Dried berry pomace as a source of high value-added bioproduct: drying kinetics and bioactive quality indices

Figures & data

Table 1. Proximate composition of freeze dried Merlot grape, cranberry, highbush blueberry and wild lowbush blueberry pomaces

Freeze Dried Pomace	Moisture	Protein*	Ash*	Fat*	Carbohydrates^*1	Soluble Dietary Fiber*	Insoluble Dietary Fiber*	Calories^*1
	g/100 g	(g/100 g)	(g/100 g)	(g/100 g)	(g/100 g)	(g/100 g)	(g/100 g)	(per 100 g)
Fermented Merlot grape	47.53 ^c	11.02^a	7.9^a	6.95^a	72.35^d	5.3^b	49.1^d	395.5^c
Cranberry	71.53^a	4.55 ^c	0.70^b	2.50^bc	91.25^a	3.5 ^c	57.7^a	405.5^ab
Highbush blueberry	53.62^bc	12.03^a	0.95^b	2.99^b	83.55 ^c	3.4^c	52.2^c	409.5^a
Lowbush blueberry	57.91^b	8.34^b	1.15^b	2.21 ^c	87.05^b	8.2^a	53.8^b	401.5^b

*Dry matter basis; ¹ Calculated by difference and reported on dry matter basis; Values followed by different letters within columns are significantly different at p ≤ 0.05 (LSD test)

Figure 1. Experimental and predicted (Page model) moisture ratio of fermented Merlot grape pomace dried at 50, 60, and 70°C at half and full load density conditions

Figure 2. Experimental and predicted (Page model) moisture ratio of cranberry pomace dried at 50, 60, and 70°C at half and full load density conditions

Figure 3. Experimental and predicted (Page model) moisture ratio of highbush blueberry pomace dried at 50, 60, and 70°C at half and full load density conditions

Figure 4. Experimental and predicted (Page model) moisture ratio of wild low bush blueberry pomace dried at 50, 60, and 70°C at half and full load density conditions

Table 2. Kinetic parameters of drying models as affected by pomace type, load density, and temperature

Pomace Type	Models	Load Density in Drying Tray (kg m^−2), half or full	Bed Thickness (mm)	T (°C)	Model constants			R^2	χ^2	RSME
					k (s^−1)	a (dimensionless)	n (dimensionless)
Fermented Merlot Grape	Lewis/Newton	2.1, half	5.3	50	0.00015	-	-	0.980	0.0096	0.081
				60	0.00025	-	-	0.992	0.0023	0.015
				70	0.00035	-	-	0.990	0.00004	0.006
		4.2, full	8.1	50	0.000095	-	-	0.996	0.00121	0.034
				60	0.00020	-	-	0.966	0.00243	0.048
				70	0.000225	-	-	0.979	0.00118	0.031
	Henderson-Pabis	2.1, half	5.3	50	0.00015	0.874	-	0.991	0.00398	0.058
				60	0.00025	0.966	-	0.994	0.00019	0.013
				70	0.00515	0.995	-	0.992	0.0042	0.139
		4.2, full	8.1	50	0.000095	0.946	-	0.998	0.00041	0.019
				60	0.000173	0.956	-	0.996	0.0003	0.016
				70	0.000250	1.189	-	0.988	0.0030	0.052
	Page	2.1, half	5.3	50	0.000512	-	0.884	0.998	0.00005	0.007
				60	0.000354	-	0.964	0.998	0.00004	0.006
				70	0.0003	-	0.999	0.998	0.00003	0.005
		4.2, full	8.1	50	0.000161	-	0.954	0.999	0.00002	0.001
				60	0.000074	-	1.093	0.995	0.00014	0.011
				70	0.000084	-	1.109	0.997	0.00009	0.009
Cranberry	Lewis/Newton	4.2, half	3.99	50	0.0002	-	-	0.938	0.001448	0.117
				60	0.000225	-	-	0.949	0.00888	0.089
				70	0.000275	-	-	0.932	0.00484	0.067
		8.4, full	8.32	50	0.00006	-	-	0.987	0.00065	0.025
				60	0.000085	-	-	0.979	0.00287	0.052
				70	0.000093	-	-	0.968	0.00139	0.036
	Henderson-Pabis	4.2, half	3.99	50	0.000225	1.532	-	0.968	0.02547	0.151
				60	0.000225	1.403	-	0.970	0.01866	0.112
				70	0.00035	1.573	-	0.961	0.0291	0.160
		8.4, full	8.32	50	0.00007	1.080	-	0.994	0.00124	0.034
				60	0.000088	1.139	-	0.990	0.00185	0.041
				70	0.000098	1.219	-	0.984	0.00654	0.077
	Page	4.2, half	3.99	50	0.0000096	-	1.291	0.994	0.00032	0.017
				60	0.000017	-	1.272	0.995	0.00015	0.010
				70	0.000014	-	1.327	0.996	0.00017	0.012
		8.4, full	8.32	50	0.000014	-	1.147	0.999	0.00002	0.004
				60	0.0000134	-	1.182	0.999	0.00003	0.006
				70	0.0000119	-	1.216	0.998	0.00008	0.0008
Highbush blueberry	Lewis/Newton	3.07, half	3.39	50	0.00020	-	-	0.938	0.01448	0.117
				60	0.000225	-	-	0.949	0.00888	0.089
				70	0.000275	-	-	0.932	0.00484	0.067
		6.14, full	7.20	50	0.000060	-	-	0.987	0.00065	0.025
				60	0.000085	-	-	0.979	0.00287	0.052
				70	0.000093	-	-	0.968	0.00139	0.036
	Henderson-Pabis	3.07, half	3.39	50	0.000300	1.411	-	0.956	0.01574	0.067
				60	0.000375	1.397	-	0.975	0.01416	0.110
				70	0.000525	1.541	-	0.963	0.02918	0.158
		6.14, full	7.20	50	0.000095	1.132	-	0.989	0.00222	0.045
				60	0.00020	1.455	-	0.971	0.01995	0.135
				70	0.000225	1.521	-	0.962	0.02427	0.149
	Page	3.07, half	3.39	50	0.0000329	-	1.223	0.993	0.00023	0.014
				60	0.0000316	-	1.261	0.996	0.00018	0.012
				70	0.0000191	-	1.357	0.995	0.00016	0.012
		6.14, full	7.20	50	0.0000277	-	1.124	0.998	0.00009	0.009
				60	0.0000146	-	1.235	0.995	0.00032	0.017
				70	0.0000137	-	1.267	0.995	0.00025	0.015
Lowbush blueberry	Lewis/Newton	3.15, half	3.82	50	0.0002	-	-	0.961	0.00215	0.045
				60	0.000250	-	-	0.980	0.00156	0.038
				70	0.000350	-	-	0.975	0.00372	0.059
		6.30, full	7.00	50	0.000085	-	-	0.981	0.00103	0.031
				60	0.00025	-	-	0.980	0.00156	0.038
				70	0.000175	-	-	0.952	0.00591	0.071
	Henderson-Pabis	3.15, half	3.82	50	0.0002	1.291	-	0.975	0.00848	0.088
				60	0.000275	1.200	-	0.988	0.00367	0.057
				70	0.00035	1.211	-	0.985	0.00366	0.057
		6.30, full	7.00	50	0.00009	1.139	-	0.990	0.00219	0.045
				60	0.000125	1.178	-	0.992	0.00669	0.078
				70	0.00020	1.342	-	0.972	0.01035	0.097
	Page	3.15, half	3.82	50	0.0000475	-	1.148	0.996	0.00012	0.01
				60	0.000061	-	1.151	0.999	0.00003	0.005
				70	0.0000617	-	1.181	0.998	0.00002	0.004
		6.30, full	7.00	50	0.0000243	-	1.127	0.998	0.00009	0.009
				60	0.000028	-	1.146	0.999	0.00007	0.008
				70	0.0000195	-	1.220	0.996	0.00021	0.013

