Influence of lipids in the generation of phenylacetaldehyde in wort-related model systems

The effect of lipids on the formation of the Strecker aldehyde phenylacetaldehyde during wort boiling was studied to determine the role that small changes in the lipid content of the wort have in the production of significant flavor compounds in beer. Wort was treated with 0-2.77 mmol per liter of glucose, linoleic acid, or 2,4-decadienal and heated at 60-98 degrees C for 1 h. After this time, the amount of the Strecker aldehyde phenylacetaldehyde increased in the samples treated with linoleic acid or decadienal but not in the samples treated with glucose. Thus, the amount of phenylacetaldehyde produced in the presence of linoleic acid was 1.1-2.5 times the amount of the Strecker aldehyde produced in the control wort, and this amount increased to 3.6-4.6 times when decadienal was employed. The higher reactivity of decadienal than linoleic acid for this reaction decreased with temperature and was related to the oxidation of linoleic acid that occurred to a higher extent at higher temperatures. The above results suggest that lipids can contribute to the formation of Strecker aldehydes during wort boiling and that changes in the lipid content of the wort will produce significant changes in the formation of Strecker aldehydes in addition to other well-known consequences in beer quality and yeast metabolism. On the other hand, because of the high glucose content in wort, small changes in its content are not expected to affect the amount of Strecker aldehydes produced.     

Effect of reducing dietary mineral content on growth performance, water intake, excreta dry matter content and blood parameters of broilers

1. The objective of this study was to investigate whether it is possible to reduce phosphorus (P) excretion by feeding a lower level of dietary P than that currently recommended, without compromising welfare, and whether this is sensitive to the level of dietary calcium (Ca). 2. A randomised complete block design was used with a total of 224 1-d-old male chicks of a commercial genotype in two batches. Chicks had a 10-d adaptation period. After this, they were moved to cages and allocated to one of 4 dietary treatments (4 and 3 birds per cage in batch 1 and 2, respectively). A standard level of Ca and P (8.3 and 6.6 g/kg, respectively) was compared with three lower levels of Ca (7.3, 6.3 and 5.3 g/kg) all at the same reduced level of P (5.5 g/kg). Records were made of live weight of birds on an individual basis and feed and water consumption on a cage basis. Every 7 d, the dry matter (DM) content of a sample of mixed excreta from each cage was measured. Birds were slaughtered and samples taken for analysis of plasma mineral content, retention of N, Ca and P and tibia bone strength. 3. The initial reduction in dietary mineral level did not adversely affect performance or bone strength. However, decreasing dietary Ca level below 7.3 g/kg, at constant P, led to reduced feed consumption and bone strength. Dietary treatment had no significant overall effect on water intake, water : feed ratio, excreta DM content, Ca and P retention or metabolisability of DM. There was no significant correlation between mean plasma Ca or P level and DM content of rectal digesta. 4. In conclusion, reducing dietary P from 6.6 to 5.5 g/kg to reduce potential environmental impact of broiler production had an adverse effect on bird welfare when the level of Ca was reduced below 7.3 g/kg, as a result of decreased feed intake in the early growth period and reduced skeletal strength.     

Lack of prolonged activity of lavender essential oils as acaricides against the poultry red mite (Dermanyssusgallinae) under laboratory conditions

Managing the poultry red mite, Dermanyssus gallinae (De Geer) by conventional means (i.e., synthetic acaricides) has become increasingly problematic. As a possible alternative, research has identified several plant essential oils that are toxic to D. gallinae. However, essential oils are highly volatile and any acaricidal effect they exert could be short-lived in practice.This study investigated the short-lived toxicity of six lavender essential oils to D. gallinae. In sealed Petri-dishes, mites were exposed to filter papers impregnated with essential oil at a concentration of 0.14 mg/cm³. When filter papers were used immediately after impregnation, 66–90% D. gallinae mortality was observed after 24 h, depending upon the essential oil used. If impregnated filter papers were left in a fume cupboard for 24 h prior to use, mortality rates of D.gallinae fell to 11% or less.     

Use of Sequential Extraction in the Study of Heavy Metal Retention by Silty Soils

This study focused on the capability of two silty soils (tills) having low clay contents and CEC to retain and release two heavy metals, Pb and Cu. Samples of two non contaminated till deposits from the Eastern Townships region of Quebec, Canada, were artificially contaminated with concentrated solutions of these heavy metals. The latter were later extracted from the various geochemical phases of the soils by using the sequential extraction procedure. The results show that silty soils may have a relatively high heavy metal retention capacity due to the presence of carbonate and that this retention capacity can be comparable in magnitude to the retention capacity of certain clayey soils. This is particularly positive in the context of municipal waste disposal (landfills) in Quebec, where some old sanitary landfill sites are underlain by till deposits. A high buffering capacity is not as desirable in the case a deposit needs to undergo remediation.     

Corticosterone plasma concentration in male mule ducks: effects of sampling sites, repeated samplings and ACTH injections.

1. Changes in plasma corticosterone concentrations according to puncture sites and various challenges including injections of an ACTH agonist (Immediate Synacthen) were investigated in male mule ducks. 2. Lower concentrations were measured in samples drawn by puncture from the occipital sinus than at a wing vein site. 3. Immobilisation and a single intramuscular injection of saline solution (1 ml, 0.9%) had no effect on plasma corticosterone after 15 min. 4. A single intramuscular injection of ACTH (5 microg/kg body weight) produced a rise (P<0.05) in corticosterone. Maximum concentrations were measured after 10 min and, in the absence of further sampling, a return to initial levels was observed by 1 h. 5. On the other hand, repeated bleedings following ACTH challenge maintained higher corticosterone concentrations. 6. A single intramuscular injection of ACTH at doses ranging between 0.625 to 20 microg/kg body weight increased corticosterone concentrations (P<0.05) in a dose-dependent manner, with the responses plateauing at doses of 1.25 microg/kg and higher.     

Domestication of plants for sustainable agriculture in drylands: Experience from the Negev Desert

With globalization in the last century, introduction of exotic plant species for commercial use has become more accessible. Such attempts may involve extreme land changes. We stress that domestication of native species should be preferred to the introduction of exotic species. We took the initial steps in domesticating several species by examining commercial uses and studying aspects of plant physiology. The following desert plants were considered: Bassia indica, for salt phytoremediation and for livestock feed; Commiphora gileadensis, as an agent against cancer cells; Artemisia sieberi and A. judaica, as plants with allopathic traits; Ficus palmate, as a stand for fig plantation; Balanites aegyptiaca, as a medicinal plant and for other uses; Portulaca oleracea and Scorzonera judaica, as food crops with added values; and Pistacia atlantica, as rootstock for P. vera.