DRIED MILK POWDER: V. THE PHOTOLYSIS OF RIBOFLAVIN IN MILK POWDERS

1946 ◽  
Vol 24f (2) ◽  
pp. 123-129 ◽  
Author(s):  
W. A. Bryce
Keyword(s):  
Absorption Spectrum ◽  
Visible Light ◽  
Spectral Region ◽  
Wave Length ◽  
Milk Powder ◽  
Skim Milk ◽  
Ultra Violet ◽  
Wave Band ◽  
Violet Light ◽  
Whole Milk

Exposure of milk powders to sunlight resulted in a much greater destruction of riboflavin than did exposure to ultra-violet light in the range 3200 to 4200 Å. The rate of photolysis was greater for skim-milk powders than for whole milk powders. Increased intensities of visible light accelerated riboflavin destruction. In the spectral region of 4200 to 5600 Å the wave band causing the greatest destruction in liquid skim-milk had a principal wave-length of 4450 Å, which corresponded to a maximum in the absorption spectrum of riboflavin. The rate of photolysis of riboflavin was a function of both wave-length and intensity of the impinging energy.

DRIED MILK POWDER: III. THE EFFECT OF LIGHT ON KEEPING QUALITY

1945 ◽  
Vol 23f (6) ◽  
pp. 334-339 ◽  
Author(s):  
Jesse A. Pearce ◽  
W. A. Bryce
Keyword(s):  
Wave Length ◽  
Milk Powder ◽  
Skim Milk ◽  
Ultra Violet ◽  
Average Temperature ◽  
Violet Light ◽  
Whole Milk ◽  
The Difference ◽  
Whole Milk Powder ◽  
Effect Of Light

At an average temperature of 6 °C., exposure of both whole and skim milk powders to sunlight caused more rapid deterioration in quality than occurred in the dark. Ultra-violet light with a principal wave length of 3800 Å accelerated deterioration in whole milk powder stored at 38 °C., but had no significant effect on skim milk powders; the effect of this light on whole milk powders was less pronounced than that produced by sunlight. Storage of samples at 38 °C. under different light intensities indicated that the differences between ultraviolet and sunlight were the result of the difference in total energy of light falling upon the sample, rather than the difference in wave length of the activating light.

Thermal Resistance of Listeria monocytogenes Scott A in Ultrafiltered Milk as Related to the Effect of Different Milk Components

2010 ◽  
Vol 73 (11) ◽  
pp. 2110-2115 ◽  
Author(s):  
KINGA SZLACHTA ◽  
SUSANNE E. KELLER ◽  
ARLETTE SHAZER ◽  
STUART CHIRTEL
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Milk Fat ◽  
Milk Powder ◽  
Skim Milk ◽  
Skim Milk Powder ◽  
Single Measure ◽  
Total Solids ◽  
Whole Milk ◽  
Milk Components

Pasteurization parameters for grade A milk are well established and set by regulation. However, as solids levels increase, an increased amount of heat is required to destroy any pathogens present. This effect is not well characterized. In this work, the effect of increased dairy solids levels on the thermal resistance of Listeria monocytogenes was examined through the use of ultrafiltered (UF) milk, reconstituted milk powder, and the milk components lactose and caseinate. From the results obtained, lactose and caseinate did not appear to affect thermal resistance. In addition, the level of milk fat, up to 10% of the total solids in UF whole milk, did not result in statistically significant changes to thermal resistance when compared with UF skim milk. Reconstituted skim milk powder at 27% total solids (D62-value = 1.16 ± 0.2 [SD] min, z = 5.7) did result in increased thermal resistance, as compared with reconstituted skim milk powder at 17.5% (D62-value = 0.86 ± 0.02 min, z = 5.57) and UF whole milk at 27% total solids (D62-value = 0.66 ± 0.07 min, z = 5.16). However, that increase appeared to be due to the increase in salt levels, not to increases in caseinate, fat, or lactose. Consequently, total solids, as a single measure, could not be used to predict increased thermal resistance of L. monocytogenes in concentrated milk.

scholarly journals Photochemical reactions in the fluorite region II─Photochemical decomposition of formaldehyde vapour

1937 ◽  
Vol 163 (913) ◽  
pp. 221-227 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Absorption Spectrum ◽  
Ground State ◽  
Wave Length ◽  
Ultra Violet ◽  
Photochemical Reactions ◽  
Photochemical Decomposition ◽  
The Subject ◽  
Region Ii ◽  
Formaldehyde Vapour

The photochemical decomposition of formaldehyde in the near ultra­-violet has been the subject of several investigations. It is known (Norrish and Kirkbride 1932) that the products are chiefly carbon monoxide and hydrogen, and that neither the composition of the products nor the quantum yield depends appreciably on wave-length. Recently Price (1935) has investigated the far ultra-violet absorption spectrum of formaldehyde. The first band observed in this region occurs at about 1745 A and is very diffuse, whereas the first bands in acetaldehyde (Price 1935) and acetone (Noyes, Duncan and Manning 1934) occur at longer wave-lengths and are relatively much sharper. Price ascribes this diffuseness to a predissociation resulting from the interaction of the upper state in formaldehyde with the ground state and assumes that the primary dissociation at about 1745 A should be CH 2 O → hv 1745 A CH 2 + O.

