Hereford yearling steers (N= 144) were alloted to one of three pasture systems: tall fescue, smooth bromegrass-red clover or orchardgrassred clover. After the grazing period, steers were finished in drylot and then serially slaughtered at 0, 56, 84 and 112 days. Carcass quality grades and yield grade numbers increased when steers were fed grain up to 112 days. Tenderness of loin steaks increased up to 84 days, after which no improvements were observed. Sensory panel scores for grassy flavor of steaks and ground beef decreased up to 112 days. Fifty-three compounds were identified in the volatiles of melted subcutaneous fat by direct sampling-gas chromatography/mass spectrometry. The major differences between volatiles from fat of forage-fed compared to grain-fed steers were the higher concentrations of 2,3-octanedione and various diterpenoids present in the samples of the forage-fed animals.

Dried whey and whey protein are important food ingredients. Functionality of whey products has been studied extensively. Flavor inconsistency and flavors which may carry through to the finished product can limit whey ingredient applications in dairy and nondairy foods. The goal of this research was to determine the flavor and flavor variability of commercially produced liquid Cheddar cheese whey. Liquid Cheddar cheese whey from five culture blends from two different stirred-curd Cheddar cheese manufacturing facilities was collected. Whey flavor was characterized using instrumental and sensory methods. Wide variation in whey headspace volatiles was observed between different manufacturing facilities (P < 0.05). Hexanal and diacetyl were two key volatiles that varied widely (P < 0.05). FFA profiles determined by solid-phase microextraction and degree of proteolysis of the whey samples were also different (P < 0.05). Differences in whey flavor profiles were also confirmed by descriptive sensory analysis (P < 0.05). Differences in liquid whey flavor were attributed to differences in milk source, processing and handling and starter culture blend. The flavor of liquid Cheddar cheese whey is variable and impacted by milk source and starter culture rotation. Results from this study will aid future studies that address the impact of liquid whey flavor variability on flavor of dried whey ingredients.

The effects of added conjugated linoleic acid (CLA) on the sensory, chemical, and physical characteristics of 2% total fat (wt/wt) fluid milk were studied. Milks with 2% (wt/wt) total fat (2% CLA, 1% CLA 1% milkfat, 2% milkfat) were made by the addition of cream or CLA triglyceride oil into skim milk followed by HTST pasteurization and homogenization. The effects of adding vitamin E (200 ppm) and rosemary extract (0.1% wt/wt based on fat content) were investigated to prevent lipid oxidation. HTST pasteurization resulted in a significant decrease of the cis-9/trans-11 isomer and other minor CLA isomers. The cis-9/trans-11 isomer concentration remained stable through 2 wk of refrigerated storage. A significant loss of both the cis-9/trans-11 and the cis-10/trans-12 isomers occurred after 3 wk of refrigerated storage. The loss was attributed to lipase activity from excessive microbial growth. No differences were found in hexanal or other common indicators of lipid oxidation between milks with or without added CLA (P > 0.05). Descriptive sensory analysis revealed that milks with 1 or 2% CLA exhibited low intensities of a "grassy/vegetable oil" flavor, not present in control milks. The antioxidant treatments were deemed to be ineffective, under the storage conditions of this study, and did not produce significant differences from the control samples (P > 0.05). CLA-Fortified milk had significantly lower L* and b* values compared with 2% milkfat milk. No significant differences existed in viscosity. Consumer acceptability scores (n = 100) were lower (P < 0.05) for CLA-fortified milks compared to control milks, but the addition of chocolate flavor increased acceptability (P < 0.05).

The oxidative stability of liquid Cheddar cheese whey was evaluated using 2 Lactococcus lactis starter cultures in combination and alone along with a control, utilizing glucono-delta-lactone for acid development. Fresh and stored whey were evaluated for volatile composition, free fatty acids, and flavor by descriptive sensory analysis. A significant increase in volatile lipid oxidation products, most notably, hexanal, occurred during storage, and a corresponding decline in the free fatty acid linoleic acid was found. The flavor and aroma characteristic, cardboardy, was correlated to the increase in volatile lipid oxidation products and the decline in linoleic acid. Evidence strongly suggested that lipid oxidation was initiated during whey production and escalated during storage and that the starter cultures significantly influenced the level of volatile lipid oxidation products. Further understanding of the impact of starter cultures on whey may allow for the production of higher quality whey ingredients with wider food application.

The influence of gel structure type and amount of lipid on texture of whey protein isolate (WPI) gels was evaluated by descriptive sensory analysis and determination of fracture and water-holding properties. A series of 16 gels of varying structure (particulate or stranded) and lipid composition (0% to 20%) were developed at a constant protein concentration (12% w/v). Stranded gels had higher values for fracture strain, strain hardening, and held-water. Particulate and stranded gels were similar in fracture stress. Eighteen sensory texture attributes were used to evaluate gels throughout the mastication process that was separated by the following phases: prefracture, 1st bite, chew-down, and preswallowing. The 1st bite property of firmness and preswallowing properties of number of chews and time to swallow were the only sensory properties associated with lipid content. Fracture stress was correlated with these properties. The remaining 15 texture terms were primarily determined by gel structure type. It appears that gel structure type determines the primary texture properties of WPI emulsion gels. An increase in lipid content increases gel firmness and amount of chews required; however, it did not change the primary texture sensation.