Effect of chemical modifications on morphological and functional characteristics of water-chestnut starches and their utilization as a fat-replacer in low-fat mayonnaise

Isolated water-chestnut starches were subjected to succinylation, hydroxypropylation, and acetylation followed by evaluation of their morphological and physicochemical properties. The Pakistani water-chestnut starch granules were oval in shape while the granular size of the starch was found to be between 4.5 and 37m. The solubility of the starches followed the order SWS (succinylated water-chestnut starch)>HPWS (hydroxypropylated water-chestnut starch)>AWS (acetylated water-chestnut starch)>NWS (native water-chestnut starch). The breakdown viscosity of the chemically modified starches was significantly higher than NWS at p<0.05. The pasting temperature and setback viscosity also reduced significantly due to chemical treatment of the chestnut starches. The hardness of SWS was less than that of native starch after 7 days of storage at 4 degrees C indicating reduced percent retrogradation in these starches. The chemically modified starches were also used to prepare low-fat mayonnaise. The use of 10% starch paste (native/chemically modified) resulted in 80% oil replacement in mayonnaise. The low-fat mayonnaise prepared using chemically modified chestnut starches were found to have quite similar textural and sensory properties compared to full-fat mayonnaise. However, in terms of overall-acceptability the low-fat mayonnaise prepared from HPWS was the least preferred by sensory panelists because of its runny texture.