The role of homogenization in the manufacture of halloumi and mozzarella cheese from recombined milk*

When halloumi and mozzarella cheese are made from normal recombined milk, neither product exhibits the characteristic stretch and melt behaviour of the fresh milk cheeses. The present study demonstrates that this problem may be overcome either by using low homogenization pressures to prepare the recombined milk or by coating the fat in the recombined milk emulsion with phospholipid and homogenizing at the usual pressure. The influence of homogenization of milk on the properties of the cheese is discussed in terms of a polymer network model.     

A SURVEY OF HISTAMINE LEVELS IN COMMERCIALLY PROCESSED SCOMBROID FISH PRODUCTS12

Analysis of 100 samples of each of 3 types of commercially processed scombroid fish products obtained at the retail level showed mean histamine concentrations (mg/100 g) of 3.58 for chunk light tuna, 1.50 for albacore tuna, and 2.56 for mackerel. Only 2 samples of chunk light tuna and 2 of mackerel contained greater than 10 mg% histamine. The highest level of histamine found in albacore tuna was 5.35 mg/100 g, while 99% ofthe samples had less than 5 mg% histamine. Chunk light tuna samples contained up to 28.0 mg/100 g, and mackerel samples contained up to 31.5 mg/100 g; 92% of the chunk light tuna and 95% of the mackerel had less than 5% histamine. The histamine levels found in these products were far below any level associated with food poisoning incidents.     

A GENERALIZED NEWTON METHOD FOR HIGHER-ORDER FINITE ELEMENT APPROXIMATIONS IN NON-LINEAR ELASTICITY

A generalized Newton method is proposed in conjunction with a higher-order Lagrangian finite element discretization of bodies undergoing finite elastic deformations. The method is based on a gradient-like modification of the Newton method, designed to suppress the sensitivity of higher-order elements during the early iterations, thus allowing for solutions to be obtained using moderately large step-sizes.     

The incidence of watery muscle in commercial British pigs

Measurements of the pH of the leg muscle approximately 45 min after slaughter (pH₁) have been made in 4737 commercial pigs slaughtered at eight factories in Great Britain. The values found lie on a single-peaked distribution curve with a maximum at pH 6.4–6.5. No evidence was obtained of any marked influence on pH₁ distribution due to sex, weight or period of lairage. Indications of watery muscle were observed in about two per 1000 of the pigs examined. The distribution of watery muscle between factories was very irregular, most of the watery carcases being observed in a single factory.     

ON SOME EXPLICIT APPROXIMATE SOLUTIONS OF THE MAXWELL-STEFAN EQUATIONS FOR THE MULTICOMPONENT FILM MODEL

An explicit approximate solution of the Maxwell-Stefan equations, which describe mass transfer in multi-componcnt gas mixtures, for a film model is developed as a generalisation of a method by Burghardt and Krupiczka for diffusion through a mixture of stagnant gases. The consistent approach to explicit approximations described here also leads to the earlier general method of Krishna. Numerical examples demonstrate the superiority of the new approximation in problems involving mass transfer at high rates.     

真空灭弧室 配电开关 断路器和接触器的高可靠性元件

自从20世纪50年代中期将真空灭弧室(VI)用作配电操作开关、断路器和接触器的电流分断元件以来,其作用逐步增强.在电路的开断和配电保护领域,该电气产品已经占统治地位.真空灭弧室甚至被引入到电力输送中的通断产品的领域上.真空灭弧室受到追捧的原因有:结构紧凑、适用范围广、成本低、极好的电寿命和机械寿命,以及使用方便.其中,最重要的优点是公认的高可靠性.     

HISTAMINE PRODUCTION BY FOOD-BORNE BACTERIAL SPECIES12

A total of 112 bacterial strains representing 38 species were tested for their potential to elicit food poisoning outbreaks via histamine formation in foods. Proteus morganii and Enterobacter aerogenes displayed a quantitative superiority in terms of histamine production on a trypticase-soy broth-histidine (TSBH) medium and a tuna fish infusion broth (TFIB). When bacteria were incubated under standardized conditions in TSBH medium, histamine accumulated to levels exceeding 50 nmoles/ml of media with a total of 23 strains, including 13 of 15 P. morganii strains, 3 of 3 E. aerogenes strains, 3 of 12 Hafnia alvei strains, 1 of 4 Providencia alcalifaciens strains, 1 of 5 Enterobacter cloacae strains, 1 of 1 Proteus rettgeri strains, and 1 of 1 Citrobacter diversus strains. However, only 8 of the 15 P. morganii strains and the 3 E. aerogenes strains were capable of generating histamine in excess of 200 nmoles/ml in the TSBH medium. Of the 23 strains capable of appreciable histamine production in TSBH medium, P. morganii and E. aerogenes were, by far, the most prolific histamine producers in TFIB. Of the organisms tested, only P. morganii and E. aerogenes would appear to have the capability of forming sufficient histamine in scombroid fish products to elicit food poisoning outbreaks.     

Effect of amidation on the foaming and physico-chemical properties of bovine serum albumin

Amidation of bovine serum albumin (BSA) was achieved by a water-soluble carbo-diimide, ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-mediated reaction using ammonium chloride as the nucleophile. Partial and substantial amidation of 0.5% (w/v) BSA in 5.5 m ammonium chloride solution with 1 times 10-²mmol EDC over 120 min and 1 times 10^-1mmol EDC over 10 min respectively was achieved on a large scale using diafiltration for rapid termination of the reaction and purification. Residual ammonium chloride otherwise enhanced foaming properties. The amidated proteins were characterized by isoelectric focusing, electrophoresis and hydrophobicity and disulphide- and sulphydryl-group measurements. Compared with native BSA, partially amidated BSA (PA-BSA) produced enhanced foam expansion and foam stability values. This was attributed to minimal denaturation and to the presence of both acidic and basic components (pI range 5.25–7.50) within the single protein. In contrast, substantially amidated BSA (SA-BSA) (pI range 7–9.1) had similar foaming properties to those of the ultrafiltered BSA control which were slightly lower than those of native BSA. However SA-BSA interacted synergistically with native BSA producing enhanced foaming properties particularly at the 1:1 ratio through electrostatic interactions, conformational changes and increased hydrophobicity.