Ultrasonication and the quality of human milk: variation of power and time of exposure

Testing the effects of processing on donor human Milk: Analytical methods

Holder pasteurization is the current recommended method for donor human milk treatment. This method effectively eliminates most life-threatening contaminants in donor milk, but it also greatly reduces some of its biological properties. Consequently, there is a growing interest for developing novel processing methods that can ensure both microbial inactivation and a higher retention of the functional components of donor milk. Our aim was to offer a comprehensive overview of the analytical techniques available for the evaluation of such methods. To suggest an efficient workflow for the analysis of processed donor milk, a safety analytical panel as well as a nutritional value and functionality analytical panel are discussed, together with the principles, benefits, and drawbacks of the available techniques. Concluding on the suitability of a novel method requires a multifactorial approach which can be achieved by a combination of analytical targets and by using complementary assays to cross-validate the obtained results.

Effects of High-Pressure Processing, UV-C Irradiation and Thermoultrasonication on Donor Human Milk Safety and Quality

Holder pasteurization (HoP) is the current recommended treatment for donor human milk. Although this method inactivates microbial contaminants, it also negatively affects various milk components. High-pressure processing (HPP, 400, 500, and 600 MPa), ultraviolet-C irradiation (UV-C, 2,430, 3,645, and 4,863 J/L) and thermoultrasonication (TUS, 1,080 and 1,620 kJ/L) were investigated as alternatives to thermal pasteurization (HoP). We assessed the effects of these methods on microbiological safety, and on concentration and functionality of immunoglobulin A, lactoferrin, lysozyme and bile salt-stimulated lipase, with LC-MS/MS-based proteomics and activity assays. HoP, HPP, TUS, and UV-C at 4863 J/L, achieved >5-log10 microbial reduction. Native protein levels and functionality showed the highest reduction following HoP, while no significant reduction was found after less intense HPP and all UV-C treatments. Immunoglobulin A, lactoferrin, and lysozyme contents were also preserved after low intensity TUS, but bile salt-stimulated lipase activity was significantly reduced. This study demonstrated that HPP and UV-C may be considered as suitable alternatives to HoP, since they were able to ensure sufficient microbial inactivation while at the same time better preserving the bioactive components of donor human milk. In summary, our results provide valuable insights regarding the evaluation and selection of suitable processing methods for donor human milk treatment, which may replace HoP in the future.

25 Years of Research in Human Lactation: From Discovery to Translation

Researchers have recently called for human lactation research to be conceptualized as a biological framework where maternal and infant factors impacting human milk, in terms of composition, volume and energy content are studied along with relationships to infant growth, development and health. This approach allows for the development of evidence-based interventions that are more likely to support breastfeeding and lactation in pursuit of global breastfeeding goals. Here we summarize the seminal findings of our research programme using a biological systems approach traversing breast anatomy, milk secretion, physiology of milk removal with respect to breastfeeding and expression, milk composition and infant intake, and infant gastric emptying, culminating in the exploration of relationships with infant growth, development of body composition, and health. This approach has allowed the translation of the findings with respect to education, and clinical practice. It also sets a foundation for improved study design for future investigations in human lactation.

Neither thermosonication nor cold sonication is better than pasteurization for milk shelf life

High-power, low-frequency ultrasound has been suggested as a novel processing technique with the potential to extend milk shelf life via inactivation of bacteria and spores that survive standard pasteurization. The primary objective of this research was to determine whether short-duration (≤60 s) sonication treatment, in conjunction with pasteurization, can increase shelf life while producing no adverse aroma effect. Skim milk was inoculated with Paenibacillus amylolyticus, a spore-forming, thermotolerant and psychrophilic milk contamination bacterium. Milk was sonicated under 6 selected amplitude and time conditions, except for control. Both cold sonicated (C-S) and thermosonicated (T-S) milk and milk treatments were pasteurized; however, T-S milk was sonicated after pasteurization (72.5 ± 0.3°C; mean ± SD), whereas C-S milk was sonicated at 12.5 ± 5°C (mean ± SD) before pasteurization. Milk was refrigerated up to 50 d and total aerobic counts were enumerated on pasteurized control, C-S, and T-S milk weekly. Neither C-S nor T-S treatments reduced total aerobic counts to an equivalent level as pasteurization alone. Counts in pasteurized controls and C-S milk did not exceed 3.00 log cfu/mL for up to 50 d; counts in T-S milk exceeded 5.00 cfu/mL by d 36. Aroma qualities (cooked, lacks freshness, and rubbery) of 2 T-S treatment intensities [170 µm peak-to-peak (p-p) for 60s and 200 µm_p-p for 10 s] and pasteurized controls were evaluated by a trained descriptive sensory panel. No significant differences were observed in cooked or lacks freshness aromas among samples. Only the milk treated with 170 µm_p-p for 60 s had significantly higher rubbery aroma on d 1 compared with milk treated with 200 µm_p-p for 10 s. Although the sensory effects of T-S on milk may not limit the commercial feasibility of cold sonication or thermosonication, conditions that differ from those used in the present study should be considered in the future. Neither C-S nor T-S were appropriate techniques for reducing bacterial count in fluid milk beyond standard pasteurization and, in fact, increased counts of spore-forming spoilage bacteria.

