https://ir.unisa.ac.za/handle/10500/30858 2026-06-26T22:04:17Z https://ir.unisa.ac.za/handle/10500/32655 Effect of preservatives and storage conditions on quality of Marula (Sclerocarya birrea) fruit juice Gosh, Lekhuleni Isobel Lerato The aim of the United Nations Sustainable Development Goals (SDGs) is, among other things, to eradicate hunger and malnutrition and guarantee that all people have access to sufficient nutrient-dense food by 2030. The introduction of underutilised indigenous fruit species such as marula (Sclerocarya birrea subsp. caffra), which is reported to be abundant in vitamin C and minerals needed by humans for the fulfilment of their recommended daily dietary requirements, seems to be a reliable strategy to achieve these goals. This multi-disciplinary study was conducted to investigate (i) the impact of geographical region on the physicochemical properties of marula fruits and juice, and (ii) the effect of a treatment combination of preservatives and storage conditions on the physicochemical properties, mineral retention and microbial activities of 100% marula fruit juice. The aim of the study was therefore to establish the most suitable preservatives and storage conditions for processed marula fruit juice, for the purpose of the future commercialisation of this product. Fruit and its juice utillised for for the analysis of physicochemical properties including calcium, iron, fruit mass, total soluble sugars, total flavonoids, and vitamin C were harvested from Bushbuckridge, Giyani and Tzaneen, all of which are classified as lowveld regions of South Africa. The effect of treatment combinations (preservatives and storage settings) on quality, including phytochemicals and minerals, was assessed by subjecting marula fruit juice to preservatives (sodium metabisulphite and sodium benzoate) and storage conditions (4, 6, and 10˚C) for a duration of 20 days. Concerning the assessment of microbial activity, the spread plate count approach was employed, encompassing incubation, enumeration of colony-forming units, and species identification. For the physicochemical properties investigation, study revealed that fruits harvested in the Bushbuckridge region exhibited a greater mass (44.6 g) compared to those from other places. In comparison to other regions, the Tzaneen region fruit had a higher total soluble sugar concentration of 12.9 ˚Brix. Regarding the impact of varying presevatives and storage conditions on quality retention, results demonstrated that the combination of sodium benzoate and a storage temperature of 10˚C resulted in the highest preservation of total flavonoid content (2.49 mg QE/ml) after 20 days, compared to other treatments. Retention of higher vitamin C content (83.26 mg/100 ml) was noted under the treatment combination (+ positive control - pasteurized at 10˚C). For minerals, the treatment iv combination of sodium benzoate and 4˚C yielded enhanced calcium retention (81.3 mg/L) relative to alternative treatments. The maximum retention of iron content (33.1 mg/L) was recorded with the treatment combination of sodium benzoate and 4˚C, in comparison to other treatments. Regarding microbiological quality, juice samples treated with sodium metabisulphite, irrespective of storage conditions, exhibited the lowest yeast count (3.2 x 102 cfu/ml) in comparison to other treatments. Therefore, regional variances, the use of preservatives, and low storage temperatures all have a direct impact on marula fruit and juice. As a result, marula fruit juice manufacturers should take these factors into account since they have a direct impact on the juice's marketability and potential for commercialisation.; Inhloso yeMhlabuhlangene Tinjongo Tekutfutfukisa Letisimeme (SDGs) kutsi, emkhatsini waletinye tintfo, kucedza indlala