Hatsue Moritaka

Effect of monovalent and divalent cations on the rheological properties of gellan gels

Abstract The complex shear modulus of gellan solutions, with and without sodium chloride, potassium chloride, magnesium chloride, calcium chloride and calcium lactate, was measured on cooling to monitor the gelation. The gelling temperature shifted to higher temperatures with increasing salt concentration. Complex Youngs modulus and compressive break-force were observed for cylindrically moulded gellan gels as a function of salt and polymer concentration, C s and C p , and of temperature. The storage Youngs modulus and the break-force increased up to a certain C s and then decreased with increasing C s , while the melting temperature of gellan gels shifted to higher temperatures with increasing C s .

Effects of Potassium Chloride and Sodium Chloride on the Thermal Properties of Gellan Gum Gels.

The exothermic and endothermic peaks in cooling and heating curves of differential scanning calorimetry (DSC) for gellan gum gels without and with potassium chloride and sodium chloride were analyzed. The gelling and melting temperatures shifted to higher temperatures with increasing gellan and salt concentration in the concentration range of gellan from 0.3 to 2.0% (w/w). The exothermic and endothermic enthalpy increased with increasing gellan and salt concentrations. Cooling DSC curves showed one exothermic peak for samples with salts and at low gellan concentration. Heating DSC curves showed many peaks for all samples except 0.3% (w/w) gellan gum gels. The sol-gel transition of samples was examined numerically by using a zipper model approach. The introduction of cations increases the number of junction zones or zippers and decreases the rotational freedom of parallel links. This makes the structure of junction zones more heat resistant, and increases the elastic modulus of the gel.

Rheological properties of matrix-particle gellan gum gel: effects of calcium chloride on the matrix

Abstract The effects of particle gel (PG) on the rheological properties of gellan gum gels were investigated. Samples were 1.2% gellan gum gels with 5 mM CaCl 2 (MG-CaCl 2 ) or without CaCl 2 (MG), to which various amounts a particle gel of 1.2% gellan gum containing 5 mM CaCl 2 (PG-CaCl 2 ) was added. Breaking stress and storage Youngs modulus of MG containing PG-CaCl 2 increased with increased PG-CaCl 2 content, while those of MG-CaCl 2 containing PG-CaCl 2 decreased. PG-CaCl 2 behaved as an active filler in MG and as an inactive filler in MG-CaCl 2 . Activation of PG-CaCl 2 may be the result of interaction between calcium ions in the particles and carboxyl groups in the gellan gum molecules of the matrix.

Effect of Carbon Dioxide in Carbonated Drinks on Linguapalatal Swallowing Pressure

This study aimed to investigate the influence of carbonated drinks with gas volumes (GV) of 0, 1.5, and 2.7 on linguapalatal swallowing pressure, intraoral carbonation perception, and maximum velocity of a bolus through the pharynx in healthy volunteers (N = 20, all female, age range; 20-21 years). The volunteers swallowed a 12-mL drink in the natural state. Linguapalatal swallowing pressure was measured using a special sensor sheet, and maximum velocity of the bolus through the pharynx was measured using ultrasonic diagnostic imaging equipment. Peak magnitude, integrated value, and duration of linguapalatal swallowing pressure and maximum velocity of a liquid bolus through the pharynx increased with an increase in carbon dioxide content in the carbonated drink. The total integrated values of carbonated drinks with GV of 1.5 and 2.7 were larger than that of the drink without carbon dioxide. These results suggest that the carbon dioxide dissolved in carbonated drinks influences the activity of taste receptors in the mouth and results in neuromotor responses.

Relation between the Rheological Properties and the Swallowing Characteristics of Vegetable Juices Fortified with Carrot Puree

The relation between the rheological properties and the swallowing characteristics of vegetable juices fortified with 0–30.0% carrot puree (CP) was evaluated. The apparent viscosity of vegetable juices increased with increasing CP concentrations, and a increases in yield stress were observed at and above 17.5% CP. In a sensory evaluation, texture perceived in the oral cavity varied as between vegetable juices with >17.5% CP and those with <12.5% CP. The maximum velocity in the pharyngeal region was classified into three same-quality subgroups: vegetable juices with 0–12.5% CP, with 10.0–25.0% CP, and with 17.5–30.0% CP. It significantly decreased with increasing CP concentrations.

