Effects of carboxymethylation on the physicochemical properties of natural dietary fibers

• Main Authors: Ying Liew, 劉穎
• Other Authors: 周志輝
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5253014%22.&searchmode=basic

碩士 === 國立中興大學 === 食品暨應用生物科技學系所 === 107 === The present study was divided into two parts, of which the first part was aimed to review on dietary fiber, its applications, and available modification techniques to modify dietary fiber. Dietary fiber, classified into soluble dietary fiber (SDF) and insoluble dietary fiber (IDF), is found to have beneficial health effects for human beings via different physiological effects. Owing to the trend of inadequate dietary fiber intake, manufacturers incorporate dietary fiber into foods and beverages in an attempt to allow consumers to have an easy accessibility to dietary fiber. Besides, biosafety, biodegradability, and sustainability of dietary fiber also make it one of the exploitable materials for non-food applications. Although dietary fiber is widely made use of in food and non-food applications, limitations like insolubility of IDF and high viscosity of SDF may not fit in with certain applications. In order to overcome these limitations, chemical, enzymatic, mechanical, and mixed methods modifications can be applied on IDF and SDF to produce new dietary fiber derivatives and meet market needs. By means of these modification strategies, the prominent changes of IDF is increased water solubility, which resembles the SDF. Carboxymethylation is a cost-effective and simple chemical modification, and thus the second part of the present study was aimed to investigate the effectiveness of carboxymethylation in altering the physicochemical properties of different natural dietary fibers, such as apple peel fiber, orange peel fiber, and guar gum. The experimental results showed that carboxymethylation increased water solubility of dietary fibers of apple peel and orange peel greatly; while their viscosity also gained significantly (p ＜ 0.05). As for carboxymethyl guar gum (CMGG), the degree of substitution (DS) was affected by different ratios (1:0.75, 1:1.5, 1:3) of guar gum to sodium hydroxide (NaOH). The DS values increased (p ＜ 0.05) with increased addition of NaOH. With increasing values of DS, CMGG showed a marked declination (p ＜ 0.05) in viscosity but with improved solution clarity. Basically, all of the dietary fibers showed no visible color changes before and after carboxymethylation.