Enzymatic synthesis of lactic acid derivatives with emulsifying properties

Novozym 435 (50 g l^–1) catalyzed the synthesis of n-octyl--d-glucopyranoside lactate by transesterification between n-octyl--d-glucopyranoside (30 g l^–1) and ethyl lactate (100 g l^–1) in acetone. In 12 h, a molar yield of 87% n-octyl -d-glucopiranoside lactate was obtained at a overall conversion of 90%.     

Effect of cations, pH and sulfate content on the viscosity and emulsifying activity of the Halomonas eurihalina exopolysaccharide

The effects of monovalent and divalent cations on the rheological behavior of Halomonas eurihalina exopolysaccharide (EPS) were studied. Sodium, potassium, magnesium and calcium were added and the relative abilities to increase viscosity were as follows: KCl > NaCl > MgCl₂ > CaCl₂. The highest viscosity value was measured in acidic 10⁻⁴ M KCl, in which a gel formed. A loss of sulfate content seemed to correlate with the increase of viscosity. H. eurihalina produced EPS in all growth media. Addition of hydrophobic substrates to culture media produced changes in chemical composition and emulsifying activity of the EPS. Xylene was the most effectively emulsified substance and the EPS produced on tetradecane and on corn oil the most active emulsifier. Received 25 July 1997/ Accepted in revised form 30 January 1998     

Green enzymatic production of glyceryl monoundecylenate using immobilized Candida antarctica lipase B

Enzymatic synthesis of glyceryl monoundecylenate (GMU) was performed using indigenously immobilized Candida anatarctica lipase B preparation (named as PyCal) using glycerol and undecylenic acid as substrates. The effect of molar ratio, enzyme load, reaction time, and organic solvent on the reaction conversion was determined. Both batch and continuous processes for GMU synthesis with shortened reaction time were developed. Under optimized batch reaction conditions such as 1:5 molar ratio of undecylenic acid and glycerol, 2?h of reaction time at 30% substrate concentration in tert-butyl alcohol, conversion of 82% in the absence of molecular sieve, and conversion of 93% in the presence of molecular sieve were achieved. Packed bed reactor studies resulted in high conversion of 86% in 10-min residence time. Characterization of formed GMU was performed by FTIR, MS/MS. Enzymatic process resulted in GMU as a predominant product in high yield and shorter reaction time periods with GMU content of 92% and DAG content of 8%. Optimized GMU synthesis in the present study can be used as a useful reference for industrial synthesis of fatty acid esters of glycerol by the enzymatic route.     

Effect of Compositional Factors against the Thermal Oxidative Deterioration of Novel Food Emulsions

This work attempts to determine any relationship between certain endogenous parameters and the oxidative deterioration of protein-stabilized oil-in-water emulsions. The contribution of compositional factors (e.g., type and amount of emulsifier, fat phase, etc.) is further elucidated. Among 10% cottonseed o/w emulsions prepared by 1% emulsifier (Tween, sodium caseinate, or whey protein), lipid autoxidation (at 40°C) was much faster in the Tween emulsion than in the protein ones, with whey protein presenting a clear antioxidant effect. Increase in protein concentration (0.5–2% w/w) led to a decrease in droplet size but an increase in oxidative stability, in terms of conjugated diene hydroperoxides formation at 232 nm. The type of lipid phase significantly affected the rate of thermal oxidation at 60°C. In the most oxidatively vulnerable sunflower-oil-based emulsions, an increase in fat content (10–40%) resulted in a reduction of oxidative deterioration. By selecting a more concentrated emulsion (20% o/w, 2% emulsifier), in order to structurally approach real novel food products, any influence of the composition of the emulsifier (combination of Tween and sodium caseinate preparation) was subsequently tested. An increase in protein proportion in the emulsifier was found to inhibit proportionally the oxidative instability of the emulsions, as evaluated by the determination of both primary (conjugated diene and lipid hydroperoxides) and secondary [thiobarbituric acid-reactive substances (TBARS)] oxidation products.     

Bacterial exopolysaccharides produced by newly discovered bacteria belonging to the genus Halomonas, isolated from hypersaline habitats in Morocco

We have studied the exopolysaccharides (EPS) from a new group of moderately halophilic bacteria belonging to the genus Halomonas. The quantity of EPS produced, its chemical composition and physical properties depend greatly upon the bacterial strain. The majority of the polymers produced viscous solutions and/or emulsified different hydrocarbon compounds. The most interesting strain, S-30, produced EPS at 2.8 g/l with a maximum viscosity of 23.5 Pa·5 and exhibited pseudoplastic behavior. This EPS emulsified five hydrocarbons more efficiently than did four control surfactants tested. Its monosaccharide composition was glucose:galactose:manose:glucuronic acid in equimolar ratio. Some two-thirds of the strains tested emulsified crude oil better than control surfactants did. There are many potential industrial applications for polysaccharides with these qualities. Journal of Industrial Microbiology & Biotechnology (2000)24, 374–378. Received 09 August 1999/ Accepted in revised form 23 March 2000     

