Oxidation of Cholesterol in Commercially Processed Cow's Milk

1987 ◽  
Vol 50 (10) ◽  
pp. 867-871 ◽  
Author(s):  
MAE Z. CLEVELAND ◽  
NATHOLYN D. HARRIS
Keyword(s):  
Skim Milk ◽  
Milk Lipid ◽  
Oxidized Cholesterol ◽  
Heated Milk ◽  
Whole Milk ◽  
Dry Milk ◽  
Liquid Milk ◽  
Milk Lipids ◽  
And Storage ◽  
Layer Chromatography

Pasteurized whole milk, ultra-high temperature heated milk, canned evaporated milk, skim milk and instant nonfat dry milk were analyzed for presence of oxidized cholesterol compounds. Effects of heating whole milk and storage of whole milk lipid extracts were also examined. Analytical thin-layer chromatography data indicate that cholesterol in liquid milk was stable during commercial pasteurization, sterilization and evaporation. However, instant non-fat dry milk contained 7-hydroxy-cholesterol. Heating whole milk for 12 h at 85°C did not produce oxysterols, but GC-MS analysis indicate that storage of whole milk lipids may have produced steroidal ketones.

Survival of Listeria monocytogenes During the Manufacture and Storage of Nonfat Dry Milk

1985 ◽  
Vol 48 (9) ◽  
pp. 740-742 ◽  
Author(s):  
MICHAEL P. DOYLE ◽  
LOUISE M. MESKE ◽  
ELMER H. MARTH
Keyword(s):  
Listeria Monocytogenes ◽  
Spray Drying ◽  
Skim Milk ◽  
Inlet Temperature ◽  
Outlet Temperature ◽  
Drying Process ◽  
Dry Milk ◽  
Nonfat Dry Milk ◽  
And Storage ◽  
Moisture Resistant

The ability of Listeria monocytogenes to survive in skim milk during spray drying and to persist in nonfat dry milk during storage was examined. Concentrated (30% solids) and unconcentrated skim milks were inoculated with ca. 105 to 106 L. monocytogenes/ml and spray dried (inlet temperature, 165 ± 2°C; outlet temperature 67 ± 2°C) to a moisture content of 3.6 to 6.4%. The nonfat dry milk was packaged in moisture-resistant film and stored at 25°C for up to 16 wk. A reduction of ca. 1 to 1.5 log10 L. monocytogenes/g occurred during the spray drying process, irrespective of whether the milk was concentrated or not before spray drying. The organism progressively died during storage at 25°C, with a >4-log10 CFU/g decrease occurring within 16 wk of storage.

Growth of Listeria monocytogenes at 10°C in Milk Preincubated with Selected Pseudomonads1

1988 ◽  
Vol 51 (4) ◽  
pp. 277-282 ◽  
Author(s):  
DOUGLAS L. MARSHALL ◽  
RONALD H. SCHMIDT
Keyword(s):  
Listeria Monocytogenes ◽  
Skim Milk ◽  
Growth Curves ◽  
Milk Composition ◽  
Pseudomonas Fragi ◽  
Pseudomonas Spp ◽  
Generation Times ◽  
Whole Milk ◽  
Dry Milk ◽  
Stimulation Of

Preliminary studies involving co-inoculation of Listeria monocytogenes with Pseudomonas fragi into whole or skim milk demonstrated that neither inhibition nor stimulation of growth occurred for either organism. Additional investigations involved preincubation of whole milk, skim milk, and 10% reconstituted nonfat dry milk (NDM) for 3 d at 10°C with P. fragi, Pseudomonas fluorescens P26, P. fluorescens T25, or P. fluorescens B52, followed by inoculation with L. monocytogenes and further incubation at 10°C. Growth curves of L. monocytogenes were constructed for each treatment combination and generation times were statistically compared for differences. Results indicated that L. monocytogenes did not affect growth or survival of the preincubated Pseudomonas spp. However, growth rates of L. monocytogenes were significantly (P<0.05) enhanced in milks preincubated with pseudomonads. Doubling times of L. monocytogenes were reduced by up to 3 h when grown in milk preincubated with Pseudomonas spp. Three strains of P. fluorescens showed more stimulation of the growth rate of L. monocytogenes compared to P. fragi in preincubated whole or skim milk but not in preincubated NDM. Milk composition had little effect on growth of either genus when incubated alone. Results of this study indicate that L. monocytogenes can grow in the presence of Pseudomonas spp. either as a co-inoculant or following preincubation in milk at 10°C. Furthermore, data suggest that the presence of the pseudomonads may enhance growth of L. monocytogenes in milk.