Table 3. Effective moisture coefficient and activation energy as affected by pomace type, load density, and temperature

Pomace Type	Load Density in Drying Tray (kg m^−2), half or full	Bed Thickness (mm)	Temperature (°C)	Deff x 10^−10 (m^2 s^−1)	Ea (kJ mol^−1)	R^2 (Ea assessment)
Fermented Merlot grape	2.1, half	5.30	50	4.28^ij	48.22a	0.963
			60	6.19^ef
			70	11.9^c
	4.2, full	8.10	50	5.84^fg	40.56a	0.821
			60	12.9^b
			70	14.0^a
Cranberry	4.2, half	3.99	50	2.43 ^l	23.99 c	0.992
			60	3.25^lk
			70	4.46^ij
	8.4, full	8.32	50	3.25^lk	28.21bc	0.962
			60	4.54^ihj
			70	5.52^fgh
Highbush blueberry	3.07, half	3.39	50	4.06 ^kj	24.34 c	0.948
			60	5.27^fghi
			70	6.89^e
	6.14, full	6.36	50	5.52^fgh	35.53b	0.938
			60	9.74^d
			70	11.9^bc
Lowbush blueberry	3.15, half	3.82	50	3.25^lk	18.69 c	0.998
			60	4.06 ^kj
			70	4.87^ghij
	6.30, full	7.00	50	5.03^ghij	30.31b	0.944
			60	6.17^ef
			70	9.74^d

* = dry matter basis; Significant differences within each column denoted by lowercase letters (LSD, p ≤ 0.05)

Table 4. Fermented Merlot grape pomace phenolic content and antioxidant activity: Comparison of freeze drying and cabinet convection air drying methods

