Extraction and physicochemical characterization of a potential multifunctional pharma-excipient from crab shell wastes

An efficient and beneficial waste disposal mechanism is highly desired. This study was carried out to extract and characterize a potential multifunctional pharmaceutical excipient from crab shell wastes. Shells of  Pachygrapsus mamoratus were obtained from Oron, a coastal town in Akwa Ibom State of Nigeria. Chitin was extracted from the powdered shell by deproteination and demineralization; and chitosan was derived by  alkaline deacetylation of the chitin. The polymer was subjected to Fourier transform infrared (FTIR)  spectroscopy and differential scanning calorimetry (DSC). It was also evaluated for flow properties, pH and  hydration and swelling characteristics. The shells gave a yield of 17% chitosan. FTIR analysis of the polymer showed C-H bond of substituted cyclic hydrocarbon, cyclic C-N bond, C-O bond of glucose molecules, C-H bond of side chain –CH2OH, presence of β-ester linkage, N-H of amides and bonded and free O-H groups. The last  transition in the thermogram of chitosan was a polymer degradation exotherm with a peak at 337.9°C. The  chitosan had higher bulk density, higher flow rate, lower Carr’s index and lower Hausner’s ratio compared to sodium carboxymethylcellulose. It also had lower hydration and swelling capacities. Therefore, the crab shell-derived chitosan has better thermal stability, better flow properties but poorer swelling properties compared to sodium carboxymethylcelluose.Key words: Crab shell, chitosan, physicochemical characteristics, pharmaceutical excipient

Characterisation, in vitro digestibility and expected glycemic index of commercial starches as uncooked ingredients

When selecting a native starch for specific food purposes, it is important to consider the differences between starches of varying botanical sources (cereal, tubers and roots). In this study uncooked starches as ingredients (corn, rice, wheat, tapioca and potato) were characterized according to microstructure, some (physicochemical, functional and thermal) properties, in vitro digestibility and expected glycemic index. There was a significant variation in the granule shape and size distribution of the starches, when studied using Scanning Electron Microscopy (SEM) and particle size analysis. Particle size results distinguished among starches in monomodal (corn, tapioca, potato) and bimodal (rice, wheat) populations. Among all the samples, the potato showed the biggest size distribution granules while the rice showed the lowest. The examined properties and nutritional characteristics of starches were significantly different. Thermal properties were studied by means of Differential Scanning Calorimeter (DSC). DSC studies found that the transition temperatures (58.8 °C - 78.7 °C) and enthalpies of gelatinization (2.3 J/g - 8.2 J/g) of the starches appeared to be greatly influenced by microstructure and chemical composition (e.g. resistant starch). Potato and corn starches were hydrolyzed more slowly and to a lesser extent than ones. In particular, the highest resistant starch was recorded for potato. Nutritional properties such as slowly digestible starch and expected glycemic index values followed the order: rice > wheat > tapioca >corn > potato. In general, these results provide the baseline information on the development of novel foods or native starch blends with tailored functional properties such as slow digestibility