Pyruvate as an Indicator of Quality in Grading Nonfat Dry Milk1

1982 ◽  
Vol 45 (6) ◽  
pp. 561-565 ◽  
Author(s):  
R. T. MARSHALL ◽  
Y. H. LEE ◽  
B. L. O'BRIEN ◽  
W. A. MOATS
Keyword(s):  
Geometric Mean ◽  
Regression Line ◽  
Skim Milk ◽  
Plate Count ◽  
Department Of Agriculture ◽  
Standard Plate Count ◽  
Geometric Average ◽  
Dry Milk ◽  
Standard Plate ◽  
Microscopic Count

Samples of skim milk and nonfat dry milk (NDM) made from it were collected, paired and tested for pyruvate concentration, [P], and Direct Microscopic count (DMC). The skim milk was tested for Standard Plate Count (SPC) and Psychrotrophic Plate Count (PPC). The geometric average DMC of skim milk was more than three times higher than that of the paired NDM samples. However, [P] of NDM was not significantly different from that of the skim milk. Although [P] of skim milk was poorly correlated with SPC and PPC, r = .31 and .26, respectively, it was relatively well correlated with DMC, r = .64. Data were widely dispersed around the regression line when [P] was ≤ 4.0 mg/L. However, [P] increased rapidly when DMCs were > 106/ml. A limit of 10 mg/L of [P] in NDM reconstituted 1:9 was chosen to represent the current U.S. Department of Agriculture Standard for DMC in NDM. This limit failed to classify about 10% of the samples correctly, assuming that each geometric mean DMC was correct. However, the probability that samples meeting the DMC standard would be rejected by the pyruvate test was quite low and the probability was moderate that samples which would be acceptable by the pyruvate test would be rejected by the DMC. For the latter, 28% of the samples having DMCs of ≥ 107/ml contained < 10 mg/L of pyruvate. No sample having ≥ 10 mg/L of pyruvate had a DMC of ≤ 107/ml. Pyruvate concentration in NDM did not change during storage at 5 or 32°C for 90 days.

scholarly journals Changes in Particle Size, Sedimentation, and Protein Microstructure of Ultra-High-Temperature Skim Milk Considering Plasmin Concentration and Storage Temperature

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2339
Author(s):  
So-Yul Yun ◽  
Jee-Young Imm
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Storage Temperature ◽  
Whey Proteins ◽  
Skim Milk ◽  
Storage Period ◽  
Sediment Analysis ◽  
Sediment Formation ◽  
And Storage ◽  
Ultra High Temperature

Age gelation is a major quality defect in ultra-high-temperature (UHT) pasteurized milk during extended storage. Changes in plasmin (PL)-induced sedimentation were investigated during storage (23 °C and 37 °C, four weeks) of UHT skim milk treated with PL (2.5, 10, and 15 U/L). The increase in particle size and broadening of the particle size distribution of samples during storage were dependent on the PL concentration, storage period, and storage temperature. Sediment analysis indicated that elevated storage temperature accelerated protein sedimentation. The initial PL concentration was positively correlated with the amount of protein sediment in samples stored at 23 °C for four weeks (r = 0.615; p < 0.01), whereas this correlation was negative in samples stored at 37 °C for the same time (r = −0.358; p < 0.01) due to extensive proteolysis. SDS-PAGE revealed that whey proteins remained soluble over storage at 23 °C for four weeks, but they mostly disappeared from the soluble phase of PL-added samples after two weeks’ storage at 37 °C. Transmission electron micrographs of PL-containing UHT skim milk during storage at different temperatures supported the trend of sediment analysis well. Based on the Fourier transform infrared spectra of UHT skim milk stored at 23 °C for three weeks, PL-induced particle size enlargement was due to protein aggregation and the formation of intermolecular β-sheet structures, which contributed to casein destabilization, leading to sediment formation.

scholarly journals FATTY ACID PROFILE OF NON-CONFORMING POOLED HUMAN MILK AS AFFECTED BY THE PROCESSING AND STORAGE CONDITIONS

2021 ◽  
Vol 9 (2) ◽  
pp. 46-54
Author(s):  
Otávio A. S. Ribeiro ◽  
Kely P. Correa ◽  
Mauricio O. Leite ◽  
Marcio A. Martins ◽  
Jane S. R. Coimbra
Keyword(s):  
Fatty Acid ◽  
Human Milk ◽  
Fatty Acid Profile ◽  
Storage Period ◽  
Storage Conditions ◽  
Milk Lipid ◽  
Fatty Acid Profiles ◽  
Operational Conditions ◽  
Processing And Storage ◽  
And Storage

