The relationship among consumer acceptability, descriptive sensory attributes, and shelf-life was determined for 2% milk pasteurized at 77, 79, 82, and 85 degrees C. Sensory descriptive attributes and volatile compound composition were monitored over the shelf-life of the products to determine if treatments could be differentiated at various times through out the shelf-life of the product. Consumers preferred 79 degrees C milk over other treatments on d 0; however, at d 6 postpasteurization, 79 and 82 degrees C milks were preferred over the 77 degrees C treatment. Consumers were grouped into 8 clusters based on product liking for both d 0 and d 6 evaluations. The largest cluster liked all pasteurization treatments, and 79 degrees C milk was highly acceptable to all consumers who liked milk. Similar sensory descriptors indicated the end of shelf-life for all pasteurization treatments even though treatments could be differentiated by descriptors on d 0. This research reveals that altering the pasteurization temperature from 79 degrees C may cause a decrease in consumer acceptability to some consumers. Also, altering pasteurization temperature did not affect shelf-life or sensory descriptors and volatile compound composition at the end of shelf-life.

The relationship between the consumer acceptability of Cheddar cheese and its descriptive sensory attributes was determined using preference mapping and logistic regression for three Cheddar cheeses. A trained panel (n = 9) differentiated the cheeses based on taste, aroma and textural attributes. The overall order of consumer preference (P < 0.05) for the three cheeses was 9, 7 and 12 months of aging time, respectively. The trained panel characterized the 7‐ and 9‐month‐old cheeses as having young/undeveloped flavors such as “cooked,”“buttery” and “creamy” flavors, and had volatiles that were responsible for the creamy flavor in cheeses. The 12‐month‐old cheese was characterized by aged/developed flavors and included volatile compounds responsible for fruity aromas and sulfurous, earthy and free fatty acid flavors. External preference mapping revealed six clusters of consumers with varying Cheddar cheese preferences; 74, 95 and 61% of the consumers found 7‐, 9‐ and 12‐month‐old cheeses to be acceptable, respectively.

Average diameters and particle size distributions in fluid milks with different fat contents and subjected to various homogenization pressures with a "microfluidizer" were evaluated. Skim, 2%, and whole milks were microfluidized at 50, 100, 150, and 200 MPa. Cream containing 41% milk fat was microfluidized at 50, 100, and 150 MPa. Particle sizes were determined by laser light scattering. As microfluidization pressure was increased from 50 to 100 MPa, particle sizes in skim, 2%, and whole milks decreased. Microfluidization at pressures greater than 100 MPa had little additional effect on reducing the particle sizes in skim and 2% milks compared with microfluidization at 100 MPa, but the particle sizes in whole milk increased as the microfluidization pressure was increased from 100 to 200 MPa due to formation of homogenization clusters. The particle sizes in cream increased as the microfluidization pressure was increased from 50 to 150 MPa. When the microfluidization pressure was held constant, the particle sizes increased as the milk fat concentration was increased. The coefficients of variations of the volume-weighted particle size distributions for cream were higher than for skim, 2%, and whole milks. Larger "big" particles and smaller "small" particles were formed in whole milk after microfluidization at 200 MPa than at 100 MPa. Although microfluidization can be used to produce small particles in skim, 2%, and whole milks, a higher than optimum pressure (above 100 MPa) applied to whole milk will not lead to the minimum d(43) (volume-weighted average diameter) due to formation of clusters.

Sensory characteristics of the spoilage aromas of milk containing Pseudomonas species were determined. Two strains each of P. fluorescens, P. fragi, and P. putida were evaluated. Milk (skim and whole) was doublesteamed and inoculated with 10 3 CFU/mL (ca) of Pseudomonas. Milk samples were stored at 5 o C for 1 mo. Plate counts were conducted every 3 rd day to determine growth rates. Descriptive aroma analysis was conducted weekly (n = 4) using 10 trained panelists. All 6 strains grew at refrigeration temperatures and there was no difference in growth among strains. Type and onset of spoilage depended on strain of Pseudomonas and milkfat content. This information may aid in shelf-life prediction of milk.

The effects of sodium acetate (SA) and monopotassium phosphate (MKP) on total aerobic plate counts (APC), pH, odor, and appearance of catfish fillets during storage at 4°C were determined. Use of 0.75% and 1.0% SA lowered (P &lt; 0.05) initial APC by 0.6 to 0.7 log units compared to the control. Microbial counts of SA-treated fillets remained lower than the control during storage, resulting in a 6-day shelf-life increase. MKP alone had no effect on APC values, but it did influence the activity of SA. The results indicate that a combination of SA and MKP could prolong the microbiological shelf life of catfish to 12 days at 4°C. Fillets treated with 1% SA alone or SA-MKP combinations had pH values and odor scores that were similar to fresh controls for up to 9 days; however, appearance scores were lower after 3 days, probably due to a brownish and watery appearance. MKP alone is not recommended for shelf-life extension of catfish fillets. Conversely, SA alone or combined with MKP is recommended to extend the microbiological shelf life of refrigerated catfish fillets.

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Sensory properties and rate of meltdown of nonfat (0% fat) and low-fat (2% fat) vanilla ice creams processed either by conventional valve homogenization or microfluidization of their mixes were compared with each other and to ice cream (10% fat) processed by conventional valve homogenization. Mixes for frozen dairy desserts containing 0, 2, and 10% fat were manufactured. Some of the nonfat and low-fat ice cream mixes were processed by microfluidization at 50, 100, 150, and 200 MPa, and the remaining nonfat and low-fat ice cream mixes and all of the ice cream mix were processed by conventional valve homogenization at 13.8 MPa, first stage, and 3.4 MPa, second stage. The finished frozen and hardened products were evaluated at d 1 and 45 for meltdown rate and for flavor and body and texture by preference testing. Nonfat and low-fat ice creams that usually had a slower meltdown were produced when processing their mixes by microfluidization instead of by conventional valve homogenization. Sensory scores for the ice cream were significantly higher than sensory scores for the nonfat and low-fat ice creams, but the sensory scores for the conventional valve homogenized controls for the nonfat ice cream and low-fat ice cream were not significantly different from the sensory scores for the nonfat ice cream and low-fat ice cream processed by microfluidization of the mixes, respectively. Microfluidization produced nonfat and low-fat ice creams that usually had a slower meltdown without affecting sensory properties.