Browsing by Author "Ndlovu, Phindile Faith."

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The development of indigenous marula (sclerocarya birrea) fruit leather : effect of drying temperature and sugar concentration on the drying characteristics, physico-chemical and consumer sensory properties of marula fruit leathers.
(2016) Ndlovu, Phindile Faith.; Tesfay, Samson Zeray.; Ngcobo, Mduduzi Elijah Khulekani.
Fruits indigenous to African countries are highly recognised and valued by rural communities for food security purposes. An examples of such fruits include but not limited to marula fruits (Sclerocarya birrea), which is indigenous to many parts of Southern Africa. In some parts of the continent, the role and usefulness of indigenous fruit species still receives little attention in agricultural research. Amongst others, this results from the magnitude postharvest quality losses due to the high moisture content characteristic of these fruits and a lack of access to required postharvest infrastructure by small-scale farmers. The processing of high moisture content commodities offers a convenient way of preserving their quality. The main aim of this research was to develop fruit leathers from the indigenous marula fruits as means of quality preservation. The development of new products from indigenous fruit crops as a means of preserving the fruits quality (nutrients) has a potential of enabling farmers, particularly small-scale farmers, to diversify on their on-farm business and farming activities. It also has the potential of improving the nutrition security and economy of the rural communities. Marula fruit are normally processed and conserved into various product forms (e.g. jams, juice, flavoured water, sweets, essential oils, traditional beer and world exported beverages such as Amarula Cream) which are readily available in the market. The production of such products from the indigenous fruits involves different processing techniques and these techniques ranges from highly sophisticated processes to simple traditional ones. The choice of the processing technique used is dependent on the characteristics of the intended product. Drying is one of the techniques that have not been widely applied in the processing of indigenous fruits. The application of this technique offers the potential to produce healthy, nutritious and flavourful ready to eat snack from the indigenous fruits such as fruit energy bars and fruit rolls which can be accessible and available throughout the year. Very little information have been reported on product development of indigenous marula fruit in previous years. The study conducted independent drying experiments to evaluate the effects of different drying temperature (50, 60 and 70 °C) and different added sugar concentrations (0, 5 and 10% w/w) on the drying kinetics of the marula fruits pulp. Moisture loss from the fruits’ pulp and different drying models in explaining the heat and mass transfer processes and for predicting the drying behaviour of the fruit leathers during drying were assessed. The textural, colour and consumer sensory attributes of the dried fruit leathers were also evaluated. The moisture loss and drying behaviour of the marula fruit leathers were significantly (p ≤ 0.05) affected by the drying temperature and added sugar content. During the evaluation of the colour properties, the drying temperature and the added sugar content increased significantly (p ≤ 0.05) the colour of the fruit leathers. However, the colour properties of fruit leathers with high added sugar concentration for each drying temperature were significantly (p ≤ 0.05) reduced. The texture attributes of the marula fruit leather significantly (p ≤ 0.05) increased with drying temperature (50 and 60 °C) and sugar concentration (0, 5 and 10% w/w), but significantly decreased at 70 °C for 10% w/w treated fruit leathers. The consumer sensory evaluation was also conducted to assess the acceptability of the fruit leathers. In general, all fruit leathers were accepted by panellists, and this demonstrated that marula fruit leather would form an acceptable new product. The sensory analysis showed that the mostly liked and preferred fruit leathers by the panellists were the ones prepared at 50 °C with 10% w/w added sugar.
Rapid monitoring and quantification of unripe banana flour adulteration using visible-near infrared spectroscopy.
(2021) Ndlovu, Phindile Faith.; Magwaza, Lembe Samukelo.; Tesfay, Samson Zeray.; Mphahlele, Rebogile Ramasele.
A general lack of strict regulations in South Africa to monitor processed foodstuff increases chances of unfair producers and traders to intentionally mislabel and adulterate high valued food products with inferior lookalikes. Recently, unripe banana flour (UBF) has gained global attention and has been identified as a replacement for cereals flours due to its gluten free traits and resistant starch nutritional qualities, yet has no quality control standards. The objective of this research was to develop rapid prediction models based on a visible to near infrared (Vis- NIR) spectroscopy (Vis-NIRS) combined with multivariate analysis to classify, detect, and quantify different adulteration levels of staple flours (i.e. wheat and maize flours) in unripe banana flour. The other aim was to identify important biomarkers of unripe banana flour that could be used to discriminate unripe banana flour adulteration at different concentration levels. A critical evaluation of the portable Vis-NIR spectroscopy combined with chemometrics analysis indicated that it was possible to discriminate between unripe banana flour with wheat and maize flours and associated different adulteration levels. The partial least square (PLS) regression (PLSR) analysis quantified individually maize and wheat flours, based on different adulteration levels, showed that optimal PLSR detection models performances were obtained using the first derivative Savitsky-Golay (7-point smoothing, 2nd order polynomial) and the second derivative Savitsky-Golay (19-point smoothing, 2nd order polynomial). The study to optimise and test the handheld Vis-NIR instruments’ feasibilty to simulteniously develop a standard model for rapid solution to detect both maize and wheat flours adulteration indicated high classification and prediction accuracies could be achived through principal component analysis (PCA) and partial least squeres regression (PLSR). The study found that gluten could be utilised as a biomarker to test for unwanted adulteration of unripe banana flour with wheat flour, and showed good and reliable rapid spectroscopic PLSR model was achieved with high precision. Near infrared spectroscopy showed great potential to detect the nutritional changes of unripe banana flour during adulteration based on resistant starch content. The results of this investigation indicated that wheat adulteration is a threat to unripe banana flour importnt attribute as signification reduction of this parameter was observed with the increasing levels wheat adultearation. Vis-NIR spectroscopy with multivariate analysis detected the varying resistant starch concentration unripe banana flour samples successfully with high accuracy. The results and stability of the models developed in this study demonstrated clearly that the Vis- NIRS method has a potential of providing unripe banana flour processing industry with a rapid and non-destructive technique to manage unripe banana flour quality as well as adulteration by staple flours, therefore ensuring fair and safe trading of the product in retail markets of South Africa.