Al and Fe in PM 2.5 and PM 10 Suspended Particles in South-Central Florida: The Impact of the Long Range Transport of African Mineral Dust

Aluminum and iron were measured in daily samples collected at urban and rural sites near Ft. Myers, Florida, in 1995–1996 using a dichotomous sampler. Al and Fe concentrations were low during most of the year but they increased dramatically duringsummer when African dust was advected into Florida. The ratioof fine (less than 2.5 m diameter) to coarse (2.5–10 m) Al and Fe is relatively constant in African dust events with the fine accounting for a third to a half of the total. Also the mass ratio of Al-to-Fe is relatively constant at 1.8, a value similar to average crustal material. In contrast, in non-African dust the fine-to-coarse and Al-to-Fe ratios are extremely variable and generally much lower than those duringAfrican events when dust concentrations ranged up to 86 g m^-3. The timing and magnitude of the Ft. Myers dust peaks closely matched those measured concurrently in Miami, 200 km to the southeast. Large areas of the eastern United States are frequently impacted by African dust every summer. Although dustconcentrations can reach very high values it seems unlikely that African dust events alone will cause a violation of the Environmental Protection Agency's standards for PM 2.5 or PM 10. However, African dust in conjunction with emissions from local and regional sources could conceivably present a problemwith compliance. The probability of such an occurrence is heightened by the fact that dust concentrations are highest in the summer when pollution levels are often at a maximum in theeastern states.     

Comparison of volatile compounds isolated from the skin and flesh of four potato cultivars after baking

Four potato cultivars, Cara, Nadine, Fianna, and Marfona, were selected. Potatoes were baked in their skins prior to separating the skin and flesh and preparing extracts of the volatile flavor compounds using a modified Likens--Nickerson apparatus. The concentrated extracts were analyzed by gas chromatography--mass spectrometry. Volatiles were identified and classified according to their origin, that is, lipid, sugar degradation and/or Maillard reaction not involving sulfur amino acids, sulfur compounds, methoxypyrazines, and other compounds. Quantitative and qualitative differences were observed between isolates from flesh and skins and among cultivars grown at different sites. Strongest isolates from skin were obtained for Nadine. For flesh, Cara gave isolates approximately 10-fold more concentrated than the other three cultivars. For skin, sugar degradation and/or the Maillard reaction was by far the most important source in all cultivars except Nadine, for which 62% of the volatiles were accounted for by the sesquiterpene solavetivone. Lipid and sugar degradation and/or the Maillard reaction were the main origins of volatiles in flesh. Calculated aroma values for a selection of the key potato volatiles identified reinforce the effects of cultivar and growing site on baked potato flavor.     

Effect of high-pressure treatment on the texture of cherry tomato

The effect of high-pressure treatment (200-600 MPa for 20 min) on the texture of cherry tomatoes and on the key softening enzymes (pectinmethylesterase and polygalacturonase) was investigated. When subjected to high-pressure treatment whole cherry tomatoes showed increasing textural damage with increasing pressures up to 400 MPa. However, treatment at pressures above 400 MPa (500-600 MPa) led to less apparent damage than treatment at 300 and 400 MPa; the tomatoes appearing more like the untreated samples. These visual changes were reflected in the texture (firmness) and amount of cell rupture in the tomatoes, with the least firmness and the most cell rupture being seen after treatment at 400 MPa. Light and scanning electron microscopy supported these observations. Although a sample of purified commercial pectinmethylesterase was partially inactivated at pressures above 200 MPa, irrespective of pH (4-9), in the whole cherry tomatoes no significant inactivation was seen even after treatment at 600 MPa, presumably because other components in the tomato offered protection or the isoenzymes were different. Polygalacturonase was more susceptible to pressure, being almost totally inactivated after treatment at 500 MPa. It is concluded that the textural changes in tomato induced by pressure involve at least two related phenomena. Initially, damage is caused by the greater compressibilty of the gaseous phase (air) compared to liquid-solid components, giving rise to a compact structure which, on pressure release, is damaged as the air rapidly expands, leading to increases in membrane permeability. This permits egress of water, and the damage also enables enzymatic action to increase, causing further cell damage and softening. The major enzyme involved in the further softening is polygalacturonase, which is inactivated at 500 MPa and above, and not pectinmethylesterase, which in the whole fruit, is barotolerant.     