Fermented Merlot pomace	Total Phenolics (mg gallic acid eq. 100 g^−1*	Flavonols (mg quercetin eq.100 g^−1*	Anthocyanins (mg malvidin-3-glucoside eq. 100 g^−1*	ABTS (µmol Trolox eq 100 g^−1*	FRAP (µmol Trolox eq 100 g^−1*
Freeze dried	4235.77^a	133.40^a	295.48^a	31221.73^a	20192.20^a
Half load, 50°C drying temperature	3561.39^bc	116.84^ab	173.35^b	26211.27^bc	16909.75^bc
Full load, 50°C drying temperature	3808.35^bd	129.83^a	188.50^b	27825.03^bd	18370.89^d
Half load, 60°C drying temperature	3839.47^bd	127.79^a	185.71^b	27853.45^d	18237.59^d
Full load, 60°C drying temperature	3421.31 ^c	113.34^ab	165.82^b	25452.67 ^c	16064.52^b
Half load, 70°C drying temperature	3964.93^ad	110.22^ab	170.13^b	28779.25^d	18601.39^d
Full load, 70°C drying temperature	3920.86^ad	117.12^ab	179.09^b	28288.57^d	17878.16 ^cd

* = dry matter basis; Significant differences within each column denoted by lowercase letters (LSD, p ≤ 0.05)

Table 5. Cranberry pomace phenolic content and antioxidant activity: Comparison of freeze drying and cabinet convection air drying methods

Cranberry pomace	Total Phenolics (mg gallic acid eq. 100 g^−1*	Flavonols (mg quercetin eq.100 g^−1*	Anthocyanins (mg cyanidin-3-glucoside eq. 100 g^−1*	ABTS (µmol Trolox eq 100 g^−1*	FRAP (µmol Trolox eq 100 g^−1*
Freeze dried	1516.72^a	298.53^a	147.22^a	9609.56^a	6964.98^a
Half load, 50°C drying temperature	1497.47^a	291.21^a	119.28^ab	9300.96^a	6976.13^a
Full load, 50°C drying temperature	1437.09^a	285.70^a	113.67^ab	9055.55^a	6868.48^a
Half load, 60°C drying temperature	1424.09^a	289.94^a	114.75^ab	9087.18^a	6731.07^a
Full load, 60°C drying temperature	1354.49^a	293.15^a	110.96^ab	8885.22^a	6713.49^a
Half load, 70°C drying temperature	1453.09^a	298.31^a	119.82^ab	9146.65^a	7080.56^a
Full load, 70°C drying temperature	1454.74^a	303.38^a	106.96^b	8933.53^a	6933.65^a

* = dry matter basis; Significant differences within each column denoted by lowercase letters (LSD, p ≤ 0.05)

Table 6. Highbush blueberry pomace phenolic content and antioxidant activity: Comparison of freeze drying and cabinet convection air drying methods

Highbush blueberry pomace	Total Phenolics (mg gallic acid eq. 100 g^−1*	Flavonols (mg quercetin eq.100 g^−1*	Anthocyanins (mg cyanidin-3-glucoside eq. 100 g^−1*	ABTS (µmol Trolox eq 100 g^−1*	FRAP (µmol Trolox eq 100 g^−1*
Freeze dried	2052.44^a	420.72^abc	1411.92^ab	14628.42^a	12628.54^a
Half load, 50°C drying temperature	1918.03^a	392.29 ^cd	1360.28^b	13669.19^ab	11899.08^ab
Full load, 50°C drying temperature	1997.19^a	410.62^bc	1297.36 ^cd	14334.16^ab	12610.34^a
Half load, 60°C drying temperature	1964.19^a	394.55 ^cd	1313.51 ^c	13662.52^ab	11886.61^ab
Full load, 60°C drying temperature	1949.14^a	396.25^bcd	1252.74^d	13594.08^ab	11773.88^ab
Half load, 70°C drying temperature	1985.36^a	426.38^ab	1333.96 ^c	13844.71^ab	12082.79^ab
Full load, 70°C drying temperature	1834.67^a	376.25^d	1112.32^e	12887.46^b	10853.69^b

* = dry matter basis; Significant differences within each column denoted by lowercase letters (LSD, p ≤ 0.05)

Table 7. Wild lowbush blueberry pomace phenolic content and antioxidant activity: Comparison of freeze drying and cabinet convection air drying methods

Lowbush blueberry pomace	Total Phenolics (mg gallic acid eq. 100 g^−1*	Flavonols (mg quercetin eq.100 g^−1*	Anthocyanins (mg cyanidin-3-glucoside eq. 100 g^−1*	ABTS (µmol Trolox eq 100 g^−1*	FRAP (µmol Trolox eq 100 g^−1*
Freeze dried	2082.26^a	334.56^ab	1586.74^a	14829.00^a	12611.66^a
Half load, 50°C drying temperature	1911.17^a	309.22^bc	1459.43^b	13825.85^abc	11162.69^bc
Full load, 50°C drying temperature	1806.12^a	284.04 ^cd	1317.26 ^c	12926.16^bc	10375.77 ^c
Half load, 60°C drying temperature	1933.58^a	315.66^b	1452.73^b	13489.20^abc	11033.10^bc
Full load, 60°C drying temperature	1821.25^a	283.20 ^cd	1271.66 ^c	12793.63^bc	10316.52 ^c
Half load, 70°C drying temperature	2027.75^a	331.35^ab	1513.44^ab	14189.31^ab	12051.32^ab
Full load, 70°C drying temperature	1776.37^a	275.04^d	1135.27^d	12417.53 ^c	10078.82 ^c

* = dry matter basis; Significant differences within each column denoted by lowercase letters (LSD, p ≤ 0.05)