Effect of drying on the physical properties of adzuki

DOI: 10.5433/1679-0359.2016v37n6p3871

Effect of drying on the physical properties of adzuki bean Efeito da secagem nas propriedades físicas dos grãos de feijão adzuki Udenys Cabral Mendes1; Osvaldo Resende2*; Juliana Rodrigues Donadon3; Dieimisson Paulo Almeida4; Anisio Correa da Rocha2; Daniel Emanuel Cabral de Oliveira5 Abstract The goal of the present study was to assess the effect of drying on the physical properties of adzuki bean (Vigna angularis Willd.). Adzuki beans with moisture content of 47.9% were dried in a oven with forced air ventilation at temperatures of 40, 60 and 80 °C and relative humidity of 18.5, 8.6, and 3.8%, respectively, until the moisture content reached 12.9%. We used 15 adzuki beans individualised in aluminium capsules. The orthogonal axes of the beans (length, width, and thickness) were measured at intervals of five percentage points during the reduction of moisture content. The parameters determined were: sphericity; circularity; volume of beans; volumetric contraction index; volume contraction percentage; surface area; projected area; and surface-volume ratio. The drying conditions altered the physical properties of adzuki bean. As a result of moisture content reduction, there was increased sphericity and surface-volume ratio, and decreased volume, unitary volumetric contraction, surface area, and projected area. Circularity was not influenced by the drying temperatures within the range of moisture content analysed. Key words: Vigna angularis Willd. Shape. Size. Volume.

Resumo O objetivo neste trabalho foi avaliar o efeito da secagem dos grãos de feijão adzuki (Vigna angularis Willd.) nas propriedades físicas, ao longo do processo de secagem. Grãos de feijão adzuki com teor de água de 47,9% (b.u.) foram submetidos à secagem, em estufa com ventilação de ar forçado, nas temperaturas 40, 60 e 80 °C e umidades relativas de 18,5; 8,6 e 3,8%, respectivamente, até o teor de água, até atingir 12,9% (b.u.). Foram utilizados 15 grãos, individualizados em cápsulas de alumínio. Os eixos ortogonais dos grãos (comprimento, largura e espessura) foram mensurados em intervalos de cinco pontos percentuais durante a redução do teor de água. Determinaram-se os parâmetros esfericidade, circularidade, volume do grão, índice de contração volumétrica, porcentagem de contração volumétrica, área superficial, área projetada e a relação superfície-volume. As condições de secagem alteram as propriedades físicas dos grãos de feijão adzuki. Com a redução no teor de água há um aumento da esfericidade e da relação superfície-volume, e a diminuição do volume, da contração volumétrica unitária, e das áreas superficial e projetada. A circularidade não foi influenciada pelas temperaturas de secagem na faixa de teor de água analisada. Palavras-chave: Vigna angularis Willd. Forma. Tamanho. Volume. Discente de Doutorado, Universidade Estadual Paulista, UNESP, Ilha Solteira, SP, Brasil. E-mail: [email protected] Profs., Instituto Federal Goiano, IF Goiano, Campus Rio Verde, Rio Verde, GO, Brasil. E-mail: [email protected]; [email protected] 3 Profª, Universidade Federal Mato Grosso do Sul, UFMS, Campo Grande, MS, Brasil. E-mail: [email protected] 4 Discente de Doutorado, UNESP, Campus Jaboticabal, SP, Brasil. E-mail: [email protected] 5 Discente de Doutorado, IF Goiano, Campus Rio Verde, Rio Verde, GO, Brasil. E-mail: [email protected] * Author for correspondence 1 2

Received: Sept. 15, 2015 – Approved: Apr. 08, 2016

Semina: Ciências Agrárias, Londrina, v. 37, n. 6, p. 3871-3880, nov./dez. 2016

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Mendes, U. C. et al.