kanye nekungadli kahle kanye nekucinisekisa kutsi bonkhe bantfu bayakhona kutfola kudla lokwenele lokunemsoco ngemnyaka wa 2030. Kwetfulwa kwetinhlobo tetitselo temdzabu letingakasetjentiswa kahle letifana nemaganu imarula (Sclerocarya birrea subsp. caffra), letisetjentiswa kancane. kuvithamin C kanye nemaminerali ladzingwa bantfu kwentela kugcwalisa tidzingo tabo tekudla letinconyiwe tetinsuku tonkhe, kubonakala ngatsi lisu leletsembekile lekufeza lemigomo. Lolucwaningo lolunetifundvo letiningi lwentelwe kuphenya (i) umtselela wesigodzi sendzawo etimphahleni tephysicochemical tetitselo temarula kanye nejusi, kanye (ii) nemphumela wenhlanganisela yekwelapha yetintfo letilondvolotako kanye netimo tekugcina etimphahleni tephysicochemical, kugcinwa kwemaminerali ejusi yemarula 100%. Inhloso yalolucwaningo bekukusungula tintfo letifanele kakhulu tekugcina kanye netimo tekugcina ijusi yetitselo temarula lecubunguliwe, ngenhloso yekutsengisa lomkhicito esikhatsini lesitako. Titselo kanye nejusi yato lesetjentiselwa kuhlatiya tintfo temtimba letifaka ekhatsi ikhalsiyamu, i-ayoni, bukhulu besitselo, shukela loncibilikako lophelele, ema flavonoids laphelele kanye nevithamin C kwavunwa eBushbuckridge, eGiyani nase Tzaneen, konkhe loku kuhlukaniswe njengetindzawo letiphansi eNingizimu Afrika Umphumela wekuhlanganiswa kwekwelapha (tintfo letilondvolotako kanye netindzawo tekugcina) ngelizinga, kufaka ekhatsi emakhemikhali etitjalo kanye nemamineral, kwahlolwa ngekubeka ijusi yetitselo temarula ngetintfo letilondvolotako (isodium metabisulphite kanye nesodium benzoate) kanye netimo tekugcina (4, 6, kanye na 10 ̊C) sikhatsi lseingemalanga langu-20. Mayelana nekuhlolwa kwemsebenti wetintfo letincane, indlela yekubala emapuleti lasakateke yasetjentiswa, lefaka ekhatsi kufukamela, kubalwa kwemayunithi lakha emakoloni kanye nekukhonjwa kwetinhlobo. Kuloluphenyo lwephysicochemical, lolucwaningo lwaveta kutsi titselo letivunwe esigodzini sase Bushbuckridge tikhombisa bukhulu lobukhulu (44.6 g) uma kucatsaniswa naleto letivela kuletinye tindzawo. Uma kucatsaniswa naletinye tifundza, sitselo sesigodzi sase Tzaneen besinesibalo lesiphakeme sashukela loncibilikako lesiphelele lesingu 12.9 ̊Brix. vi Mayelana nemtselela wetintfo letehlukene tekugcina kanye netimo tekugcina ekugcineni lizinga, imiphumela yakhombisa kutsi kuhlanganiswa kwesodium benzoate kanye nelizinga lekushisa lekugcina la 10 ̊C kwaholela ekugcineni lokusetulu kwalokucuketfwe kweflavonoid lephelele (2.49 mg QE/ml) ngemuva kwemalanga lamashumi lamabili (20), uma kucatsaniswa naletinye tindlela tekwelapha. Kugcinwa kwe vithamin C lesetulu (83.26 mg/100 ml) kwaphawulwa ngaphansi kwekuhlanganiswa kwekwelashwa (+ kulawula lokuhle - pasteurized ku 10 ̊C). Kumaminerali, inhlanganisela yekwelapha ye-sodium benzoate kanye na 4 ̊C kwakhicita kugcinwa kwe khalsiyamu lokukhulisiwe (81.3 mg/L) uma kucatsaniswa naletinye tindlela tekwelapha. Kugcinwa lokukhulu kwe-ayoni (33.1 mg/L) kwabhalwa ngekuhlanganiswa kwekwelapha kwesodium benzoate kanye na 4 ̊C, uma kucatsaniswa naletinye tindlela tekwelapha. Mayelana nelizinga letintfo letincane, emasampula ejusi laphatfwe ngesodium metabisulphite, kungakhatsaleki kutsi timo tekugcina, tikhombisa sibalo lesiphansi semvubelo (3.2 x 102 cfu/ml) uma kucatsaniswa naletinye tindlela tekwelapha. Ngako-ke, kwehluka kwesifundza, kusetjentiswa kwetintfo letilondvolotako kanye nelizinga lekushisa leliphansi kwekugcina konkhe kunemitselela lecondzile esitselweni semarula kanye nejusi. Ngenca yaloko, bakhiciti bejusi yetitselo temarula kumele batsatse letintfo njengoba tinemtselela locondzile ekutsengiseni kwejusi kanye nemandla ekutsengisa.; Xikongomelo xa Swikongomelo swa Nhluvukiso lowu Yisekaka Emahlweni (tiSDG) swa United Nations, exikarhi xin'wana, i ku herisa ndlala na