Influence of Thickeners on the Fragmentation of Fish Meat Sausage by Mastication

The influence of food thickeners (potato starch, guar gum, and xanthan gum and deionized water) on the breakdown of solid food was numerically analyzed, and an investigation was made into the cumulative size distribution of food fragments, textural properties, sensory evaluation and maximum transit velocity of a bolus in the pharynx. The results suggest that evaluating the breakability into small pieces was easily influenced by the addition ratio of the dispersion medium. However, in respect of the destruction process for the solid body, each sample was more strongly affected by the type of the dispersion medium than by the addition ratio of this medium. The destruction process was strongly influenced by the history of the breakdown caused by mastication when a liquid dispersion medium was added to the solid. However, when a high-viscosity sol was added to the solid, the destruction process was random and not affected by any history.

Rheological and Thermal Properties of Gellan Gum Gels

Complex Young’s modulus (E‘), compressive break-force (Ph) and curves of differencial scanning calorimetry (DSC) of gel Ian gum solution, with and without salt, were observed gellan gum gels as a function of salt and polymer concentration, Cs and Cg. E’ and Ph increased up to a certain Cs and then decreased with increasing Cs. The gelling and melting temperatures shifted to higher temperatures with increasing Cs and Cg. The sol-gel transition of samples was examined numerically by using zipper model approach. The introduction of cations increases the number of junction zones or zipper N and decreases the rotational freedom G of parallel links.

Effect of carrot puree in vegetable juice on linguapalatal swallowing pressure

This study aimed to ascertain the influence of various amounts (0-30%) of carrot puree (CP) in vegetable juice on linguapalatal swallowing pressure in healthy volunteers. Twenty healthy women (age range: 20-22 years) swallowed a 17-ml drink in a natural state, and linguapalatal swallowing pressure was measured using a special sensor sheet. Peak magnitude (maximum pressure of the tongue pushing on the hard palate), integrated values of linguapalatal swallowing pressure on the waveform, and duration of linguapalatal swallowing pressure were increased with increases in CP concentrations. The total integrated value for 30% CP vegetable juice was larger than that of vegetable juice with no CP. The apparent viscosity of the vegetable juice with a low CP concentration was smaller than that with a high CP concentration at the same shear rate. These results suggest that vegetable juice containing CP affects mechanoreceptor activity in the mouth and generates a neuromotor response. PRACTICAL APPLICATIONS This study aimed to ascertain the influence of various amounts of carrot puree (CP) in vegetable juice on linguapalatal swallowing pressure measured by using a special sensor sheet in healthy volunteers. Obtained results of this study clearly showed that vegetable juice containing CP affects the movement of the tongue in maneuvering the bolus. Moreover, the results demonstrated that this effect depended on the concentration of CP in the vegetable juice. These findings are expected to provide clinically valuable data on the effect of mechanical stimulation during the oral stage of swallowing.

Swallowing and the Rheological Properties of Soft Drink and Agar Gel

Mastication and swallowing are essential steps in food ingestion and nutrient absorption in humans. Mastication is the process in which food taken from the mouth is crushed and mixed with saliva in the oral cavity to create food boluses that are optimal for swallowing. The use of facial and jaw muscles, in addition to teeth, is necessary for mastication. Foods with gel-like texture are crushed by mastication, and the resulting boluses are transferred from the oral cavity to the pharynx with assistance from tongue pressure and then to the esophagus by suction generated upon elevation of the larynx. Bolus formation by mastication is closely associated with the swallowing process. Meanwhile, liquid foods are transferred from the oral cavity to the pharynx without mastication. However, the swallowing method of a drink changes by the additions included in the drink. It is important to know the relationship between physical property of drink and the linguapalatal swallowing pressure, the relationship between the preprandial food size and the nature of food bolus, and then the relationship between the texture property of the food bolus and the swallowing.

Effects of Thickeners on Rheological Properties of Agar Gels Treated with Freezing-thawing.

寒天ゲルの冷凍耐性に及ぼす寒天濃度,グアーガム,ι-カラギーナン,LBG添加の影響について検討した.(1) 寒天濃度を増加させると冷凍耐性は向上したが,その改善効果は小さかった.(2) 力学特性については,LBGの添加により改善効果が認められた.グアーガム添加による効果はなかった.(3) 離漿については,LBGおよびι-カラギーナンの添加により顕著に改善された.