Resonance Rayleigh scattering methods for the determination of chitosan with Congo red as probe

Two methods were presented for the sensitive and selective determination of chitosan (CTS) with Congo red (CR) as probe based on resonance Rayleigh scattering (RRS) intensities in health products. In weakly acidic buffer solution, the binding of CTS to CR, could result in the enhancement of the RRS intensities. Moreover, after adding OP emulsifier (octyl‐phenyl polyoxyethylene ether) to the system, the RRS intensities showed more significantly enhancement. The maximum RRS signals for the CTS–CR system and the CTS–CR–OP system were located at 380 nm and 376 nm, respectively. Under optimum experimental conditions, the increased RRS intensities (ΔI) of these two systems were linear to CTS concentration in the range of 0.40–8.00 μg/ml and 0.05–1.00 μg/ml. Their limits of detection (LOD) were 44.81 ng/ml and 6.99 ng/ml, which indicated that the latter system was more sensitive than the former. In this work, the optimum conditions and the effects of some foreign substances on the determination were studied. In addition, the effect of the molecular weight of CTS and the reasons for the enhancement of resonance light scattering were discussed. Finally, these two methods were applied to the determination of chitosan in health products with satisfactory results.     

Enhancing Effect of Lipids and Emulsifiers on the Accumulation of Quercetin Metabolites in Blood Plasma after the Short-term Ingestion of Onion by Rats

The effects of co-ingested lipids and emulsifiers on the accumulation of quercetin metabolites in blood plasma after the short-term ingestion of onion by rats were investigated. Plasma extracts of rats that had been fed onion-containing diets for one and two weeks were analyzed by HPLC with electrochemical detection after a treatment with sulfatase/β-glucuronidase. Almost all of the quercetin metabolites in the plasma were sulfate/glucuronide conjugates of quercetin and isorhamnetin. More than 4.6% (w/w) of soybean oil in the diets significantly enhanced the accumulation of quercetin metabolites in the plasma. Fish oil and beef tallow increased this to an extent similar to that with soybean oil, and lecithin was more effective than the other three lipids. Two emulsifiers, sodium caseinate and sucrose fatty acid ester, also showed an enhancing effect on the accumulation of quercetin metabolites. These results indicate that co-ingested lipids and emulsifiers could enhance the bioavailability of quercetin glucosides in onion.     

国内外营养型脂肪乳剂研究进展

分析国内外脂肪乳剂的上市情况,对比上市脂肪乳剂的处方组成,从产品研发和质量升级等方面深入探讨国内脂肪乳剂的发展趋 势,以期为该类制剂的研究和开发提供借鉴和参考。     

The effects of a novel synthetic emulsifier product on growth performance of chickens for fattening and weaned piglets

Two experiments were conducted to evaluate the effects of a novel synthetic emulsifier product (AVI-MUL TOP) on the growth performance of chickens for fattening and weaned piglets. The emulsifier product consists of 50% vegetal bi-distillated oleic acid emulsified with 50% glyceryl polyethyleneglycol ricinoleate. In experiment 1, 480 1-day-old female Cobb500 chickens for fattening were assigned to two treatments: (1) a control diet (CTR); and (2) the control diet+the emulsifier (AMT, 1 g/kg from day 0 to day 10, 0.75 g/kg from day 10 to day 20 and 0.5 g/kg from day 20 to day 34 of the trial). AMT supplementation increased BW on days 20 and 34 (P<0.01). Dietary AMT increased the average daily gain and average daily feed intake (ADFI) from day 10 to day 20, from day 20 to day 34 and from day 0 to day 34 (P<0.01). A reduced feed conversion ratio was observed in the AMT group from day 10 to day 20 (P<0.01). In experiment 2, 96 Stambo HBI×Dalland piglets were weaned at 24 days and assigned to two treatments (the basal diet without the product (CTR) or with 2 g/kg emulsifier from day 0 to day 14 and 1.5 g/kg from day 14 to day 42 (AMT)). There was an increase in the ADFI associated with AMT supplementation from day 14 to day 42 (P=0.04). These results indicated that supplementation with the synthetic emulsifier may significantly improve the growth performance of chickens for fattening and numerically improve that of weaned piglets.     

银耳粗多糖对桉叶油的乳化性研究

对不同浓度、温度、pH、NaCl浓度条件下,银耳粗多糖对桉叶油的乳化能力,以及乳化体系的稳定性进行了研究。结果表明,银耳粗多糖对桉叶油的乳化性随浓度增大上升,在浓度1%时达到最大,随后呈下降趋势;在pH 4.0~8.0之间;有较好的乳化性及乳化稳定性,在此范围以外,随pH的升高、降低,银耳粗多糖的乳化和乳化性均呈下降趋势;随着温度和NaCl浓度升高,银耳粗多糖的乳化活性和乳化稳定性有所降低。