A New High Hydrostatic Pressure Process to Assure the Microbial Safety of Human Milk While Preserving the Biological Activity of Its Main Components

Background: The main process used to pasteurize human milk is the low-temperature, long-time Holder method. More recently, the high-temperature, short-time method has been investigated. Both processes lead to the appropriate inactivation of vegetative bacterial forms but are ineffective against bacterial spores. Research Aims/Questions: We aimed to accomplish two main objectives: inactivation of all pathogens, including spores; and preservation of the activity of milk components. Design/Methods: Recently, a novel high-hydrostatic pressure process has been developed by HPBioTECH. Using the same raw human milk samples, we compared the effects of this method with those of the Holder method on vegetative and spore forms of pathogens and on bioactive components (lipase activity, immunoproteins). Results: Two main microbial strains were selected: Staphylococcus aureus (as a reference for vegetative forms) and Bacillus cereus (as a reference for spores). Use of the high-hydrostatic pressure process led to microbial decontamination of 6 log for both S. aureus and B. cereus. Additionally, the bioactivity of the main components of human milk was preserved, with activities of lipase, α-lactalbumin, casein, lysozyme, lactoferrin, and sIgA of ~80, 96-99, 98-100, 95-100, 93-97, and 63-64%, respectively. Conclusions: Use of this novel high-hydrostatic pressure process to generate microbiologically safe human milk may provide important benefits for preterm infants, including improved assimilation of human milk (leading increased weight gain) and improved resistance to infections. Because 10% of all human milk collected is contaminated by B. cereus, use of this method will also prevent waste.

Donkey milk as a supplement in infant formula: Benefits and technological challenges

The aim of this review paper is to assess the applicability of donkey's milk to infants suffering from Cow Milk Protein Allergy (CMPA) compared to human and other available milk types. The bioactive and immune-supportive character which could be beneficial as a fortifier to the formula-fed infants is described while limitations of this type of milk are also discussed. Studies showed that human and donkey's milk have similar, overall, chemical composition as well as protein homogeneity and antigenic similarities. Several in vitro and in vivo studies showed that donkey's milk has nutraceutical and functional properties that can support immunity, alter metabolism and beneficially modify gut microbiota. Clinical studies illustrated that donkeys' milk is well tolerated (82.6%-88%) by infants. Finally, the effect that processing (i.e. thermal, non-thermal treatments, drying methods) has on donkey milk components is also discussed pointing out the need for minimally processing this type of milk.

Human Milk Processing: A Systematic Review of Innovative Techniques to Ensure the Safety and Quality of Donor Milk

Pasteurization, performed at 62.5°C for 30 minutes (holder pasteurization), is currently recommended in all international human milk banks guidelines, but it affects some human milk bioactive and nutritive components. The present systematic review is aimed at critically reviewing evidence on the suitability of human milk processing techniques other than holder pasteurization, both thermal and nonthermal, to ensure microbiological safety, and on the effects of these techniques on biologically active donor milk components. A systematic review of English and non-English articles using Medline, PubMed, Embase, SCOPUS, and CAB Abstracts, with no restriction in publication date was performed. Search terms included: human, breast, donor, or banked milk, breastmilk, breast fed, breastfed, breastfeed; HTST, Flash, High Pressure, UV, ultrasonic or nonthermal; process, pasteuris, pasteuriz. Only primary research articles published in peer-reviewed journals were included, providing or not a comparison with holder pasteurized human milk, provided that the pasteurization technique was clearly described, and not intended for domestic use. Additional studies were identified by searching bibliographies of relevant articles. Twenty-six studies were identified as being relevant. Two examined both High Pressure Processing and High-Temperature-Short-Time pasteurization; 10 only examined High Pressure Processing; 10 only examined High-Temperature-Short-Time; 2 articles examined ultraviolet irradiation; 2 articles examined (thermo-)ultrasonic processing. The results indicate that data about safety for microbiological control are still scarce for most of the novel technologies, and that consensus on processing conditions is necessary for nonthermal technologies, before any conclusions on the qualitative and nutritional advantages of these techniques can be drawn.

