The Impact of Beta-Casein Genetic Variant on the Physicochemical Properties of Various Fermented Milk Types*

Dorota Najgebauer-Lejko; Iwona Radkowska; Magda Filipczak-Fiutak

doi:10.2478/aoas-2025-0113

The Impact of Beta-Casein Genetic Variant on the Physicochemical Properties of Various Fermented Milk Types*

Annals of Animal Science

Volume 26 (2026): Issue 3 (August 2026)

By: Dorota Najgebauer-Lejko, Iwona Radkowska and Magda Filipczak-Fiutak

Open Access

|Sep 2026

Figures & Tables

Fermented milk types with the most popular examples (Tamime et al., 2007).

Table 1.

Basic chemical composition of A1 and A2 fermented milks (g/100 g; x±SD, n=4)

A1	A2
TS	11.00 a±0.28	11.12 a±0.26
MSNF	9.13 a±0.20	9.23 a±0.19
Protein	3.63 a±0.28	3.66 a±0.20
Fat	1.87 a±0.13	1.89 a±0.16
Ash	0.8002 a±0.0081	0.7910 a±0.0233
Carbohydrates	4.68 a±0.25*	4.80 a±0.23*

TS – total solids; MSNF – milk solids non-fat;

* Carbohydrates = MSNF – protein–ash.

a – values in rows with the same letter do not differ significantly (P>0.05).

Table 2.

Acidity and antioxidant characteristics of the fresh (0w) and stored (3w) A1 and A2 fermented milks (x ±SD, n=4)

Characteristic		ABT-yoghurt		Kefir		Cultured milk
Characteristic		0w	3w	0w	3w	0w	3w
pH	A1	4.75 b±0.15	4.41 a±0.09	4.58 a±0.03	4.54 a±0.03	4.49 a±0.01	4.47 a±0.04
	A2	4.72b±0.08	4.40 a±0.08	4.58 a±0.03	4.54 a±0.04	4.50 a±0.02	4.45 a±0.03
Acidity (% lactic acid)	A1	0.70 a±0.06	0.83 b±0.03	0.92 a±0.03	0.89 a±0.02	0.98 a±0.03	0.95 a±0.03
	A2	0.70 a±0.03	0.81 b±0.05	0.90 a±0.02	0.90 a±0.01	0.94 a±0.03	0.96 a±0.02
FRAP (mMFe²⁺/kg)	A1	0.97 a±0.36	0.83 a±0.11	0.72 a±0.01	0.74 a±0.03	0.92 a±0.10	0.88 a±0.22
	A2	0.96 a±0.28	0.76 a±0.05	0.67 a±0.09	0.66 a±0.08	0.87 a±0.12	0.81 a±0.10
ARP (mMTE/kg)	A1	0.32 a±0.27	0.25 a±0.09	0.23 a±0.19	0.26 a±0.13	0.29 a±0.25	0.29 a±0.14
	A2	0.29 a±0.16	0.30 a±0.15	0.23 a±0.16	0.27 a±0.11	0.31 a±0.26	0.31 a±0.17

FRAP – ferric reducing antioxidant power; ARP – anti-radical power, TE – trolox equivalents.

a, b – different letters denote statistically significant differences between average values within the specific type of fermented milk (P≤0.05).

Table 3.

Textural and rheological characteristics of the analysed fresh (0w) and stored (3w) fermented milks (x ±SD, n=4)

Attribute		ABT-yoghurt		Kefir		Cultured milk
Attribute		0w	3w	0w	3w	0w	3w
Hardness (N)	A1	0.85 a±0.09	1.13 b±0.16	0.39 a±0.01	0.49 bc±0.04	0.45 a±0.02	0.50 a, b±0.01
	A2	0.97 a±0.07	1.28 b±0.04	0.46 b±0.04	0.54 c±0.07	0.51 b±0.02	0.59 c±0.06
Adhesiveness (\|N·s\|)	A1	1.52 a±0.19	2.41 a±0.37	0.63 a±0.05	0.89 a±0.17	0.74 a±0.14	1.08 b±0.09
	A2	2.25 a±0.62	1.63 a±0.93	0.92 a±0.29	1.39 b±0.38	1.12 b±0.24	1.21 b±0.31
Cohesiveness (−)	A1	0.44 c±0.01	0.38 a±0.01	0.48 a±0.01	0.46 a±0.04	0.50 a±0.00	0.48 a±0.01
	A2	0.41 b±0.01	0.37 a±0.03	0.50 a±0.02	0.47 a±0.02	0.43 a±0.12	0.51 a±0.01
Gumminess (N)	A1	0.37 a±0.04	0.43 a, b±0.05	0.19 a±0.00	0.22 a, b±0.01	0.22 a, b±0.01	0.22 a±0.01
	A2	0.40 a±0.03	0.47 b±0.02	0.23 b±0.01	0.26 c±0.04	0.26 b±0.02	0.29 c±0.02
Hysteresis loop area (kPa · s⁻¹)	A1	4.63 a±0.25	4.73 a±0.31	1.46 a±0.10	1.50 a±0.09	1.70 a±0.07	1.71 a±0.06
	A2	8.54 b±0.09	8.61 b±0.35	1.93 b±0.09	1.78 b±0.16	1.91 b±0.04	2.10 c±0.17
k (Pa sⁿ)	A1	2.89 a±0.26	4.17 b±0.40	1.55 a±0.40	5.19 b±0.74	6.73 a±0.24	6.58 a±0.35
	A2	7.90 c±0.65	12.23 d±0.90	4.42 b±0.35	4.92 b±0.73	7.29 a±0.71	7.27 a±0.67
n	A1	0.40 c±0.01	0.24 b±0.01	0.37 c±0.02	0.29 b±0.05	0.25 a±0.01	0.27 a±0.01
	A2	0.26 b±0.03	0.16 a±0.02	0.23 a±0.01	0.32 b±0.01	0.24 a±0.03	0.26 a±0.04
Initial η (Pas)	A1	4.90 a±0.28	4.79 a±0.06	1.71 a±0.11	2.32 b±0.38	2.48 a±0.11	2.71 a±0.22
	A2	6.07 b±0.21	6.88 c±0.46	2.17 a, b±0.18	2.57 b±0.25	2.82 a±0.14	2.87 a±0.26
Final η (Pas)	A1	0.21 b±0.01	0.15 a±0.00	0.14 a±0.01	0.16 a±0.03	0.16 a±0.00	0.19 b±0.01
	A2	0.24 c±0.02	0.18 a, b±0.01	0.16 a±0.01	0.17 a±0.01	0.18 b±0.01	0.21 c±0.00
τ₀ (Pa)	A1	23.13 a±1.11	25.74 b±1.00	12.68 a±1.31	12.81 a±1.55	11.26 a±1.75	13.29 a±0.97
	A2	29.67 c±1.16	29.28 c±1.01	10.96 a±1.30	11.92 a±0.99	18.03 b±1.03	17.11 b±0.59

