Effect of transient thermal shocks on alcoholic fermentation performance.

Stuck and sluggish fermentations are among the main problems in winemaking industry leading to important economic losses. Several factors have been described as causes of stuck and sluggish fermentations, being exposure to extreme temperatures barely studied. The objective of this study was to identify thermal conditions leading to stuck and sluggish fermentations, focusing on the impact of an abrupt and transient decrease/increase of temperature on fermentation performance and yeast viability/vitality. Different strains of Saccharomyces cerevisiae, SBB11, T73, and PDM were evaluated in synthetic grape must fermentations. Cold shocks (9 °C and 1.5 °C for 16 h) carried out on different days during the fermentation process were unable to alter fermentation performance. Conversely, shock temperatures higher than 32 °C, applied in early stages of the process, lead to sluggish fermentation showing a delay directly related to the temperature increase. Fermentation delay was associated with a decrease in cell vitality. The impact of the heat shock on fermentation performance was different depending on the strain evaluated and nitrogen supplementation (with or without diammonium phosphate addition). None of the conditions evaluated produced a stuck fermentation and importantly, in all cases must nutrition improved fermentation performance after a heat shock.

Incidence of osmophilic yeasts and Zygosaccharomyces rouxii during the production of concentrate grape juices.

Zygosaccharomyces rouxii is the main spoilage yeast of grape juice concentrates. Detection and identification of Z. rouxii during the production of grape juice concentrate is critical to prevent spoilage in the final product. In this work, three grape juice concentrate processing plants were assessed by identifying osmophilic yeasts in juices and surfaces during different stages of a complete production line. Subsequently, molecular typing of Z. rouxii isolates was done to determine the strain distribution of this spoilage yeast. Osmotolerant yeast species, other than Z. rouxii, were mainly recovered from processing plant environments. Z. rouxii was only isolated from surface samples with grape juice remains. Z. rouxii was largely isolated from grape juice samples with some degree of concentration. Storage of grape juice pre-concentrate and concentrate allowed an increase in the Z. rouxii population. A widely distributed dominant molecular Z. rouxii pattern was found in samples from all three processing plants, suggesting resident microbes inside the plant.

Probabilistic model for the spoilage wine yeast Dekkera bruxellensis as a function of pH, ethanol and free SO2 using time as a dummy variable.

The present study uses a probabilistic model to determine the growth/no growth interfaces of the spoilage wine yeast Dekkera bruxellensis CH29 as a function of ethanol (10-15%, v/v), pH (3.4-4.0) and free SO2 (0-50 mg/l) using time (7, 14, 21 and 30 days) as a dummy variable. The model, built with a total of 756 growth/no growth data obtained in a simile wine medium, could have application in the winery industry to determine the wine conditions needed to inhibit the growth of this species. Thereby, at 12.5% of ethanol and pH 3.7 for a growth probability of 0.01, it is necessary to add 30 mg/l of free SO2 to inhibit yeast growth for 7 days. However, the concentration of free SO2 should be raised to 48 mg/l to achieve a probability of no growth of 0.99 for 30 days under the same wine conditions. Other combinations of environmental variables can also be determined using the mathematical model depending on the needs of the industry.

Factors influencing combined exposure to three indicator polychlorinated biphenyls in an adult cohort from Bolivia.

Polychlorinated biphenyls are persistent organic pollutants that have been used for decades in several industrial applications. Although production of polychlorinated biphenyls was restricted from the 1970s in most countries, substantial amounts remain in old equipment and buildings and they have been detected in various environmental and biological matrices. The main objective of this study was to analyze predictors of the combined exposure to three non-dioxin-like polychlorinated biphenyls (congeners 138, 153 and 180) in serum and adipose tissue from an adult cohort (n=112) living in the city of Santa Cruz de la Sierra (Bolivia) and surrounding towns/villages. A second aim was to identify modifiers that might influence the statistical associations found, using crude, partially-adjusted, and global multiple linear regression models. Main predictors of serum concentrations were occupation and fatty food consumption, while those for adipose tissue concentrations included age, smoking habit, fatty food consumption, and residence. The differences between the two matrices might be derived from their biological meaning, given that adipose tissue concentrations are an indicator of chronic exposure to polychlorinated biphenyls while serum levels are a good predictor of ongoing exposure and the mobilization of polychlorinated biphenyls stored in fatty tissues. Body mass index was found to be an important modifier of these associations.

Contribution of sociodemographic characteristics, occupation, diet and lifestyle to DDT and DDE concentrations in serum and adipose tissue from a Bolivian cohort.

The organochlorine pesticide p,p'-Dichlorodiphenyltrichloroethane (DDT) was widely used in the early 1960s-70s for vector control in tropical and subtropical areas of South America. Due to its persistence, DDT has a high potential to bioaccumulate in the food chain and living organisms and is a major public health concern, especially in South America. The main purpose of the present study was to investigate predictors of serum and adipose tissue concentrations of p,p'-DDT and its main metabolite, p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), in an adult cohort (n=112) from Santa Cruz de la Sierra, Bolivia, using multiple linear regression models. These models explained 29.3-47.8% of the variability in adipose tissue concentrations of p,p'-DDT and p,p'-DDE, respectively, and 32.9-47.0% of that in serum. Main exposure predictors included age, occupational class, residence, diet, smoking habit, and accumulated breastfeeding time. This is one of the few studies to explore predictors of human exposure to these chemicals using a multivariate approach in a South American population. Results show that predictors of human exposure to p,p'-DDT and p,p'-DDE in Santa Cruz de la Sierra may diverge from those found in other populations of the world, due to particular sociodemographic and lifestyle characteristics of this region.

