Structural Properties of Vegetables During Air Drying

Figures & data

Table 1 The obtained experimental data points for true density, apparent density and porosity for various vegetables. Moisture values in bold denote the initial moisture content of each vegetable

Material	Moisture (kg/kg db)	True density (kg/m^3)	Apparent density (kg/m^3)	Porosity
Mushroom	0,06	1281	788	0,38
	1,46	1150	890	0,23
	5,32	1020	925	0,09
	7,89	995	929	0,07
	12,69	971	916	0,06
Green pepper	0,06	1299	1123	0,14
	1,78	1095	1015	0,07
	6,37	1053	1021	0,03
	8,46	1001	989	0,01
	16,00	982	1003	–
Courgete	0,06	1482	1155	0,22
	1,48	1223	1080	0,12
	5,01	1036	1018	0,02
	9,56	1015	992	0,02
	13,70	992	1010	–
Pea	0,03	1263	867	0,31
	1,09	1134	938	0,17
	2,36	1072	933	0,13
	3,55	1057	955	0,10
Celery	0,04	1311	1075	0,18
	1,58	1124	1032	0,08
	3,96	1045	1015	0,03
	6,92	1028	989	0,04
	13,17	1025	1002	0,02
Leek	0,05	1384	779	0,44
	1,58	1172	889	0,24
	4,16	1045	952	0,09
	7,98	1019	985	0,03
	10,27	1007	962	0,04
Corn	0,04	1342	1165	0,13
	1,11	1169	1085	0,07
	1,92	1102	1045	0,05
	2,62	1080	1030	0,05
Tomato	0,10	1395	614	0,56
	1,56	1105	752	0,32
	4,53	1052	869	0,17
	9,26	1042	949	0,09
	13,13	1034	971	0,06
	19,84	1032	982	0,05
Garlic	0,22	1383	1241	0,10
	1,03	1181	1131	0,04
	1,85	1126	1085	0,04
	2,09	1118	1077	0,04
Carrot	0,07	1753	1373	0,22
	1,38	1240	1126	0,09
	4,95	1095	1040	0,05
	6,15	1046	989	0,05
	7,17	1009	969	0,04
Spinach	0,05	1700	723	0,57
	1,49	1256	863	0,31
	3,86	1105	895	0,19
	7,26	1036	949	0,08
	8,50	989	919	0,07
Onion	0,04	1486	1150	0,23
	1,25	1210	1040	0,14
	4,16	1058	1010	0,05
	6,20	1030	995	0,03
	9,79	1023	989	0,03

Figure 1 (a) True density experimental data for carrot; (b) apparent density data for carrot; (c) true density experimental data for garlic; (d) apparent density data for garlic; (e) true density experimental data for onion; and (f) apparent density data for onion. Trendlines of all experimental data have been included in each figure.

Figure 2 (a) True and apparent density of mushroom vs. moisture content; (b) porosity of mushroom vs. moisture content; (c) true and apparent density of green pepper vs. moisture content; (d) porosity of green pepper vs. moisture content; (e) true and apparent density of courgete vs. moisture content; and (f) porosity of courgete vs. moisture content. Experimental data obtained in this article (Table 1).

Figure 3 (a) True and apparent density of pea vs. moisture content; (b) porosity of pea vs. moisture content; (c) true and apparent density of celery vs. moisture content; (d) porosity of celery vs. moisture content; (e) true and apparent density of leek vs. moisture content; and (f) porosity of leek vs. moisture content. Experimental data obtained in this article (Table 1).

Figure 4 (a) True and apparent density of corn vs. moisture content; (b) porosity of corn vs. moisture content; (c) true and apparent density of tomato vs. moisture content; (d) porosity of tomato vs. moisture content; (e) True and apparent density of garlic vs. moisture content; and (f) porosity of garlic vs. moisture content. Experimental data obtained in this article (Table 1).

Figure 5 (a) True and apparent density of carrot vs. moisture content; (b) porosity of carrot vs. moisture content; (c) true and apparent density of spinach vs. moisture content; (d) porosity of spinach vs. moisture content; (e) true and apparent density of onion vs. moisture content; and (f) porosity of onion vs. moisture content. Experimental data obtained in this article (Table 1).

Table 2 Mathematical model for calculating apparent density, true density and porosity as a function of moisture content

1. Properties
ρt True density	(kg/m^3)
ρap Apparent density	(kg/m^3)
ε Porosity	(−)
2. Factors
χ Material moisture content	(kg/kg db)
3. Properties Equations
ρt = (1+X)/(1/ ρs+X/ ρw)	(1)
ρap = (1+X)/(1/ ρa0+β′·X/ ρw)	(2)
ε = 1 - ρap/ρt	(3)
4. Parameters
ρw Enclosed water density	(kg/m^3)
ρs Dry solid density	(kg/m^3)
ρa0 Dry solid apparent density	(kg/m^3)
β′ volume-shrinkage coefficient	(−)
5. Parameter values
ρw = 1000
ρs = obtained form correlation of true density experimental data
ρa0, β′ = obtained form correlation of apparent density experimental data

Table 3 Results of the application of the mathematical model

		True density			Apparent density				Porosity
Material	Data points	%AAD	ρs [kg/m^3]	Figure	%AAD	ρa0 [kg/m^3]	β′	Figure	%AAD	Figure
Mushroom	5	2.74	1303	2a	0.93	780	1.05	2a	22.71	2b
Green pepper	5	1.55	1322	2c	1.08	1131	1.00	2c	26.43	2d
Courgete	5	2.50	1529	2e	0.92	1166	1.00	2e	34.70	2f
Pea	4	0.70	1273	3a	0.73	864	1.02	3a	4.55	3b
Celery	5	0.69	1329	3c	0.51	1079	1.00	3c	22.17	3d
Leek	5	1.72	1409	3e	0.90	770	0.99	3e	20.52	3f
Corn	4	0.64	1359	4a	0.48	1173	1.01	4a	5.76	4b
Tomato	6	1.25	1450	4c	1.58	592	0.98	4c	11.70	4d
Garlic	4	0.64	1480	4e	0.26	1311	1.00	4e	12.69	4f
Carrot	5	1.65	1856	5a	1.81	1416	1.03	5a	6.82	5b
Spinach	5	2.42	1762	5c	1.21	714	1.04	5c	24.87	5d
Onion	5	1.65	1490	5e	0.30	1157	1.03	5e	25.65	5f