TEXTURE OF SALT STOCK WHOLE CUCUMBER PICKLES: CORRELATION OF INSTRUMENTAL AND SENSORY MEASUREMENTS*

Correlations were determined between Texture Profile Analysis (TPA) parameters of brittleness, hardness or total work of compression obtained with the Instron testing machine and sensory responses of firmness or crispness in evaluating texture of fermented salt stock whole cucumbers (1-in. diam) of three ‘firm’ pickling cultivars (Explorer, Chipper, GY 3), two ‘soft’ pickling cultivars (Green F, Mincu) and a partheonocarpic slicer (MSU 6902 G). Correlations were also determined between the TPA parameters and Magness-Taylor fruit pressure test (FPT) firmness. Correlations were good between TPA parameters and FPT firmness. Correlations were poorer between instrumental and sensory methods due largely to inordinately high sensory scores assigned to salt stock of the slicer by all panelists. Mean textural values from the various methods were compared with those obtained in the same manner for raw cucumbers. TPA brittleness tended to disappear in salt stock. Processing reduced mean TPA values across the six varieties to 39-86% of raw fruit values. Mean FPT firmness was relatively unchanged at 99% that of raw fruit. Desalting from 16% down to 8 % or 4% NaCl reduced TPA values but increased FPT firmness.     

TEXTURE IMPROVEMENT OF FRESH-PACK DILL PICKLES BY ADDITION OF LACTOSE AND SUCROSE

The influence of small amounts of lactose or sucrose on texture of fresh-pack dill pickles was evaluated by Instron texture profile analysis (TPA). Pickles were prepared with 0, 2, 4 and 6% by weight of either lactose or sucrose in a commerical brine. After equilibration of pickles with brine (30, 64 and 77 days), TPA values were obtained for brittleness, hardness, elasticity and total work of compression. Analysis of variance for the linear regression showed significant relationships between TPA values and sugar concentration. A minimum of 6% sugar is considered necessary for meaningful texture improvement. Sensory evaluation showed that sweetness may be detectable at the 4% and 6% sucrose levels. The presence of lactose was not objectionable at these levels.     

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 CHARACTERIZATION OF COOKED POTATO TEXTURE

Uniaxial compression, Texture Profile Analysis (TPA) and chemical measurements were related to sensory texture evaluation of potato quality during storage. Principal component analysis grouped the varieties into three types of variation: mealiness versus firmness and springiness (PC1), moistness versus adhesiveness (PC2) and hardness versus adhesiveness and moistness (PC3). In uniaxial compression the variable 'stress', 'work up to fracture' and 'total work during compression' described the same type of information in the data. These uniaxial data and most of the TPA data were highly correlated. Uniaxial compression data (stress, strain, modulus of deformability), starch structural data (area, roundness, aspect ratio), specific gravity and pectin methyl esterase activity discriminated between the varieties and harvest times. Partial Least Squares Regression showed stress, strain, modulus of deformability and specific gravity to be the most important variables in distinguishing between two groups of sensory texture attributes explaining 65% of the total variance in the sensory data. Coefficients of correlation between predicted and measured sensory attributes were in the range 0.36–0.79. The TPA data were not found to be relevant substitutions for the sensory attributes.     

INFLUENCE OF GROWING ENVIRONMENT AND STORAGE DURATION ON QUALITY OF FRESH-PACK CUCUMBER PICKLES3

Fruit of several pickling cucumbers (Cucumis sativus L.) grown in 1978 and 1979 in several environments under two soil nitrogen levels (high vs. normal) were stored for various time periods before fresh-pack processing. Firmness, color and general appearance as examined after equilibration were all highly affected by cultivar, growing environment, and storage duration but somewhat less by nitrogen level. Unexpectedly, color and appearance improved during the first 24 h after harvest. Acceptable firmness was maintained for at least 72 h after harvest. Fruit of genetically firm cultivars generally showed less change in firmness than did fruit of less firm cultivars.     

TEXTURE ANALYSIS OF TEXTURED SOY PROTEIN PRODUCTS: RELATIONS BETWEEN INSTRUMENTAL AND SENSORY EVALUATION*

The Minnesota Texture Method, designed to differentiate objectively textural differences in commercial textured soy protein (TSP) products and their mixtures with ground beef, was correlated statistically with sensory evaluation. The results indicated substantial predictability of sensory evaluations from MTM on eight selected commercial TSP products and their mixtures with ground beef.     

INSTRUMENTAL TEXTURE STUDIES ON CHOCOLATE IV: COMPARISON BETWEEN INSTRUMENTAL AND SENSORY TEXTURE STUDIES

Texture characteristics of solidified plain chocolate and milk chocolate were determined in instrumental and sensory studies. The instrumental parameters included compression strength, melting properties, maximum tensile force during hesion testing and the maximum size of dispersed solid components. To classify the sensory texture impressions into intensity ranges, by using appropriate samples, a reference scale was derived allowing a sensory panel to assign unknown chocolate samples to the respective intensity ranges. Instrumental control of the reference samples ensures satisfactory relations between instrumental and sensory data.     

