INFLUENCE OF DIFFERENT TEMPERATURES AND AIRFLOWS ON DRYING OF NATURAL AND PULPED COFFEE

Alves, Guilherme E.; Borém, Flávio M.; Andrade, Ednilton T.; Isquierdo, Éder P.; Siqueira, Valdiney C.; Dias, Camila de A.

doi:10.1590/1809-4430-Eng.Agric.v40n2p192-200/2020

Acessibilidade / Reportar erro

Brasil

Español English

sumário « anterior atual seguinte »

Sumário

Scientific Paper, Post-Harvest Science and Technology • Eng. agríc. (Online) 40 (2) • Mar-Apr 2020 • https://doi.org/10.1590/1809-4430-Eng.Agric.v40n2p192-200/2020 copy

INFLUENCE OF DIFFERENT TEMPERATURES AND AIRFLOWS ON DRYING OF NATURAL AND PULPED COFFEE

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

This study aimed to evaluate drying kinetics for natural and pulped coffee, using different temperatures and drying airflows. For the conduction of the experiment, coffee fruits (Coffea arabica L. cv. Topázio) were harvested manually, selecting only ripe fruits and subsequent to the hydraulic separation. For drying the coffee, use a mechanical dryer with two temperatures (40 and 45°C) and four drying air streams (24; 60; 96 and 132 m³.min^-1.m^-2). Twelve models for employees to describe the drying kinetics of coffees. Among the models used to describe the drying process of natural coffee and pulped coffee, according to the results of the coefficient of determination, relative mean error, standard deviation of estimates and distribution of waste distribution, proposed model for the only one that presents fit for all as conditions study. The temperature of 45 ° C and the airflows of 96 and 132 m³.min^-1.m^-2 provide the shortest drying times regardless of the coffee processing type.

KEYWORDS
Coffea arabica L.; mathematical modeling; drying rate

Model designation	Model	Equation
Dois termos	$MR = a^{.} exp ({-k}_{0}^{.} t) + b^{.} exp ({-k}_{1}^{.} t)$	(6)
Exponencial de dois termos	$MR = a^{.} exp (-k^{.} t) + (1 -a) exp (-k^{.} a^{.} t)$	(7)
Henderson & Pabis modificado	$MR = a^{.} exp (-k^{.} t) + b^{.} exp ({-k}_{0}^{.} t) + c^{.} exp ({-k}_{1}^{.} t)$	(8)
Henderson & Pabis	$MR = a^{.} exp (-k^{.} t)$	(9)
Midilli	$MR = a^{.} exp (-k^{.} t^{n}) + b^{.} t$	(10)
Newton	$MR = exp (-k^{.} t)$	(11)
Page	$MR = exp (-k^{.} t^{n})$	(12)
Thompson	$MR = exp {[- a - {(- a^{2} + 4^{.} b^{.} t)}^{0, 5}]^{.} {(2^{.} b)}^{- 1}}$	(13)
Verma	$MR = -a^{.} exp (-k^{.} t) + (1 -a) exp ({-k}_{1}^{.} t)$	(14)
Wang e Sing	$MR = 1 + a^{.} t + b^{.} t^{2}$	(15)
Valcam	$MR = a + b^{.} t + c^{.} t^{1, 5} + d^{.} t^{2}$	(16)
Modelo Proposto	$MR = (a^{.} \exp {(k_{0}^{.} t)}^{n})^{.} {(b + \exp^{.} {(k_{1}^{.} t)}^{n})}^{- 1}$	(17)

Processing	Tem (°C)	Airflow (m³ min⁻¹ m⁻²)	Drying time (h)	Moisture content (db)		Drying rate (g kg⁻¹ h⁻¹)
Processing	Tem (°C)	Airflow (m³ min⁻¹ m⁻²)	Drying time (h)	Initial	Final	Mean	Maximum
NAT	40	24	73.20	2.19	0.125	39.84	209.25
		60	71.06	2.19	0.125	41.77	217.17
		96	67.92	2.19	0.125	42.44	223.33
		132	66.10	2.20	0.125	44.16	234.27
	45	24	47.93	1.93	0.125	43.78	222.09
		60	45.84	1.93	0.125	45.57	240.23
		96	44.08	1.96	0.125	47.57	239.78
		132	44.46	1.95	0.125	48.79	256.78
CD	40	24	13.30	0.98	0.125	64.27	164.85
		60	12.84	0.99	0.125	69.91	177.63
		96	12.59	0.99	0.125	70.24	177.99
		132	12.13	0.99	0.125	76.45	178.19
	45	24	10.65	1.00	0.125	80.35	210.79
		60	10.44	1.01	0.125	81.24	211.08
		96	10.10	1.01	0.125	88.77	211.20
		132	10.15	1.01	0.125	88.27	221.00

