The objectives of this study were to determine the volatile components responsible for the sensory perception of nutty flavor in Cheddar cheese. Cheddar cheeses with and without nutty flavors were selected by descriptive sensory analysis. Volatile aroma components from Cheddar cheeses with and without nutty flavors were isolated and characterized using solvent extraction with high vacuum distillation, dynamic headspace analysis, gas chromatography-olfactometry, and gas chromatography-mass spectrometry. More than 50 aroma-active compounds were detected in Cheddar cheeses. Consistent differences were observed between nutty and not nutty Cheddar cheeses. Strecker aldehydes were detected in higher amounts in Cheddar cheeses with nutty flavors compared with Cheddar cheeses without nutty flavors. Strecker aldehydes, dimethyl sulfide, and propionic acid were evaluated in young and aged Cheddar cheese models for nutty flavor by descriptive sensory analysis. Dimethyl sulfide and propionic acid did not contribute to nutty flavor in Cheddar cheese. The addition of Strecker aldehydes to young (<4 mo old) Cheddar cheese models resulted in nutty/malty flavor perceived by sensory analysis. When Strecker aldehydes were incorporated into aged (>9 mo old) Cheddar cheese models, nutty flavor perception increased. Strecker aldehydes contribute to nutty flavor in aged Cheddar cheese.

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.

Abstract:This study identifies and semi-quantifies aroma volatiles in brewed green tea samples. The objectives of this study were to identify using a gas chromatograph-mass spectrometer (GC-MS) paired with a headspace solid-phase micro-extraction (HS-SPME) the common volatile compounds that may be responsible for aroma/flavor of the brewed liquor of a range of green tea samples from various countries as consumed and to determine if green teas from the same region have similarities in volatile composition when green tea samples are prepared for consumption. Twenty-four green tea samples from eight different countries were brewed as recommended for consumer brewing. The aroma volatiles were extracted by HS-SPME, separated on a gas chromatograph and identified using a mass spectrometer. Thirty-eight compounds were identified and the concentrations were semi-quantified. The concentrations were lower than those reported by other researchers, probably because this research examined headspace volatiles from brewed tea rather than solvent extraction of leaves. No relationship to country of origin was found, which indicates that other factors have a greater influence than country of origin on aroma.

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.

Flavor variability in skim milk powder (SMP) has been documented by descriptive sensory analysis and instrumental analysis. However, research has not addressed how or if SMP flavor variability impacts consumer acceptance of ingredient applications. Twenty reconstituted low‐heat SMPs were screened using a previously established defined sensory language. Two SMPs free of off‐flavors (flavor similar to fresh fluid skim milk) and 2 SMPs exhibiting off‐flavors (exhibiting flavors not found in fluid skim milk) were selected for further study. Volatile compounds were determined using solid phase microextraction (SPME) with gas chromatography‐mass spectrometry (GC‐MS). Each SMP was subsequently directly reconstituted or incorporated into standard formulas for vanilla ice cream, strawberry yogurt, hot cocoa mix, and white chocolate bars. Consumer acceptance testing was conducted. Descriptive panelists documented sweet aromatic and cooked flavors in the fresh‐flavored SMP and these flavors as well as fatty/fryer oil and animal‐like flavors in the off‐flavored SMP. Concurrently, instrumental volatile analysis revealed higher relative abundances of lipid oxidation compounds in the off‐flavored SMP. Consumer acceptance scores were lower for the off‐flavored SMP than for the fresh‐flavored SMP when evaluated directly reconstituted (P < 0.05) and for ingredient applications made using off‐flavored SMP (P < 0.05). Off‐flavors in SMP documented by descriptive analysis and trained panelists can carry through into ingredient applications with SMP and negatively affect consumer acceptability.