RAPID COMMUNICATION: Impact of contemporary light sources on oxidation of fresh ground beef.

Meat color is considered one of the driving factors in consumer purchasing decisions. The objective of this study was to determine the impact of 2 different lighting sources on color and lipid oxidation of ground beef patties in a controlled environment. USDA Select top rounds ( = 20) were processed to produce ground beef at 2 different fat levels (5 and 25%) and made into patties (113.4 g). Patties were packaged with oxygen permeable polyvinyl chloride, assigned to one of three lighting treatments (low UV fluorescent [FLO], light emitting diode [LED], and no light [DRK, negative control]), and placed within deli cases at 5°C. Patty removal for evaluation occurred on retail display d 1, 3, 5, and 7. Objective color measurements were obtained using a HunterLab MiniScan 45/0 LAV. These values were utilized to determine myoglobin redox forms as a measure of myoglobin oxidation. Additionally, thiobarbituric acid reactive substances (TBARS) were measured to indicate lipid oxidation. Objective color measurement for a* (redness), decreased for all light treatments by retail display day ( < 0.0001). Oxymyoglobin values for all light treatments decreased daily but showed no differences between treatments until d 5 ( < 0.0001) where DRK > LED > FLO. Conversely, metmyoglobin values increased daily ( < 0.0001), but showed no differences between treatments until d 5 where FLO > LED > DRK. TBARS values increased by day for each fat percentage ( < 0.0001) with 5% fat patties having higher TBARS values indicating great oxidation occurring in the phospholipids than adipose tissues. Results indicate that light treatment affected discoloration and metmyoglobin formation in ground beef patties LED lighting may lead to increased meat quality shelf life in a retail setting.

Effect of forage species on fatty acid content and performance of pasture-finished steers.

Consumers are increasingly concerned with the form and quantity of fat present in the foods they consume. This is leading to a shift in the way food is produced. In particular the animal industry is increasing the number of organic and naturally finished meat animals rather than finishing them on grains. The objective of this study was to determine if different pasture compositions (i.e. grass only or grass legume mixtures) would impact the fatty acid (FA) meat composition of beef steers (Bos taurus L.). The pasture treatments were tall fescue [Lollium arundinaceum (Schreb.) S.J. Darbysh] only, or tall fescue combined with either red clover (Trifolium pretense L.) or alfalfa (Medicago sativa L. ssp. sativa L.). Beef steers (n=9-10 per treatment) rotationally grazed each pasture treatment. Forage from treatments were different for crude protein (CP), in vitro true digestibility (IVTD) and the FA myristric (C14:0), palmitic (C16:0), palmitoleic (C16:1), stearic (C18:0), oleic (C18:1), linoleic (C18:2), and total FA. Steers grazing mixtures with either red clover (RC) or alfalfa (ALF) had greater average daily gains (ADG) than tall fescue only. Additionally, RC treatment steers had larger ribeye areas (REA) and greater finishing weights than those in the ALF treatment. However, the differences found between pasture treatments in FA concentration did not translate to any differences in the FA concentration of meat harvested from steers. Thus, it is concluded that although the pastures contained different FA concentrations, with the levels of legumes present, this does not influence the FA composition of beef.

Effect of fat level on the perception of five flavor chemicals in ice cream with or without fat mimetics by using a descriptive test.

Fat mimetics are commonly used in the manufacture of low-fat and fat-free ice creams. However, the use of fat mimetics affects flavor and texture characteristics of ice cream, which results in decreased overall acceptability by consumers. The initial objective of this study was to investigate the release behavior of 5 strawberry flavor compounds in ice creams with Simplesse((R)), Litesse((R)), and Litesse((R))/Simplesse((R)) mixes using descriptive analysis. Fat mimetics and flavor formulation significantly influenced the perception of Furaneoltrade mark (cooked sugar flavor), alpha-ionone (violet flavor), and gamma-undecalactone (peach flavor), but there was no interaction between ice cream type and flavor formulation for the 3 flavors. Furaneol and ethyl-3-methyl-3-phenylglycidate (candy flavor) were perceived more strongly in full-fat ice cream, while cis-3-hexen-1-ol (grassy flavor), alpha-ionone, and gamma-undecalactone were perceived more strongly in low-fat ice cream. Ice creams with Simplesse and full-fat ice cream had similar sensory characteristics, while ice creams with Litesse were similar to low-fat ice creams in flavor characteristics, and ice creams with Litesse/Simplesse mixes were closer in flavor profile to low-fat ice cream but had similar texture properties to those of full-fat ice cream. Simplesse was found to be a better fat mimetic for duplicating the flavor profiles and mouthfeel of full-fat ice cream.

Conjugated linoleic acid content of beef differs by feeding regime and muscle.

