COLOR CHANGES OF MILK POWDER DUE TO HEAT TREATMENTS AND SEASON OF MANUFACTURE CAMBIOS EN EL COLOR DE LECHE EN POLVO DEBIDO A TRATAMIENTOS TÉRMICOS Y ESTACIÓN DE ELABORACIÓN

The manufacture of Domiati cheese by ultrafiltration (UF) processing of recombined milk bas been described in several reports (El-Shibinyet al.1982; Bogaard, 1986). This method has several potential advantages in areas short in milk production. In Egypt, a new plant has been established recently for the manufacture of Domiati cheese on the basis of this technology.The behaviour of fresh pasteurized skim milk during UF has been described (Glover, 1971; Setti & Peri, 1976; Patel & Reuter, 1985; Chiang & Cheryan, 1986). Similar studies are lacking for reconstituted skim milk or recombined milk. Skim milk powder is usually subjected to variable heat treatments during processing which are known to affect its properties. These heat treatments have been used as a basis for classification of skim milk powders. Therefore, studies on UF of reconstituted milks previously subjected to different heat treatments would be important in the adaptation of this technology to cheese manufacture.We describe here results obtained for permeation rates of reconstituted skim milk during UF compared with fresh pasteurized skim milk.

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Visual and Optical Absorbance Detection of Melamine in Milk by Melamine-Induced Aggregation of Gold Nanoparticles

Nanomaterials ◽

10.3390/nano11051142 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1142

Author(s):

Shafiquzzaman Siddiquee ◽

Suryani Saallah ◽

Noor Aini Bohari ◽

Gilbert Ringgit ◽

Jumardi Roslan ◽

...

Keyword(s):

Gold Nanoparticles ◽

Infant Formula ◽

Milk Powder ◽

High Sensitivity ◽

Detection Methods ◽

Optical Absorbance ◽

Color Changes ◽

Naked Eye ◽

Relative Standard ◽

Induced Aggregation

The present study reported a facile method for the determination of melamine in milk powder products based on the aggregation of reactant-free 5 nm gold nanoparticles (AuNPs). The strong electrostatic attraction between the positively charged exocyclic amine groups present in the melamine molecule and the negatively charged ions bound to the AuNPs induced aggregation of the AuNPs, resulting in visible color changes that could be seen with the naked eye and monitored by ultraviolet–visible (UV–Vis) absorbance spectra. The method shows high sensitivity with detection limits of 1 × 10−9 M for visual detection and 1 × 10−11 M for UV–Vis analysis, which is far below the safety limit of melamine ingestion in infant formula (1 ppm = 7.9 × 10−6 M) and the detection limit acquired by most AuNP-based melamine detection methods. Good recoveries were obtained over the range of 94.7–95.5% with a relative standard deviation of mean recovery (RSD) ranging from 1.40 to 5.81. The method provides a simple, feasible, fast and real-time detection of melamine adulterants in infant formula by the naked eye, without the aid of advanced instruments.

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Rheological properties at small (dynamic) and large (yield) deformations of acid gels made from heated milk

Journal of Dairy Research ◽

10.1017/s0022029997002380 ◽

1997 ◽

Vol 64 (4) ◽

pp. 591-600 ◽

Cited By ~ 204

Author(s):

JOHN A. LUCEY ◽

CHENG TET TEO ◽

PETER A. MUNRO ◽

HARJINDER SINGH

Keyword(s):

Rheological Properties ◽

Whey Proteins ◽

Milk Powder ◽

Skim Milk ◽

High Heat ◽

Skim Milk Powder ◽

Heat Treatments ◽

Heated Milk ◽

Large Yield ◽

Powder Manufacture

The effect of a range of milk heat treatments on the rheological properties, at small and large deformations, of acid skim milk gels was investigated. Gels were made from reconstituted skim milk heated at 75, 80, 85 and 90°C for 15 or 30 min by acidification with glucono-δ-lactone at 30°C. Gels were also made from skim milk powder (SMP) samples that had been given a range of preheat treatments during powder manufacture. Heating milks at temperatures [ges ]80°C for 15 min increased the storage moduli (G′) compared with unheated milk and produced gels with G′ in the range 300–450 Pa. Acid gels made from high-heat or medium-heat SMP had higher G′ than gels made from low-heat or ultra-low-heat SMP. Cooling gels to low temperatures resulted in an increase in G′. The yield stress of gels slightly decreased with mild heat treatments of milk, and then increased again to a maximum, finally decreasing slightly with very high heat treatments of milk. The strain at yielding decreased markedly with increasing heat treatment of milk, making these gels brittle and easier to fracture. We propose that denatured whey proteins aggregated with casein particles during the acidification of heated milk and were responsible for most of the effects observed in this study.

