Flavor and stability of pasteurized milk with elevated levels of conjugated linoleic acid and vaccenic acid.

The objectives of this study were to determine if flavor differences between 2% fat pasteurized milks with and without naturally enhanced vaccenic acid (VA) and cis-9, trans-11 conjugated linoleic acids (CLA) levels could be detected over the commercial shelf life of the product and to determine if milk with elevated VA and cis-9, trans-11 CLA levels was more susceptible to development of light-induced oxidative flavor defects. Cows were fed a control diet or the same ration supplemented with 2% soybean oil and 1% fish oil (CLA diet). The milk, standardized to 2% fat, was pasteurized, homogenized, and stored in plastic containers at 4 degrees C. Oxidation was induced by exposing half of the containers to light. Testing was conducted at 1, 7, and 14 d postpasteurization. Average cis-9, trans-11 CLA content of the milks from the control and CLA diet groups was 0.52 and 4.74 g/100 g of fatty acids, respectively (8-fold increase). Average VA content of the milk from the control and CLA diet groups was 1.43 and 12.06 g/100 g of fatty acids, respectively (7.5-fold increase). Together, VA plus CLA represented almost 17% of the total milk fatty acids. There was no effect of light exposure on fatty acid composition initially or over the 14-d storage period. Although VA, cis-9, trans-11 CLA, and degree of unsaturation were significantly elevated in the milk from the CLA diet group, untrained panelists were unable to detect flavor differences initially or over time in 15 of 16 triangle test evaluations. Similarly, sensory results indicated no difference in susceptibility to the development of oxidized off-flavors between the milk from the control and CLA diet groups, even when oxidation was induced by light exposure.

Effect of copper on the degradation of phenanthrene by soil micro-organisms.

AIMS: The effect of copper on the degradation by soil micro-organisms of phenanthrene, a polycyclic aromatic hydrocarbon, was investigated. METHODS AND RESULTS: Inert nylon filters were incubated in the soil for 28 days at 25 degrees C. Each filter was inoculated with a soil suspension, phenanthrene (400 ppm), copper (0, 70, 700 or 7000 ppm) and nitrogen/phosphorus sources. The filters were assessed for phenanthrene degradation, microbial respiration and colonization. Phenanthrene degradation proceeded even at toxic copper levels (700/7000 ppm), indicating the presence of phenanthrene-degrading, copper-resistant and/or -tolerant microbes. However, copper at these high levels reduced microbial activity (CO2 evolution). CONCLUSION: High levels of copper caused an incomplete mineralization of phenanthrene and possible accumulation of its metabolites. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of heavy metals in soils could seriously affect the bioremediation of PAH-polluted environments.

Effects of multibuffer supplementation on acid-base balance and 2,3-diphosphoglycerate following repetitive anaerobic exercise.

The purpose of this investigation was to determine the effects of a 3.5-day dietary multibuffer supplement (containing predominantly inorganic phosphate, or Pi, along with bicarbonate and carnosine, i.e., PhosFuel) on repetitive (four trials separated by 2 min rest) Wingate test (WT) performances and whole blood 2,3-diphosphoglycerate (2,3-DPG) concentrations in 10 recreationally trained road cyclists (T) and 10 normally active but untrained (UT) men. A 2-week washout period was utilized between experimental sessions. Venous blood samples were obtained via cannula once before exercise (baseline), immediately post each WT, and 3 min after the final WT (recovery). The data indicate that this supplement does not affect acid-base status with following intense anaerobic exercise and does not improve repetitive WT performance. However, the supplement does enhance post-exercise levels of 2,3-DPG and the 2,3-DPG/Hb ratio in recreationally trained cyclists while improving acute recovery of peak power in these men.

Effects of amount of protein and ruminally protected amino acids in the diet of dairy cows fed supplemental fat.

The objectives of this experiment were to investigate the effects of amount of dietary CP and ruminally protected AA supplementation on production of milk and milk components, ruminal fermentation, and nutrient digestibilities by cows fed diets containing high oil corn and tallow. Holstein cows in midlactation producing 22 to 25 kg/d of milk were used in a 5 x 5 Latin square design. Treatments were 1) control (16.8% CP, no added fat); 2) 14.2% CP, no AA; 3) 14.2% CP, with AA; 4) 17.5% CP, no AA; and 5) 17.5% CP, with AA. Diets 2 to 5 contained supplemental fat from high oil corn and tallow. Diets consisted of 33% alfalfa haylage, 17% corn silage, and 50% concentrate DM. Intake of DM was not different among treatments. Dietary fat increased yields of milk, fat, SNF, and total solids and percentages of fat and total solids. Increasing CP from 14.2 to 17.5% did not alter production or composition of milk. Supplemental AA increased yields of 4% FCM, milk fat, milk CP, true protein, and casein protein and percentages of CP, true protein, and casein protein in milk when either 14.2 or 17.5% CP was in the diet. Supplemental fat did not alter ruminal fermentation, but increases in dietary CP increased total VFA concentration in the rumen without affecting proportions of individual VFA. Apparent digestibilities of DM, OM, CP, starch, and energy in the total tract were greater for cows fed the 17.5% CP diets. Addition of AA to the 14.2% CP diet increased apparent digestibilities of DM, OM, ADF, NDF, and energy in the total tract but decreased digestibilities for cows fed the 17.5% CP diets. Feeding AA to midlactation cows in diets containing supplemental fat may alleviate the decrease in milk protein percentage associated with fat supplementation; this response was similar for cows fed diets that contained either 14.2 or 17.5% CP.

Performance of cows in early lactation fed isonitrogenous diets containing soybean meal or animal by-product meals.

Eighty primiparous cows were assigned to either soybean meal, fish meal, or A and B treatments. Commercial supplement A was a blend of meat and bone, meat, poultry, blood, and feather meals. Commercial supplement B included the same ingredients as A but had a higher amount of blood meal and also a low concentration of fish meal. In vitro undegradabilities of protein were 32.0, 37.8, 38.8, and 42.4% for soybean meal, fish meal, A, and B rations, respectively. Milk yields and body weight changes were not significantly affected by treatments. Because of the lower milk fat content on fish meal diet, FCM yield was lower for cows fed fish meal than soybean meal or B supplements. Milk protein content was 3.19, 3.19, 3.03, and 3.09% on soybean meal, fish meal, A, and B diets, respectively. The calculated protein efficiency (100* output/input) on soybean meal, fish meal, A, and B diets were 47.8, 51.6, 45.9, and 48.7, respectively. The undegraded protein in the fish meal after an 18-h in vitro incubation with protease enzyme (Streptomyces griseus, type V) had a higher concentration of methionine and lysine than the undegraded protein of other supplements. Flavor of milk produced on the soybean and fish meal diets was evaluated. No flavor differences were detected.

Ascorbic acid for the common cold. A prophylactic and therapeutic trial.

Three hundred eleven employees of the National Institutes of Health volunteered to take 1 gm of ascorbic acid or lactose placebo in capsules three times a day for nine months. At the onset of a cold, the volunteers were given an additional 3 gm daily of either a placebo or ascorbic acid. One hundred ninety volunteers completed the study. Dropouts were defined as those who missed at least one month of drug ingestion. They represented 44% of the placebo group and 34% of those taking ascorbic acid. Analysis of these data showed that ascorbic acid had at best only a minor influence on the duration and severity of colds, and that the effects demonstrated might be explained equally well by a break in the double blind.