The project objective was to determine the CLA content of three muscles (Longissimus lumborum, LD; Semimembranosus, SM; Triceps brachii, TB), in both raw and cooked states, in cattle finished on pasture or with grain supplements. Cattle were randomly assigned to one of four finishing regimens; pasture (n=11), pasture with grain supplement (n=11), pasture with grain supplement containing soyoil (n=12), and feedlot (n=12). In the raw state, TB had higher (P<0.05) CLA than LD or SM on a mg/g sample basis. Total CLA was higher (P<0.05) in the soyoil diet when compared to the other three feeding regimes on a mg/g sample basis and when expressed as mg/g fat in both raw and cooked analyses. Pasture inclusion produced higher levels (P<0.05) of total CLA than the feedlot diet on a mg/g fat basis for cooked samples while maintaining acceptable eating quality.

Changes in the profile of genistein, daidzein, and their conjugates during thermal processing of tofu.

Profiles of genistein, daidzein, genistin, daidzin, and their acetyl- and malonyl-beta-glycosides were determined in tofu as affected by temperature and time. Tofu was heated in water at 80, 90, and 100 degrees C for 0 (control), 10, 20, 30, and 40 min, and the contents of the isoflavones of interest were quantified using reversed-phase HPLC. Total isoflavone content decreased most likely due to leaching of isoflavones into the water. Because the content of the isoflavones of the genistein series was little affected by the treatments, the decrease in the total isoflavone content was almost exclusively due to a decrease of the daidzein series. Changes in the profile of the daidzein series suggest little decarboxylation of the malonylglycoside to the acetylglycoside, but considerable de-esterification of the malonyl- and acetylglycoside to the beta-glucoside. Strongly temperature dependent decreases of the aglycon suggest possible thermal degradation of daidzein in addition to losses due to leaching.

Effects of milk fat, cocoa butter, or selected fat replacers on flavor volatiles of chocolate ice cream.

Selected volatile compounds of chocolate ice creams containing 0.6, 4.0, 6.0, or 9.0% milk fat or containing 2.5% milk fat, cocoa butter, or one of three fat replacers (Simplesse, Dairy Lo, or Oatrim) were analyzed by gas chromatography and gas chromatography-mass spectrometry using headspace solid-phase microextraction. The headspace concentration of most of the selected volatile compounds increased with decreasing milk fat concentration. Fat replacers generally increased the concentration of volatiles found in the headspace compared with milk fat or cocoa butter. Few differences in flavor volatiles were found between the ice cream containing milk fat and the ice cream containing cocoa butter. Among the selected volatiles, the concentration of 2,5-dimethyl-3(2-methyl propyl) pyrazine was the most highly correlated (negatively) with the concentration of milk fat, and it best discriminated among ice creams containing milk fat, cocoa butter, or one of the fat replacers.

Viability of microencapsulated bifidobacteria in set yogurt during refrigerated storage.

Bifidobacteria are probiotic organisms that improve the microbial balance in the human gut. They can be incorporated as live cultures in fermented dairy foods, including yogurt, for transmission to humans. Because bifidobacteria are sensitive to high acidity, their viability in yogurt is limited. The objective of the present study was to investigate the effect of microencapsulation on the viability of bifidobacteria in yogurt during refrigerated storage for 30 d. Live bifidobacterial cells were encapsulated in kappa-carrageenan. Cell enumeration, determination of titratable acidity and pH, quantitation of lactic and acetic acids, and sensory evaluation (consumer test) were carried out on the yogurt samples. Microbiological results showed a decline of 78 and 70.5% in the population of Bifidobacterium longum B6 and B. longum ATCC 15708, respectively, for the treatments containing nonencapsulated cells. No difference in bifidobacterial population was observed in the encapsulated treatments. The acetic acid content in the yogurt with nonencapsulated bifidobacteria was higher than that in the plain yogurt (control) and encapsulated treatments. The increase in lactic acid content during storage was not different among the various treatments for B. longum B6, but was greater for nonencapsulated than encapsulated B. longum 15708 and the control. Consumers judged the nonencapsulated treatment as the most sour, which was likely due to the higher acetic acid content. Consumers preferred the control and nonencapsulated treatments over the encapsulated treatment. Microencapsulation appears to increase the viability of bifidobacteria in yogurt. This technique can be used to transmit bifidobacteria via fermented products provided that sensory characteristics of the product are improved or maintained.

Potential nutrition messages in magazines read by college students.

Advertisements in magazines read by 12% or more of college students enrolled in an introductory nutrition class were surveyed for hidden food and nutrition messages. Meanings were identified by categories of activities, products, and people. Less than 10% of the ads featuring people fell into food categories. Of these, more were for alcohol and supplements; fewer were for basic or extra-calorie foods. Hidden messages for females could imply beauty through fashion products, beauty aids, and supplements but with a nutrition slimming plan. Males may be receiving a subtle message that food choices do not matter, and that alcohol and supplements are desirable in everyday life.