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Indian Pediatr 2012;49: 836-837
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Changes in Biochemical Contents of Expressed
Breast Milk on Refrigerator Storage
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Bhaswati Ghoshal, Subhrajit lahiri, *Kaushik Kar and Nirmalya Sarkar,
From the Departments of Pediatric Medicine, Calcutta
National Medical College and *Department of Biochemistry,
Calcutta National Medical College, Kolkata, West Bengal, India.
Email:
[email protected] m
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To determine the biochemical integrity of refrigerated breast milk for
96 hours at 4ºC, a longitudinal observational study done with fresh milk
samples. It is found that there were significant changes in pH, serum
albumin and lactose concentrations in breast milk though within normal
range.
Key words: Expressed breastmilk, Lactose, Storage,
Temperature.
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In this observational study
the integrity of human breast milk (HBM) in terms of pH, total
proteins, serum albumin, triglycerides and lactose in stored breast
milk were determined with the aim of providing guidelines for
storage of expressed breast milk in home refrigerators for working
mothers as well as in neonatal intensive care unit.
25 mL of aseptically obtained HBM samples were
analysed at 0 (reading taken as control), 24, 48, 72, and 96 hours
for the said parameters. (Table I). A convenience
sample of 26 mothers was chosen to detect a difference of 1 SD from
the mean for each analysis. To determine changes over time, the data
were analyzed by repeated-measures ANOVA. Significant differences
were defined as P<.01 due to multiple comparisons.
TABLE I Showing the Parameters Measured in the Stored Milk
Parameter |
Day 1 |
Day 2 |
Day 3 |
Day 4 |
pH |
6.99 ± .12 |
6.15 ±.12 |
6.14 ± 00 |
6.13 ± .17 |
Total protein(g/dL) |
1.60 ±.32
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1.7 ± 00 |
1.64 ± .61 |
1.41 ± .44 |
Albumin(g/dL) |
.5512 ±.16 |
0.87 ± 00 |
0.27 ± .21 |
.2884 ± .17 |
Lactose(mg/dL) |
6077.36 ± 816.82 |
6000 ± .88 |
5845 ± .455 |
5462.24 ± 771.5 |
Triglyceride(mg/dL) |
2325.52 ± 566.72 |
2290 ± 670 |
1980 ± 780.78 |
1896.40 ± 840.30 |
We found that the drop in pH (6.99±.12 to
6.13±.17) (P<0.001) and albumin were significant(.55±.16 to
.29±.17 g/dL) (P<0.001). However, the albumin content even on
day four was within the recommended range. Total protein in breast
milk also decreased (1.60±.32 to 1.41±.44 g/dL), however not
significantly. Triglycerides content decreases with time
(2325.52±566.72 to 1896.40±840.30 mg/dL), though the difference was
not significant. Lactose content significantly decreased over time.
(6077.36±816.82 to 5462.24±771.5 mg/dL) (P<.01).
The observed change in pH will not alter the
functions of the enzymes of the breast milk [1] and may be due to
the lipolysis and release of free fatty acids occurring in the
breast milk during storage at temperatures at or above -20ºC [2].
The greater fall in pH with increase in duration of storage could be
justified by the increased time available for lipolysis to occur.
Slutzah, et al. found an inverse relationship between free
fatty acid concentration and pH on milk storage [3]. The change in
free fatty acid and pH may be due to bacterial proliferation as ,the
pasteurised milk sample which remain sterile after 3 rd
day of storage did not show any change of pH or free fatty acid [3].
We also observed that the lactose concentration in milk in our
mothers is less than the international standards, though it is said
that, race, age, parity, or diets do not greatly affect milk
composition [4]. However in an Indian study it is found that the
lactose content of breast milk of term Indian mothers is lower,
similar to our study [5]. Since it would be unethical to perform a
controlled study to find out side effects of "expired human milk" on
newborns, we have to rely on such biochemical changes and laboratory
parameters to determine the duration of safe storage of human milk.
In conclusion, we can store mother’s milk at
refrigerator temperature of 4 ºC
for 96 hours without changing its overall integrity in the form of
pH, serum albumin, total protein, lipid and lactose content and can
use it for feeding neonates and infants.
Acknowledgments: Dr Debabrata Nandi, MBBS, Jr,
Pediatrics, CNMC for helping in data collection. Dr Amitava Sen, MD,
for constant support and overall guidance.
References
1. Hamosh M, Henderson T, Ellis L, Mae J, Hamosh
P. Digestive enzymes in human milk: stability at suboptimal storage
temperatures. J Pediatr Gastroenterol Nutr. 1997; 24:38-43.
2. Hegde AM, Vikyath R. Cariogenic potential of
stored human milk an in vitro study. J Clin Pediatric Dentistry.
2007;32:27-32.
3. Slutzah M, Codipilly CN, Potak D, Clark RM, Schanler
RJ. Refrigerator storage of expressed human milk in the neonatal
intensive care unit. J Pediatr. 2010; 156:26-8.
4. JR. The composition of human milk. Semin
Perinatol. 1979;3:225-39.
5. Narang APS, Bains HS, Kansal S,Singh D. Serial
composition of human milk in preterm and term mothers. Indian
Journal of Clinical Biochemistry. 2006; 21: 89-94.
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