Human milk pasteurization: benefits and risks

PURPOSE OF REVIEW

Recent findings substantiate that the optimal method of nourishing preterm, very low birth weight infants (VLBW, born <1500 g) is through appropriately nutrient-enriched human milk, which is frequently provided as pasteurized donor milk. The availability of donor milk for VLBW infants during initial hospitalization continues to increase with the launch of new milk banks in North America. The majority of North American neonatal ICUs now have written policies governing the provision of donor milk. The purpose of this review is to summarize recent evidence regarding the risks and benefits of pasteurization of human milk and outcomes associated with its provision to VLBW preterm infants.

RECENT FINDINGS

Studies investigating the impact of collection, storage and pasteurization on the bacteriostatic, immunologic and nutritional aspects of human milk continue to be published, generally revealing a partial, but not complete reduction in bioactivity. Risk of contamination of pasteurized donor human milk with pathogenic agents is mitigated through pasteurization. New pasteurization methods aiming to maintain the safety of pooled human milk while better preserving bioactivity are under investigation.

SUMMARY

Provision of a human milk-derived diet to preterm VLBW infants is associated with improved outcomes.

Cytokines, Chemokines, and Growth Factors in Banked Human Donor Milk for Preterm Infants

BACKGROUND

There has been a recent increase in availability of banked donor milk for feeding of preterm infants. This milk is pooled from donations to milk banks from carefully screened lactating women. The milk is then pasteurized by the Holder method to remove all microbes. The processed milk is frozen, banked, and sold to neonatal intensive care units (NICUs). The nutrient bioavailability of banked donor milk has been described, but little is known about preservation of immune components such as cytokines, chemokines, and growth factors (CCGF).

OBJECTIVE

The objective was to compare CCGF in banked donor milk with mother's own milk (MOM).

METHODS

Aliquots (0.5 mL) were collected daily from MOM pumped by 45 mothers of NICU-admitted infants weighing < 1500 grams at birth. All daily aliquots of each mother's milk were pooled each week during 6 weeks of an infant's NICU stay or for as long as the mother provided MOM. The weekly pooled milk was measured for a panel of CCGF through multiplexing using magnetic beads and a MAGPIX instrument. Banked donor milk samples (n = 25) were handled and measured in the same way as MOM.

RESULTS

Multiplex analysis revealed that there were levels of CCGF in banked donor milk samples comparable to values obtained from MOM after 6 weeks of lactation.

CONCLUSION

These data suggest that many important CCGF are not destroyed by Holder pasteurization.

Effect of Holder pasteurization and frozen storage on macronutrients and energy content of breast milk

OBJECTIVES

The aim of this study was to explore the effect of Holder pasteurization and frozen storage at -20°C after pasteurization on fat, total nitrogen, lactose, and energy content of breast milk. Both procedures are routinely practiced in human milk banks.

METHODS

A total of 34 samples of frozen breast milk, donated by 28 women, were collected. Once thawed, an aliquot of each sample was analyzed before pasteurization; the remaining milk was pasteurized (Holder method) and split into 8 aliquots. One aliquot was analyzed after pasteurization and the remainder frozen at -20°C and analyzed 30, 60, 90, 120, and 180 days later. For every aliquot, fat, total nitrogen, lactose, and energy content were determined using the device human Milk Analyzer.

RESULTS

We observed a significant reduction in fat (3.5%; -0.17 (-0.29; -0.04) g/dL) and energy content (2.8%; -2.03 (-3.60; -0.46) g/dL) after pasteurization. A significant decrease over time was observed for fat, lactose and energy content. No significant changes were observed for nitrogen content. Mean differences between day 0 postpasteurization and day 180 were -0.13 (-0.21; -0.06) g/dL for fat, -0.08 (-0.13; -0.03) g/dL for lactose, and -1.55 (-2.38; -0.71) kcal/dL for energy content. The relative decreases were 2.8%, 1.7%, and 2.2%, respectively. Overall (postpasteurization + frozen storage), a 6.2% and 5% decrease were observed for fat and energy, respectively.

CONCLUSIONS

Holder pasteurization decreased fat and energy content of human milk. Frozen storage at -20°C of pasteurized milk significantly reduced fat, lactose, and energy content of human milk.