QTL analysis of quality traits in the spring wheat cross RL4452 × 'AC Domain'

Wheat grain quality is a complex group of traits of tremendous importance to wheat producers, end‐users and breeders. Quantitative trait locus (QTL) analysis studied the genetics of milling, mixograph, farinograph, baking, starch and noodle colour traits in the spring wheat population RL4452/‘AC Domain’. Forty‐seven traits were measured on the population and 99 QTLs were detected over 18 chromosomes for 41 quality traits. Forty‐four of these QTLs mapped to three major QTL clusters on chromosomes 1B, 4D, and 7D. Fourteen QTLs mapped near Glu‐B1, 20 QTLs mapped near a major plant height QTL on chromosome 4D, and 10 QTLs mapped near a major time to maturity QTL on chromosome 7D. Large QTLs were detected for grain and flour protein content, farinograph absorption, mixograph parameters, and dietary fibre on chromosome 2BS. QTLs for yellow alkaline noodle colour parameter L* mapped to chromosomes 5B and 5D, while the largest QTL for the b* parameter mapped to 7AL.     

Relationships between antioxidant activity, color, and flavor compounds of crystal malt extracts.

Aqueous extracts were prepared from five barley crystal malts (color range 15-440 degrees EBC, European Brewing Convention units). Antioxidant activity was determined by using the 2,2'-azinobis(3-ethylbenothiazoline-6-sulfonic acid) (ABTS(*)(+)) radical cation scavenging method. Antioxidant activity increased with increasing color value although the rate of increase decreased with increasing color value. Color was measured in CIELAB space. Extracts of the 15, 23, and 72 degrees EBC malts followed the same dilution pathway as did the 148 degrees EBC sample at higher dilution levels, indicating that they could each be used to give the same color by appropriate dilution. The 440 degrees EBC sample followed a different dilution pathway, indicating that different compounds were responsible for color in this extract. Fifteen selected volatile compounds were monitored using gas chromatography/mass spectrometry (GC/MS). Levels of methylpropanal, 2-methylbutanal, and 3-methylbutanal were highest for the 72 degrees EBC sample. When odor threshold values of the selected compounds were taken into account, 3-methylbutanal was the most important contributor to flavor. Relationships between levels of the lipid oxidation products, hexanal and (E)-2-nonenal, and antioxidant activity were complex, and increasing antioxidant activity for samples in the range of 15-148 degrees EBC did not result in reduced levels of these lipid-derived compounds. When different colored malt extracts were diluted to give the same a* and b* values, calculated antioxidant activity and amounts of 3-methylbutanal, hexanal, and (E)-2-nonenal decreased with increasing degrees EBC value.     

Effect of roasting on the antioxidant activity of coffee brews

Colombian Arabica coffee beans were roasted to give light, medium, and dark samples. Their aqueous extracts were analyzed by gel filtration chromatography, UV-visible spectrophotometry, capillary electrophoresis, and the ABTS(*)(+) assay. A progressive decrease in antioxidant activity (associated mainly with chlorogenic acids in the green beans) with degree of roasting was observed with the simultaneous generation of high (HMM) and low molecular mass (LMM) compounds possessing antioxidant activity. Maximum antioxidant activity was observed for the medium-roasted coffee; the dark coffee had a lower antioxidant activity despite the increase in color. Analysis of the gel filtration chromatography fractions showed that the LMM fraction made a greater contribution to total antioxidant activity than the HMM components.     

