PREDICTION OF INSTRUMENTAL AND SENSORY TEXTURAL CHARACTERISTICS OF MAHON CHEESE FROM ULTRASONIC MEASUREMENTS

Ultrasonic velocity was related to sensory and instrumental texture measurements. A semi-logarithmic model (Weber-Fechner) was used to relate the sensory and instrumental texture measurements. The ultrasonic velocity ranged from 1650 to 1723 m/s for the softest and hardest cheese, respectively. As expected from theoretical equations, the ultrasonic velocity was related to the square root of the instrumental measurements. The deformability modulus (r²=0.93) and the slope in puncture (r²=0.85) were the most closely related parameters. A model developed from the relationship between sensory and instrumental texture and the relationship between ultrasonic velocity and instrumental texture, was used to relate velocity to sensory measurements. Elasticity (r²= 0.84) and firmness (r²= 0.81) were the sensory attributes which best correlated with ultrasonic velocity. From the obtained results, it was concluded that ultrasonic velocity measurements could be used to assess instrumental and sensory properties of Mahon cheese texture nondestructively, and therefore could be used for grading purposes.     

SENSORY TEXTURE PROFILE, GRAIN PHYSICO-CHEMICAL CHARACTERISTICS AND INSTRUMENTAL MEASUREMENTS OF COOKED RICE

Three samples of raw-milled rice, and 4 differently parboiled rices were used to study and to relate sensory perception to instrumental measurements. Variance analysis showed that some physico-chemical characteristics indicated great differences among rice samples: thickness of cooked grain, length/width ratio, water uptake, elastic recovery, white core rate and amylose and protein contents. The most discerning sensory attributes were: elasticity, stickiness, pastiness, mealiness, length of grain, firmness, crunchiness, time in mouth, brittle texture and juiciness. The correlation circle of the principal component analysis (PCA) showed high correlation between some sensory characteristics and instrumental measurements. Melting texture, surface moistness, juiciness, were positively correlated with water uptake (r = 0.70, 0.61, 0.71). Granular texture, crunchiness, brittleness and mealiness were significantly affected by white core presence (r = 0.81, 0.74, 0.86, 0.83). Elasticity was dependent upon elastic recovery and firmness measured by the Viscoelastograph, but not linearly. Length of cooked grain was correlated with the length/width ratio of raw grain (r = 0.83). Pastiness, compactness, stickiness were slightly influenced by the thickness of raw grain (r = 0.81, 0.67, 0.72). To a weaker extent, the sensory firmness was associated with the firmness measured by extrusion force using an Ottawa cell (r = 0.58). PCA showed greatdifferences in texture between rices. Two of the parboiled rices were very elastic, another was firm, granular, crunchy and mealy. The remaining two, cooked longer, were moister and more melting. Among the 3 samples of raw-milled rices, differences in grain length feeling and melting-granular-brittle characteristics. were distinguished.     

INSTRUMENTAL AND SENSORY EVALUATION OF TEXTURAL CHANGES DURING ROASTING OF CASHEW KERNELS

Textural changes in cashew kernels roasted in hot‐air oven at controlled temperatures in the range of 140–180C for 30–120 min were studied using both instrumental and sensory evaluations. The Kramer shear force decreased exponentially, whereas the color lightness index and the total color difference exhibited linear relationships with roasting time at all temperatures. The changes in sensory parameters such as acceptability, appearance and taste were adequately described by third‐degree polynomials. The optimum roasting conditions for cashew kernels based on hedonic sensory evaluations were determined to be 140C–33.3 min, 160C–11.2 min and 180C–5.7 min, and resulted in similar values of Kramer shear force and color lightness index estimated from the developed models. The instrumental measurements could be used for monitoring the roasting process to produce optimally roasted cashew kernels.     

RELATIONSHIPS BETWEEN SENSORY AND RHEOLOGICAL MEASUREMENTS OF TEXTURE IN MATURING COMMERCIAL CHEDDAR CHEESE OVER A RANGE OF MOISTURE AND pH AT THE POINT OF MANUFACTURE

Textural characteristics of 10 Cheddar cheeses with a range of moisture contents and pH values were investigated by sensory and instrumental methods, over a 9‐month maturing period. A trained panel of nine assessors described the sensory texture characteristics of the cheeses using 11 texture parameters. Instrumental parameters were derived using texture profile analysis. Relationships between sensory, instrumental, compositional and maturation properties of the cheeses were determined with the aid of principal component analysis and multiple linear regression. Nine sensory parameters significantly correlated with instrumental parameters, e.g., sensory rubbery correlated with instrumental firmness (R = 0.696, P < 0.001), chewiness (R = 0.679, P < 0.001), fracture stress (R = 0.669, P < 0.001) and springiness (R = 0.643, P < 0.001). Sensory firmness corresponded closely with instrumental firmness (R = 0.539, P < 0.001) and fracture stress (R = 0.518, P < 0.001). Sensory and instrumental texture parameters were significantly affected by changes in moisture content, pH and maturation.