# Effect of cold maturation on the milk acification kinetics

L. Rey-Cadilhac, Cirine Zerrouk, Typhaine Morvant, Steve Labrie, Julien
Chamberland

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► To cite this version:

L. Rey-Cadilhac, Cirine Zerrouk, Typhaine Morvant, Steve Labrie, Julien Chamberland. Effect of cold maturation on the milk acification kinetics. American Dairy Science Association meeting, Jun 2025, Louisville (Kentucky), United States. Journal of Dairy Science, 108 (Suppl.1), pp.208. hal-05140592

HAL Id: hal-05140592

https://hal.science/hal-05140592v1

Submitted on 2 Jul 2025

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Distributed under a Creative Commons Attribution 4.0 International License
# Effect of cold maturation on the milk acidification kinetic

L. Rey-Cadilhac¹,², C. Zerrouk¹, T. Morvant¹, S. Labrie¹, J. Chamberland¹

¹ STELA Dairy Research Center, INAF, Dep. Food Science, Université Laval, Québec, Canada

² PEGASE, INRAE, Institut Agro, Saint-Gilles, France

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INAF
INSTITUT SUR LA
NUTRITION ET LES
ALIMENTS FONCTIONNELS

Abstract #: 2373

## Introduction

Variability of cheese properties (moisture and texture) in relation to the variability of acidification and drainage despite macro-elements standardization → effect of limiting microelements (amino-acids, B vitamins) for starters ?

Cold maturation = milk stored ~ 12°C for < 24 h rather than < 4°C, prior to cheese making (e.g. used in Comté process) → improves the milk quality for cheese production by:

* ↗ solubilization of β-casein and colloidal calcium phosphate

* ↗ growth of psychrotrophic bacteria while increasing the milk mesophilic microflora

* generating growth factors through proteolysis notably → less limiting micro-elements?

→ **Can cold maturation enhance the acidification rate during milk fermentation?**

## Material & Methods

### Experimental design:

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UHT
cow milk
2 % fat
(2 batches)

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**Cold maturation**

[12 °C for 16 h]

→ Without strain = CTL

→ With single strains

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**Pasteurisation**

[63 °C for 30 min]

Amino-acids & B-vitamins (B1, B2, B3, B5, B7-B8) content analysis

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**Acidification kinetics**

[32 °C for 24 h]

→ Commercial starter (R604, CHR-Hansen) = *L. lactis* subsp. *cremoris* + *L. lactis* subsp. *Lactis*

Tested strains from LMA bio bank:

* lactic bacteria of interest (*Lacticaseibacillus paracasei*, *Lactococcus lactis*)

* bacteria of cheese-making environment (*Pseudomonas azotoformans*, *Staphylococcus epidermidis*, *Staphylococcus borealis*)

* yeasts (from genus *Cyberlindnera*, *Debaryomyces*, *Kazachstania*, *Pichia*, *Rhodotorula*)

3 replications per strain tested

### Acidification kinetics by a spectrofluorometric method (Gutsal et al., 2018):

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### Statistical analysis:

Statistical model to study the **effect on acidification parameters (maximum slope and time to maximum slope):**

1. **of cold maturation:** Comparison of CTL vs each STRAIN: Mixed model with *Treatment* (CTL vs STRAIN) as a fixed effect (n= 4 for CTL and n=3 for each STRAIN)

2. **of cold maturation with ≠ STRAINS:** Comparison across STRAINS : Mixed model with *Treatment* (STRAIN) as a fixed effect (n=3 for each STRAIN)

3. **of amino-acid composition:** Mixed model with amino-acids concentrations as fixed effects (data of strains with less than 3 repetitions were included: n=50) – backward selection

1), 2) et 3) with *UHT milk batch* as a random effect → **statistical results differ from the abstract as batch has been introduced in the model as a random effect.**

## Objective

The aim of this study was to inoculate milk with different dairy microorganisms in order to determine the effect of cold maturation on milk acidification kinetics with the idea of reducing the variability of the cheese-making process.

**Hypothesis:** Cold maturation → production of growth factors by the strains (of which the amino-acids and B-vitamins) → stimulation of lactic bacteria starter growth and activity → of the maximal acidification slope and of the time to reach this maximal slope

## Results

1. **Effect of COLD MATURATION (STRAIN vs CTL) on acidification parameters:**

Except for two strains, cold maturation had no effect on the maximum slope and the time to reach the maximum slope.

*Staphylococcus epidermidis* with lower maximum slope (*P*=0.016) but also lower time to maximum slope than CTL (*P*=0.036). *Lacticaseibacillus paracasei* with a tendency to lower maximum slope than CTL (*P*=0.078).

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2. **Effect of STRAINS (associated with cold maturation) on acidification parameters:**

No significant effect of the STRAINS on the maximum slope (*P*=0.143) nor the time to reach this maximum slope (*P*=0.782).

3. **Effect of amino-acid composition on acidification parameter**

Significative effect of alanine amino-acid on the maximum slope (*P*=0.035): ↗ alanine content → ↘ maximum slope.

Significative effect of isoleucine (*P*=0.024) and valine (*P*=0.024) amino-acids on the time to maximum slope : ↗ isoleucine or valine → ↘ time to reach maximum slope.

Results on the effect of B vitamins to come.

## Summary

Hypothesis not verified in the conditions tested:

Cold maturation ☑ acidification kinetic, but limited number of statistical individuals and high variability in the kinetics curves.

Higher essential amino-acids ☑ optimisation of acidification kinetics, but rather a lower acidification.

## Conclusion

Cold maturation of UHT milk using a single strain does not appear to be an effective method for reducing residual variability in the cheese-making process by enhancing acidification kinetics.

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