Storage and thermal stability of selected vegetable purees processed with microwave-assisted thermal sterilization

Zeyad Albahr; Juthathip Promsorn; Zhongwei Tang; Girish M. Ganjyal; Juming Tang; Shyam S. Sablani; Zeyad Albahr; Juthathip Promsorn; Zhongwei Tang; Girish M. Ganjyal; Juming Tang; Shyam S. Sablani

doi:10.48130/fia-0024-0010

Figures (8) Tables (4)

Figure 1.
Weight loss of the MATS- processed beetroot, cabbage, and carrot puree samples during 6 months of storage at 37.8 °C (n = 3). Values with the same superscript letters are not significantly different (p > 0.05).
Figure 2.
The changes in visual color in beetroot, red cabbage, and carrot purees after the MATS treatment and at the end of 6 months of storage at 37.8 °C.
Figure 3.
Instrumental color changes of the MATS-processed beetroot during 6 months of storage at 37.8 °C: (a) lightness, (b) yellowness, (c) redness, and (d) total color difference, values with the same superscript letters are not significantly (p > 0.05) different, n = 6.
Figure 4.
Instrumental color changes of the MATS-processed cabbage puree during 6 months of storage at 37.8 °C: (a) lightness, (b) redness, (c) blueness, and (d) total color difference. Values with the same superscript letters are not significantly different (p > 0.05), n = 6.
Figure 5.
Instrumental color changes of the MATS-processed carrot puree during 6 months of storage at 37.8 °C: (a) lightness, (b) redness, (c) yellowness, and (d) total color difference. Values with the same superscript letters are not significantly different (p > 0.05), n = 6.
Figure 6.
Concentration of natural pigments (betacyanins, betaxanthins, total monomeric anthocyanins (MAC), and beta-carotene) in MATS-processed beetroot puree samples during 6 months of storage at 37.8 °C (n = 6). Values with the same color and superscript letters are not significantly different (p > 0.05).
Figure 7.
Concentration of betalains [(a) betacyanins, (b) betaxanthins] during the 6 months of storage at 37.8 °C fitted with the first order and fractional conversion models, n = 6.
Figure 8.
Concentration of total monomeric anthocyanins (MAC) during the 6 months of storage at 37.8 °C fitted with the first order and fractional conversion models, n = 6.

MATS processing parameters	Unit	Product
MATS processing parameters	Unit	Carrot puree	Beetroot puree	Cabbage puree
Pre-heating temperature	°C	61	61	61
Pre-heating time	min	20	20	20
Water temperature in microwave heating section	°C	124	124	124
Microwave heating time	min	3.04	3.40	3.70
Water temperature in the holding section	°C	124	124	124
Holding time	min	3.12	3.49	3.80
Cooling water temperature	°C	20	20	20
Cooling time	min	5	5	5
Belt speed	inch/min	42.0	37.5	34.5
Microwave power for cavities (both 1^st and 2^nd/3^rd/4^th cavities)	kW	11.7/3.2/ 3.7	11.7/3.2/ 3.7	11.7/3.2/ 3.7

Table 1.

Processing conditions of the three MATS treatments for the purees.

Vegetable puree	Quality attribute	Before MATS	After MATS
Beetroot	pH	6.30 ± 0.02a	6.03 ± 0.19b
	L*	12.5 ± 0.65a	14.05 ± 0.53b
	a*	1.90 ± 0.20a	7.64 ± 0.93b
	b*	0.22 ± 0.16a	2.36 ± 0.31b
	ΔE	None	6.39 ± 1.09
	BC (mg/100 g)	33.7 ± 4.86a	27.0 ± 2.91b
	BX (mg/100 g)	21.7 ± 2.97a	15.4 ± 1.93b
Cabbage	pH	5.90 ± 0.02a	5.62 ± 0.01b
	L*	19.1 ± 0.48a	24.1 ± 1.61b
	a*	5.32 ± 0.23a	3.13 ± 0.27b
	b*	–6.92 ± 0.17a	–4.42 ± 0.22b
	ΔE	None	6.09 ± 1.20
	MAC (mg/100 g)	47.45 ± 4.00a	35.09 ± 4.34b
Carrot	pH	5.57 ± 0.04a	5.35 ± 0.03b
	L*	40.9 ± 0.52a	36.3 ± 0.55b
	a*	27.3 ± 0.78a	18.1 ± 0.38b
	b*	36.0 ± 1.33a	37.0 ± 1.02b
	ΔE	None	10.5 ± 0.97
	β-Carotene (μg/g)	55.1 ± 12.1a	57.4 ± 2.07a
BC: betacyanin in beetroot puree, BX: betaxanthin in beetroot puree, and MAC: total monomeric anthocyanins in cabbage puree. Values with the same superscript letters are not significantly different (p > 0.05).

