PULSED ELECTRIC FIELD PROCESSING OF MOTHER’S MILK
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Date
2021
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Abstract
Mother’s milk commonly regarded as “liquid gold” provides essential
nutrients for the growth and development of infants. When mother’s own milk is
not available for the infants, donor mother’s milk from mother’s milk bank is the
only alternative. Holder pasteurization (62.5 °C for 30 min) is the recommended
method for processing and preserving mother’s milk and is the widely adopted
method in all mother’s milk banks. Holder pasteurization completely inactivates all
the pathogens in mother’s milk but also destroys the bioactive components which
are heat - labile. Pulsed electric field (PEF) technology, which is one of the novel,
non - thermal methods has been investigated to process mother’s milk with better
retention of immunoglobulin A (IgA) levels. Mother’s milk samples were collected
from milk banks attached to hospitals in Chennai and also from local donor
mother’s in and around Koduveli village. Mother’s milk was processed using PEF
technology by applying different voltage gradients (25 kV, 30kV and 35kV) with
different treatment times (3000 /i? and 4500 /is). A lab model PEF equipment
comprising of PEF chamber which consists of two stainless steel circular, parallel
plate electrodes were used for PEF processing. The distance between electrodes in
PEF chamber was adjusted to 0,5cm. Pulse forming network (PFN) in PEF system
produced square pulses of 2.5 /js pulse width. The processed samples were
collected in sterile bottles. Physicochemical, nutrient, immunoglobulin and
microbial load analysis were carried out before and after PEF processing, IgA, the
predominant immunoglobulin found in human milk was determined using
immunoturbidimetry method and statistical analysis was performed using one way
analysis of variance (ANOVA). No significant difference (P>0.05) in pH, total
titratable acidity (“D) and fat content was observed between raw and PEF
processed mother’s milk samples. A significant difference (P<0.05) between the
mean concentration of protein content in raw mother’s milk and PEF processed
mother’s milk samples was observed. The level of retention of IgA (71 - 75%) was
higher in PEF treated milk when compared to holder pasteurized milk (52.74%).
The results showed that the microbial load were completely eliminated at higher
voltage gradient (35kV) at both treatment times (3000 /is and 4500 /is) and were
chosen as the optimized treatments. Storage studies were conducted at 5 “C and
-20 "C for the optimized treatments and the results were compared with the holder
pasteurized mother’s milk samples. pH, total titratable acidity ("D), TPC and
coliform count were performed at regular intervals throughout the storage period.
The results showed that PEF treated samples stored at 5 ®C remained shelf stable
for 17 days whereas pasteurized milk samples stored at 5 ®C remained shelf stable
for 5 days. The PEF treated samples stored at -20 ®C remained stable throughout
the storage period of 12 weeks. Thus the study revealed that the PEF treatment can
be used as an effective alternate method for processing mother’s milk.