Study of gala apples (<i>Malus pumila</i>) thin-layer microwave drying: drying kinetics, diffusivity, structure and color

KRIAA, Karim; NASSAR, Ahmed Fayez

doi:10.1590/fst.26420

Acessibilidade / Reportar erro

Brasil

Food Science and Technology

Español English

Brasil

Español English

sumário « anterior atual seguinte »

Sumário

Original Article • Food Sci. Technol (Campinas) 41 (suppl 2) • 2021 • https://doi.org/10.1590/fst.26420 copy

Study of gala apples (Malus pumila) thin-layer microwave drying: drying kinetics, diffusivity, structure and color

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

The effect of microwave power, sample thickness, and diameter on drying kinetics, effective moisture diffusivity, and activation energy of apple cylinders for microwave drying were investigated. Also, the effect of the microwave power on the quality of the dried apples was studied by measuring the surface color change and scanning the surface structure. The same mass of fresh apples was dried at different power levels. Two diameters and three thicknesses were studied. Aghbashlo model showed the best fitting for the drying kinetics of apple. The drying time was reduced by increasing the power and the diameter, but the thickness had no clear effect. The effective diffusivity values ranged between 1.47 × 10^-7 and 24.4 × 10^-7 m²/s. The effective diffusivity increased by increasing the three studied parameters. The parameters' effects on the drying time and the diffusivity were studied using a full factorial experimental design. The power and the diameter had the highest effect on the drying time. However, the thickness had the highest effect on the effective diffusivity.

Keywords:
microwave drying; kinetics; color change; SEM; design of experience

Factor	Coded Factor	Level
Factor	Coded Factor	-1	0	1
Power P (Watt)	X₁	360	500	775
Diameter D (mm)	X₂	10.5	-	17.5
Thickness t (mm)	X₃	3.3	4.5	6

No.	Name	Reference	Model
1	Lewis (Newton, exponential)	(Lewis, 1921Lewis, W. K. (1921). The rate of drying of solid materials. Journal of Industrial and Engineering Chemistry, 13(5), 427-432. http://dx.doi.org/10.1021/ie50137a021. http://dx.doi.org/10.1021/ie50137a021... )	$M R = e x p (- k t)$
2	Page	(Page, 1949Page, G. E. (1949). Factors influencing the maximum rates of air drying shelled corn in thin layers (M. Sc. thesis). Purdue University, West Lafayette.)	$M R = e x p (- k t^{n})$
3	Henderson and Pabis	(Henderson & Pabis, 1961Henderson, S. M., & Pabis, S. (1961). Grain drying theory, II. Temperature effects on drying coefficients. Journal of Agricultural Engineering Research, 6, 169-174.)	$M R = a \cdot e x p (- k t)$
4	Logarithmic	(Hukill, 1954Hukill, W. V. (1954). Grain drying. In J. A. Anderson & A. W. Alcock (Eds.), Storage of cereal grains and their products. St. Paul, Minnesota: Am. Ass. Cereal Chem.)	$M R = a \cdot e x p (- k t) + c$
5	Modified Two-Term exponential	(Sharaf-Eldeen et al., 1980Sharaf-Eldeen, Y. I., Blaisdell, J. L., & Hamdy, M. Y. (1980). A model for ear corn drying. Transactions of the ASAE. American Society of Agricultural Engineers, 23(5), 1261-1265. http://dx.doi.org/10.13031/2013.34757. http://dx.doi.org/10.13031/2013.34757... )	$M R = a \cdot e x p (- k t) + (1 - a) \cdot e x p (- k a t)$
6	Parabolic (Wang & Singh)	(Wang & Singh, 1978Wang, G. Y., & Singh, R. P. (1978). Single layer drying equation for rough rice. Materials Science, 78-3001.)	$M R = 1 + a t + b t^{2}$
7	Verma	(Verma et al., 1985Verma, L. R., Bucklin, R. A., Endan, J. B., & Wratten, F. T. (1985). Effects of drying air parameters on rice drying models. Transactions of the ASAE, 28(1), 296-301. http://dx.doi.org/10.13031/2013.32245. http://dx.doi.org/10.13031/2013.32245... )	$M R = a \cdot e x p (- k t) + (1 - a) \cdot e x p (- g t)$
8	Aghbashlo	(Aghbashlo, et al., 2009Aghbashlo, M., Kianmehr, M. H., & Samimi-Akhijahani, H. (2009). Evaluation of thin-layer drying models for describing drying kinetics of barberries (Barberries Vulgaris). Journal of Food Process Engineering, 32(2), 278-293. http://dx.doi.org/10.1111/j.1745-4530.2007.00216.x. http://dx.doi.org/10.1111/j.1745-4530.20... )	$M R = e x p (- k_{1} t / (1 + k_{2} t))$

