel vir voedselsekuriteit. Impilo en 2001-5-2 word aanbeveel om vitamien A tekorte aan te spreek. | af |
| dc.description.sponsorship | South African Sugar Association | en_ZA |
| dc.description.sponsorship | Agricultural Research Council | en_ZA |
| dc.description.sponsorship | National Research Foundation (NRF) | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11660/1128 | |
| 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 | Sweet potatoes -- South Africa | en_ZA |
| dc.subject | Sweet potatoes -- South Africa -- Analysis | en_ZA |
| dc.subject | Sweet potatoes -- Varieties -- South Africa | en_ZA |
| dc.subject | Sweet potatoes -- South Africa -- Composition | en_ZA |
| dc.subject | Beta carotene | en_ZA |
| dc.subject | GGE biplot | en_ZA |
| dc.subject | Elston index | en_ZA |
| dc.subject | Thesis (Ph.D. (Plant Sciences (Plant Breeding))--University of the Free State, 2010 | en_ZA |
| dc.subject | Vitamin A deficiency | en_ZA |
| dc.subject | Color measurement | en_ZA |
| dc.title | Agronomic performance, consumer acceptability and nutrient content of new sweet potato varieties in South Africa | en_ZA |
| dc.type | Thesis | en_ZA |