Preparation, functional and pasting behavior of starch phosphates of red cocoyam (Colocosia esculenta) and white cocoyam (Colocosia antiquorum): a comparative study
A contemporary strategy in the starch industries is the diversification of raw materials. However, the hydrophilic nature of starch limits its use as a raw material for food and packaging products, resulting in a low level of biodegradation. To address this issue, it is imperative that starch be chemically modified. Starch phosphates are among the most common and commonly used chemically modified starches. In this study, native red cocoyam starch (NRCS) and native white cocoyam starch (NWCS) were chemically modified with di-sodium hydrogen orthophosphate as phosphorylating agent to produce red cocoyam starch phosphate (PRCS) and white cocoyam starch phosphate (PWCS). The functional and pasting properties of the native and starch phosphates of both cocoyam species were evaluated and compared. The starch yield increased from ~ 17% for NRCS to ~ 25% for PRCS and from ~ 12% for NWCS to ~ 20% for PWCS. The water and oil absorption capacities were 97.00 & 143.00% for NRCS and 78.00 & 164.00% for NWCS, whereas for PRCS it was 160.00 & 153.00% and for PWCS it was 127.00 & 173.00% respectively. NRCS and PRCS had a foam capacity of 8.80 and 9.00% while NWCS and PWCS had 8.00 and 10.00% respectively. Phosphorylation had a significant impact on the pasting properties leading to a reduction in the peak, breakdown, set back, and final viscosities of the native cocoyam starches. In conclusion, phosphorylation considerably improved the functional and pasting qualities of red and white cocoyam starch, revealing its tremendous application potential in the formulation of food components, as a stabilizer, tablet binders in pharmaceutical industries, as well as in the packaging industries.