Pulped coffee (40 °C)
Model	Airflow (m³ min⁻¹m⁻²)
	24			60			96			132
	SD	P (%)	r²(%)	SD	P (%)	r²(%)	SD	P (%)	r²(%)	SD	P (%)	r²(%)
6	0.03	29.57	99.47	0.04	48.03	98.67	0.04	50.66	98.74	0.03	12.10	99.48
7	0.04	68.18	98.32	0.04	51.16	98.59	0.04	54.14	98.65	0.04	25.31	98.58
8	0.02	23.36	99.71	0.08	46.47	94.04	0.09	38.27	95.03	0.02	4.57	99.79
9	0.04	63.22	98.46	0.04	48.03	98.67	0.04	50.67	98.74	0.04	24.00	98.66
10	0.02	19.61	99.68	0.02	15.29	99.69	0.02	15.94	99.70	0.02	6.61	99.74
11	0.04	68.18	98.32	0.04	51.16	98.59	0.04	54.14	98.65	0.04	25.31	98.58
12	0.03	29.01	99.33	0.03	23.33	99.35	0.03	23.93	99.41	0.03	12.97	99.31
13	0.04	68.18	98.32	0.04	51.15	98.59	0.04	54.15	98.65	0.04	25.32	98.58
14	0.03	31.43	99.40	0.02	23.88	99.44	0.04	54.14	98.65	0.03	12.72	99.41
15	0.02	13.98	99.72	0.02	12.53	99.64	0.02	15.84	99.65	0.02	2.73	99.69
16	0.01	6.78	99.87	0.01	4.43	99.85	0.01	5.71	99.87	0.01	3.21	99.84
17	0.01	3.85	99.88	0.01	5.85	99.86	0.01	5.20	99.87	0.01	3.17	99.85
Pulped coffee 45 °C
6	0.03	37.23	99.38	0.02	23.48	99.60	0.02	30.35	99.60	0.02	38.94	99.53
7	0.04	76.11	98.65	0.02	29.03	99.51	0.02	37.38	99.52	0.03	83.47	98.91
8	0.12	128.02	90.73	0.04	56.92	98.95	0.02	36.60	99.68	0.15	205.23	84.59
9	0.04	72.50	98.70	0.03	56.93	98.95	0.03	72.78	98.90	0.03	79.41	98.96
10	0.02	29.24	99.57	0.02	21.58	99.66	0.02	26.21	99.67	0.02	32.76	99.64
11	0.04	76.11	98.65	0.03	61.01	98.88	0.03	78.32	98.81	0.03	83.45	98.91
12	0.03	38.50	99.23	0.02	24.27	99.49	0.02	30.12	99.51	0.03	41.11	99.40
13	0.04	76.11	98.65	0.03	61.03	98.88	0.04	78.35	98.81	0.03	83.47	98.91
14	0.04	76.10	98.65	0.02	27.14	99.68	0.04	78.35	98.81	0.02	32.38	99.69
15	0.03	33.09	99.37	0.03	42.01	99.40	0.03	56.64	99.42	0.03	61.99	99.21
16	0.02	7.99	99.79	0.01	12.12	99.85	0.01	16.85	99.85	0.01	12.18	99.84
17	0.02	7.81	99.76	0.01	7.48	99.84	0.01	7.81	99.86	0.02	3.40	99.82
Natural coffee 40 °C
6	0.01	2.43	99.95	0.01	4.23	99.93	0.01	2.99	99.96	0.01	3.87	99.94
7	0.02	18.00	99.42	0.04	34.88	97.21	0.02	19.60	99.47	0.02	23.40	99.26
8	0.01	1.61	99.96	0.00	2.63	99.99	0.00	2.05	100.00	0.01	3.87	99.94
9	0.03	24.46	98.63	0.03	25.85	98.66	0.03	26.55	98.67	0.03	29.56	98.46
10	0.01	2.45	99.96	0.00	1.08	99.99	0.00	2.21	99.98	0.01	2.66	99.96
11	0.04	32.92	97.28	0.04	34.88	97.21	0.04	34.80	97.44	0.04	38.02	97.07
12	0.01	4.30	99.94	0.00	4.80	99.96	0.01	5.52	99.95	0.01	6.62	99.92
13	0.01	4.14	99.92	0.01	3.59	99.90	0.01	3.12	99.95	0.01	3.17	99.93
14	0.01	3.11	99.91	0.04	34.88	97.21	0.01	4.21	99.93	0.04	38.02	97.07
15	0.12	87.40	78.66	0.12	98.53	76.07	0.12	101.93	76.40	0.13	114.05	72.19
16	0.02	11.59	99.65	0.02	11.82	99.61	0.02	13.14	99.61	0.02	16.08	99.45
17	0.01	2.04	99.96	0.01	2.54	99.93	0.01	1.60	99.98	0.01	2.69	99.96
Natural coffee 45 °C
6	0.01	1.78	99.96	0.01	2.06	99.96	0.01	2.22	99.95	0.01	2.22	99.94
7	0.01	2.46	99.94	0.02	12.73	99.26	0.01	3.25	99.93	0.02	17.10	99.07
8	0.01	1.78	99.96	0.01	2.06	99.96	0.00	1.48	99.99	0.00	0.86	100.00
9	0.02	11.35	99.61	0.01	8.01	99.71	0.02	12.02	99.56	0.02	12.15	99.57
10	0.00	1.04	99.98	0.00	1.24	99.98	0.00	1.07	99.98	0.00	0.83	99.98
11	0.02	15.96	99.17	0.02	12.73	99.26	0.02	17.06	99.05	0.02	17.10	99.07
12	0.00	2.84	99.97	0.00	1.45	99.98	0.00	2.91	99.97	0.01	3.88	99.95
13	0.01	1.82	99.94	0.01	3.17	99.90	0.01	2.11	99.93	0.01	2.14	99.91
14	0.01	2.53	99.94	0.01	2.59	99.95	0.01	3.17	99.93	0.01	4.07	99.90
15	0.08	45.58	91.63	0.07	36.89	93.38	0.08	46.94	91.04	0.08	47.22	90.98
16	0.01	3.10	99.96	0.01	2.42	99.96	0.01	3.37	99.95	0.01	2.55	99.95
17	0.01	1.67	99.97	0.01	1.94	99.97	0.01	1.95	99.96	0.01	2.67	99.94

