DRIED MILK POWDER: VII. THE EFFECT OF SEASON OF PRODUCTION ON KEEPING QUALITY

1947 ◽  
Vol 25f (1) ◽  
pp. 13-17
Author(s):  
Jesse A. Pearce ◽  
W. A. Bryce

Milk powders of 1% butterfat content, produced in the fall of the year, had higher initial palatability scores than similar powders prepared in the spring.. The skim milk powders from fall milk decreased in quality throughout a storage period of 16 wk. at temperatures of 80°, 100°, or 120° F. Similar powders from spring milk stored at 80° F. increased in quality throughout the storage period while those stored at 100° and 120° F. first increased and then decreased in quality. Powders of 26 or 28% butterfat, produced in the spring or in the fall, had equal initial palatability scores and when stored deteriorated equally. Fail milk powder containing 30% butterfat was better initially than the comparable spring sample, but, when stored, quality changes in both types were about equal. At each storage temperature all whole milk powders deteriorated at about the same rate.

1946 ◽  
Vol 24f (1) ◽  
pp. 61-69 ◽  
Author(s):  
W. A. Bryce ◽  
J. A. Pearce

Milk powders with fat contents of 1, 26, 28, and 30% from two plants were tempered to moisture contents of 2, 3, and 5% and stored for periods up to 16 weeks at temperatures of from 40° to 140° F. Appreciable deterioration, assessed by palatability, occurred in the whole milk powders stored at temperatures of 60° F. and higher, and there was considerable difference in the stability of powders from the two plants. For both plants, the keeping quality of powders of 26 and 28% of butter fat was equal. At 80° F. and lower, the powder containing 30% of butter fat was more stable than the 26 and 28% powders from the same plant, but at higher temperatures the 30% powder deteriorated more rapidly. At 80° F. the average decrease in palatability of whole milk powders with 2% moisture was two palatability units. The palatability of the skim-milk powder increased greatly at all temperatures during the early part of the storage period, but later decreased at temperatures of from 100° to 140° F. Skim-milk powder of 2% moisture stored at 80° F. had a palatability score 2.5 units higher than the initial score. In general, a moisture content of 3% was preferable to moisture contents of 2 and 5% for both whole and skim-milk powders. The differences in stability of powders from different plants were enhanced by increased moisture contents and higher storage temperatures.


1946 ◽  
Vol 24f (6) ◽  
pp. 445-449
Author(s):  
Jesse A. Pearce ◽  
W. A. Bryce

Skim (1% fat) and whole (26, 28, and 30% fat) milk powders (2% moisture) from two plants were packed in air, carbon dioxide, nitrogen, 80% carbon dioxide and 20% nitrogen, 20% carbon dioxide and 80% nitrogen, and under vacuum, and stored for 12 months at 80° F. Quality was assessed by a tasting panel of 14 persons. Packing in an inert gas or under vacuum effected a general improvement in the quality of skim-milk powders. This was attributed to removal of volatile degradation products during the packing process and early storage. The storage life of whole milk powders was increased from a maximum of three months when packed in air to nine months when packed in inert gases or vacuum.


Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2339
Author(s):  
So-Yul Yun ◽  
Jee-Young Imm

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.


1991 ◽  
Vol 54 (7) ◽  
pp. 532-536 ◽  
Author(s):  
GERALDINE M. FARRELL ◽  
AHMED E. YOUSEF ◽  
ELMER H. MARTH

Autoclaved whole milk, low-fat milk, protein-fortified skim milk and regular skim milk were inoculated to contain ca. 105 to 106 Borrelia burgdorferi strains 35210, 35211, or EBNI/ml and stored at 34°C for 16 d. Similarly inoculated skim milk also was held at 5°C for 46 d. Numbers of survivors were estimated by the Most Probable Number (MPN) technique. In all instances, numbers of B. burgdorferi decreased over the storage period. At 34°C, no strain of B. burgdorferi was detected after day 12. The mean D-values, at 34°C, for strains 35210, 35211, and EBNI were 2.2, 2.4, and 2.2 d, respectively. The mean D-values, at 34°C, for all strains in whole milk, low-fat milk, protein-fortified skim milk, and regular skim milk were 2.4, 2.3, 1.9, and 2.4 d, respectively. At 5°C, spirochete numbers in regular skim milk decreased, but all three strains remained at a detectable level for 46 d. The mean D-values, at 5°C, for strains 35210, 35211, and EBNI were 12, 15, and 12 d, respectively.


2010 ◽  
Vol 73 (11) ◽  
pp. 2110-2115 ◽  
Author(s):  
KINGA SZLACHTA ◽  
SUSANNE E. KELLER ◽  
ARLETTE SHAZER ◽  
STUART CHIRTEL

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.


2019 ◽  
Vol 86 (3) ◽  
pp. 341-346
Author(s):  
Lizandra F. Paludetti ◽  
Alan L. Kelly ◽  
Bernadette O'Brien ◽  
David Gleeson

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.


2015 ◽  
Vol 34 (4) ◽  
Author(s):  
Shaikh Adil ◽  
Sudhakar Changade ◽  
Anant Dhotre ◽  
Santosh Chopde

The objective of this study was evaluation of the shelf life of reconstituted <italic>kheer</italic> packed in previously sterilized cups and stored at 10± 1°C for 3 days. During period of studies the samples were examined for sensory evaluation after the first, second and third day using five treatments T1 (Pumpkin flesh <italic>kheer</italic>), T2 (1 per cent pumpkin powder + 43 per cent skim milk powder), T3 (2 per cent pumpkin powder + 42 per cent skim milk powder), T4 (3 per cent pumpkin powder + 41 per cent skim milk powder) and T5 (4 per cent pumpkin powder + 40 per cent skim milk powder). Samples were studied for sensory properties <italic>viz</italic>. colour, flavour, body texture, appearance and overall acceptability. Statistical analysis for shelf life studies revealed that both the treatments and storage period had significant effect on sensory qualities of the product. The scores for colour, flavour, body and texture, appearance and overall acceptability of all <italic>kheer</italic> samples decreased with the advancement of storage period. The rate of decline in the flavour score of T3 was more as compared to all other treatments. The score for T3 was (7.12) on first day which dropped to (6.05) on third day. The rate of decrease of scores for body and texture was more in treatment T5 than T1, T2, T3 and T4. There was a statistically significant difference in the appearance of reconstituted <italic>kheer</italic> samples for all the treatments on the day of preparation. The difference between all treatments was non-significant on second and third day of storage. The overall acceptability for T1, T2, T3, T4 and T5 samples decreased with the progress of storage period.


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