Introduction Adzuki bean (Vigna angularis Willd.) possibly originated in China, which is the world’s largest producer. Japan and South Korea are also major producers. In Brazil, adzuki bean is more expensive than common bean (Phaseolus vulgaris L.). Even though its production is still small, it has been increasing in recent years and the product is easily found in supermarkets (VIEIRA, 2002; ALMEIDA et al., 2013). According to Yousif et al. (2003), in Asian countries like Japan, China and Korea, this adzuki bean is consumed in the form of paste, cooked and sweetened, as desserts and snacks. In Brazil, it is mainly consumed in Japanese colonies, especially as sweets and many eastern delicacies. In south-western Goiás, Brazil, adzuki bean is well adapted in the first crop (sown in October or November) and reaches the productivity of 1,638.41 kg ha-1 (GUARESCHI et al., 2009). For safe storage of adzuki beans, it is necessary to reduce the moisture content to recommended levels. Therefore, it becomes essential to use the drying process, which is one of the stages of the pre-processing of agricultural products that allows storage for longer periods of time, without the risk of product deterioration. This process inhibits the development of micro-organisms and reduces the rates of enzymatic and non-enzymatic reactions (CORRÊA et al., 2011). According to Goneli et al. (2011), information about the size and volumeamong other physical characteristics of agricultural products-are considered of great importance for studies involving heat and mass transfer and air movement in granular masses. Knowledge of physical properties is also important for the development of equipment used for post-harvest operations of agricultural products (VARNAMKHASTI et al., 2008; GONELI et al., 2011), or the adaptation of existing equipment targeting higher income (GONELI, 2008).

In this regard, numerous authors have investigated the variations of physical properties relating to moisture content and drying temperature in various products, namely: castor bean (GONELI, 2008); physic nut fruits (SIQUEIRA et al., 2012), physic nut seeds (SIQUEIRA et al., 2013); and soya beans (OLIVEIRA et al., 2013). Since beans are an important source of protein in the diet and considering the importance of the drying process and the effects of this post-harvest step on the physical properties of the beans, the goal of the present study was to assess the effect of drying temperatures on the physical properties of adzuki bean throughout the drying process.

Material and Method The experiment was conducted in the Laboratory of Post-Harvest Plant Products of the Goiano Federal Institute of Education, Science and Technology – Rio Verde Campus (Goiano FI – Rio Verde Campus). Adzuki beans (Vigna angularis Willd.) with 47.9% of moisture content (wet basis [wb]) were dried in a oven with forced air ventilation at temperatures of 40, 60 and 80 °C and relative humidity of 18.5, 8.6, and 3.8%, respectively, until the moisture content reached 12.9% (wb). We placed 15 adzuki beans individualised in aluminium capsules, with 60.12 mm diameter and 41.0 mm high, as proposed by Siqueira et al. (2012). The length, width and thickness of the beans were measured using a digital calliper with 0.01-mm resolution, at intervals of five percentage points during the reduction of moisture content (Figure 1). The reduction of moisture content was assessed by weighing a tray with 100 g of the product held in the same drying conditions to which the 15 grains were submitted.

3872 Semina: Ciências Agrárias, Londrina, v. 37, n. 6, p. 3871-3880, nov./dez. 2016

the expression 3 proposed by Mohsenin (1986). The unitary volumetric

the relationship between Bv for each moisture content and initial vo

volumetric contraction index (Їψ) was obtained by means of the expres

Effect drying on thedrawing physical properties of adzuki Figure 1.ofSchematic of adzuki beanbean (Vigna calculated by analogy to a sphere of the same medium geometric diame angularis Willd.) with orthogonal dimensions.

AKINNTUNDE; AKINTUNDE, 2004). For this calculation, it was ne Figure 1. Schematic drawing of adzuki bean (Vigna angularis Willd.) with orthogonal dimensions.

diameter (Gd) according to the expression 7 (MOHSENIN, 1986). The p in which accordance with Goneli (2008) using the expression 8, and the su a: largest expression 9. axis of the beans, m; b: medium axis of the beans, m; c: smallest axis of the beans, m.

 a.b.c1 / 3  Sp   .100 a    a.b.c1/ 3  b C  Sp  1 0 0 .100 a a  

in which

in which a: largest axis of the beans, m; a: largest axis of the beans, m; b: medium axis of the beans, m; b: medium axis of the beans, m; c: smallest axis of the beans, m. Figure 1. Schematic drawing of adzuki bean (VignaC  c: smallest axis of the beans, m.angularis Willd.) with orthogonal dimensions.

