Residual Calcium Content of Sweet Potato Slices after Osmotic Pre-treatment with Salt (NaCl) Solution

摘要

Light yellow-flesh, matured sweet potato was used in a lab osmotic pre-treatment in sodium chloride (NaCl) solution with varying salt concentrations. The samples were subsequently dried via oven-drying. Measurements of residual calcium were taken. The dried potato slices (1 kg each of the representatives) were ashed in a muffle furnace at temperature of about 570°C for 30 mins. Solutions of the ashes were made by properly stirring with little volumes of distilled water in a beaker respectively. When the suspended solids were present in sufficient amounts to clog the nebulizer, the sample was allowed to settle and the supernatant liquid analyzed directly. The results obtained after AAS determination of calcium contents by checking absorbance against the concentration in a standard curve were analyzed using three factor design statistical analysis. Results show that potato slices of about 6mm thickness should be adopted since it yields potato products with relative higher calcium content than 2 mm and 4 mm thickness. The concentration of the salt solution should be adjusted to 10% m/v strength, as results to products with relatively higher calcium content. Where SSC of 10% m/v couldn’t give product with required texture, 20% m/v could be alternative. Time of soaking should be within 20 – 40 minutes since the nutrition (Calcium) of the product is improved within this resident duration. Generally, to ensure potato products with more conserved calcium and required texture, potato slice thickness of 6 mm, salt solution concentration of about 10 to 20% m/v, and soaking time within 20 – 40 minutes should be adopted during pretreatment processing.