INSTRUMENTAL AND SENSORY MEASUREMENT OF BEEF PATTY AND SAUSAGE TEXTURE

Beef sausages and beef patties of different texture were produced by varying the fat content in the raw mix over the range 5–30%. Batter shear stress and strain increased linearly with increased fat level (P<0.09 and 0.001, respectively). Although batter shear stress was not related to sensory scores, shear strain was directly related to moistness and inversely related to grittiness scores (P<0.05). Batter sensory moistness increased and firmness and grittiness deceased linearly with fat content (P<0.001). Changes in fat content did not affect the peak force of cooked patties, and there were poor correlations between patty peak force and sensory scores. Patty juiciness and softness increased and patty cohesiveness and chewiness decreased with fat content (P<0.001). Batter cook yield increased and patty cook yield decreased with increasing fat level (P<0.001). Sensory scores, using trained panelists, were more sensitive to the effect of fat content on patty and sausage texture than instrumental measurements.     

BALANCING MACROMINERAL COMPOSITION OF FRESH-PACK CUCUMBER PICKLES TO IMPROVE NUTRITIONAL QUALITY AND MAINTAIN FLAVOR1

The macromineral nutritional balance of fresh-pack dill cucumber pickles was improved without loss of flavor quality. A product with flavor acceptability equal to the original product was obtained if NaCl was reduced by 40%, from 2.0% to 1.2%. To replace the 0.8% reduction in NaCl 0.8% KCl was added. CaCl₂ and MgCl₂ were added proportionately to match the daily value (DV) of the added KCl. In addition to changes in mineral composition, low levels of both citric acid and hot pepper sauce were added to improve flavor acceptability. The flavor acceptability of dill pickles was rated higher (P <0.05) than the 2.0% NaCl control when the NaCl concentration was reduced 20% from 2.0 to 1.6%, and 0.4% KCl was added to replace the NaCl. Again, CaCl₂ and MgCl₂ were added at a level which gave the same proportion of the DVs of these minerals as 0.4% KCl. The highest flavor acceptability in the product with 20% less NaCl was obtained when only citric acid was added as a flavor modifier.     

RELATIONSHIP BETWEEN INSTRUMENTAL AND SENSORY ANALYSIS OF TEXTURE AND COLOR OF POTATO CHIPS

The instrumental and sensory analysis of the texture and color of commercial potato chips were compared. The instrumental measurement was a puncture test with an Intron Universal Testing Machine, and the parameters used were fracture force, deformation and stiffness. The instrumental color quantification was a computerized video image analysis technique, and the color was expressed as L*a*b* values. Sensory evaluation of texture and color was performed by a sensory panel especially trained in evaluating potato chips. The sensory attributes were "hardness", "chewiness", "crunchiness", and "tenderness" for texture analysis, and "yellow color", "burnt aspect", "sugar colored aspect" and "transparency" for color analysis. The factor analysis of the sensory attributes indicated that texture can be divided into two principal components, one represented by "hardness", "crunchiness" and "chewiness", and the other by "tenderness" alone. The factor analysis of the color can be divided into two principal components, one including "yellow color" and "burnt aspect", and the other "sugar colored aspect" and "transparency". Discriminant analysis showed that "tenderness" and "crunchiness" could predict correctly over 90% of the data. Fracture force correlated well with all of the sensory attributes (R² > 0.76), and L* with the sensory color attributes (R² > 0.79). The "Tenderness" was the individual sensory attribute which had the highest correlation (R²= 0.95) with fracture force.     

RELATIONSHIP BETWEEN INSTRUMENTAL AND SENSORY PARAMETERS OF COOKED SWEETPOTATO TEXTURE1

This study compared two instrumental methods, namely uniaxial compression and texture profile analysis (TPA), with sensory evaluation in describing the textural properties of cooked sweetpotatoes. The steamed cooked samples (1.35 × 2.2 cm cylinder) of four cultivars and six selections were subjected to a trained texture profile panel for sensory ratings and the two instrumental methods for determination of the mechanical properties. Factor analysis indicated that the 15 sensory variables were grouped into 3 main factors, namely moistness-firmness (factor 1), particles (factor 2), and fiber (factor 3). Among the instrumental parameters, shear stress of compression and fracturability, hardness, and gumminess of TPA correlated highly (R = 0.73–0.95) with both the mouthfeel and mechanical-type sensory notes. These parameters of the two instrumental methods were linearly related (R²≥ 0.95) and could be converted from one to another with a high degree of reliability. Regression equations based on shear stress significantly explained (R²= 0.71–0.91) eight of the sensory notes. These instrumental parameters can be good predictors of cooked sweetpotato texture.     

INSTRUMENTAL AND SENSORY TEXTURE ASSESSMENT AND FRACTURE MECHANISMS OF CHEDDAR AND CHESHIRE CHEESES

Textural attributes of Cheddar and Cheshire cheeses, falling within narrow compositional ranges, were assessed by sensory panels, and from force-compression curves generated by compression between two plates, and, for Cheddar cheese only, by penetrometry. Individual sensory measurements did not relate well to any instrumental one, and were better at discriminating between cheeses. Samples of each cheese variety were fractured in different ways and the fracture surfaces were examined in a scanning electron microscope. Fracture surfaces were formed by cutting directly through the matrix, tearing of the matrix along planes high in fat or cracking at grain boundaries. It is suggested that consideration of fracture mechanism may aid the selection and development of useful instrumental methods for texture assessment of cheese.