b 1 0 0 a

Vg The The shape of of thethe adzuki shape adzukibeans, beans,considered considered spheroid, in natural position, was obtained b ψ u resting 100 C V .V spheroid, in natural resting position, was obtained g 0 g through the sphericity and circularity according to the expressions 1 andΨu2,=a respectively, proposed(4) by Correções through the sphericity and circularity according Vg 0 Mohsenin (1986). The volume of each beanproposed (Bv) was obtained throughout according to ψ  the ψ drying  ψ ut  process 100 to the expressions 1 and 2, respectively, Página 3873: u  u0  .a.b(Ψ .c u) was determined by Mohsenin3 (1986). volume of(1986). each bean thebyexpression proposedThe by Mohsenin The unitary volumetric contraction I   Bv (u0   in which (5) ut 6 ).100 ) was obtained throughout the drying process (3) v the(Brelationship between B for each moisture content and initial volume using the expression 4. The v a: largest axis of the beans, m; S=π  Dg according to the expression 3 proposed by Mohsenin S=π  Dg volumetricb:contraction (Їψ)m;was obtained by means of the expressionS5, and medium axis ofindex the beans, .D the surface area (S) was (1986). The unitary volumetric contraction (Ψu) S=π  Ggd (6) c:by smallest axis to of the beans, m.of the same medium geometric diameter using the expression Correções (6) calculated analogy arelationship sphere 6 (TUNDEwas determined by the between Bv for The shape of the adzuki beans, considered spheroid, inPágina natural resting position, was obtained each moisture content and initial2004). volume AKINNTUNDE; AKINTUNDE, Forusing this the calculation, it was 3873: necessary toS determine the geometric ⅓ SV= (9) (7) = (a.b.c) through the sphericity and circularity according to the expressions 1 and 2,Grespectively, d G d proposed by expression 4. The volumetric contraction index (Їψ) diameter (G to expression 7 (MOHSENIN, Thethe projected area (P calculated in d) according a) was to (3) Mohsenin Thethe of each bean (Bv) was obtained1986). throughout drying process according was obtained by(1986). means ofvolume the expression 5, and ab Pa(Ψu) was determined accordance (2008) usingbythe expression and thecontraction surface-volume ratio (SV) the the with expression proposed by Mohsenin (1986). The unitary8,volumetric by using (8) the surface areaGoneli (S)3 was calculated analogy to 4 S=π expression  Gd (6) Bv geometric for each moisture content and initial volume using the 4. The expression a spherethe9. ofrelationship the samebetween medium diameter in which: volumetric contraction index (Їψ) was obtained by means of the expression 5, and the surface area (S) was using the expression 6 (TUNDE-AKINNTUNDE; SS SV= (9) (9) calculated 2004). by analogy sphere of the same it medium the 6 (TUNDESVexpression  Gat time t, m3;(1) AKINTUNDE, Forto athis calculation, was geometric diameterBusing v = bean volume, Gv d AKINNTUNDE; 2004). For this(G calculation, it was necessary to determine thebeans, geometric Bv0 = initial volume of m3 necessary to determineAKINTUNDE, the geometric diameter ) d diameter the expression 7 (MOHSENIN, The area (Pgeometric calculated 3 in at 5% significance and p d) according to a) was diameter. d = medium compared using the F-test according to the(Gbexpression 7 (MOHSENIN, 1986). in1986). which: Bprojected =Gbean volume, at time t, m ; Bv0 = initial v C   1 0Goneli 0 (2008) using the expression 8, and the surface-volume (2) ® accordance with ratio (SV) using the 3 in which: SISVAR statistical software (FERREIRA, 2011). The projected area of beans, m ; S = sphericity; C = circularity; a (Pa) was calculated in accordance volume Página 3877 p expression 9. with Goneli (2008) using the expression 8, and the Ψu = unitary volumetric The average relative error (P) was calculated contraction, decimal; Gv = according to 3 - Sphericity (S Bvp); = bean volume, 3 at time t, m ; (3) surface-volume ratio (SV) using the expression 9. bean volume, at time t, m ; Gv0 = initial volume of Bv0 = initial volume of beans, m3 3 ) -Volumetric contraction index (I u beans, m ; Їψu G= =volumetric contraction index, %; medium geometric diameter. d Vg (1)contraction, decimal; ψ = initial unitary volumetric ψu  (4) u0 Página 3877  a.b.c1 / 3  V ψ = unitary volumetric contraction, at time t, g 0 Sp   ut .100 (1) - Sphericity (Sp); a   decimal; Gd = medium geometric diameter, m; Pa = b ψ ut   100 ψ u   C ψ  (5) 2 -Volumetric index (Iu) u0 projected area, mcontraction ; and SV =(2) surface-volume ratio.  1 0 0 u

a b C = .100 a

S=π  Dg

ψu  ψ u 

(2)

Vg Vg0

 ψu0  ψ ut  100

(3)

The experimental design used was completely (3) randomized using a 3 x 8 factorial (6) scheme, three drying temperatures (40, 60, and 80 °C) and eight (4) 37.9; moisture contents (47.9; 42.9; (7)32.9; 27.9; 22.9; 17.9; and 12.9% [wb]) with fifteen repetitions.

