Valorization of avocado (Persea americana) residual paste: Microwave-assisted extraction, optimization and addition to an artisanal pork ham

Figures & data

Table 1. Ham formulations, control and added with extracts obtained by MAE optimized conditions from avocado residual pulp (ARP) at 0.5, 1 and 1.5% (w/w).

	Weight (g)
Ingredients	Control	T0.5	T1.0	T1.5
Pork leg meat	55.9	55.9	55.9	55.9
Water	38.0	37.5	37.0	36.5
Curing salts	1.7	1.7	1.7	1.7
Corn Starch	1.7	1.7	1.7	1.7
Maltodextrin	1.1	1.1	1.1	1.1
NaCl	1.0	1.0	1.0	1.0
Spices	0.5	0.5	0.5	0.5
Carrageenan	0.1	0.1	0.1	0.1
Extract of avocado residual paste	0.0	0.5	1.0	1.5

Table 2. 3^k-p factorial design with responses for total soluble polyphenols (TSP) and antioxidant capacity indices (FRAP and DPPH) of extracts obtained by microwave-assisted extraction (MAE) from avocado residual paste (ARP).

Treatment	XS^1 (%)	XP^2 (W)	Xt^3 (s)	TSP (mg GAE/g DW)	DPPH (mg TE/g DW)	FRAP (mg TE/g DW)
Control	–	–	–	16.13 ± 0.62^f	8.64 ± 0.02^i	1.74 ± 0.09^i
1	Ethanol	100	80	31.70 ± 0.45ª	23.88 ± 0.03^c	18.25 ± 0.05^g
2	Ethanol	480	240	26.40 ± 0.03^c	25.97 ± 0.04^b	22.19 ± 0.18ª
3	Ethanol	300	140	29.96 ± 0.03^b	25.95 ± 0.03ª	18.59 ± 0.11^c
4	Ethanol/Water (70/30)	100	240	23.25 ± 0.05^d	8.99 ± 0.02^h	15.22 ± 0.09^d
5	Ethanol/Water (70/30)	480	140	31.18 ± 0.54ª	7.49 ± 0.05^j	18.89 ± 0.08^b
6	Ethanol/Water (70/30)	300	80	23.71 ± 1.29^d	9.26 ± 0.02^g	14.25 ± 0.12^e
7	Water	100	140	11.19 ± 0.04^g	10.02 ± 0.12^d	1.81 ± 0.09^i
8	Water	480	80	14.00 ± 0.02^e	9.71 ± 0.03^f	4.89 ± 0.05^h
9	Water	300	240	15.64 ± 0.01^f	9.83 ± 0.02^e	9.05 ± 0.09^f

Factors assessed: solvent type (X_S¹); microwave power expressed in Watts, W (X_p²); extraction time expressed in seconds, s (X_t³). Different letters indicate significant differences among means of treatments (p ≤ .05).

Table 3. Analysis of variance of the regression model for the content of phenolic compounds, antioxidant activity measured by DPPH and FRAP in avocado residual paste (ARP).