nsiko na ku tiyisisa leswaku vanhu hinkwavo va na mfikelelo wa swakudya leswi nga tala swiaki swa mirhi swo ringanela hi kwalomuya ka 2030. Ku sungula ku tirhisiwa kwa mixaka ya mihandzu ya xintu leyi tirhisiwaka switsongo yo tanihi makanyi (Sclerocarya birrea subsp. caffra), leyi yi vikiwaka ku va yi tele yi vhitamini ya C na timinerali leswi dingiwaka hi vanhu ku fikelela swilaveko wa vona swa madyelo ya siku na siku leswi bumabumeriwaka, swi tikomba swi ri qhinga ro tshembeka ku fikelela swikongomelo leswi. Ndzavisiso lowa marhavinyingi wu endleriwile ku lavisisa (i) nkhumbo wa xifundza xa ndhawu ya misava hi mayelana na swihlawulekisi swa fizikokhemikali swa mihandzu ya makanyi na juzi ya makanyi (ii) xitandzhaku xa nkatsaniso wa makhomelo wa swisivelakubola na swiyimo swa vuhlayiselo, na nhlayiso wa timinerali na migingiriko ya switsongwatsongwana ya 100% ta juzi ya mihandzu ya makanyi. Hikokwalaho, xikongomelo xa ndzavisiso lowu a ku ri ku tumbuluxa swisivelakubola leswi ringaneleke swinene na swiyimo swa vuhlayiselo swa juzi ya mihandzu ya makanyi leyi phurosesiweke, hi xikongomelo xa vubindzurisi bya nkarhi lowu taka wa xikumiwa lexi. Muhandzu na juzi ya wona leswi tirhisiweke eka nxopaxopo swihlawulekisi swa fizikokhemikali ku katsa na khalisiyamu, ayoni, ntiko wa mihandzu, machukela lama n'okaka hinkwawo, tifulavhonoyidi hinkwato na vhitamini ya C swi hlengeletiwile eBushbuckridge, Giyani na Tzaneen, hinkwaswo swa swona swi ntlawahatiwa tanihi swifundza swa le timbalankoveni ta Afrika-Dzonga. Xitandzhaku xa mikatsaniso ya makhomelo (swisivelakubola na tindhawu ta vuhlayiselo) eka risima, ku katsa na tifayitokhemikali na timinerali, xi kamberiwile hi ku endla juzi ya mihandzu ya makanyi yi va na swisivelakubola (sodium metabisulphite na sodium benzoate) na swiyimo swa vuhlayiselo (4, 6, na 10˚C) ku ringana nkarhivunavi wa 20 wa masiku. Hi mayelana na makambelelo ya nghingiriko wa switsongwatsongwana, nhlayelo wa puleti yo hangalasela wu tirhisiwile, leswi katsaka andziso wa switsongwatsongwana, nhlayelo wa tiyuniti leti vumbaka tikholoni na ntiveko wa mixaka ya swihanyi. Eka vulavisisi bya fizikokhemikali, ndzavisiso lowu wu paluxe leswaku mihandzu leyi hlengeletiweke eka xifundza xa Bushbuckridge yi kombe ntiko lowukulu wa (44.6 g) loko wu pimanisiwa na lowuya wa le tindhawini tin'wana. Hi ku viii pimanisiwa na swifundza swin'wana, xifundza xa Tzaneen xi vile na nkhuvangano wa machukela lama n'okaka hinkwawo wa 12.9 ˚Brix. Hi mayelana na nkhumbo wa swisivelakubola leswi hambanaka na swiyimo swa vuhlayiselo eka nhlayiso wa risima, mivuyelo yi kombise leswaku nkatsaniso wa sodium benzoate na mahiselo ya vuhlayiselo ya 10˚C wu vange nhlayiso wa henhlahenhla wa vundzeni wa tifulavhonoyidi hinkwato (2.49 mg QE/ml) endzhaku ka 20 wa masiku, loko ku pimanisiwa na makhomelo man'wana. Nhlayiso wa vundzeni bya vhitamini ya C bya le henhla (83.26 mg/100 ml) byi lemukiwile ehansi ka nkatsaniso wa makhomelo (+ vulawurinene - ku hisisa kufika eka 10˚C). Eka timinerali, nkatsaniso wa makhomelo wa sodium benzoate na 4˚C swi nyike nhlayiso wa khalisiyamu lowu antswisiweke (81.3 mg/L) loko ku fananisiwa na makhomelo man'wana. Nhlayiso wa mpimohenhla wa vundzeni bya ayoni (33.1 mg/L) wu rhekodiwile eka nkatsaniso wa makhomelo wa sodium benzoate na 4˚C, hi ku pimanisiwa na makhomelo man'wana. Hi mayelana na risima ra ntivoswitsongwatsongwana, tisampulu ta juzi leti cheriweke sodium metabisulphite, swi nga ri na mhaka swiyimo swa vuhlayiselo, ti kombe nhlayelo wa xiviriso wa le hansihansi (3.2 x 102 cfu/ml) hi ku pimanisiwa na makahomelo man'wana. Hikokwalaho, mihambano ya swifundza, ntirhiso wa swisivelakubola na mahiselo ya vuhlayiselo ya le hansi hinkwaswo swi na nkhumbo wo kongoma eka mihandzu ya makanyi na juzi ya makanyi. Hikokwalaho, vamaki