Effects of Lactobacillus cultures on performance of laying hens,and total cholesterol,lipid and fatty acid composition of egg yolk

BACKGROUND: The use of antibiotic growth promoters in animal feeds is not approved for laying hens in many countries, and economically feasible biological measures which include probiotics are developed to improve hen performance. The present study investigated the effects of probiotics on hen performance for a 48‐week period and the cholesterol, total lipid and fatty acid composition of egg yolk at 24, 28 and 32 weeks of age. RESULTS: Egg weight of Lactobacillus culture (LC)‐fed hens was significantly (P < 0.05) greater than that of control hens throughout the laying period. From 20 to 44 weeks of age, LC‐fed hens produced a significantly (P < 0.05) lower percentage of small eggs and a higher percentage of large eggs, and from 45 to 68 weeks of age a significantly (P < 0.05) lower percentage of medium eggs and a higher percentage of large and extra‐large eggs than control hens. Significantly (P < 0.05) less cholesterol was found in egg yolks of hens fed LC at 24 and 28 weeks of age, but not at 32 weeks of age. The total lipid content and the fatty acid composition of egg yolks were similar between the treatments at 24, 28 and 32 weeks of age, except for stearic acid (C_{18 : 0}), which was significantly reduced in the egg yolk of LC‐fed hens at 28–32 weeks of age. CONCLUSION: The greatest benefit of LC was in increasing egg weight and improving egg size by influencing a shift from small and medium to large and extra‐large eggs. Copyright © 2008 Society of Chemical Industry     

Inhibition of mutagenic PhIP formation by epigallocatechin gallate via scavenging of phenylacetaldehyde

Chemical model investigation showed that both epigallocatechin gallate (EGCG) and its peracetate, which has all the hydroxyl groups acetylated, effectively reduced the formation of 2‐amino‐1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine (PhIP), the most abundant mutagenic heterocyclic amine found in foods. Mechanistic study was subsequently carried out to characterize the probable inhibitory mechanism involved. GC‐MS analysis showed that EGCG in only one‐fourth molar quantity of phenylalanine reduced formation of phenylacetaldehyde, a key PhIP intermediate by nearly 90%. Its peracetate also showed similar inhibitory activity. This further supported the existence of an antioxidant‐independent mechanism contributing to the inhibition of PhIP formation by EGCG. Subsequent LC‐MS analyses of samples from a wide range of model systems consisting of PhIP precursors showed the generation of characteristic analytes with molecular weight corresponding to the sum of EGCG and phenylalanine fragment(s) only in models where phenylalanine and EGCG were simultaneously present. An isotope‐labeling study revealed that these analytes all contained fragment(s) of phenylalanine origin. Direct reaction employing phenylacetaldehyde and EGCG further confirmed the capability of EGCG to form adducts with phenylacetaldehyde, thus reducing its availability for PhIP formation. Finally, an investigation of the time course of the generation of postulated adduction products supported EGCG as an effective inhibitor of PhIP formation in prolonged heating processes.     

Identification of inhibitory substances affecting bioleaching of heavy metals from anaerobically digested sewage sludge

Significant inhibitory effects of the filtrate medium of anaerobically digested sewage sludge on iron oxidation by Acidithiobacillus ferrooxidans ANYL-1 were observed in our preliminary experiments, indicating the presence of inhibitory substances in anaerobically digested sewage sludge. The objectives of the present study were to identify the possible inhibitory substances and to evaluate their impacts on metal solubilization during bioleaching of sewage sludge. The results showed that the concentrations of total reducing sugars, all tested metal ions, and anions were too low to suppress iron oxidation, and only organic acids, especially acetic and propionic acids, were found at concentrations higher than their inhibitory levels. The presence of 10.8 mM acetic acid and 9.88 mM propionic acid in sewage sludge (sludge N) led to long lag periods of 6 and 7 days for solubilization of Cu and Cr, respectively, as compared to a lag period of only 1 day in the control and another sludge (sludge S) with a low level of organic acids. Meanwhile the leaching time for maximum solubilization of Zn also extended to 6 days in the presence of organic acids as compared to 3 days in the control. Acetic and propionic acids posed an unfavorable bioleaching condition for anaerobically digested sewage sludge; therefore, further studies are required to explore the means to remove the inhibitory effects to improve the heavy metal bioleaching efficiency.     

Characterising the release of flavour compounds from chewing gum through HS-SPME analysis and mathematical modelling

The headspace solid-phase microextraction (HS-SPME) technique combined with GC–MS was evaluated to study 33 selected flavour compounds released from chewing gum. The operating conditions of SPME were optimised, including different fibres (PDMS, DVB/CAR/PDMS, PA and PDMS/DVB), sample size, extraction time and temperature. The results indicated that while HS-SPME was a rapid and valuable technique, poor reproducibility occurred under all conditions. It was found that this deficiency could be alleviated by utilising mathematical modelling techniques, an approach which had not been previously used in the analysis of flavour compounds in chewing gum by HS-SPME. Compared to the instrumental analysis data themselves, the models provided more insights to the release behaviour of flavour compounds from chewing gum and the more reproducible kinetic rate constants might be used for comparing the release of different compounds or the same compound under different conditions.     

A Wide Range Measuring System for Thin Lubricating Film: From Nano to Micro Thickness

This paper introduces a newly developed lubricating-film-thickness measuring system, which implements the multi-beam intensity-based (MBI) scheme proposed recently by the authors. Some details about the software of the testing system and instrumentation of the MBI approach are discussed. For efficient determination of the fringe order range of measured points, a simple counting strategy was suggested. It is shown that this measuring system can provide a measurement range from nano to micrometers and a high resolution on the nanometer level. Besides being able to detect ultra-thin lubricating film thickness, the system can also measure tiny local variations in film thickness on a nano-scale in the conventional EHL regime. The capability of the system is demonstrated by the determination of film thickness in the range of 1nm to 2.542m with a standard deviation of 0.89nm. In addition, some analyses are given for further understanding the optical EHL and the testing system in this paper.     

Wear of aluminium bronze on steel under conditions of boundary lubrication

An investigation was conducted to examine the wear of aluminium bronze against tool steel when lubricated under a boundary lubrication regime by aviation kerosene, both with and without the inclusion of a commercially available boundary additive. The objective was to isolate the mechanisms of boundary film formation, protection and wear of the metal surfaces, through mechanical measurements and analyses of surfaces and debris.A model is proposed to explain these mechanisms in terms of material transfer and subsequent competing reactions between dissolved oxygen and long chain hydrocarbon acid molecules, and the metal surface.     

The Effect of the Electric Double Layer on a Very Thin Water Lubricating Film

This paper discusses the effect of the electric double layer on a very thin water lubricating film with and without consideration of the elastic deformation of the opposing surfaces. A modified Reynolds equation that considers the electric double layer is used in a numerical analysis. The effect of zeta potential on the film thickness and pressure is numerically calculated. For both hydrodynamic and elastohydrodynamic cases, the electric double layer significantly increases the lubricating film thickness. The pressure is also marginally increased, as illustrated in the hydrodynamic analysis. However, the effect on pressure is almost unnoticeable in the elastohydrodynamic analysis. Overall, the electric-double-layer effect is only significant for a water-film thickness of less than approximately 100 nanometers.