The fatty acid's contents of non-conform pooled human milk can be affected by different processing and storage operational conditions. Besides, the knowledge of changes in the human milk fatty acid profile can help indicate its use in a given storage period, according to each newborn's specific need. Thus, in the present work, changes in the fatty acid profiles of three types of human milk (raw; pasteurized at 62.5 °C for 30 min; homogenized at 40 oC for 30 s followed by pasteurization) were studied during storage for six months in a freezer at -18 oC. Large variations were observed in the concentrations of polyunsaturated fatty acids, particularly of docosahexaenoic acid, with a reduction of almost 50% of its total. Palmitic and stearic acid contents also changed according to the conditions of processing and storage. Correlations between the decrease of long fatty acid chains and the increase of medium and short chains were verified.  Thus, we observe that operational conditions of processing and storing change human milk lipid profile, with some nutritional losses.

scholarly journals Physical Properties of Nonfat Dry Milk and Skim Milk Powder

2017 ◽  
Vol 12 (2) ◽  
pp. 149-154 ◽  
Author(s):  
A.K. Abdalla ◽  
K. Smith ◽  
J. Lucey
Keyword(s):  
Physical Properties ◽  
Milk Powder ◽  
Skim Milk ◽  
Skim Milk Powder ◽  
Dry Milk ◽  
Nonfat Dry Milk

A note on the effects of frequency and method of feeding milk substitute on the performance of Friesian and Ayrshire calves

1973 ◽  
Vol 17 (3) ◽  
pp. 333-336 ◽  
Author(s):  
P. J. Broadbent
Keyword(s):  
Food Intake ◽  
Cold Water ◽  
Live Weight ◽  
Drinking Behaviour ◽  
Milk Consumption ◽  
Blood Temperature ◽  
Whole Milk ◽  
Milk Substitute ◽  
Liquid Milk ◽  
Ad Libitum

SUMMARY1. Forty British Friesian and 33 Ayrshire male calves were reared on one of three treatments differing in frequency and method of feedingwhole milk and milk substitute.2. The calves were introduced to their treatments on arrival. The Ayrshire calves were offered whole milk for 24 days as two feeds of up to 1·42 litres warm milk each (2W), or one feed of up to 2·84 litres warm milk (1W) daily, or cold milk ad libitum (AC). Thereafter they received milk substitute on one of the following regimes which were applied to the Friesian calves from arrival. The regimes were 454 g milk-substitute powder reconstituted at the rate of 158 g per litre warm water (approximately blood temperature) given in two feeds of 227 g per day (2W) or one feed of 454 g per day (1W), and milk-substitute powder reconstituted with cold water at the rate of 100 g per litre offered ad libitum (AC).3. Calves on treatment AC had higher live-weight gains and consumed more whole milk, milk substitute and less concentrates than those on other treatments. These differences were significant. There were differences in drinking behaviour on treatment AC between Friesian and Ayrshire calves which may have been due to differences in age at the start of the experiment. Solid food intake was affected by both level and pattern of liquid milk consumption. The practical and financial implications of treatment AC are discussed.

Nutrition and Lactation

PEDIATRICS ◽  
1981 ◽  
Vol 68 (3) ◽  
pp. 435-443
Author(s):  
Lewis A. Barness ◽  
Peter R. Dallman ◽  
Homer Anderson ◽  
Platon Jack Collipp ◽  
Buford L. Nichols ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Human Milk ◽  
Milk Fat ◽  
Maternal Diet ◽  
Fluid Phase ◽  
Active Role ◽  
Milk Lipid ◽  
Comprehensive Survey ◽  
Milk Lipids ◽  
Breast Fed

Lactation is a continuation of intrauterine gestation. In both processes, maternal diet plays an active role in the provision of nutrients, maternal nutritional stores and endocrine adaptations serve to buffer the short-term variations in maternal nutritional intake, blood flow plays an overriding role in nutrient transfer to the fetus and newborn infant, and the nutrient demands of the recipient are the highest of any stage in human development. Human milk is remarkable in its variability. Recent data suggest that the variability often improves the nutrient composition as part of a complex adaptation to the infant's specific needs. A comprehensive survey of the literature on lactation and human milk is provided in two review articles.1,2 NUTRIENTS Lipids Milk lipids provide the major fraction of calories in human milk, yet they are the most variable constituent.3 Preceding a nursing, the fluid phase of milk stored within the gland resembles skimmed milk. During the course of a nursing, the contraction of smooth muscle launches the fat droplets. This draught reflex is essential for caloric adequacy for the breast-fed infant.2 Women living under unfavorable socioeconomic conditions have reduced total milk lipid.4-6 There is evidence that supplementing the diets of these women leads to increased milk fat. Under controlled metabolic ward conditions, a high-caloric, high-fat diet can be demonstrated to increase milk fat production.7 The distribution of the spectrum of fatty acids in human milk also is responsive to dietary changes.7-13 Women who are malnourished also produce an excess of 12:0 and 14:0 fatty acids.14

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