Concentrations of organochlorine pesticides and polychlorinated biphenyls in human serum and adipose tissue from Bolivia.

Organochlorine pesticides and polychlorinated biphenyls (PCBs) are synthetic chemicals that are highly resistant to biodegradation and have proven adverse health effects. The objectives of this study were to determine concentrations of three selected organochlorine pesticides (p,p'-DDT, p,p'-DDE, HCB) and three specific PCB congeners (PCB 138, 153, 180) in adipose tissue and serum samples from an urban adult population (n=112) in the city of Santa Cruz de la Sierra, Bolivia, and to investigate their relationships within and between the two matrices and with selected socio-demographic characteristics. The percentages of samples positive for these compounds ranged from 40% for PCB 180 to 100% for p,p'-DDE in adipose tissue, and from 21% for HCB to 93% for p,p'-DDE in serum. Median number of residues per sample was five for adipose tissue and three for serum. Geometric mean concentrations indicate a considerable historical and recent exposure to organochlorine pesticides and PCBs in this population. Adipose tissue:serum ratios ranged from 149.3 to 590.3 (wet basis) and from 0.9 to 3.5 (lipid basis). We found positive and statistically significant correlations between adipose tissue and serum concentrations only in p,p'-DDE and HCB. This novel study in Bolivia underlines the need for human biomonitoring to assess exposure to environmental pollutants in South America.

Exposure to manganese: health effects on the general population, a pilot study in central Mexico.

To support a risk assessment of manganese exposure in two communities living within a manganese mining district a cross-sectional study was performed on a sample of the adult population of long-term residents. One community was exposed to a point source from an ore primary refining plant. Manganese is an essential mineral for human life. It is also the fourth in importance for industrial metal making. Data were collected on socioeconomic living conditions, emission sources, environmental media concentrations (air, water, soil, dust, food), respiratory symptomatology, and a neuropsychological examination (Mini-Mental Screening test, the Hooper Visual Organization test, the Ardila-Ostroski, and others). We examined 73 subjects (52 women), most of low socioeconomic status. Environmental air concentrations were 2 to 3 times higher than those in other urban concentrations. Manganese blood concentrations ranged from 7.5 to 88 microg/L, with a median concentration of 15, the upper quartile starting at 20 microg/L; the upper 10% was above 25 microg/L. Lead and manganese were highly correlated; there was an inverse relation to hemoglobin. Reduced levels of plasma lipid peroxidation were associated with blood manganese. Using multivariate logistic regression, we identified B-Mn as increasing the risk of deficient cognitive performance 12 times (Mini-Mental score of less than 17).

Origin and diversity of North American hard spring wheats.

Genetic diversity is an important safeguard against crop vulnerability to biotic and abiotic stresses. Coefficient-of-parentage (COP) values of 248 North American hard spring wheat (Triticum aestivum L. em. Thell) cultivars released from 1901 to 1991 were used to estimate the genetic similarity of cultivars. COP values were used: to (1) quantify germ plasm sources and their contributions to the North American hard spring wheat gene pool; (2) measure changes in genetic diversity through time; and (3) identify major groupings of related cultivars. Landraces and local cultivars that contributed to the formation of the gene pool were: spring wheat (64%), winter wheat (16%), T. turgidum var. durum L. (10%), and T. turgidum var. emmer L. (8%). 'Fife', 'Hard Red Calcutta', and 'Turkey Red' accounted for 18%, 13%, and 8%, respectively, of the hard spring wheat origins. 'Era' and 'Butte' in the US, and 'Neepawa' and 'HY 320' in Canada, were the most commonly used named parents of cultivars released from 1981 to 1991. Both Canada and US had the greatest level of similarity among new cultivar releases in the 1930s (Canada: r=0.39, US: r=0.34). Genetic similarity in the US declined to r=0.14 in the 1940s and remained relatively constant thereafter. Similarity among released Canadian cultivars remained relatively high until the 1970s when the introduction of new market classes resulted in a 50% reduction in genetic similarity to approximately the same level of similarity found in the US. Cluster analysis was used to group cultivars released after 1941 into 13 clusters of similar genotypes. The cultivar clusters may have value for the stratified sampling of spring wheat germ plasm or in identifying diverse germ plasm for intermating.

Bacterial aspartate kinase-like activity in human platelet.

One form of a group of enzymes known as aspartate kinases, primarily reported in prokaryotes and plants, might also exist in animal cells. Here we report the immunodetection of an aspartate kinase-like activity in human platelets using antibodies against the pure form of the enzyme purified from Escherichia coli. Moreover, the enrichment of platelet extracts with the bacterial kinase results in the phosphorylation of discrete forms mainly of membrane-bound endogenous polypeptides.