Acidogenic fermentation of blended food‐waste in combination with primary sludge for the production of volatile fatty acids

The performance of a laboratory‐scale anaerobic acidogenic fermenter fed with a mixture of blended kitchen food‐waste and primary sludge from a sewage treatment plant was investigated for the production of volatile fatty acids (VFA). The operating variables for acidogenic fermentation were kitchen food‐waste content (10 and 25 wt %), hydraulic retention time (HRT: 1, 3 and 5 days), temperature (ambient: 18 ± 2 °C, and mesophilic: 35 ± 2 °C) and pH (varied from 5.2 to 6.7). The experimental results indicated that effluent VFA concentrations and VFA production rates were higher at ambient temperature than at mesophilic conditions. The net amount of VFA with 10 wt % food‐waste increased up to 920 mg dm^?3 with an increase of HRT, but contrasting results (a decrease of 2610 mg dm^?3) were found due to the conversion of VFA into biogas in the case of 25 wt % food‐waste, which increased significantly at HRT of 3–5 days. In terms of biogas composition (CO₂ and CH₄), the organic matter was converted into CO₂ through the oxidative pathway by facultative species at low temperature while mesophilic temperature and optimum pH (6.3–7.8) played a pivotal role in increasing rate of conversion of VFA into biogas by methanogenesis. Rates of VFA production and their conversion are dependent on the food‐waste content in the mixture. Yet, the higher concentration of food‐waste (25% compared with 10%) did not produce VFA proportionally due to the increased rate of conversion of VFA into gaseous products. The maximum VFA production rate (0.318 g VFA_produced g^?1 VS_fed day^?1) was achieved in the 10 wt % food‐waste at ambient temperature and at a 5‐day HRT. Copyright © 2005 Society of Chemical Industry     

Stimulatory effects of tannins and cholic acid on tryptic hydrolysis of proteins: Ecological implications

The biochemical basis for considering tannins as digestion inhibitors has been reexamined. Both stimulatory and inhibitory effects of tannins on tryptic hydrolysis are reported. We show how stimulation may result from tannin-induced structural changes in the substrate protein, effectively denaturing it. The surfactant and bile constituent cholic acid also produced similar stimulatory effects. These results have considerable implications for normal digestive physiology as well as for the impact of tannins on argicultural and natural herbivore populations.     

Microwave Demulsification in Removing Naphthenic Acids from Diesel Oil

Emulsification is an undesired phenomenon in the refining of highly acidic oil by alkali-washing electro-refining. In this article, a novel microwave method is applied for demulsification in the removing of naphthenic acid from diesel oil. The internal heating is attributed to molecular rotation and ionic conduction. The decrease of interface zeta-potential and the viscosity of diesel oil are responsible for the demulsification with microwave irradiation. The results exhibited that the demulsification rate is maximized when the optimum microwave irradiation power, exposure time, and irradiation pressure for Anshan and Liaohe diesel oil are deemed to be 375 W, 5/6 min and 0.05 MPa, respectively.     

锌(Ⅱ)-氨基酸配合物分子内配体间疏水作用

应用 p H电位滴定法研究了配合物 Zn( Aa) 2 [Aa-=L- val(缬氨酸根 ) ,L- phe(苯丙氨酸根 ) ,L- trp(色氨酸根 ) ,L- tyr(酪氨酸根 ) ]在水和 2 0 %、40 %及 60 %二氧六环 /水溶液中的稳定性 [t=2 5℃ ,c=0 .1 mol/L Na Cl O4]。配合物 Zn( Aa) 2 相对于母体配合物 Zn( Aa) + 稳定性用Δlog K=log KZn( Aa)Zn( Aa) 2 - log KZn Zn( Aa) 表示。结果表明 :与 L-丙氨酸 ( L- ala)配合物 Zn( L- ala) 2 相比 ,所有这些氨基酸配合物 Zn( Aa) 2 均具有相对较大的 Δlog K值 ,表明这些配合物分子内存在着额外的稳定化作用。这种稳定性化作用可能主要归因于配合物分子内氨基酸侧链之间的疏水作用 ,并且这种作用随着氨基酸侧链结构及溶剂极性变化而变化     

Long-chain fatty ammonium quaternaries in papermaking

A series of long-chain quaternary ammonium halogen esters (UKK-chemicals), quaternary dimethyl tallow epoxypropyl ammonium halogens (EPK1), quaternary ditallow methyl epoxypropyl ammonium halogens (EPK2), and EPK2 oligomers (EPK2P) were synthesized. At acidic, neutral, or slightly basic conditions, EPK1-, EPK2-, EPK2P-, and UKK-chemicals operate as cationic chemicals. They can be used, for example, as stock sizings, surface sizings, or fixatives. Stock sizing, surface sizing, and fixative experiments indicate that EPK1-, EPK2-, EPK2P-, and UKK-chemicals function at least as well as or better than the corresponding synthetic chemicals used in papermaking.     

