# Impact of pasteurization and homogenization on the digestion of human milk: an in vivo study in the preterm infant

Samira Cássia de Oliveira, Olivia Ménard, Amandine Bellanger, Patrick

Pladys, Yann Le Gouar, Gwenaele Henry, Emelyne Dirson, Florence

Rousseau, Frédéric Carrière, Didier Dupont, et al.

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## To cite this version:

Samira Cássia de Oliveira, Olivia Ménard, Amandine Bellanger, Patrick Pladys, Yann Le Gouar, et al. Impact of pasteurization and homogenization on the digestion of human milk: an in vivo study in the preterm infant. 15. Euro Fed Lipid Congress Oil, Fats and Lipids: New Technologies and Applications for a Healthier Life, Aug 2017, Uppsala, Sweden., 2017. hal-01583187

HAL Id: hal-01583187

https://hal.science/hal-01583187

Submitted on 6 Sep 2017

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# Impact of pasteurization and homogenization on the digestion of human milk: an in vivo study in the preterm infant

SAMIRA DE OLIVEIRA¹, OLIVIA MÉNARD¹, AMANDINE BELLANGER²,³, PATRICK PLADYS²,³, YANN LE GOUAR¹, GWENAËLE HENRY¹, EMELYNE DIRSON², FLORENCE ROUSSEAU¹, FRÉDERIC CARRIÈRE⁴, DIDIER DUPONT¹, AMÉLIE DEGLAIRE¹, CLAIRE BOURLIEU¹

## Context

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Ensuring adequate growth of preterm newborns remains a challenge. When breastfeeding not possible → pasteurized human milk from milk banks is preferentially administered. Holder pasteurization (62.5°; 30 min) is applied for sanitary reasons but may reduce fat absorption through the inactivation of milk endogenous lipases. Conversely, homogenization of Holder-pasteurized human milk (PHM) may improve fat absorption and weight gain.

(Thomaz et al., 1999; Rayol et al., 1993; Martinez et al., 1987)

## Objective

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Impact on
digestive kinetics?

→ To investigate the impact of the homogenization and pasteurization of human milk on its gastric digestion in preterm infants

ClinicalTrials.gov
NCT02112331

## Experimental design

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©Thierry Pasquet

➤ Randomized controlled trial

➤ Hospitalized tube-fed preterm infants (GA < 32 wks)

➤ 6-day experimental period; 2 independent groups

### GROUP A
HM from their own mother

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Raw HM

→ collected < 24h
before feeding

n=12, GA 30.0 ± 1.1 wk, age at first day 27 ± 12 d, Body weight at first day 1.83 ± 0.41 kg

Holder pasteurization

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### GROUP B
HM from anonymous donor

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Pasteurized
HM (PHM)

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Pasteurized +
Homogenized HM

→ The same pool from one donor was used for the two types of milk
n=8, GA 29.5 ± 1.5 wk, age at first day 32 ± 21 d, Body weight at first day 1.73 ± 0.48 kg

Indirect homogenization by
ultrasonication

→ 595 W, 3 periods of 5 min interrupted
by 30s of pause

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➤ 2 test meal/day, for each test meal, **two gastric effluent collections:** before the meal and **35, 60 or 90 min after the ingestion start**

## Materials & Methods

### Multi-scale characterization of HM and digested samples

#### Biochemical composition: kinetics of lipolysis and proteolysis

#### Structural disintegration

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Human Milk
analyzer

Gas and thin layer
chromatography

Instantaneous lipolysis level:

→ % of free fatty acids vs. total acyl chains present at a given time

Lipolytic activity in gastric aspirates:

→ Titration of butyric acid released from tributyrin at pH 4.5 and 37 °C (Gargouri et al., 1986)

% of intact protein remaining at a given time:

→ Lactoferrin, α-lactalbumin, serum albumin, β-casein
(data not shown here)

SDS-Page + densitometry;

Cation exchange
chromatography

Confocal
microscopy

Particle size distribution

Fluorescent probes:

→ Proteins (FastGreen®), apolar lipids (Lipidtox®) and polar lipids (Rhodamine-PE®)

→ Results were expressed as means ± SD
P < 0.001 (**); P < 0.01 (**); P < 0.05 (*);
P > 0.05 (NS).

## GROUP A

### Pasteurization affected the emulsion disintegration of HM

#### Particle size distribution

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## Results

### But did not impact gastric lipolysis

#### Instantaneous lipolysis level

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Pre-lipolysis: n = 4 infants

Raw HM = 2.2 ± 0.8%

Pasteurized HM = 3.2 ± 0.6%

#### Lipolytic activity

→ Pre-lipolysis occurred prior to pasteurization in all milks and groups ranging between 2.2-4.0%. The global gastric lipolytic activity detected in fasted state averaged 17.5±2.9 U/mL/kg at pH 4.5.

→ Postprandial lipolytic activity increased with time and was higher after administration of Raw HM compared to Past HM (n=5) whereas it was not different after administration of Past HM vs. P+Homog HM (n=4)

## GROUP B

### Homogenization affected the initial structure and the emulsion disintegration of HM

#### Particle size distribution in HM

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→ Six-fold increase in the specific surface area after homogenization: from 4.1 ± 1.2 m²/g to 25.5 ± 3.8 m²/g of fat

→ The lipid fraction kept its initial structure all over the gastric digestion (**native globules** vs. **blend of droplets**)

→ Past HM and P+Homog HM (n = 4 pools): same macronutrients

composition, same pre-lipolysis degree (4.4 ± 1.0%) but **different structure**

→ Hormonal feedback triggered by higher lipolysis level

→ Difference of colloidal behavior

#### Homogenization increased gastric lipolysis

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(PHM: n=38 points;

P+Homog: n=36 points)

#### Homogenization reduced the meal emptying rate

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#### % of ingested meal remaining in the stomach

Meal: ***

Time: ***

Meal * Time: NS

(PHM: n=36 points;

P+Homog: n=32 points)

T ½, half-emptying of the ingested meal.

## Conclusion

➤ The initial structure of HM modulated the hydrolysis kinetics (lipolysis and proteolysis) and the emulsion disintegration during the gastric digestion in preterm infants

➤ Overall, in vivo data gathered here are crucial for a better understanding of milk neonatal digestion and help supporting the nutritional management of preterm infants.

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STLO

www6.rennes.inra.fr/stlo

Ref: (De Oliveira et al. 2017. JACN; De Oliveira et al. 2017. Clinical Nutrition ESPEN)

1 STLO, Agrocampus Ouest, INRA, Rennes, France

2 CHU Rennes, Pediatrics department, France

3 University of Rennes 1, Faculty of Medicine, France

4 CNRS, Aix Marseille University, UMR7282 EIPL, France

* claire.bourlieu-lacanal@inra.fr

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INFOGEST

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