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Influence of Heat Treatments on Microstructures in an Fe-Co-V Alloy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052572 ◽

1974 ◽

Vol 32 ◽

pp. 512-513

Author(s):

S. Mahajan ◽

M. R. Pinnel ◽

J. E. Bennett

Keyword(s):

Single Phase ◽

Alloy Composition ◽

Supersaturated Solid Solution ◽

Cell Formation ◽

Heat Treatments ◽

Air Cooling ◽

Iced Brine ◽

Transmission Electron ◽

The Matrix ◽

Bcc Structure

The microstructural changes in an Fe-Co-V alloy (composition by wt.%: 2.97 V, 48.70 Co, 47.34 Fe and balance impurities, such as C, P and Ni) resulting from different heat treatments have been evaluated by optical metallography and transmission electron microscopy. Results indicate that, on air cooling or quenching into iced-brine from the high temperature single phase ϒ (fcc) field, vanadium can be retained in a supersaturated solid solution (α2) which has bcc structure. For the range of cooling rates employed, a portion of the material appears to undergo the γ-α2 transformation massively and the remainder martensitically. Figure 1 shows dislocation topology in a region that may have transformed martensitically. Dislocations are homogeneously distributed throughout the matrix, and there is no evidence for cell formation. The majority of the dislocations project along the projections of <111> vectors onto the (111) plane, implying that they are predominantly of screw character.

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Microstructural Development in Nb-Ti Multifilamentary Superconductors During Processing

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100117911 ◽

1985 ◽

Vol 43 ◽

pp. 190-191

Author(s):

A. W. West

Keyword(s):

Heat Treatment ◽

Critical Current Density ◽

Copper Matrix ◽

Wire Drawing ◽

Heat Treatments ◽

Microstructural Development ◽

Final Size ◽

Density Values ◽

The Wire ◽

Multifilamentary Superconductors

The influence of the filament microstructure on the critical current density values, Jc, of Nb-Ti multifilamentary superconducting composites has been well documented. However the development of these microstructures during composite processing is still under investigation.During manufacture, the multifilamentary composite is given several heat treatments interspersed in the wire-drawing schedule. Typically, these heat treatments are for 5 to 80 hours at temperatures between 523 and 573K. A short heat treatment of approximately 3 hours at 573K is usually given to the wire at final size. Originally this heat treatment was given to soften the copper matrix, but recent work has shown that it can markedly change both the Jc value and microstructure of the composite.

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Microstructure Development in a High Current Density NbTi Superconducting Composite

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010011790x ◽

1985 ◽

Vol 43 ◽

pp. 186-189

Author(s):

P. J. Lee ◽

D. C. Larbalestier

Keyword(s):

Current Density ◽

High Current Density ◽

Cold Drawing ◽

Heat Treatments ◽

Grain Structure ◽

Fine Grain ◽

Boundary Film ◽

Quantitative Basis ◽

Cold Worked ◽

Very High

Several features of the metallurgy of superconducting composites of Nb-Ti in a Cu matrix are of interest. The cold drawing strains are generally of order 8-10, producing a very fine grain structure of diameter 30-50 nm. Heat treatments of as little as 3 hours at 300 C (∼ 0.27 TM) produce a thin (1-3 nm) Ti-rich grain boundary film, the precipitate later growing out at triple points to 50-100 nm dia. Further plastic deformation of these larger a-Ti precipitates by strains of 3-4 produces an elongated ribbon morphology (of order 3 x 50 nm in transverse section) and it is the thickness and separation of these precipitates which are believed to control the superconducting properties. The present paper describes initial attempts to put our understanding of the metallurgy of these heavily cold-worked composites on a quantitative basis. The composite studied was fabricated in our own laboratory, using six intermediate heat treatments. This process enabled very high critical current density (Jc) values to be obtained. Samples were cut from the composite at many processing stages and a report of the structure of a number of these samples is made here.

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