Comparative studies on the effect of dying methods on quality properties of yellow fleshed sweet potato flour
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Date
2022
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Department of Food Science and Technolgy, Faculty of Technology, Obafemi Awolowo Universty, Ile Ife
Abstract
This study optimized the processing parameters of yellow-fleshed sweet potato flour (YFSP) using drum drier; compared the quality properties (proximate composition; mineral content, physicochemical, pasting, functional and rehydration properties) of flour produced from sun; oven and drum drier and determined the sensory properties of the reconstituted sweet potato flour. These were with a view to producing acceptable YFSP flour using different drying procedures.
The tubers were weighed, sorted, washed, peeled, diced, wet milled into slurry for drum dried samples while oven and sun-dried samples were milled, sifted, weighed and packaged. The pretreatments and drying conditions were blanching at 85 ºC for 3mins 30secs, steam cooking at 120 °C for 2mins, sun drying (3 – 4 days at 27 ± 2 °C), oven drying (70 °C for 8 hours) and drum drying at 150 ºC, 10 rpm, 100 ml (84.05%). The proximate composition, mineral content, physicochemical, pasting, functional, rehydration and sensory evaluation of reconstituted YFSP dough were determined using standard methods. Appropriate descriptive and inferential statistics were used to analyze the data.
The proximate composition of the samples showed that oven drying method decreased the moisture content of untreated and treated YFSP flour samples (4.88 – 5.31%) and the ash content (1.50 – 1.62%). All the drying methods increased the carbohydrate contents (73.15 – 81.33%) of YFSP flour samples. Sulphiting decreased the pH of the treated samples (5.58 - 5.90) while untreated sun and drum dried samples had increased pH (6.12 - 6.47). Drum drying method increased the mean particle size of drum dried samples compared to other methods. Untreated and treated samples had lower water absorption capacity (WAC) of 106.5 – 126% and oil absorption capacity (OAC) of 83.5 – 106%. Pretreatment reduced the WAC and OAC of YFSP flour samples. Drum drying method increased the WAC (531%) and OAC (168%) of the drum dried flour samples while it decreased the gelatinization temperature (78.5 ºC) and dispersibility (35%) of the samples. Swelling and rehydration capacities of untreated and treated samples increased as the drying temperatures increased from 80 and 90 ºC. The results showed that drying methods had effect on the pasting profile of the flour samples with the drum dried samples having the lowest values compared to other samples. The mineral contents: calcium (0.47 – 1.37 mg/100 g) and potassium (0.37 – 0.47 mg/100 g) of all the flour samples decreased during pretreatment and processing. Blanched sun-dried samples were the best overall flour based on the sensory properties (colour, taste, texture, mouthfeel and overall acceptability) while drum dried samples had the best functional properties based on water and oil absorption, swelling and rehydration capacity at 28 ± 2 ºC, 60 ºC and 70 ºC. The reconstituted dough from sun and oven drying methods were acceptable by the panelists, except for the drum dried dough. However, dough of steam cooked and sun-dried samples were ranked best. The study concluded that acceptable yellow-fleshed sweet potato flour could be produced from yellow fleshed sweet potato tubers by employing either of sun drying, oven drying or drum drying methods.
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BADIORA,O.A (2022) Comparative studies on the effect of dying methods on quality properties of yellow fleshed sweet potato flour ,Department of Food Science and Technolgy ,Obafemi Awolowo Universty ,Ile Ife