Serodiagnosis of equine monocytic ehrlichiosis in selected groups of horses in Minnesota

Antibody titer to Ehrlichia risticii was determined, in 2,549 equine serum samples, using an indirect fluorescent antibody assay. During 1986, samples were obtained from the Minnesota State-Federal Equine Infectious Anemia Diagnostic Laboratory, the Minnesota Racing Laboratory, from horses admitted to the University of Minnesota Veterinary Teaching Hospital, and as a result of field investigations of horses with acute diarrhea. Results of the study revealed antibody prevalence of 33, 24, 47, and 25% for the respective groups. There was no statistical association between seropositive status and age, sex, breed, or clinical problem of horses referred to the teaching hospital. There was an increase in the total percentage of seropositive samples over the duration of the sample collection period, suggesting a seasonal exposure pattern, and E risticii was associated with clinical and subclinical infections in horses of Minnesota.     

Adaptation of a colorimetric microtitration assay for quantifying Pasteurella haemolytica A1 leukotoxin and antileukotoxin

A colorimetric microtitration assay was adapted to quantify the cytotoxicity of Pasteurella haemolytica A1 leukotoxin to bovine neutrophils used as target cells. The viability of leukotoxin-treated target cells was detected by use of a tetrazolium dye that living cells reduced to dark blue formazan. The amount of formazan formed (which was quantified by use of an ELISA plate reader) was directly proportional to the number of viable target cells. This assay system also was used to measure leukotoxin-neutralization antibody titers of bovine serum and lung lavage specimens obtained during vaccination experiments. The major advantages of this assay over other methods such as the 51Cr-release and trypan blue-exclusion assays are precision, rapidity, and low cost; it also does not use radioisotopes.     

Hulless barley and β-glucanase affect ileal digesta soluble beta-glucan molecular weight and digestive tract characteristics of coccidiosis-vaccinated broilers

Exogenous β-glucanase (BGase) in barley-based feed has been shown to reduce digesta viscosity in chickens, and thereby improve performance. Less well studied is the potential for BGase to convert barley β-glucan into low molecular weight carbohydrates, which might influence digestive tract function and enteric disease. Coccidiosis-vaccinated broiler chickens were fed graded levels of hulless barley (HB) and BGase to determine their effects on β-glucan depolymerization and digestive tract characteristics. Broilers were fed high β-glucan HB (0%, 30% and 60% replacing wheat) and BGase (0%, 0.01% and 0.1%) in a 3 × 3 factorial arrangement. A total of 5,346 broilers were raised in litter floor pens and vaccinated for coccidiosis on d 5. Each treatment was assigned to 1 pen in each of 9 rooms. The significance level was set at P ≤ 0.05. At both 11 and 33 d of broiler ages, peak molecular weight of β-glucan in ileal digesta decreased with increasing BGase for 30% and 60% HB. The maximum molecular weight for the smallest 10% β-glucan molecules (MW-10%) decreased with BGase at both ages for 30% and 60% HB; for birds fed 0% HB, only 0.1% BGase decreased MW-10%. The 0.1% BGase increased caecal short chain fatty acids (SCFA) compared to the 0.01% BGase at d 11 only for the 60% HB. Ileal pH increased with increasing HB and BGase at d 11 and 33. Caecal pH was lower for 0.1% BGase than 0% BGase for 60% HB at d 11. Relative mRNA expression of interleukin 6 (IL-6) and IL-8 in the ileum increased with 0.1% BGase at d 11 and 33, respectively, whereas expression of ileal mucin 2 (MUC2) decreased with 0.1% BGase at d 33. In the caeca, interactions between HB and BGase were significant for monocarboxylate transporter 1 (MCT1) and mucin 5AC (MUC5AC) on d 11, but no treatment effects were found at d 33. In conclusion, BGase depolymerized high molecular weight β-glucan in HB in a dose-dependent manner. Hulless barley and BGase did not increase SCFA concentrations (except for 60% HB with 0.1% BGase at d 11) and caused minor effects on digestive tract histomorphological measurements and relative mRNA gene expression.