SENSORY PROPERTIES AND CONSUMER PERCEPTION OF 'HOME-MADE'AND COMMERCIAL DAIRY ICE CREAM

Sensory properties and consumer perception of 2 'home-made'and 4 commercial dairy ice creams were examined. Conventional profiling by a trained panel found that most samples differed significantly in all attributes, but distinction of 'home-made'from commercial products was limited to few attributes. Principal component analysis separated the 'home-made'products from the commercial ones mainly on the basis of differences in appearance, aroma, creamy flavors and textural attributes. A consumer group (n=105) recorded preconception of 'home-made'ice cream acceptance, then received the product samples, in unlabeled condition, for assessment of degree of liking (DOL) and for identification as 'home-made'or commercial. Internal preference mapping of the DOL ratings showed that consumers were more closely grouped around samples which had higher intensities of certain attributes. Higher 'denseness', 'vanilla'aroma and 'buttery'flavor, were associated with more liking for commercial products. The 'home-made'high fat sample, although liked, tended to be grouped with commercial products. More marked textural attributes of 'ice crystals'and 'breakage'aided identification of the low-fat 'home-made'formulation, which was less liked overall. Overall, differences between the 'home-made'and commercial samples were small but consumer perception of the term 'home-made'was viewed favorably for dairy ice cream.     

PREFERENCE MAPPING OF TEXTURE OF DULCE DE LECHE

The texture of 12 commercial samples of dulce de leche was characterized by means of texture profile analysis. Two sensory manual texture attributes (hardness and ropiness) were evaluated by a panel of 11 trained assessors. A panel of 50 consumers evaluated the texture acceptability of the samples using a 9‐point structured scale. Consumers showed highly significant different degrees of liking for the texture of the evaluated samples of dulce de leche. Clusters identified with Pearson's correlation coefficient showed opposite preference patterns and provided more useful information regarding market segmentation than clusters identified with Euclidean distances. External preference mapping and partial least squares regression showed that hardness was a driver of liking for one segment of consumers, whereas for the other one it was a driver of disliking. When all the consumers were considered, external preference mapping indicated that the ideal texture of dulce de leche would be intermediate, showing the importance of identifying preference patterns and suggesting that data averaging in consumer preferences might affect information recovery, and may lead to wrong conclusions. Different preference mapping techniques were compared; it was found out that when the relationship between acceptability and texture attributes was not linear, external preference mapping showed the best results.     

TASTE COMPONENTS OF CHEDDAR CHEESE: FRACTIONATION AND OPTIMIZATION OF CHEDDAR CHEESE TASTE IN WATER

To determine the taste components of Cheddar cheese, we fractionated one mild Cheddar cheese and one aged Cheddar cheese by water extraction, freeze‐drying and gel filtration. Salty, sour and umami were the three predominant tastes present in the fractions. Neither trigeminal sensations nor astringency was perceived. We used response surface methodology to reconstruct a mild Cheddar cheese taste and an aged Cheddar cheese taste in water. Less salt and less acid were needed to simulate the taste of mild Cheddar cheese, compared with aged Cheddar cheese. Our optimized water solutions (containing sodium chloride, lactic acid and monosodium glutamate) were as similar to the real cheese samples as were the water extracts of the standard cheeses. However, neither our optimized solutions nor the water extracts matched the taste of the actual cheeses.     

SENSORY PROFILE DESCRIPTION OF MOZZARELLA CHEESE AND ITS RELATIONSHIP WITH CONSUMER PREFERENCE

The aim of this work was to set up the sensory profile and consumer preference test of three different Mozzarella cheeses (from full-fat cow milk, from low-fat cow milk and from full-fat water buffalo milk). The most remarkable difference in composition was the fat content. Nine commercial Mozzarella cheeses (three for each type) were evaluated in triplicate by a trained panel consisting of 10 assessors. Six Mozzarella cheeses (two for each type) out of the nine samples were selected and used for the preference test by 105 consumers. The three different Mozzarella cheeses were sensorially well differentiated. A good discrimination between the Mozzarella cheeses was obtained using the internal preference map method. The combination of cluster analysis and internal preference mapping has lead to a deeper understanding of consumer liking for Mozzarella cheeses.     

PAIRED PREFERENCE TESTS: d' VALUES FROM MEXICAN CONSUMERS WITH VARIOUS RESPONSE OPTIONS

Three groups, each comprising 200 consumers, performed paired preference tests between two flavors of potato chips. For one group, a “No Preference” option was allowed, while for the second group, it was not. For a third group, a “No Preference” option was allowed while the preference responses were differentiated as “Strong Preference” and “Weak Preference.” For all three groups, d′ values representing overall strength of preference did not differ significantly.     

EFFECT OF FREEZING AND FROZEN STORAGE ON THE SENSORIAL CHARACTERISTICS OF LOS PEDROCHES, A SPANISH EWE CHEESE

The aim of the present work was to study the sensorial characteristics of Los Pedroches cheese after freezing, monitoring the effects of the speed and time of frozen storage. Changes were observed in the hardness, creaminess and eyes of cheeses after 3-months frozen storage. The paste hardened, becoming less creamy, and the number and size of the eyes decreased substantially. However, these attributes remained unchanged during storage periods of up to 9 months. Odor, flavor intensity, acidity and grainy were modified as a consequence of frozen storage. The speed of the freezing process only affected the grainy of the cheese; this was greater in slowly-frozen cheeses.     

