Investigation on the phase behaviour of gelatin/agarose mixture in an environment of reduced solvent quality

Investigation on the phase behaviour of a biopolymer mixture has been performed using 7.5% (w/w) gelatin and 1.5% (w/w) agarose in the presence of variable amounts of polydextrose as the co-solute from low to high levels of total solids. Mechanical observation of the system was performed using small deformation dynamic oscillation in shear along with thermal studies using modulated differential scanning calorimetry. Micrographs provided images of the changing morphology of the network with the addition of co-solute. Agarose and gelatin form non-interactive bicontinuous phases in the aqueous environment. Systematic increase in the concentration of polydextrose prevents the formation of a stable agarose network, with the polysaccharide chains dispersing in the high solids environment. Gelatin, on the other hand, retains its conformational stability even at a saturating co-solute environment through enhanced protein structuring. Vitrification studies on the high solids system at subzero temperatures provides information on the structural and molecular relaxation identified as a glass transition phenomenon. Fourier transform infrared spectroscopy was used to analyse potential direct interaction between polymers and co-solute. The extent of amorphicity in the system was confirmed using wide angle X-ray diffraction.

Physicochemical properties of flours and starches derived from traditional Indonesian tubers and roots

Flours and starches isolated from traditional tubers and roots grown in Indonesia have physical and chemical properties suitable for certain food applications. Compared to other flour samples, cassava and canna flours contained the highest amount of total starch (TS) (77.4 and 77.1 %, respectively). Taro starch had the lowest amount of TS among other starch samples with 75.4 %. The highest amount of amylose was observed from yam and canna flours (25.2 and 23.2 %, respectively). Among starch samples, canna starch contained the highest amylose content (30.4 %), while taro had the lowest (7.6 %). In terms of protein content, arrowroot flour had the highest amount (7.7 %), in contrast to cassava flour which had the lowest (1.5 %). Compared to other flours, canna and konjac flour were the most slowly digested which indicated by their high amount of resistant starch (RS). Canna starch had the highest swelling power and viscosity than other starches and flours. The clearest paste was observed from cassava flour and starch as opposed to konjac starch which was the most opaque paste.