Factor	SS	df	MS	F	p
TSP
XS^1: Solvent type (L)	1134.727	1	1134.727	4721.791	.000000
(XS^1)^2: Solvent type (Q)	11.409	1	11.409	47.473	.000002
XP^2: Microwave power (L)	28.980	1	28.980	120.592	.000000
(XP^2)^2: Microwave power (Q)	5.309	1	5.309	22.091	.000178
Xt^3: Extraction time (L)	9.095	1	9.095	37.846	.000008
(Xt^3)^2: Extraction time (Q)	120.753	1	120.753	502.474	.000000
XS^1 x XP^2	54.746	1	54.746	227.809	.000000
XS^1x (XP^2)^2	91.8351	1	91.835	382.142	.000000
Error	4.326	18	0.240
R^2	0.99699
Adjusted R^2	0.99566
CV (%)	2.13
Adeq Precision	72.4838
DPPH
XS^1: Solvent type (L)	1063.316	1	1063.316	1276854	.000000
(XS^1)^2: Solvent type (Q)	829.339	1	829.339	995889	.000000
XP^2: Microwave power (L)	0.009	1	0.009	11	.004378
(XP^2)^2: Microwave power (Q)	0.987	1	0.987	1185	.000000
Xt^3: Extraction time (L)	2.720	1	2.720	3266	.000000
(Xt^3)^2: Extraction time (Q)	4.071	1	4.071	4888	.000000
XS^1 x XP^2	1.693	1	1.693	2033	.000000
XS^1x (XP^2)^2	7.570	1	7.570	9090	.000000
Error	0.015	18	0.01
R^2	0.9999
Adjusted R^2	0.9999
CV (%)	0.1981
Adeq Precision	1109.3635
FRAP
XS^1: Solvent type (L)	543.830	1	543.8298	92067.75	.000000
(XS^1)^2: Solvent type (Q)	55.788	1	55.7876	9444.57	.000000
XP^2: Microwave power (L)	202.400	1	202.3997	34265.29	.000000
(XP^2)^2: Microwave power (Q)	15.277	1	15.2769	2586.31	.000000
Xt^3: Extraction time (L)	105.863	1	105.8635	17922.17	.000000
(Xt^3)^2: Extraction time (Q)	3.955	1	3.9545	669.49	.000000
XS^1 x XP^2	0.011	1	0.0112	1.90	.184814
XS^1x (XP^2)^2	3.030	1	3.0297	512.92	.000000
Error	0.106	18	0.0059
R^2	0.99991
Adjusted R^2	0.99987
CV (%)	0.6127
Adeq Precision	456.0153

solvent type (X_S¹); microwave power expressed in Watts, W (X_p²); extraction time expressed in seconds, s (X_t³); L: linear interactions; Q: quadratic interactions; CV: coefficient of variation; Adeq. Precision: adequation precision.

Figure 1. Response surface plot for total soluble polyphenols (TSP), as phenolic compounds, of extracts obtained by microwave-assisted extraction (MAE) of avocado residual paste (ARP). (a) Effect of solvent ratio (X_S¹), and microwave power (X_P²); (b) Effect of extraction time (X_t³), and microwave power (X_P²).

Figure 2. Response surface plot for antioxidant capacity indices of extracts obtained by microwave-assisted extraction (MAE) of avocado residual paste (ARP). (a) Effect of solvent ratio (X_S¹), and microwave power (X_P²) over DPPH; (b) Effect of extraction time (X_t³), and microwave power (X_P²) over DPPH; (c) Effect of solvent ratio (X_S¹), and microwave power (X_P²) over FRAP; (d) Effect of extraction time (X_t³), and microwave power (X_P²) over FRAP.

Table 4. Experimental validation of predicted values at optimal conditions for microwave-assisted extraction (MAE) of total soluble polyphenols (TSP) and antioxidant capacity indices (DPPH and FRAP) from avocado residual paste (ARP).

Parameter	TSP (mg GAE/g DW)	DPPH (mg TE/g DW)	FRAP (mg TE/g DW)
Optimal response	31.25	24.74	21.27
+5% confidence interval	32.80	25.98	22.33
−5% confidence interval	29.68	23.50	20.20
Experimental value	31.24 ± 0.43	24.51 ± 0.28	21.58 ± 0.47

Figure 3. Color parameters evaluated in the formulated hams. Control: ham without added extract; T-0.5%: ham with the addition of 0.5% extract; T-1.0%: ham with the addition of 1% extract; T-1.5%: ham with the addition of 1.5% extract. Different literals in each parameter indicate significant differences (p ≤ .05).

Figure 4. Total soluble polyphenols (TSP) content in the formulated hams. Control: ham without added extract; T-0.5%: ham with the addition of 0.5% extract; T-1.0%: ham with the addition of 1% extract; T-1.5%: ham with the addition of 1.5% extract. Different literals indicate differences (p ≤ .05).

Figure 5. Sensory scores for cooked ham (control) and formulations added with extracts (0.5, 1 and 1.5% w/w) obtained by microwave-assisted extraction (MAE) of avocado residual paste (ARP).