Development of a Probiotic Cheddar Cheese Containing Human-Derived Lactobacillus paracasei Strains

Cheddar cheese was manufactured with either Lactobacillus salivarius NFBC 310, NFBC 321, or NFBC 348 or L. paracasei NFBC 338 or NFBC 364 as the dairy starter adjunct. These five strains had previously been isolated from the human small intestine and have been characterized extensively with respect to their probiotic potential. Enumeration of these strains in mature Cheddar cheese, however, was complicated by the presence of high numbers (>10⁷ CFU/g of cheese) of nonstarter lactic acid bacteria, principally composed of lactobacilli which proliferate as the cheese ripens. Attempts to differentiate the adjunct lactobacilli from the nonstarter lactobacilli based on bile tolerance and growth temperature were unsuccessful. In contrast, the randomly amplified polymorphic DNA method allowed the generation of discrete DNA fingerprints for each strain which were clearly distinguishable from those generated from the natural flora of the cheeses. Using this approach, it was found that both L. paracasei strains grew and sustained high viability in cheese during ripening, while each of the L. salivarius species declined over the ripening period. These data demonstrate that Cheddar cheese can be an effective vehicle for delivery of some probiotic organisms to the consumer.     

SENSORY EVALUATION OF VANILLA-DAIRY DESSERTS BY REPERTORY GRID METHOD AND FREE CHOICE PROFILE

“Natillas” are semisolid dairy desserts widely consumed in Spain, with notable differences existing between commercial brands in their composition and sensory and physical properties. The repertory grid method, in conjunction with the free choice profile (FCP), was used to provide data on how consumers perceived eight commercial “natillas” samples. The most frequent terms used were: vanilla flavor, sweetness, consistency and liquid texture as described by 77, 67, 57 and 53% of the consumers, respectively. A three‐dimensional solution was chosen. Dimension 1 accounted for 27.23% of variance and separated the samples largely by yellow‐color intensity and consistency. Dimension 2 (15.88%) was mainly related to the visual attributes of texture, creaminess and different notes of flavor. The third dimension (11.34%) was related to structural‐texture attributes, orange‐yellow color and acid and artificial flavors. The assessors plot showed two clusters. Analysis of each group data revealed differences in their perception of sample variation, mainly regarding texture and color.     

CHANGES IN THE PERCEIVED TEXTURAL PROPERTIES OF CHEDDAR CHEESE DURING MATURATION

The perceived textural attributes of an English Cheddar were measured by a trained panel at various intervals during ripening, including those corresponding to mild and medium maturation times for this variety. The moisture content and pH were also monitored. After the recommended ripening period of 50 weeks the matured cheese was significantly less springy, firmer, harder, crumblier and creamier, indicating that textural attributes are related to the age of the Cheddar. Measures beyond the recommended maturation period revealed further significant differences. Comparisons of the measures taken at mild, medium and full maturity also revealed differences in the textural properties of the different classes of Cheddar. Significant correlations (p ≥0.01) between pH and springiness, crumbliness by fingers and creaminess suggested a strong relationship between these textural attributes and the extent of proteolysis. The results of this study revealed a strong relationship between age and the textural attributes of cheddar when restricted to one particular variety.     

Persistence of Mycobacterium paratuberculosis during Manufacture and Ripening of Cheddar Cheese

Model Cheddar cheeses were prepared from pasteurized milk artificially contaminated with high 10⁴ to 10⁵ CFU/ml) and low (10¹ to 10² CFU/ml) inocula of three different Mycobacterium paratuberculosis strains. A reference strain, NCTC 8578, and two strains (806PSS and 796PSS) previously isolated from pasteurized milk for retail sale were investigated in this study. The manufactured Cheddar cheeses were similar in pH, salt, moisture, and fat composition to commercial Cheddar. The survival of M. paratuberculosis cells was monitored over a 27-week ripening period by plating homogenized cheese samples onto HEYM agar medium supplemented with the antibiotics vancomycin, amphotericin B, and nalidixic acid without a decontamination step. A concentration effect was observed in M. paratuberculosis numbers between the inoculated milk and the 1-day old cheeses for each strain. For all manufactured cheeses, a slow gradual decrease in M. paratuberculosis CFU in cheese was observed over the ripening period. In all cases where high levels (>3.6 log₁₀) of M. paratuberculosis were present in 1-day cheeses, the organism was culturable after the 27-week ripening period. The D values calculated for strains 806PSS, 796PSS, and NCTC 8578 were 107, 96, and 90 days, respectively. At low levels of contamination, M. paratuberculosis was only culturable from 27-week-old cheese spiked with strain 806PSS. M. paratuberculosis was recovered from the whey fraction in 10 of the 12 manufactured cheeses. Up to 4% of the initial M. paratuberculosis load was recovered in the culture-positive whey fractions at either the high or low initial inoculum.