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This study investigated the influence of the type and concentration of pectin on the sensory attributes and physical properties of a model strawberry jam. The methods used for the sensory evaluation and determination of physical characteristics that affect human taste and flavor perception are outlined. Increasing pectin concentration altered the solid (elastic) properties of the model strawberry jam. Each sensory attribute showed high correlation with various physical properties as determined by viscosity measurements. These results allowed us to predict the human oral cavity conditions during taste and flavor perception. From this study, it is clear that humans assess the physical properties of foods by the tongue movements and adjustments in the oral cavity conditions according to the taste and flavor characteristics.

The recently proposed short back extrusion (SBE) method is an improved immersed-type BE method. A translational concentric cylinder rheometer is used. As the measurement position is inside the sample, the upflow in the annular space is smooth even over a short distance (5 to 15 mm). Measurement over a short distance decreases the amount of sample adhering to the plunger; this facilitates repeated measurements, as the removal of the adhering sample after each measurement is not needed. The rheometer analysis program can perform automated Newtonian, power-law, and Herschel–Bulkley flow analyses by introducing novel mathematical solutions and obtaining constitutive equations for the various flow types. Herschel–Bulkley fluids exhibit semisolid properties and thixotropic flow characteristics, specifically, stress growth or time-dependent behavior. Currently, SBE viscometry is the only available method to evaluate viscosity and yield stress simply and simultaneously and this study presented the results compared with rotational cone-plate viscometry.

The short back extrusion (SBE) method of the translational concentric cylinder viscometer improves upon the back extrusion (BE) method by starting from an immersed position and acting over a short distance. According to this improvement, the SBE method can measure the flow behavior consecutively in short distance movement. Also using novel mathematical formulas, the analysis program automatic determines between Newtonian, power law, and Herschel-Bulkley flow and can be presented to the constitutive equation and the graph of the flow behavior. In the first part, the theory and mathematical analyses were presented; in this second part, the verification is presented to prove the accuracy of the SBE method using viscosity standard for Newtonian flow, locust bean gum solution for power-law flow, and commercial mayonnaise for Herschel-Bulkley flow. There are no viscosity standards in the non-Newtonian fluid, so the SBE method analysis was compared with the cone-plate viscometry. In special, the viscosity measurement of Herschel-Bulkley fluids using conventional cone-plate viscometry is very difficult because of the destruction of the sample structure by the rotational measurement. The yield stress of truly starting to flow cannot be measured and only the viscosity in the destroyed state can be measured. There is no other viscometry that can easily determine the characteristics of a fluid and display constitutive equations and graphs. Recently, the oscillatory shear testing has conducted replacing cone-plate viscometry but the SBE method can regain the right to measure viscosity of Herschel-Bulkley fluids.

The short back extrusion (SBE) method of the translational concentric cylinder viscometer improves upon the back extrusion (BE) method by starting from an immersed position and acting over a short distance. According to this improvement, the SBE method can measure the flow behavior consecutively in short distance movement. Also using novel mathematical formulas, the analysis program automatic determines between Newtonian, power law, and Herschel-Bulkley flow and can be presented to the constitutive equation and the graph of the flow behavior. In the first part, the theory and mathematical analyses were presented; in this second part, the verification is presented to prove the accuracy of the SBE method using viscosity standard for Newtonian flow, locust bean gum solution for power-law flow, and commercial mayonnaise for Herschel-Bulkley flow. There are no viscosity standards in the non-Newtonian fluid, so the SBE method analysis was compared with the cone-plate viscometry. In special, the viscosity measurement of Herschel-Bulkley fluids using conventional cone-plate viscometry is very difficult because of the destruction of the sample structure by the rotational measurement. The yield stress of truly starting to flow cannot be measured and only the viscosity in the destroyed state can be measured. There is no other viscometry that can easily determine the characteristics of a fluid and display constitutive equations and graphs. Recently, the oscillatory shear testing has conducted replacing cone-plate viscometry but the SBE method can regain the right to measure viscosity of Herschel-Bulkley fluids.

The primary objective of this study was to investigate the correlations between instrument measurements and sensory attributes of strawberry jam. For this purpose, a series of low sugar strawberry jams were prepared by using different contents of pectin from different sources, which were evaluated by sensory analysis for sensory attributes and by instrument measurements for specific physical properties. Model strawberry jams showed an elastic behavior that increased with higher low-methoxyl (LM) pectin content. These results showed that the apparent viscosity from viscosity measurements was highly correlated with each sensory attribute. As jam is a non-Newtonian fluid, the apparent viscosity was dependent on the shear rate. Moreover, the secondary objective of this study was to discern the physical properties affecting human texture perception based on these relationships. Hence, the instrumental texture perception based on the oral cavity condition was able to predict human texture perception based on the shear rate, which was obtained from the apparent viscosity. These results indicated that human texture perception is judged by apparent viscosity as determined by controlling tongue movement and oral cavity condition (e.g., temperature, saliva, and shear rate). Practical applications We could demonstrate the importance of texture measurement using replicated oral processing for each sensory attribute. Specifically, viscosity measurement results indicated that shear rate is a very important factor for texture perception. Moreover, our findings clarified that human texture perception is modified by apparent viscosity corresponding to shear rate. We anticipate that this technology might be applied as a measure of apparent viscosity to control texture for jam quality improvement.