Movement patterns and photosensitivity of Trichonema spp. infective larvae in non-directional light

Parasitology ◽  
1971 ◽  
Vol 62 (3) ◽  
pp. 467-478 ◽  
Author(s):  
N. A. Croll
Keyword(s):  
Visible Light ◽  
Sensory Input ◽  
Ultra Violet ◽  
Movement Patterns ◽  
Light Conditions ◽  
Infective Larvae ◽  
Violet Light ◽  
Significant Difference ◽  
Flashing Light ◽  
Individual Giving

1. Trichonema spp. infective larvae once stimulated move in darkness, dim and bright visible light and ultra-violet light. There was no significant difference between the distances moved in these photic conditions.2. Movement patterns were variable but certain shapes of tracks, rates of reversal and reversing types were typical of certain light conditions.3. The rate of reversing was dependent on light conditions and was random in direction.4. Sensory adaptation was suggested in visible light, but not in ultra-violet at 366 μm.5. Movement analyses in flashing light suggested that pulsating stimuli at intervals of 100 ms or less were required for sensory input approximating to physiologically continuous stimulation.6. Larvae showed an idiosyncrasy in their tracks, repeated tracking with the same individual giving less varied tracks than with different larvae.The author is indebted to Mr J. M. Smith for his painstaking efforts in preparing the tracks and his willing and skilful assistance throughout.

Monitoring residue concentrations in milk from farm and throughout a milk powder manufacturing process

2019 ◽  
Vol 86 (3) ◽  
pp. 341-346
Author(s):  
Lizandra F. Paludetti ◽  
Alan L. Kelly ◽  
Bernadette O'Brien ◽  
David Gleeson
Keyword(s):  
Milk Powder ◽  
Skim Milk ◽  
Skim Milk Powder ◽  
Production Chain ◽  
Feed Management ◽  
Whole Milk ◽  
Milk Volume ◽  
Residue Levels ◽  
Bulk Tank ◽  
Powder Manufacturing

AbstractThe experiments reported in this research paper aimed to investigate differences in the levels of chlorate (CHLO), perchlorate (PCHLO), trichloromethane (TCM) and iodine residues in bulk tank (BT) milk produced at different milk production periods, and to monitor those levels throughout a skim milk powder (SMP) production chain (BTs, collection tankers [CTs], whole milk silo [WMS] and skim milk silo [SMS]). Chlorate, PCHLO and iodine were measured in SMP, while TCM was measured in the milk cream. The CHLO, TCM and iodine levels in the mid-lactation milk stored in the WMS were lower than legislative and industrial specifications (0.0100 mg/kg, 0.0015 mg/kg and 150 µg/l, respectively). However, in late-lactation, these levels were numerically higher than the mid-lactation levels and specifications. Trichloromethane accumulated in the cream portion after separation. Perchlorate was not detected in any of the samples. Regarding iodine, the levels in mid-lactation reconstituted SMP were higher than that required by manufacturers (100 µg/l), indicating that the levels in milk should be lower than 142 µg/l. The higher residue levels observed in late-lactation could be related to the low milk volume produced during that period and changes in sanitation practices, while changes in feed management could have affected iodine levels. This study could assist in controlling and setting limits for CHLO, TCM and iodine levels in milk, ensuring premium quality dairy products.

scholarly journals THE PHOTOTROPIC SENSITIVITY OF PHYCOMYCES AS RELATED TO WAVE-LENGTH

1931 ◽  
Vol 14 (6) ◽  
pp. 701-711 ◽  
Author(s):  
E. S. Castle
Keyword(s):  
Absorption Spectrum ◽  
Wave Length ◽  
Ultra Violet ◽  
Photosensitive Substance

Under the circumstances of experimentation described, the sporangiophores of Phycomyces are found to be most sensitive to stimulation by light in the violet between 400 and 430 mµ. Toward the red, sensitivity falls to nearly zero near 580 mµ, while in the near ultra-violet around 370 mµ, sensitivity is still high. The previous experiments of Blaauw had placed the point of greatest sensitivity some 80 mµ nearer the red end of the spectrum. Because of the known presence in the sporangiophores of Phycomyces of "accessory" pigments, care must be taken in identifying such results with the absorption spectrum of the photosensitive substance.