va juzi ya mihandzu ya makanyi va fanele ku tekela enhlokweni swihlohloteri leswi tanihileswi swi nga na nkhumbo wo kongoma eka vumaketeki bya juzi leyi na vuswikoti bya vubindzuriseki. Abstract in English with Swazi and Tsonga translations 2025-11-01T00:00:00Z https://ir.unisa.ac.za/handle/10500/32629 Investigation of egg quality characteristics of Ross 308 broiler breeder chickens Nkune, Achy Poultry products such as chicken eggs and meat continue to have an important economic impact and are important to the growth of a country`s economy. Moreover, poultry products are globally consumed in greater quantities than any other source of animal protein, because they are reasonably priced. Ross 308 broiler chicken is the best breed of chicken nationally which was bred specifically for meat. Poultry breeders focus on egg characteristics in their selection process for reproduction, because poor egg quality results in economic losses during production. This study was conducted to investigate the characteristics of egg quality traits, the correlations among these factors, how the egg weight influences egg quality traits, and to estimate the weight of the egg from egg quality traits in Ross 308 broiler breeder chickens. A total of 1000 eggs were purchased from Daybreak Farm in Bela Bela Local Municipality, Limpopo province of South Africa to conduct the study. Eight external traits of egg quality, including egg length, egg width, shell weight, shell index, shell surface area, unit surface shell weight and shell ratio, and five internal egg quality traits such as yolk weight, albumen weight, albumen ratio, yolk ratio and yolk/albumen. The descriptive statistics were used to quantify the egg quality traits, and the correlation between weight and quality traits of egg was investigated using Pearson`s correlation, One-way Analysis of Variance (ANOVA) was applied to investigate which egg quality traits are affected by egg weight and stepwise regression analysis was used to come up with best fit model to predict egg weight from egg quality traits. The descriptive statistics revealed that egg weight had a minimum and maximum value of 32.59 g and 98.25, g respectively. Egg length had a minimum value of 46.61 mm and a maximum value of 70.36 mm, and yolk weight had a minimum value of 5.31 g and a maximum value of 34.02 g. One-way ANOVA revealed that egg weight has a substantial effect (p < 0.05) on egg length, egg width, shell weight, shell index, shell surface area, unit surface shell weight, shell ratio, yolk weight, albumen weight, albumen ratio, yolk ratio and yolk/albumen. Pearson’s correlation findings displayed that egg weight had a highly positive, remarkable association (p < 0.01) with egg length, egg width, shell weight, unit surface shell weight, albumen weight, yolk weight, yolk ratio and yolk/albumen. In addition, negative correlation (p > 0.05) was identified between egg weight and shell index, shell ratio and albumen ratio. Stepwise regression findings revealed that the model, including yolk weight, yolk ratio, albumen ratio and albumen weight, was the best-fitted model (R2 = 1.00 and RMSE = 0.05) for estimation of egg weight. The model including yolk weight, albumen weight and yolk ratio was the second best (R2 = 1.00 and RMSE = 0.34). The study concludes that the improvement of yolk weight, yolk ratio, albumen weight and albumen ratio might improve the egg weight of the Ross308 broiler chicken breed. The results of this study may be useful to farmers in considering egg quality traits during breeding to improve the egg weight of Ross 308 broiler breeder chickens. 