Total phenolics, antioxidant capacity, colour and drying characteristics of date fruit dried with different methods

İZLİ, Gökçen

doi:10.1590/1678-457X.14516

Acessibilidade / Reportar erro

Brasil

Food Science and Technology

Español English

Brasil

Español English

sumário « anterior atual seguinte »

Sumário

Research Paper • Food Sci. Technol (Campinas) 37 (1) • Jan-Mar 2017 • https://doi.org/10.1590/1678-457X.14516 copy

Total phenolics, antioxidant capacity, colour and drying characteristics of date fruit dried with different methods

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Date slices were dried with the three drying methods convective (60, 70 and 80 °C), microwave (120 W) and freeze drying to determine drying characteristics and to compare the dried fruit quality. All colour parameters changed depending on the drying method and colours closest to the fresh sample were obtained with freeze drying. It is interesting to note that the total phenolic content and antioxidant capacity in each sample rose when looked at in relation to the fresh sample. In particular, microwave-dried samples were recorded as having the highest total phenolic content and the highest antioxidant capacity. To explain the drying kinetics of the date slices, nine thin-layer drying models were also attempted. Based on statistical tests, the model developed by Midilli et al. model was found to be the best model for convective and microwave drying, but the Two Term model was the best for freeze drying. This study shows that microwave drying can produce high quality date slices with the additional advantage of reduced drying times compared to convective and freeze drying.

Keywords:
drying methods; thin-layer; date slices; colour; total phenolic content

No	Model name	Model	References
1	Henderson & Pabis	$M R = a \exp (- k t)$	Westerman et al. (1973)Westerman, P. W., White, G. M., & Ross, I. J. (1973). Relative humidity effect on the high temperature drying of shelled corn. Transactions of the ASAE, 16(6), 1136-1139. http://dx.doi.org/10.13031/2013.37715. http://dx.doi.org/10.13031/2013.37715...
2	Newton	$M R = \exp (- k t)$	Ayensu (1997)Ayensu, A. (1997). Dehydration of food crops using a solar dryer with convective heat flow. Solar Energy, 59(4-6), 121-126. http://dx.doi.org/10.1016/S0038-092X(96)00130-2. http://dx.doi.org/10.1016/S0038-092X(96)...
3	Page	$M R = \exp (- k t^{n})$	Agrawal & Singh (1977)Agrawal, Y. C., & Singh, R. D. (1977). Thin layer drying studies on short grain rice. St. Joseph: ASAE. ASAE Paper, No 3531.
4	Logarithmic	$M R = a \exp (- k t) + c$	Yagcioglu et al. (1999)Yagcioglu, A., Degirmencioglu, A., & Cagatay, F. (1999). Drying characteristics of the laurel leaves under different drying conditions. In Proceedings of the 7th International Congress on Agricultural Mechanization and Energy, Adana, Turkey.
5	Two Term	$M R = a \exp (- k_{0} t) + b \exp (- k_{1} t)$	Madamba et al. (1996)Madamba, P. S., Driscoll, R. H., & Buckle, K. A. (1996). The thin-layer drying characteristics of garlic slices. Journal of Food Engineering, 29(1), 75-97. http://dx.doi.org/10.1016/0260-8774(95)00062-3. http://dx.doi.org/10.1016/0260-8774(95)0...
6	Two Term Exponential	$M R = a \exp (- k t) + (1 - a) \exp (- k a t)$	Sharaf-Eldeen et al. (1980)Sharaf-Eldeen, Y. I., Blaisdell, J. L., & Hamdy, M. Y. (1980). A model for ear corn drying. Transactions of the ASAE, 23(5), 1261-1265. http://dx.doi.org/10.13031/2013.34757. http://dx.doi.org/10.13031/2013.34757...
7	Wang & Singh	$M R = 1 + a t + b t^{2}$	Wang & Singh (1978)Wang, C. Y., & Singh, R. P. (1978). A single layer drying equation for rough rice. St. Joseph: ASAE. ASAE Paper, N° 78-3001.
8	Diffusion Approach	$M R = a \exp (- k t) + (1 - a) \exp (- k b t)$	Kassem (1998)Kassem, A. S. (1998). Comparative studies on thin layer drying models for wheat. In Proceedings of the 13th International Congress on Agricultural Engineering, Morocco.
9	Midilli et al.	$M R = a \exp (- k t^{n}) + b t$	Midilli et al. (2002)Midilli, A., Kucuk, H., & Yapar, Z. (2002). A new model for singlelayer drying. Drying Technology, 20(7), 1503-1513. http://dx.doi.org/10.1081/DRT-120005864. http://dx.doi.org/10.1081/DRT-120005864...