Exp.	Model	Coefficient					Adj. R²	RMSE
Exp.	Model	k₁	k₂	a	c	n	Adj. R²	RMSE
1	Aghbashlo	0.058	-0.014	-	-	-	0.9993	0.00765
1'	$M R = \exp [- \frac{k_{1} t}{(1 + k_{2} t)}]$	0.055	-0.018	-	-	-	0.9996	0.00612
2		0.057	-0.027	-	-	-	0.9986	0.01162
3		0.089	-0.056	-	-	-	0.9952	0.02355
4		0.038	-0.015	-	-	-	0.9997	0.00489
5		0.058	-0.018	-	-	-	0.9991	0.00937
5'		0.058	-0.019	-	-	-	0.9985	0.01195
6		0.092	-0.028	-	-	-	0.9981	0.01341
7		0.054	-0.008	-	-	-	0.9985	0.01102
8		0.081	-0.013	-	-	-	0.9992	0.00812
9		0.138	-0.017	-	-	-	0.9971	0.01656
10		0.027	-0.007	-	-	-	0.9994	0.00676
11		0.032	-0.012	-	-	-	0.9996	0.00581
12		0.054	-0.017	-	-	-	0.9991	0.00903
13		0.048	-0.022	-	-	-	0.9978	0.01460
14		0.032	-0.016	-	-	-	0.9993	0.00766
15		0.020	-0.009	-	-	-	0.9992	0.00792
16		0.023	-0.011	-	-	-	0.9994	0.00683
17		0.030	-0.018	-	-	-	0.9994	0.00755
18		0.049	-0.027	-	-	-	0.9975	0.01639
1	Page	0.041	-	-	-	1.230	0.9974	0.01498
1'	$M R = exp (- k t^{n})$	0.034	-	-	-	1.311	0.9971	0.01653
2		0.029	-	-	-	1.453	0.9983	0.01309
3		0.046	-	-	-	1.630	0.9992	0.00991
4		0.019	-	-	-	1.380	0.9963	0.01855
5		0.034	-	-	-	1.324	0.9992	0.00863
5'		0.034	-	-	-	1.340	0.9993	0.00840
6		0.065	-	-	-	1.311	0.9997	0.00517
7		0.043	-	-	-	1.135	0.9980	0.01276
8		0.066	-	-	-	1.165	0.9991	0.00890
9		0.117	-	-	-	1.159	0.9990	0.00991
10		0.016	-	-	-	1.233	0.9974	0.01436
11		0.016	-	-	-	1.330	0.9973	0.01503
12		0.034	-	-	-	1.292	0.9984	0.01169
13		0.023	-	-	-	1.443	0.9991	0.00905
14		0.013	-	-	-	1.445	0.9977	0.01431
15		0.008	-	-	-	1.402	0.9980	0.01284
16		0.009	-	-	-	1.430	0.9978	0.01361
17		0.011	-	-	-	1.494	0.9971	0.01582
18		0.020	-	-	-	1.557	0.9989	0.01084
1	Logarithmic	0.056	-	1.208	-0.187	-	0.9991	0.00910
1'	$M R = a \exp (- k t) + c$	0.054	-	1.266	-0.237	-	0.9983	0.01250
2		0.050	-	1.510	-0.467	-	0.9965	0.01867
3		0.075	-	1.701	-0.644	-	0.9900	0.03416
4		0.033	-	1.442	-0.414	-	0.9990	0.00969
5		0.059	-	1.242	-0.201	-	0.9976	0.01507
5'		0.063	-	1.236	-0.183	-	0.9968	0.01746
6		0.091	-	1.269	-0.230	-	0.9969	0.01692
7		0.053	-	1.123	-0.104	-	0.9992	0.00802
8		0.081	-	1.134	-0.112	-	0.9994	0.00688
9		0.150	-	1.086	-0.048	-	0.9973	0.01589
10		0.024	-	1.300	-0.284	-	0.9998	0.00412
11		0.026	-	1.452	-0.428	-	0.9993	0.00753
12		0.049	-	1.315	-0.284	-	0.9992	0.00861
13		0.043	-	1.491	-0.441	-	0.9971	0.01682
14		0.023	-	1.744	-0.710	-	0.9986	0.01108
15		0.015	-	1.646	-0.613	-	0.9989	0.00945
16		0.016	-	1.775	-0.744	-	0.9987	0.01048
17		0.018	-	2.091	-1.059	-	0.9982	0.01247
18		0.046	-	1.530	-0.470	-	0.9937	0.02578