2026-04-28T00:00:00Z https://ir.unisa.ac.za/handle/10500/32088 Assessment of the food security status of Zimbabwean immigrants living in Pietermaritzburg, Kwazulu-Natal Hlatshwayo, Mavis Food insecurity is a global concern on upward trajectory and common amongst economic and political immigrants. The food security status of Zimbabwean immigrants in Pietermaritzburg, South Africa was investigated from 379 randomly selected immigrants. Food security was measured using Household Food Insecurity Access Scale (HFIAS), Household Dietary Diversity Index (HDDS) and Coping Strategy Index (CSI). The socio-demographic characteristics of the respondents showed that most immigrants were males 66%, 52.2% were younger (18-38 years) and 91.4% were employed. Most respondents 51% had tertiary education and 35.9%, earned between R3001-R4500. Based on the HFIAS, food insecurity assessment showed that that majority (75%) were food insecure, with 14% mildly food insecure, 33% moderately food secure and 28% severely food insecure. HDDS showed that 99.4% (n=378) of the respondents had a high dietary score. Dietary changes were the most adopted CSI strategy followed by rationing strategies. Food insecurity was perceived to be due to reduced /loss of employment, socio-political factors of theft, insecurity /violence, political crisis, lack of land ownership and high food prices. Age, immigration status and employment type were significantly correlated with food insecurity. Food insecurity was high in this study. However, in terms of the severity, results from HFIAS and CSI showed that most respondents were moderately food insecure. Household food insecurity was mainly due to food prices, reduced /loss of employment, and socio-political factors. Based on the findings of this study, efficient immigration processes, food aid and policies to monitor and stabilise the informal job sector are recommended.; Voedselonsekerheid is 'n groeiende wêreldwye kommer wat algemeen voorkom onder ekonomiese en politieke immigrante. Die voedselsekerheidstatus van Zimbabwiese immigrante in Pietermaritzburg, Suid-Afrika, is ondersoek aan die hand van 379 immigrante wat lukraak gekies is. Voedselsekerheid is met behulp van die Huishoudelike Voedselonsekerheidstoegangskaal (HVOTS), Huishoudelike Dieetdiversiteitstelling (HDDT) en Hanteringstrategie-indeks (HSI) gemeet. Die vi sosiodemografiese kenmerke van die respondente het aangedui dat die meerderheid manlik was (66%), 52.2% was in die ouderdomsgroep 18–38 jaar en 91.4% het gewerk. Die meeste van die respondente (51%) het tersiêre onderrig gehad en 35.9% het tussen R3 001 en R4 500 verdien. Volgens die HVOTS, het die voedselonsekerheidsassessering aangedui dat die meerderheid (75%) van die respondente voedselonseker was, met 14% effens voedselonseker, 33% matig voedselonseker en 28% erg voedselonseker. Die HDDT het aangedui dat 99.4% (n=378) van die respondente 'n hoë dieettelling gehad het. Dieetveranderinge was die HIS-strategie wat die meeste gebruik is, gevolg deur rantsoeneringstrategieë. Voedselonsekerheid is toegeskryf aan minder werksgeleenthede/werksverlies en sosiopolitieke faktore soos diefstal, onveiligheid/geweld, politieke krisis, gebrek aan grondeienaarskap en hoë kospryse. Ouderdom, immigrasiestatus en tipe indiensneming is aansienlik gekorreleer met voedselonsekerheid. Voedselonsekerheid was hoog in hierdie studie. Ten opsigte van ernstigheid het die HFIAS en HSI egter aangedui dat die meerderheid van die respondente matig voedselonseker was. Huishoudelike voedselonsekerheid is hoofsaaklik toegeskryf aan kospryse, minder werksgeleenthede/werksverlies en sosiopolitieke faktore. Op grond van die resultate van hierdie studie, word doeltreffende immigrasieprosesse, voedselbystand, en beleide om werk in die informele sektor te monitor en te stabiliseer aanbeveel. Abstract in English with Afrikaans translations. 