Instrumental Texture, Syneresis, and Microstructure of Yoghurts Prepared from Ultrafiltrated Goat Milk: Effect of Degree of Concentration

Figures & data

Table 1 Composition and physicochemical properties of raw goat milk with different degrees of concentration

Type of milk	Total solids [%]	Total protein [%]	Casein [%]	Whey proteins [%]	Non protein nitrogen [%]	Fat [%]	Lactose [%]	Ash [%]	Density [g·mL^−3]	Titratable acidity [°SH]	pH
Non-concentrated	11.25^A ± 0.06	2.97^A ± 0.04	2.33^A ± 0.04	0.34^A ± 0.01	0.30^A ± 0.01	3.0^A ± 0.05	4.55^A ± 0.05	0.79^A ± 0.01	1.0281^a,A ± 0.0004	6.6^a,A ± 0.1	6.69 ± 0.02
UF concentrated 1.5×	14.10^B ± 0.17	4.37^B ± 0.09	3.47^B ± 0.08	0.52^A,Ba ± 0.03	0.34^A ± 0.03	4.3^B ± 0.1	4.42^A ± 0.05	0.92^B ± 0.01	1.0304^b,A ± 0.0004	6.9 ± 0.1	6.69 ± 0.01
UF concentrated 2.0×	15.01^C ± 0.12	5.68^C ± 0.08	4.40^C ± 0.07	0.77^B,b ± 0.02	0.49^B ± 0.04	4.9^C ± 0.1	3.35^B ± 0.08	1.02^C ± 0.01	1.0326^B,a ± 0.0007	7.1^b ± 0.1	6.68 ± 0.02
UF concentrated 2.5×	16.73^D ± 0.12	7.35^D ± 0.24	5.17^D ± 0.08	1.64^C ± 0.15	0.55^B ± 0.04	5.8^D ± 0.1	2.31^C ± 0.04	1.12^D ± 0.01	1.0348^B,b ± 0.0008	7.2^B ± 0.1	6.66 ± 0.03
^A–D: Highly significant differences between means (P ≤ 0,01) marked with the different letters in the columns; ^a–b: Significant differences between means (P ≤ 0,05) marked with the different letters in the columns.

Table 2 Characteristic of yoghurt from goat milk with different degree of concentration

							Syneresis [%]
Type of milk	Sensory evaluation [scores]	pH	Apparent viscosity [Pa · s]	Hardness [N]	Adhesiveness ×10^3 [|N · m|]	Extrusion force [N]	Drainage method	Centrifugal method
Non-concentrated	3.83^A,a ± 0.12	4.57^A ± 0.01	0.48^A ± 0.03	0.15^a,A ± 0.01	0.14^A ± 0.02	1.20^A ± 0.08	32^A ± 2	51^A ± 4
UF concentrated 1.5×	4.54^B,a ± 0.09	4.53^A ± 0.04	1.33^B ± 0.13	0.26^b,A ± 0.02	0.47^B,a ± 0.04	2.54^B ± 0.09	12^B ± 1	16^B ± 2
UF concentrated 2.0×	4.40^B ± 0.08	4.61^a ± 0.02	2.23^C ± 0.11	0.37^a,B ± 0.04	0.73^B,b ± 0.08	3.52^C ± 0.14	14^B ± 1	13^B ± 1
UF concentrated 2.5×	4.18^b ± 0.11	4.71^B,b ± 0.04	2.47^C ± 0.20	0.49^b,B ± 0.04	1.23^C ± 0.09	5.05^D ± 0.16	6^C ± 1	11^B ± 1
^A–D: Highly significant differences between means (P ≤ 0.01) marked with the different letters in the columns; ^a–b: Significant differences between means (P ≤ 0.05) marked with the different letters in the columns.

Figure 1 Microstructure of yoghurt from goat milk: (a) non-concentrated and UF concentrated: (b) 1.5-fold, (c) 2-fold, (d) 2.5-fold (magnification 5000×).