Processing	Temperature (°C)	Airflow (m³ min⁻¹ m⁻²)	Model coefficient
Processing	Temperature (°C)	Airflow (m³ min⁻¹ m⁻²)	a	b	k₀	k₁	N
Natural	40	24	33.3836	33.1341	-15.5549	44.3614	0.0083
		60	46.0625	46.0433	-0.3655	0.9937	0.3984
		96	33.8310	33.5280	-18.1085	47.3185	0.0080
		132	60.2551	60.3382	-1.7779	5.1655	0.0861
	45	24	0.1086	-0.8896	-0.7714	0.1474	0.0480
		60	0.7720	-0.2166	1.1412	2.3307	0.0510
		96	0.1208	-0.8770	-0.4736	0.1119	0.0720
		132	0.0916	-0.9066	-0.2470	0.0402	0.1532
Pulped	40	24	0.3742	-0.6176	0.0863	0.4642	0.0885
		60	0.3402	-0.6503	0.0370	0.3516	0.1082
		96	0.3101	-0.6839	0.0036	0.2948	0.1138
		132	0.2371	-0.7575	-0.0316	0.1994	0.1340
	45	24	18.1339	17.6652	-22.3481	52.5765	0.0072
		60	17.3364	16.6682	-23.0004	52.5763	0.0075
		96	21.1488	20.5184	-21.9210	52.5764	0.0081
		132	20.4160	19.8862	-23.7046	52.5764	0.0076

Processing	Temperature (°C)	Airflow (m³ min⁻¹ m⁻²)				Mean
Processing	Temperature (°C)	24	60	96	132	Mean
CD	40	13.30aA	12.84aB	12.59aC	12.13aC
CD	45	10.65bA	10.44bAB	10.10bB	10.15bB
NAT	40	73.20	71.06	67.92	66.10	69.57a
	45	47.93	45.84	44.08	44.46	45.58b
	Mean	60.57A	58.45AB	56.00BC	55.28C

Associação Brasileira de Engenharia Agrícola SBEA - Associação Brasileira de Engenharia Agrícola, Departamento de Engenharia e Ciências Exatas FCAV/UNESP, Prof. Paulo Donato Castellane, km 5, 14884.900 | Jaboticabal - SP, Tel./Fax: +55 16 3209 7619 - Jaboticabal - SP - Brazil
E-mail: revistasbea@sbea.org.br

Acompanhe os números deste periódico no seu leitor de RSS

[1] *Corresponding author. Universidade Federal de Lavras/ Lavras - MG, Brasil. E-mail: camila.almeidadias@gmail.com