Table 2.

Quality attributes of vegetable purees after the MATS treatment, n = 6.

Food product	Type of processing	Processing conditions	Total color change (ΔE)	Ref.
Beetroot juice	HPP	600 MPa for 3 min at ambient temperatures	3.49 ± 0.04	[24]
Beetroot puree	In-package thermal pasteurization	90 °C for 10 min in hot water bath	2.44 ± 0.06 to 2.89 ± 0.12	[12]
Beetroot puree	PATS	600 MPa at for 5 min at 90 °C	2.49 ± 0.18	[25]
Beetroot slices	HPP	HPP 600 MPa for 3–30 min at ambient temperature	21.80 ± 0.30 to 27.60 ± 0.90	[26]
Beetroot puree	MATS	124 °C, 6.89 min	6.39 ± 1.09	Present study
Cabbage puree	In-package thermal pasteurization	90 °C for 10 min in hot water bath	2.81 ± 0.03 to 3.59 ± 0.03	[12]
Purple mashed potato	PATS	600 MPa at for 5 min at 90 °C	9.99 ± 0.24	[25]
Pomegranate juice	HTST	110 °C/8.6 s	6.83 ± 1.06	[27]
Strawberry puree	HPP	600 MPa for 3min	2.12 ± 0.07	[28]
Blackberry puree	HPP	600 MPa for 3min	2.15 ± 0.03	[28]
Cabbage puree	MATS	124 °C, 8.8 min	6.09 ± 1.20	Present study
Carrot puree	In-package thermal pasteurization	90 °C for 10 min in hot water bath	1.02 ± 0.64 to 2.89 ± 0.12	[13]
Pumkin puree	PATS	600 MPa at for 5 min at 90 °C	3.37 ± 2.59	[25]
Carrot juice	HPP	600 MPa at for 5 min at 4 °C	5.39 ± 0.01	[29]
Carrot puree	MATS	124 °C, 8.12 min	10.50 ± 0.97	Present study
HPP: high pressure processing, PATS: pressure-assisted thermal sterilization, and HTST: high temperature short time processing.

Table 3.

Color assessment studies of foods processed with high pressure and thermal processes.

Model	Natural pigments			ΔE of vegetable purees
Model	Betacyanins	Betaxanthins	Anthocyanins	Beetroot	Cabbage	Carrot
First order
k (month⁻¹)	0.22 ± 0.01	0.14 ± 0.03	0.25 ± 0.01	*	*	0.15 ± 0.04
t_1/2 (month⁻¹)	3.16 ± 0.20	4.80 ± 0.92	2.82 ± 0.15	*	*	4.51 ± 1.23
R²	0.986	0.870	0.989	*	*	0.784
RMSE	0.0291	0.070	0.0262	*	*	0.740
Fractional conversion
k_f (month⁻¹)	0.25 ± 0.09	0.52 ± 0.18	0.36 ± 0.03	*	*	*
C_∞	0.06 ± 0.16	0.43 ± 0.06	0.15 ± 0.03	*	*	*
t_1/2 (month⁻¹)	2.78 ± 0.98	1.34 ± 0.47	1.93 ± 0.19	*	*	*
R²	0.986	0.937	0.998	*	*	*
RMSE	0.0287	0.0505	0.0112	*	*	*
Zero order
k (month⁻¹)	0.11 ± 0.01	0.08 ± 0.02	0.11 ± 0.02	0.46 ± 0.04	1.16 ± 0.07	0.78 ± 0.68
t_1/2 (month⁻¹)	4.07 ± 0.45	5.46 ± 1.48	5.46 ± 1.48	3.89 ± 0.61	2.40 ± 0.14	1.55 ± 0.40
R²	0.938	0.771	0.898	0.972	0.957	0.750
RMSE	0.0606	0.0959	0.898	0.138	0.396	0.762
R² is correlation factor, and RMSE is root mean square error, n = 6, * R² value was low due to poor fit of the model.

Table 4.

Estimated parameters of the kinetics models for the natural pigments' degradation and overall color changes during the storage of 6 months at 37.8 °C.