a, b, c – different letters denote statistically significant differences between average values within the selected type of fermented milk (P≤0.05).

Colour profiles of fresh and stored fermented milk products produced from A1 and A2 milk.

Table 4.

Sensory properties of A1 and A2 fermented milks (x ±SD, n=14)

Sensory characteristic	ABT-yoghurt		Kefir		Cultured milk
Sensory characteristic	A1	A2	A1	A2	A1	A2
Colour	4.82 a±0.37	4.82 a±0.54	4.93 a±0.27	4.93 a±0.27	4.86 a±0.36	5.00 a±0.00
Appearance	3.64 a±0.66	3.29 a±0.75	4.32 a±0.42	4.29 a±0.80	4.00 a±0.55	4.61 b±0.59
Consistency	4.43 a±0.58	4.29 a±0.67	4.89 b±0.29	4.39 a±0.71	4.32 a±0.64	4.86 b±0.53
Odour	4.57 a±0.42	4.54 a±0.37	4.89 a±0.29	4.61 a±0.49	4.54 a±0.66	4.57 a±0.51
Taste	4.46 a±0.57	4.29 a±0.58	4.50 a±0.48	4.64 a±0.57	4.50 a±0.73	4.71 a±0.38
Total score	4.38 a±0.35	4.23 a±0.41	4.67 a±0.26	4.55 a±0.43	4.42 a±0.50	4.74 b±0.21

a, b – values in rows with different letters differ significantly within the specific fermented milk type (P≤0.05).

Table 5.

Microbiological characteristics of the analysed fermented milks (x ±SD, n=4)

A1A1	A2A2
ABT-yoghurt
Lb. acidophilus LA-5	0	8.47 a±0.04	8.39 a±0.07
	3	8.20 a±0.01	8.42 a±0.15
Bifidobacterium BB-12	0	6.42 a±0.66	6.65 a±0.95
	3	5.48 a±0.54	5.45 a±0.85
Str. thermophilus	0	9.16 a±0.74	9.13 a±0.81
	3	8.51 a±0.14	8.52 a±0.02
Kefir
Lactobacillus spp.	0	9.16 a±0.69	8.93 a±0.88
	3	6.76 b±0.31	6.73 b±1.03
Lactococcus spp.	0	9.16 a±0.04	9.19 a±0.05
	3	8.20 b±0.40	8.01 b±0.30
Yeasts	0	2.99 a±0.65	3.13 a±0.57
	3	4.33 a±0.22	3.59 a±1.28
Cultured milk
Lactococcus spp.	0	8.98 a±0.37	8.92 a±0.19
	3	7.45 b±0.05	7.44 b±0.16

a, b – different letters denote statistically significant differences between average values for a specific type of fermented milk and microorganism (P≤0.05).

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DOI: https://doi.org/10.2478/aoas-2025-0113 | Journal eISSN: 2300-8733 (formerly 1642-3402) | Journal ISSN: 1642-3402

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Language: English

Page range: 1333 - 1346

Submitted on: Jun 9, 2025

Accepted on: Oct 2, 2025

Published on: Sep 6, 2026

Published by: National Research Institute of Animal Production

In partnership with: Paradigm Publishing Services

Publication frequency: 4 issues per year

Keywords:

β-casein polymorphism,

A2 milk,

quality,

Related subjects:

© 2026 Dorota Najgebauer-Lejko, Iwona Radkowska, Magda Filipczak-Fiutak, published by National Research Institute of Animal Production
This work is licensed under the Creative Commons Attribution 4.0 License.

Volume 26 (2026): Issue 3 (August 2026)

The Impact of Beta-Casein Genetic Variant on the Physicochemical Properties of Various Fermented Milk Types*

Figures & Tables

Diagram 1.

Diagram 2.

Table 1.

Table 2.

Table 3.

Figure 1.

Table 4.

Table 5.

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