2023-11-28T00:00:00Z https://ir.unisa.ac.za/handle/10500/32017 Assessment of the impact of renewable energy supply, carbon dioxide emissions, trade, and economic growth nexus on maize production from 1979-2021 Nevhutalu, Vhugala Charity The economy most susceptible to climate change is the agriculture sector. Agricultural production is negatively affected by weather patterns and temperature which ultimately impacts the sector’s economy. Food insecurity and a disturbance in the food supply chain are the aftereffects of climate change. A study by Wu et al. (2021). It is foretold that renewable energy utilization will reduce emissions responsible for climate change. The United Nations (UN) has also laid out a global mandate of “a clean and inexpensive energy for all” as part of the 17 Sustainable Development Goals (SDGs). This study specifically focuses on SDG 7 (affordable clean energy) and 13 (climate change). Many industrialized and emerging nations use maize as an energy crop; South Africa has rarely made use of this potential owing to valid food security concerns. Maize production trends in this study showed growth throughout the years despite a few declines which were mostly as a result of climate change. Trade trends also pointed out that there is minimal maize regional trade between South Africa and the rest of the African countries. At the aggregate level, maize production for human, and animal consumption and for biofuel feedstock depends on several macroeconomic factors, some of which were explored in this study. This study was backed by several macroeconomic theories namely: the Environmental Kuznets Curve (EKC), the Mercantilist Theory of Trade, the Export-Led Growth Theory, and the Endogenous Growth Theory. The main objective of this study was to assess the impact of Carbon Dioxide Emissions (CO2), Renewable Energy Supply, Trade, and Economic Growth on maize production in South Africa from 1979 to 2021. The nexus offered vital insights on initiatives that could be prioritised to advance renewable energy in the South African agriculture industry. An Auto Regressive-Distributed Lag (ARDL) model using Bounds test econometric approach was employed to estimate the short and long-run nexus between renewable energy supply, carbon dioxide emissions, trade, economic growth, and the production of maize. The existence of unit root in the time-series data was examined using the Augment Dickey-Fuller and Phillips-Perron tests; the robustness of the long-run estimate was assessed using the Fully Modified Least Squares (FMOLS) and Canonical Cointegration Regression (CCR) models. The Pair-wise Granger Causality test was used to test for causality between carbon dioxide emissions, renewable energy supply, trade, economic growth, and maize production. The short-run results indicated that Carbon Dioxide Emissions reduce maize production and renewable energy supply increases maize production both in the short-run and long-run. Granger causality results indicated a unidirectional causality between carbon dioxide emissions, economic growth, and maize production. A bidirectional causality was observed between renewable energy supply and maize production. This study contributes to economic policy regarding the energy-climate nexus in South Africa's agricultural industry. The agricultural industry is not only an energy consumer but also has the potential to contribute to renewable energy, specifically bioenergy through the supply of biomass. Considering that maize is a major global energy crop, its demand globally trickles down to maize-producing countries, and this has implications for supply and demand locally and globally. The study’s emerging insights may be used to guide the use of renewable energy biomass supply and the impact of climate change on the agricultural economy (maize production). Text in English 2024-01-01T00:00:00Z