Development and optimization of methylcellulose-based edible coating using response surface methodology for improved quality management of ready-to-eat pomegranate arils

Figures & data

Table 1. The levels of experimental independent variables used in the central composite design.

		Levels
Independent variables		-α	Low (−1)	Centre (0)	High (+1)	+α
A	Salicylic acid (mM)	0.49	1	1.75	2.5	3.01
B	Canola oil (w/v %)	0.03	0.05	0.075	0.1	0.12
C	Tween-80 (w/v %)	0.03	0.05	0.075	0.1	0.12

Table 2. The central composite design used to formulate edible coating formulations and experimental data obtained for canola oil, tween-80 and salicylic acid applied on “Kessari” ready-to-eat pomegranate arils during refrigerated storage at 4.5°C for 12 days.

		Independent variables			Response variables
Run	Space Type	C: Salicylic acid (mM)	A: Canola Oil (%)	B: Tween-80%)	ML (%)	TSS (°Brix)	DPPH (mM AAE/mL PJ)	TPC (mg GAE/mL PJ)
1	Factorial	1	0.05	0.05	1.58	14.73	1.17	79.16
2	Factorial	1	0.1	0.05	1.58	14.57	1.29	82.6
3	Factorial	1	0.05	0.1	1.57	14.63	1.26	85.86
4	Factorial	1	0.1	0.1	1.54	14.43	1.27	86.22
5	Factorial	2.5	0.05	0.05	1.56	14.44	1.19	7.6
6	Factorial	2.5	0.1	0.05	1.55	14.53	1.26	85.46
7	Factorial	2.5	0.05	0.1	1.55	14.57	1.16	76.31
8	Factorial	2.5	0.1	0.1	1.53	14.53	1.21	81.59
9	Axial	1.75	0.03	0.075	1.61	14.73	1.09	71.72
10	Axial	1.75	0.12	0.075	1.57	14.63	1.2	75.33
11	Axial	1.75	0.075	0.03	1.6	14.63	1.24	85.11
12	Axial	1.75	0.075	0.12	1.56	14.43	1.27	84.22
13	Axial	0.49	0.075	0.075	1.51	14.35	1.33	9.6
14	Axial	3.01	0.075	0.075	1.51	14.33	1.27	86.46
15	Center	1.75	0.075	0.075	1.45	14.35	1.31	95.53
16	Center	1.75	0.075	0.075	1.43	14.22	1.3	93.58
17	Center	1.75	0.075	0.075	1.47	14.33	1.24	93.81
18	Center	1.75	0.075	0.075	1.44	14.2	1.31	96.54
19	Center	1.75	0.075	0.075	1.44	14.35	1.25	95.08
20	Center	1.75	0.075	0.075	1.45	14.23	1.27	95.97

Table 3. The regression coefficients, mean, R² and model F-values for the four experimental dependent variables.

Factors	ML (%)	TSS (°Brix)	TPC (mg GAE/mL PJ)	DPPH (mM AAE/mL PJ)
A - Canola Oil	−0.0093*	−0.0343	2.20*	0.0312*
B – Tween-80	−0.0106*	−0.0329	0.7819	0.0021
C - Salicylic acid	−0.0051	−0.0240	−1.97*	−0.0191*
AB	−0.0051	−0.0208	−1.58	−.0156
AC	−0.0011	0.0525*	2.04*	−0.0002
BC	0.0030	0.0458	−1.06	−0.0170
A^2	0.0481**	0.1470**	−7.73**	−0.0501**
B^2	−0.0453**	0.0940*	−3.79**	−0.0108
C^2	0.195*	0.0262	−2.42*	0.0047
Mean	1.53	14.46	85.59	1.24
Range	1.43–1.61	14.20–14.73	7.60–96.54	1.09–1.33
CV (%)	0.87	0.42	2.36	2.02
Adeq. precision	16.22	10.95	17.85	13.46
R^2	0.9727	0.9285	0.9673	0.9056
Adjusted R^2	0.9482	0.8641	0.9378	0.8207
Predicted R^2	0.8954	0.7413	0.7790	0.7364
Model F-value	39.64	2.33	32.82	1.66
Model P-value	<0.0001	0.0001	<0.0001	0.005
Lack of Fit P-value	0.6834	0.53	0.139	0.9342

* = p < .05; ** = p < .0001.

Figure 1. Interactive effect of canola oil and tween-80 on mass loss of pomegranate arils (cv. ‘Kessari’) (a) 3D-surface plot and (b) contour plot.

Figure 2. Interactive effect of tween-80 and canola oil on TSS of pomegranate arils (cv. ‘Kessari’) (a) 3D-surface plot and (b) contour plot.

Figure 3. Interactive effect of canola oil and tween-80 on TPC of pomegranate arils (cv. ‘Kessari’) (a) 3D-surface plot and (b) contour plot.

Figure 4. Interactive effect of tween-80 and canola oil on DPPH radical scavenging capacity of pomegranate arils (cv. ‘Kessari’) (a) 3D-surface plot and (b) contour plot.

Table 4. The experimental and predictive values obtained for pomegranate (cv. “Kessari”) arils treated with MC-based edible coating with addictive of tween-80, canola oil and salicylic acid.

Response variables	Experimental values	Predicted values
ML (%)	1.53 ± 0.06	1.48
TSS (°Brix)	14.46 ± 0.17	14.31
TPC (GAE/mL PJ)	85.59 ± 8.11	94.16
DPPH (AAE/mL PJ)	1.24 ± 0.06	1.31

Data availability statement

Data available on request from the authors.