Effects of Annealing and Additives on the Gelatinization, Structure, and Textural Characteristics of Corn Starch

Effects of NaCl on the Physical Properties of Cornstarch-Methyl Cellulose Blend and on Its Gel Prepared with Rice Flour in a Model System

This study investigated the impact of NaCl on the physical properties of cornstarch-methyl cellulose (CS-MC) mixtures and their gels prepared with rice flour in a model system. Opposite trends were observed, showing that NaCl led to decreased viscosity of the CS-MC mixtures (liquid-based), whereas a more stable and robust structure was observed for the rice-flour-added gels (solid-based) with the addition of NaCl. The interference of NaCl with the CS-MS blend's ability to form a stable gel network resulted in a thinner consistency, as the molecules of the CS-MS blend may not bind together as effectively. On the contrary, NaCl showed the potential to enhance the protein network within CS-MC gels prepared with rice flour, thereby contributing to an augmentation in the stability or firmness of the cooked gels. Careful utilization of NaCl to optimize the physical properties of the CS-MC blends, as well as the gels based on rice flour, should be performed.

Change in characteristics of film based on rice starch blended with sucrose, maltose, and trehalose after storage

The characteristics of rice starch film blended with sucrose, maltose, and trehalose at concentrations of 0%, 10%, 20%, or 30% (w/w of the starch weight) were investigated. Relative crystallinity (RC) of the rice starch film as determined by X-ray increased with increasing sucrose concentration and the RC tended to decrease with an increasing concentration of maltose and trehalose. RC was inhibited by adding sugar in the order of trehalose, maltose, and sucrose after 28 days storage. The rice starch film with 30% added sugar showed a homogeneous matrix and a lower frequency chemical shift of the proton OH group as determined on the day of preparation; however, the film with 30% added maltose cracked after 28 days storage. Adding sugar as a plasticizer affected the properties of the rice starch film by concentration and type of sugar because of the hydroxyl groups of the sugar. PRACTICAL APPLICATION: Disaccharides, such as sucrose, maltose, and trehalose, could be used as a plasticizer in a rice starch film system. The sugar conformation might be one factor for selecting the sugar to use for starch film system. Trehalose might improve film properties by inhibiting recrystallization after storage.

Some physico-chemical and thermodynamic characteristics of maize starches hydrolyzed by glucoamylase

Glucoamylolysis of maize starch at 55 °C has been studied by means of scanning electron microscopy (SEM), wide-angle X-ray diffraction spectroscopy (WAXD), and differential scanning calorimetry (DSC). It was found that hydrolysis is accompanied by changes in thermodynamic parameters of diluted aqueous dispersions of partially hydrolyzed starches. Such changes are ensured by two processes directly from hydrolysis and accompanying annealing. At relatively low degrees of hydrolysis (less than 30%), changes in thermodynamic parameters are mainly controlled by annealing. At the same time, at high degrees of hydrolysis (more than 40%), the main contribution to changes in thermodynamic parameters of partially hydrolyzed starch granules is due to the hydrolysis itself. It has been established that the main controlling parameter is the thickness of crystalline lamellae L_crl, which, when annealed, increases, but tends to decrease at deeper glucoamylolisis. It has been established that the thickness L_crl of crystalline lamellae, which increases with annealing, but shows a tendency to decrease with deeper glucoamylolysis is the most representative parameter of changes in maize starch after hydrolysis.

Effects of xylitol and stevioside on the physical and rheological properties of gelatin from cod skin

Jelly and confectionery products are high in sugar and calories. Xylitol and stevioside are natural low-calorie sweeteners and they can be used as an alternative; however, their effects on fish gelatin are unknown. The gelatin was extracted from cod skins and added to xylitol or stevioside (0, 2, 6, 10, 14, and 20% (w/v)) to form gel products. This paper investigated how xylitol and stevioside affected the physical and rheological behaviors of fish gelatin, such as color, gel strength, texture profile analysis, storage modulus (G′), loss modulus (G″), and viscosity. Results showed that the change of color and viscosity in gel products were similar when various concentrations of xylitol or stevioside were added to the fish gelatin. But the effects of xylitol/stevioside on texture profile analysis and G′, G″ were different, which might due to the structure variation in xylitol and stevioside. The linear structure of xylitol resulted in ionic interaction, hydrogen bonding, van der Waals forces, and hydrophobic association between xylitol and fish gelatin. Therefore, xylitol is a promising sweetener substitute, which was probably related to its greater solubility and number of –OH groups.