Exp.	Power P (Watt)	Diameter D (mm)	Thickness t (mm)	Time (min)	Diffusivity $\times$ 10⁷ (m²/s)
1	-1 (360)	1 (17.5)	-1 (3.3)	27.61	3.25
1'	-1 (360)	1 (17.5)	-1 (3.3)	25.81	3.35
2	0 (500)	1 (17.5)	-1 (3.3)	21.38	3.86
3	1 (775)	1 (17.5)	-1 (3.3)	11.9	6.91
4	-1 (360)	1 (17.5)	0 (4.5)	33.42	4.46
5	0 (500)	1 (17.5)	0 (4.5)	25.56	6.51
5'	0 (500)	1 (17.5)	0 (4.5)	24.94	6.60
6	1 (775)	1 (17.5)	0 (4.5)	16.63	9.89
7	-1 (360)	1 (17.5)	1 (6.0)	34.26	9.88
8	0 (500)	1 (17.5)	1 (6.0)	22.48	13.82
9	1 (775)	1 (17.5)	1 (6.0)	14.99	24.44
10	-1 (360)	-1 (10.5)	1 (6.0)	55.8	5.03
11	0 (500)	-1 (10.5)	1 (6.0)	42.09	6.74
12	1 (775)	-1 (10.5)	1 (6.0)	26.99	10.42
13	1 (775)	-1 (10.5)	0 (4.5)	25.34	6.00
14	0 (500)	-1 (10.5)	0 (4.5)	35.35	3.82
15	-1 (360)	-1 (10.5)	0 (4.5)	58.92	2.36
16	-1 (360)	-1 (10.5)	-1 (3.3)	50.64	1.47
17	0 (500)	-1 (10.5)	-1 (3.3)	35.51	2.11
18	1 (775)	-1 (10.5)	-1 (3.3)	22.06	3.42

	Factor	Sum of square (SS)	Degree of freedom	Mean square (MS)	F value	P value
Time	P	1676.549	1	1676.549	293.7982	0.000001^* * Significant at the level 5%.
	P²	134.879	1	134.879	23.6361	0.000894*
	D	1149.124	1	1149.124	201.3724	0.000012*
	t	90.225	1	90.225	15.8110	0.003224*
	t²	26.044	1	26.044	4.5639	0.061385 ^NS
	P $\times$ D	127.385	1	127.385	22.3230	0.001082*
	P $\times$ t	3.423	1	3.423	0.5998	0.458510^NS
	D $\times$ t	0.039	1	0.039	0.0068	0.936307^NS
	Error	51.358	9	5.706
	Total SS	3269.866	17
Diffusivity	D	99.2708	1	99.2708	49.7526	0.00002*
	t	241.3956	1	241.3956	120.9828	0.000000*
	t²	16.0078	1	16.0078	8.0228	0.016300*
	P	96.3119	1	96.3119	48.2696	0.000024*
	P²	6.4299	1	6.4299	3.2226	0.100123^NS
	D $\times$ t	33.8025	1	33.8025	16.9412	0.001712*
	D $\times$ P	12.3335	1	12.3335	6.1813	0.030237*
	T $\times$ P	33.9650	1	33.9650	17.0226	0.001684*
	Error	21.9482	11	1.9953
	Total SS	548.5692	19

Sociedade Brasileira de Ciência e Tecnologia de Alimentos Av. Brasil, 2880, Caixa Postal 271, 13001-970 Campinas SP - Brazil, Tel.: +55 19 3241.5793, Tel./Fax.: +55 19 3241.0527 - Campinas - SP - Brazil
E-mail: revista@sbcta.org.br

Acompanhe os números deste periódico no seu leitor de RSS

[1] *Corresponding author: afnassar@imamu.edu.sa, afnassar@eng1.cu.edu.eg