(5) Semina: Ciências Agrárias, Londrina, v. 37, n. 6, p. 3871-3880, nov./dez. 2016

I u  (u 0  ut ).100

(8)

3873

(7)


ab Pa  The data were subjected 4 to analysis of variance.

The averages were compared using the F-test in which: at 5% significance and polynomial regression S value; Y:analysis experimentally observed ® SVSISVAR  using the statistical software Gv : value calculated by the model; Ŷ(FERREIRA, 2011).

(8)

Results and Discussion

Figure 2 illustrates the sphericity and circularity (9) of adzuki beans relating to the moisture content dried at temperatures of 40, 60, and 80 °C. Figure 2A shows that the sphericity of the beans increased compared using the F-test at 5% significance polynomial regression content analysis using the n: number of experimental The average relative observations; error (P) was calculated as aandresult of moisture reduction at all ® statistical software (FERREIRA, 2011). accordingSISVAR to the following expression: temperatures. This increase was more significant at The average relative error (P) was calculated according to the following the temperature of 60expression: °C, indicating that, at the end Results and Discussion  of the drying process, the shapes(10) of the beans were Υ Υ (10) 100 P  Υthe sphericity and circularity more spherical. Figure 2 illustrates relating to the moisture content of adzuki beans n

dried at temperatures of 40, 60, and 80 °C. Figure 2A shows that the sphericity of the beans increased as a in which: result of moisture content reduction at all temperatures. This increase was more significant at the temperature ofY:60experimentally °C, indicating observed that, at thevalue; end of the drying process, the shapes of the beans were more spherical. Ŷ: value calculated by the model; Figure 2. Sphericity (A) andobservations; circularity (B) of the adzuki beans (Vigna angularis Willd.) relating to moisture n: number of experimental content, with drying conditions at temperatures of 40, 60, and 80 °C. Figure 2. Sphericity (A) and circularity (B) of the adzuki beans (Vigna angularis Willd.) relating to moisture content, with drying conditions at temperatures of 40, 60, and 80 °C.

A

B

Source: Plot Programme. Programme. Source:Sigma Sigma Plot

Corrêa et al. (2006) assessed the sphericity of wheat grains during the drying process and also Corrêa et al. (2006) assessed the sphericity of that the sphericity had decreased when the moisture observed increased sphericity as a result of moisture reduction. However, the sphericity of the grains wheat grains during the drying process and also content content was lower. observed to increased sphericity as a result of moisture submitted 36 °C had decreased, possibly due to the low water removal rate under that condition. This The values of circularity did not differ in the content reduction. However, the sphericity of the result was not observed in our work at drying temperatures close to 40temperatures °C. Al mahasneh anddifferent Rababahlevels (2007) three drying and the grains submitted to 36 °C had decreased, possibly of moisture content. The average obtained and al. (2012) that rate the sphericity had decreased when the moisture contentvalues was lower. dueSiqueira to the etlow water found removal under that were 51.80, 52.33, and 52.44% for temperatures The values ofwas circularity did notin differ in the three drying temperatures and the different levels of condition. This result not observed our work of 40, 60, and 80 °C, respectively. Various at dryingcontent. temperatures close tovalues 40 °C.obtained Al mahasneh moisture The average were 51.80, 52.33, products and 52.44% for exhibit temperatures of 40, 60, agricultural did not this behaviour, and Rababah (2007) and Siqueira et al. (2012) found and 80 °C, respectively. Various agricultural products did not exhibit this behaviour, such as cotton seeds 3874 (OZARSLAN, 2002), millet (BARYEH; MANGOPE, 2002), flax (SACILIK et al., 2003), cocoa (BARTSemina: Ciências Agrárias, Londrina, v. 37, n. 6, p. 3871-3880, nov./dez. 2016

PLANGE; BARYEH, 2003), and physic nuts (SIQUEIRA et al., 2013), whose values of circularity increased

