Effect of an Exopolysaccharide-Producing Strain of Streptococcus Thermophilus on the Yield and Texture of Mexican Manchego-Type Cheese

Figures & data

Figure 1  Apparent viscosity (η), pH, and acidity changes during milk fermentation. □, pH control; ▪, pH ropy; △, η control; ▴, η ropy; ◯, acidity control; •, acidity ropy.

Table 1  Cheese yield

	Before salting	After salting	After ripening
Control cheese	11.16 ± 0.19^a	11.67 ± 0.07^c	9.43 ± 0.04^d
Ropy-strain cheese	12.37 ± 0.28^b	12.53 ± 0.28^b	10.45 ± 0.06^e
% enhancement of yield	10.8	7.4	10.9

Different superscript letters indicate significantly different values (P < 0.001).

Table 2  Chemical composition of the cheese (g·100 g⁻¹)

	TS	Moisture	Fat	Total protein	Fat (dwb)	Total protein (dwb)
Control cheese	59.7 ± 0.5^a	40.3 ± 0.5^a	30 ± 0.0^a	21.0 ± 1.2^a	50.3 ± 1.0^a	35.3 ± 0.6^a
Ropy strain cheese	55.3 ± 0.2^b	44.7 ± 0.2^b	34 ± 0.0^b	19.0 ± 1.0^a	61.5 ± 1.0^b	34.3 ± 0.1^b

TS: total solids; NFS: non-fat solids; dwb: dry weight basis.

Different superscript letters in the same column indicate significantly different values (P < 0.005).

Figure 2  Weight variation in cheese during ripening. □, control; ▪, ropy.

Figure 3  Microstructure (×5000) of three different sections of control Mexican manchego-type cheese: (A) rind, (B) medium, and (C) centre. The scale bar indicates 5 μm.

Figure 4  Microstructure (×5000) of three different sections of ropy Mexican manchego-type cheese: (A) rind, (B) medium, and (C) centre. The scale bar indicates 5 μm.

Table 3  Textural characteristics of ropy and control cheese

	Hardness (N)	Cohesiveness	Springiness (mm)	Chewiness (Nmm)
Control cheese	8.67 ± 0.26^a	0.15 ± 0.02^a	6.90 ± 0.42^a	8.96 ± 1.21^a
Ropy strain cheese	6.73 ± 0.47^b	0.18 ± 0.01^b	6.24 ± 0.38^b	7.66 ± 1.14^a

Different superscript letters in the same column indicate significantly different values (P < 0.05).

Figure 5  TPA curves obtained for the two kinds of cheese. - - - Control, — ropy.

Figure 6  Comparison of the sensory attributes of ropy and control Mexican manchego-type cheese. □, control; ▪, ropy.