The Influence of Storage Time on Rheological Properties and Texture of Yoghurts with the Addition of Oat-Maltodextrin as the Fat Substitute

Figures & data

Table 1 Sensory evaluation scores (overall preference) and instrumental texture parameters of yoghurts produced with addition of milk fat or maltodextrin during 21 days of cooled storage (The mean values form 3 ± mean standard error).

Parameter	Day of storage	Type of yoghurt
		Control 0 kg fat/100 kg yoghurt	2 kg fat/100 kg yoghurt	2 kg maltodextrin/ 100 kg yoghurt
Sensory evaluation	1	4.39 ± 0.06	4.70 ± 0.09	4.62 ± 0.07
[scores]	7	4.51 ± 0.06	4.82 ± 0.05	4.77 ± 0.04
	14	4.29 ± 0.05	4.51 ± 0.06	4.48 ± 0.06
	21	4.12 ± 0.07	4.15 ± 0.08	4.12 ± 0.07
Hardness TPA[N]	1	0.82 ± 0.03	1.10 ± 0.00	0.87 ± 0.03
	7	1.13 ± 0.02	1.22 ± 0.00	1.03 ± 0.08
	14	1.21 ± 0.12	1.20 ± 0.06	1.09 ± 0.12
	21	1.16 ± 0.08	1.03 ± 0.11	1.03 ± 0.05
Adhesivness TPA	1	3.74 ± 0.46	5.18 ± 0.05	4.25 ± 0.26
[|N·m|] × 10^−3	7	8.09 ± 0.69	5.18 ± 0.58	4.66 ± 0.43
	14	3.89 ± 0.23	5.44 ± 0.61	5.12 ± 0.49
	21	4.63 ± 0.41	3.70 ± 0.34	5.67 ± 0.57
Cohesiveness TPA[−]	1	0.48 ± 0.02	0.47 ± 0.01	0.50 ± 0.03
	7	0.42 ± 0.02	0.45 ± 0.01	0.47 ± 0.02
	14	0.42 ± 0.01	0.40 ± 0.01	0.45 ± 0.01
	21	0.44 ± 0.02	0.44 ± 0.00	0.38 ± 0.01
Gumminess TPA[N]	1	0.40 ± 0.05	0.52 ± 0.01	0.44 ± 0.05
	7	0.47 ± 0.03	0.55 ± 0.01	0.48 ± 0.05
	14	0.50 ± 0.05	0.48 ± 0.03	0.49 ± 0.06
	21	0.50 ± 0.03	0.45 ± 0.05	0.39 ± 0.02

Table 2 The mean squares of deviation from variance analysis concerning the influence of fat or maltodextrin content in milk and storage time on sensory evaluation scores (overall preference) and instrumental texture parameters of yoghurts.

Source of variance	Degrees of freedom	Sensory evaluation	Hardness	Adhesivness	Cohesiveness	Gumminess
1. Type of milk	2	0.1569**	0.0517	0.1479	0.0004	0.0080
2. Time of storage	3	0.5390**	0.0969**	4.3923**	0.0089**	0.0065
Interaction 1 x 2	6	0.0158	0.0241	5.5400**	0.0025**	0.0063
Error	24	0.0122	0.0157	0.6421	0.0007	0.0045
** - highly significant differences between means at p £ 0.01.

Table 3 The mean of the smallest squares from variance analysis concerning the influence of fat or maltodextrin content in milk and storage time on sensory evaluation scores (overall preference) and instrumental texture parameters of yoghurts.

Parameters	Type of milk			Storage time [days]
	Control 0 kg fat/100kg yoghurt	2 kg fat/100kg yoghurt	2kgmd*/100kg yoghurt	1	7	14	21
Sensory evaluation [scores]	4.33^A,B	4.54^A	4.50^B	4.57^A,a,b	4.70^a,B,C	4.43^b,B	4.13^A,C,D
Hardness TPA [N]	1.08	1.14	1.01	0.93^A,B,a	1.13^A	1.17^B	1.07^a
Adhesivness TPA[│N·m│] x 10^−3	5.09	4.87	4.92	4.39^A	5.98^A,B,C	4.81^B	4.67^C
Cohesiveness TPA [-]	0.44	0.44	0.45	0.49^A,B,C	0.45^A,a	0.42^B	0.42^C,a
Gumminess TPA [N]	0.47	0.50	0.45	0.45	0.50	0.49	0.45
^A-C - highly significant differences between means marked with the same letters in a row (p £ 0.01), every factor separately.
^a-b - significant differences between means marked with the same letters in a row (p £ 0.05), every factor separately.
*md - maltodekstrin.

Figure 1 Changes in apparent viscosity (for (= 9 s⁻¹) of yoghurts produced with addition of 2 kg fat or maltodextrin/100 kg/yoghurt.

Figure 2 Flow curves of yoghurts with addition of 2 kg of milk fat or maltodextrin/100 kg yoghurt after 1, 7, 14, and 21 days of storage.

Table 4 Rheological parameters of yoghurts with addition of 2 kg milk fat or oat-maltodextrin/100 kg yoghurt.

Type of yoghurt	Time of storage [days]	Ostwald de Waele model			Casson model			Hysteresis loop area[W/m^3] x 10^3
		K[Pa.s^n]	n[-]	R^2	τ0[Pa]	ηc [mPa.s]	R^2
Control 0 kg fat/100 kg yoghurt	1	24.41	0.18	0.9892	26.25	48.01	0.9116	4.437
	7	20.37	0.22	0.9691	21.88	69.68	0.8496	5.398
	14	14.90	0.30	0.9350	15.41	117.70	0.7787	5.117
	21	14.32	0.31	0.9275	14.70	124.84	0.7640	5.262
2 kg fat/100 kg yoghurt	1	15.53	0.26	0.9911	16.50	93.62	0.9187	3.301
	7	15.60	0.26	0.9914	16.58	91.60	0.9291	5.717
	14	11.71	0.32	0.9832	11.96	130.53	0.8808	5.063
	21	12.15	0.28	0.9954	12.62	92.70	0.9261	5.131
2 kg malto-detrin/100 kg yoghurt	1	21.29	0.22	0.9562	22.90	69.22	0.8230	5.750
	7	18.22	0.26	0.9414	19.46	92.29	0.7909	6.074
	14	14.72	0.30	0.9321	15.39	121.41	0.7798	6.085
	21	14.77	0.25	0.9929	15.70	74.61	0.9164	4.538