The photo-degradation of polymethylmethacrylate I. The mechanism of degradation

1952 ◽  
Vol 210 (1103) ◽  
pp. 461-481 ◽  
Keyword(s):  
Thermal Degradation ◽  
Wave Length ◽  
Ultra Violet ◽  
Slow Process ◽  
Photo Degradation ◽  
Molecular Weights ◽  
Vinyl Polymers ◽  
Violet Light ◽  
Mechanism Of Degradation ◽  
Degradation Reaction

On exposure to ultra-violet light of wave-length 2537 Å, polymethylmethacrylate degrades rapidly to monomer at temperatures above 130° C in vacuo . The general features of this reaction are described, and the behaviour of polymethylmethacrylate compared with that of other vinyl polymers under similar conditions. The diffusion of monomer through polymethylmethacrylate is a comparatively slow process. The effect of this on the experimental results is described, and the limited conditions under which true rates of degradation can be measured are outlined. The overall quantum efficiency of the photo-degradation reaction is greater than 10 2 , and the intensity exponent about 0·5 for most samples. Number-average molecular weights of samples of degraded polymers have been measured, the results being similar to those obtained in an earlier study of the thermal-degradation. The results show that the mechanism of degradation is a true depolymerization process, involving initiation, a depropagation reaction, and (under most circumstances) mutual termination of reaction chains.

scholarly journals The coagulation of protein by sunlight

1922 ◽  
Vol 93 (651) ◽  
pp. 235-248 ◽  
Keyword(s):  
Temperature Coefficient ◽  
Tap Water ◽  
Wave Length ◽  
Ultra Violet ◽  
Protein Molecule ◽  
Mercury Vapour ◽  
Absorption Bands ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Mercury Vapour Lamp

It was first shown by Dreyer and Hanssen (1) in 1917 that ultra-violet light produced a change in protein solutions which appeared to be similar to coagulation by heat. They exposed various solutions in quartz chambers to the light of a Bang lamp with iron and silver electrodes. Vitellin was found most easily coagulated, while globulin, albumin and fibrinogen showed a decreasing sensitivity to ultra-violet rays in the order mentioned. These investigators also discovered that acids markedly increase the rate of precipitation. Soret (2) had shown in 1883 that there are absorption bands in the extreme ultra-violet region of the spectrum of various proteins, e. g. , casein, ovalbumin, mucin and globulin. Tyrosine likewise has this band in the ultra-violet and Soret attributed to this constituent of the protein molecule its power of absorbing ultra-violet rays. In this connection Harris and Hoyt (3) carried out some interesting experiments on the protective power of various substances for paramœcium cultures exposed to ultra-violet radiations. They found that gelatin peptone, amino-benzoic acid, cystine, leucine and especially tyrosine possessed the power of detoxicating ultra-violet rays when placed as a thin layer of aqueous solution over paramœcium cultures under a quartz-mercury lamp. The toxicity of the radiations for paramœcia or protoplasm in general can be understood in the light of the discovery of Dreyer and Hanssen coupled with that of Soret. From a physico- chemical standpoint Bovie (4) has published a study of the coagulation of proteins by ultra-violet light. By exposing solutions of crystalline ovalbumin, both dialysed and containing electrolytes, to the light of a mercury-vapour lamp, he came to the conclusion that there were two reactions involved in the coagulation of ovalbumin by ultra-violet light. The first is a photochemical one with a low temperature coefficient,—denaturation; and the second is one with a higher temperature coefficient of two and is dependent upon the electrolytes present,—coagulation. While using solutions dialysed against tap water Bovie made the observation that the protein appeared to become sensitive to light of longer wave-length, for his control tubes in glass were slowly coagulated.

scholarly journals The theory of reflexion of very long wireless waves from the ionosphere

1940 ◽  
Vol 175 (961) ◽  
pp. 143-163 ◽  
Keyword(s):  
Critical Frequency ◽  
Wave Length ◽  
Ultra Violet ◽  
Theoretical Work ◽  
Short Wave ◽  
Long Waves ◽  
Quasi Equilibrium ◽  
Physical Conditions ◽  
Reflected Wave ◽  
Violet Light

In two previous papers (which will be referred to as I and II) Best, Ratcliffe and Wilkes (1936), and Budden, Ratcliffe and Wilkes (1939) have given an account of some experiments on the nature of the downcoming wave received at Cambridge from the British Post Office transmitter at Rugby (GBR wave-length 18.8 km.; distance 90 km.). Data are there given concerning the polarization of the wave, and the height of reflexion and the daily and seasonal changes of these quantities. Reflexion of very long waves takes place low down in the ionosphere where the density of ionization is only a few hundred electrons per c.c. The purpose of this paper is to discuss the theoretical implications of the data given in I and II, and to make such deductions as are possible from them concerning physical conditions in the lowest part of the ionosphere. In § 2 the changes in reflexion height at sunset, and in following sections the polarization and amplitude of the reflected wave will be discussed. Use will be made of Chapman’s well-known theory of the production of ions in a rotating atmosphere illuminated by ultra-violet light from the sun (Chapman 1931). It will be assumed that electrons tend to disappear sufficiently rapidly for the ionization to be always in quasi-equilibrium with changes in the rate of production of ions. It has been possible to interpret short-wave absorption and critical frequency results on this basis (Appleton 1937; Best, Farmer and Ratcliffe 1938) and we are consequently encouraged to try it for long waves. Finally, in § 7 the relation of this paper to previous theoretical work on the reflexion of very long waves will be discussed.

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