Gelation properties of partially renneted milk

Figures & data

Table 1. Effect of glucono-δ-lactone (GDL) addition on the properties of acid-induced gels made from low heat (LHT) and high heat treatment (HHT) milk with rennet concentrations of 0, 0.01, 0.02, and 0.03 IMCU mL⁻¹. Gels were formed at 30^oC for 360 min.

Rennet (IMCU mL^−1)	Gelation time (min)^a		Gelation pH^a		Final G′ (Pa)^b
	LHT	HHT	LHT	HHT	LHT	HHT
0.00	116.0a	61.8a	4.61c	5.00b	34.4c	282.1c
0.01	98.7b	58.6a	4.78b	5.01b	106.8b	313.1bc
0.02	53.3c	56.1a	5.04a	5.05ab	425.8a	364.5ab
0.03	51.1c	53.6a	5.06a	5.09a	431.5a	381.4a

^aPoint when gels had an elastic modulus ≥1 Pa.

^bMeasured after 6 h of gelation.

Figure 1. Representative graphs of elastic modulus (G′) as a function of time (A and B) and milk pH (C and D) for acid-induced gels made from enzyme treated low heat (A and C) and high heat treatment (B, and D) milk with rennet concentrations of 0.00 (●), 0.01 (○), 0.02 (Δ), and 0.03 (□) IMCU mL⁻¹. Gels were made at 30^oC for 6 h.

Figure 2. Representative graphs of elastic modulus (G′) as a function of temperature for acid-induced gels made from enzyme treated low heat (A) and high heat treatment (B) milk with rennet concentrations of 0.00 (●), 0.01 (○), 0.02 (Δ) and 0.03 (□) IMCU mL⁻¹. Gels were made at 30^oC for 6 h and cooled down to 5^oC.

Figure 3. Gel hardness (A and B) and syneresis (C and D) of acid-induced bulk gel made from enzyme treated low heat (A and C) and high heat treatment (B and D) milk. Gels were formed at 30^oC for 6 h.

Table 2. Effect of rennet addition on the gelation properties of rennet-induced gels made from low heat (LHT) and high heat treatment (HHT) milk with rennet concentrations of 0, 0.01, 0.02, and 0.03 IMCU mL⁻¹. Gels were formed at 30^oC for 360 min.

Rennet (IMCU mL^−1)	Gelation time (min)^a		Gelation pH^a		Final G′ (Pa)^b
	LHT	HHT	LHT	HHT	LHT	HHT
0.00	21.3b	n.d.	6.62a	n.d.	64.2a	n.d.
0.01	22.0b	n.d.	6.62a	n.d.	59.5ab	n.d.
0.02	24.9b	n.d.	6.62a	n.d.	57.4b	n.d.
0.03	29.5a	n.d.	6.62a	n.d.	51.3c	n.d.

n.d.: not done.

^aPoint when gels had an elastic modulus ≥1 Pa.

^bMeasured after 6 h of gelation.

Figure 4. Representative graphs of elastic modulus (G′) as a function of time for rennet-induced gels made from enzyme treated low heat (A) and high heat treatment (B) milk with rennet concentrations of 0.00 (●), 0.01 (○), 0.02 (Δ), and 0.03 (□) IMCU mL⁻¹. Gels were made at 30^oC and cooled down to 5^oC.

Figure 5. Representative graphs of elastic modulus (G′) as a function of temperature for rennet-induced gels made from low heat treatment (LHT) milk with rennet concentration of 0.00 (●), 0.01 (○), 0.02 (Δ), and 0.03 (□) IMCU mL⁻¹. Gels were made at 30^oC for 6 h and cooled down to 5^oC.

Figure 6. Gel hardness (A and B) and syneresis (C) of rennet-induced bulk gels made from enzyme treated low heat (A and C) and high heat treatment (B). Gels were formed at 30^oC for 6 h.