Bisensors for amino acids

Two kinds of biosensors for amino acids (one with nonspecific enzyme as bioelement, the other with specific enzyme(s) as bioelement), including their principles, applications, recent researches and future trends were discussed in detail. 61 references were given. A part of work for gaining Ph. D in chemical and biochemical application at FPMs (Mons, Belgique) Synopsis of the first author Xia Jinlan, Male, born in 1963, now at Facult’e Polytechnique de Mons, Belgique     

Candida and Pseudomonas Lipase-Catalyzed Hydrolysis of Butteroil in the Absence of Organic Solvents

Candida rugosa lipase (CRL) and Pseudomonas fluorescein lipase (PFL) were used to hydrolyze a low-melting point butteroil fraction in the absence of orgaic solvents. CRL and PFL displayed pH activity optima of 6.7 and 7.8, and temperature-activity optima of 40–50°C and 35°C, respectively. Maximum activity for PFL was observed at 5% (v/v) water content. CRL showed higher specificity towards butyric acid relative to PFL after 3 hours of hydrolysis at 40°C (22.3 mol% vs 7.8 mol%, respectively). Both enzymes displayed, however, high specificities towards palmitic and oleic acids. CRL's inherent specificity towards butyric acid makes it an ideal choice for a biological catalyst to generate useful dairy flavor profiles.     

Contribution oftrans-18∶1 acids from dairy fat to european diets

Twelve commercial samples of French butter, purchased in October–November, and 12 other samples, purchased in May–June, were analyzed with particular attention to theirtrans-octadecenoic acid contents. The isomeric fatty acids were quantitated by a combination of gas-liquid chromatography (GLC) of total fatty acids as isopropyl esters on a polar capillary column (CPSil 88) and of silver nitrate-impregnated thin-layer chromatography followed by GLC of the pooled saturated (used as internal standards) andtrans-octadecenoic acid fractions. Autumn butters contained 3.22±0.44%trans-octadecenoic acids (relative to total fatty acids), whereas those collected during the spring contained 4.28±0.47% (P<0.01). Minimum and maximum values for the two sets of butters were 2.46 (autumn) and 5.10% (spring), respectively. The annual mean value for thetrans-octadecenoic acid content in all butter samples was 3.8% of total fatty acids (ca. 2% for thetrans-11 18∶1 acid). This value allows calculation of the daily individual intake oftrans-octadecenoic acids from dairy products by populations of member states of the European Economic Community (EEC). It varies from 0.57 g (Portugal) to 1.66 g (Denmark). The mean value for the twelve countries of the EEC is 1.16 g/person/d, which is close to data published for the United States. In France, the consumption oftrans octadecenoic acids from dairy fat is higher than that from margarines (ca. 1.5 vs. 1.1 g/person/d).     

Antioxidant activity of anacardic acids

Anacardic acids, 6-pentadec(en)ylsalicylic acids isolated from the cashew Anacardium occidentale L. (Anacardiaceae) nut and apple, were found to possess preventive antioxidant activity while salicylic acid did not show this activity. These anacardic acids prevent generation of superoxide radicals by inhibiting xanthine oxidase (EC 1.1.3.22, Grade IV) without radical-scavenging activity. Notably, the inhibition kinetics of anacardic acids do not follow hyperbolic dependence of enzyme inhibition on inhibitor contents (Michaelis–Menten equation) but follow the Hill equation instead. Anacardic acid (C_15:1) inhibited the soybean lipoxygenase-1 (EC 1.13.11.12, Type 1) catalyzed oxidation of linoleic acid with an IC₅₀ of 6.8 μM. The inhibition is a slow and reversible reaction without residual enzyme activity. The inhibition kinetics indicate that anacardic acid (C_15:1) is a competitive inhibitor and the inhibition constant, K_I, was 2.8 μM. Anacardic acids act as antioxidants in a variety ways, including inhibition of various prooxidant enzymes involved in the production of the reactive oxygen species and chelate divalent metal ions such as Fe²⁺ or Cu²⁺, but do not quench reactive oxygen species. The C₁₅-alkenyl side chain is largely associated with the activity.     

Influence of Gaseous Atmosphere on Morphology and Cellular Fatty Acid Composition of Campylobacter jejuni

ABSTRACT: We evaluated the effect of growth environment on morphology and fatty acid (FA) profiles of 2 strains of C ampylobacter jejuni (ATCC 29428 and 33560) grown under various gaseous conditions. Viable counts were determined by plate count and percentages of coccoid cells. FA profiles were measured by gas chromatography. Plate counts were lowest when cultures were grown in air and highest in CO₂ (10%), O₂ (5%), and N₂ (85%). For 29428, percentages of coccoid cells did not differ among treatments. For 33560, percentages of coccoid cells were greater than for 29428 and varied among treatments (13% to 87%). There were no significant ( P > 0.05) relationships between percentages of coccoid cells and amounts of individual or combinations of FA either between or within strains.