No	60 °C				70 °C				80 °C
No	Model coefficients	R²	RMSE	χ²(10^-4)	Model coefficients	R²	RMSE	χ²(10^-4)	Model coefficients	R²	RMSE	χ²(10^-4)
1	a = 1.16 k = 0.02753	0.9634	0.0667	44.1368	a = 1.125 k = 0.03321	0.9724	0.0567	32.3309	a = 1.096 k = 0.03638	0.9724	0.0559	30.8148
2	k = 0.02401	0.9404	0.0852	72.9711	k = 0.02975	0.9575	0.0704	50.4617	k = 0.03333	0.9632	0.0645	41.6470
3	k = 0.00197 n = 1.652	0.9986	0.0130	1.7176	k = 0.004744 n = 1.504	0.9989	0.0114	1.5244	k = 0.006856 n = 1.448	0.9983	0.0136	1.6537
4	a = 1.322 k = 0.01837 c = -0.2146	0.9833	0.0451	19.8206	a = 1.273 k = 0.02262 c = -0.1962	0.9900	0.0341	12.1484	a = 1.319 k = 0.02219 c = -0.2747	0.9951	0.0235	5.5701
5	a = -0.2754 k_o = 5.323 b = 1.275 k₁ = 0.03012	0.9784	0.0513	25.8357	a = 1.243 k_o = 0.03652 b = -0.2426 k₁ = 4.163	0.9858	0.0407	16.5055	a = 24.01 k_o = 0.06367 b = -22.97 k₁ = 0.06597	0.9943	0.0253	5.9417
6	a = 1.022 k = 0.01932	0.9655	0.0648	41.9409	a = 0.0000059 k = 504.3	0.9549	0.0724	53.4497	a = 0.0000092 k = 360.9	0.9605	0.0668	44.6484
7	a = -0.01746 b = 0.000007491	0.9810	0.0480	23.1766	a = -0.02168 b = 0.0001171	0.9907	0.0329	11.6911	a = -0.02412 b = 0.0001429	0.9966	0.0186	3.6238
8	a = 0.02629 k = 6.366 b = 0.003683	0.9247	0.0957	87.7333	a = 1.646 k = 0.0281 b = 0.9158	0.9531	0.0739	52.4178	a = -13.09 k = 0.06892 b = 0.9352	0.9966	0.0197	3.3102
9	a = 1.014 k = 0.002189 n = 1.631 b = -0.00000498	0.9987	0.0126	1.5324	a = 1.012 k = 0.005768 n = 1.448 b = -0.0001453	0.9990	0.0110	1.4541	a = 0.9972 k = 0.00867 n = 1.356 b = -0.0006357	0.9997	0.0058	0.2528

No	Microwave				Freeze
No	Model coefficients	R²	RMSE	χ²(10^-4)	Model coefficients	R²	RMSE	χ²(10^-4)
1	a = 1.088 k = 0.1862	0.9550	0.0803	64.4687	a = 0.9519 k = 0.002602	0.9909	0.0268	6.9931
2	k = 0.1731	0.9513	0.0836	70.4025	k = 0.002736	0.9888	0.0296	8.4459
3	k = 0.04973 n = 1.658	0.9994	0.0089	0.5308	k = 0.006943 n = 0.8496	0.9952	0.0194	3.5584
4	a = 1.286 k = 0.1211 c = -0.2311	0.9784	0.0557	31.2405	a = 0.9492 k = 0.002655 c = 0.005606	0.9903	0.0276	7.4329
5	a = -62.45 k_o = 0.3412 b = 63.47 k₁ = 0.3362	0.9910	0.0358	13.3582	a = 0.8359 k_o = 0.002291 b = 0.1641 k₁ = 0.4768	0.9977	0.0135	1.6582
6	a = 2.132 k = 0.2831	0.9960	0.0238	5.6057	a = 0.1518 k = 0.01547	0.9970	0.0154	2.1635
7	a = -0.1251 b = 0.003866	0.9873	0.0427	18.3072	a = -0.001602 b = 0.0006164	0.9692	0.0580	37.2475
8	a = 14.16 k = 0.06767 b = 0.9239	0.9758	0.0589	30.2738	a = 0.1113 k = 0.1841 b = 0.01321	0.9968	0.0157	2.0779
9	a = 0.9987 k = 0.05029 n = 1.645 b = -0.0003728	0.9995	0.0083	0.5088	a = 0.9955 k = 0.01014 n = 0.7787 b = -0.00000219	0.9970	0.0152	2.1221

Drying method	Colour parameters
Drying method	L*	a*	b*	C	α°	∆e
Fresh	64.92 ± 1.46^a	4.18 ± 0.87^e	35.05 ± 1.56^a	35.30 ± 1.62^bc	83.27 ± 1.24^a
Convective drying
60 °C	58.29 ± 1.73^c	6.05 ± 0.89^c	31.69 ± 1.58^c	32.27 ± 1.71^de	79.28 ± 1.08^c	7.90 ± 1.50^c
70 °C	56.61 ± 1.94^d	7.53 ± 0.73^b	34.61 ± 1.76^ab	35.43 ± 1.85^b	77.78 ± 0.75^d	9.19 ± 1.75^c
80 °C	54.25 ± 1.38^e	10.24 ± 1.45^a	35.63 ± 1.80^a	37.09 ± 2.04^a	74.05 ± 1.67^e	12.41 ± 1.96^b
Microwave drying
120W	49.27 ± 1.85^f	9.66 ± 0.21^a	30.33 ± 2.10^c	31.83 ± 2.01^e	72.31 ± 1.12^f	17.33 ± 2.14^a
Freeze drying	63.11 ± 2.20^b	5.06 ± 0.48^d	33.31 ± 1.46^b	33.70 ± 1.44^cd	81.38 ± 0.36^b	3.42 ± 1.45^d

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: gokcen.izli@btu.edu.tr