Quality Attributes of High Temperature Short Time Air Puffed Ready-to-eat Potato Snacks

Figures & data

Figure 1 Flow sheet for potato flour production.

Figure 2 Flow sheet for RTE potato snacks.

Figure 3 A typical force–time curve of RTE potato snack textural measurement.

Table 1 Coded levels for the response surface design

		Levels
Variables	Code	−2	−1	0	+1	+2	Interval of variation
Temperature, °C	X1	175	200	225	250	275	25.0
Time, s	X2	15	30	45	60	75	15.0
Moisture content % (wb)	X3	30	32.5	35	37.5	40	2.5
Air velocity, m/s	X4	2.4	3.0	3.6	4.2	4.8	0.6
Where: X1 = (Temperature (T), °C −225)/25; X2 = (Time (t), s −45)/15; X3 = (Moisture content (M), %w.b. −35)/2.5; and X4 = (Air velocity (v), m/s −3.6)/0.6.

Table 2 Treatment combinations for HTST puffing with 4 variable 2^nd order design

Coded values				Actual values
X1	X2	X3	X4	T	t	M	v
1	1	1	1	250	36	37.5	4.2
1	1	1	−1	250	36	37.5	3
1	1	−1	1	250	36	32.5	4.2
1	1	−1	−1	250	36	32.5	3
1	−1	1	1	250	18	37.5	4.2
1	−1	1	−1	250	18	37.5	3
1	−1	−1	1	250	18	32.5	4.2
1	−1	1	−1	250	18	32.5	3
−1	1	1	1	200	36	37.5	4.2
−1	1	1	−1	200	36	37.5	3
−1	1	−1	1	200	36	32.5	4.2
−1	1	−1	−1	200	36	32.5	3
−1	−1	1	1	200	18	37.5	4.2
−1	−1	1	−1	200	18	37.5	3
−1	−1	−1	1	200	18	32.5	4.2
−1	−1	−1	−1	200	18	32.5	3
2	0	0	0	275	27	35	3.6
−2	0	0	0	175	27	35	3.6
0	2	0	0	225	45	35	3.6
0	−2	0	0	225	9	35	3.6
0	0	2	0	225	27	40	3.6
0	0	−2	0	225	27	30	3.6
0	0	0	2	225	27	35	4.8
0	0	0	−2	225	27	35	2.4
0	0	0	0	225	27	35	3.6
0	0	0	0	225	27	35	3.6
0	0	0	0	225	27	35	3.6
0	0	0	0	225	27	35	3.6
0	0	0	0	225	27	35	3.6
0	0	0	0	225	27	35	3.6

Table 3 Significant coefficients of regression equation (1) ^a for the responses

		Coefficients
Factors	ER	Hardness	Colour (L value)	BD
B0	4.45	13.223	72.05	0.25
B1	0.55**	−4.034**	−3.81**	−0.05**
B2	0.08ns	−1.552**	−0.64*	−0.01ns
B3	0.13*	−1.351**	0.33ns	−0.004ns
B4	0.26**	−0.779*	0.40ns	−0.02**
B5	−0.37**	1.859**	−0.52ns	0.02**
B6	−0.11*	—	0.39ns	−0.01**
B7	−0.25**	2.381**	0.12ns	−0.001ns
B8	−0.37**	—	−0.72*	0.01**
B9	−0.16*	1.256*	−0.07ns	0.01*
B10	0.04ns	—	−0.03ns	0.02*
B11	−0.07ns	—	−3.02**	0.01*
B12	0.09ns	—	−0.56*	0.01*
B13	0.11ns	—	−0.12ns	−0.01ns
B14	−0.08ns	—	−1.56**	0.01ns
R	0.978	0.957	0.957	0.972
R^2	0.956	0.916	0.915	0.945
^aX1: Temperature (T); X2: Time (t); X3: Moisture content (M); X4: Air velocity (v). **Significant at the 1% level; *significant at the 5% level.

Figure 4 Contour plots (A) and response surface (B) for the effect of puffing temperature and puffing time on ER of RTE potato snack.

Figure 5 Contour plots (A) and response surface (B) for the effect of moisture content and air velocity on ER of RTE potato snack.

Figure 6 Contour plots (A) and response surface (B) for the effect of puffing temperature and puffing time on hardness of RTE potato snack.

Figure 7 Contour plots (A) and response surface (B) for the effect of moisture content and air velocity on hardness of RTE potato snack.

Figure 8 Contour plots (A) and response surface (B) for the effect of puffing temperature and puffing time on BD of RTE potato snack.

Figure 9 Contour plots (A) and response surface (B) for the effect of moisture content and air velocity on BD of RTE potato snack.

Figure 10 Contour plots (A) and response surface (B) for the effect of puffing temperature and puffing time on colour (L-value) of RTE potato snack.

Figure 11 Contour plots (A) and response surface (B) for the effect of moisture content and air velocity on colour (L-value) of RTE potato snack.