Effect of drying on the physical properties of adzuki bean

such as cotton seeds (OZARSLAN, 2002), millet (BARYEH; MANGOPE, 2002), flax (SACILIK et al., 2003), cocoa (BART-PLANGE; BARYEH, 2003), and physic nuts (SIQUEIRA et al., 2013), whose values of circularity increased when the moisture content was reduced. Siqueira et al. (2012) observed a reduction in circularity in physic nuts subjected to drying at 60, 75, 90, and 105 °C; however, at lower temperature the nuts behaved differently. The authors explain that these differences can be attributed to width and length contractions, which occur differently depending on the temperature. Adzuki beans may also have behaved differently from other agricultural products with respect to the contraction of their dimensions during the drying process. Figure 3 illustrates the volume values (A), surface area (B), projected area (C), and surface-volume ratio (D) of adzuki beans during the drying process. It can be observed that the volume of adzuki beans decreased when the moisture content was lower at all temperatures studied. Araujo et al. (2014) assessed the physical properties of peanut grains at different moisture contents and observed a reduction in the volume of the grains. This reduction in the volume of grains is related to volume contraction during the drying process due to the removal of water. The volume of adzuki beans was greater at the highest temperature at all levels of moisture content. Siqueira et al. (2012) also observed the same behaviour in physic nuts when subjected to drying at higher temperatures. The authors explain that, under these conditions, the water removal rate was higher and caused the hardening of the tegument, which may have hampered the contraction of the grains and, consequently, reduced their volume with less intensity.

The surface area of the adzuki beans exhibited similar behaviour than that of the bean volume, i.e., it decreased with the reduction of moisture content in all drying conditions (Figure 3B). The values of the surface area were between 2.047 x 10-5 and 1.767 x 10-5 m2. Bande et al. (2012) assessed the surface area of melon seeds with different moisture contents and observed a similar behaviour. The projected area decreased with the reduction of moisture content at the temperature of 60 °C (Figure 3C), which was a similar behaviour than that obtained by Siqueira et al. (2012) and Goneli (2008). Araujo et al. (2014) affirmed that this phenomenon occurs due to the reduction of the characteristic dimensions of the product during the desorption process, which contributes to the shrinking of the beans and, consequently, to the reduction of the projected area. The surface-area ratio of the adzuki beans increased with the reduction of moisture content. This increase was greater at the temperature of 60 °C and lower at 80 °C (Figure 3D). Similar results were obtained by Siqueira et al. (2012) when they assessed physic nuts. According to Al Mahasneh and Rababah (2007), the surface-area ratio is used for determining the projected area of particles that move with turbulence in the air current, which can be useful in the construction of grain cleaning machines, separators, and pneumatic conveyors. When the surface-volume ratio increases, there is increase in the rate of heat transfer and mass, which affects several unitary operations, such as drying and cooling.



Figure 3. Volume (A), surface area (B), projected area (C), and surface-volume ratio (D) of the adzuki beans (Vigna angularis Willd.) relating to moisture content, with drying conditions at 40, 60, and 80 °C.

A

B

C

D

Source: Sigma Plot Programme.

Source: Sigma Plot Programme.

Figure 4 illustrates the values of volumetric of fruits of castor bean and found a volume reduction According and volumetric Rababah (2007), the surface-area ratio for determining the of 46% with respect to istheused initial volume, with contraction (A) to andAl Mahasneh the unitary moisture ranging from can 71.4 be to 11.5% projected area that The move withprocess turbulence in the content air current, which useful (wb). in the contraction (B)ofof particles adzuki beans. drying caused the contraction of the adzuki beans (Figure and Khraisheh et al. (2004) that the construction of grain cleaning machines, separators, pneumatic conveyors. Whenobserved the surface-volume 4A), which was in line with the results obtained by volumetric contraction of agricultural products ratio increases, there is increase in the rate of heat transfer and mass, which affects several unitary Goneli et al. (2011). Afonso Júnior et al. (2003) and during drying occurs heterogeneously. Apparently, operations, as drying and cooling. Santos et such al. (2014) assessed the drying of coffee at the beginning of drying, the products remain with and maize grains and found theofvolumetric Figure 4 illustrates the that values volumetric contraction and the contraction the intact (A) structure andunitary retain volumetric their original shape. contraction should not be neglected during the However,ofwith the removal water,4A), the which particles (B) of adzuki beans. The drying process caused the contraction the adzuki beans of (Figure was modelling of the drying process. in line with the results obtained by Goneli et al. (2011).shrink. Afonso Júnior et al. (2003) and Santos et al. (2014) Figure 4B shows that the contraction of the Table illustrates the contraction models adjusted thebe assessed the drying of coffee and maize grains and found that 1the volumetric shouldtonot product was the same at all drying temperatures experimental data of sphericity, circularity, volume, neglected the modelling of 28% the drying process. and that during it increased from 26 to depending on unitary volumetric contraction, surface area, Figureof4B thatcontent. the contraction the product was the and same at all drying temperatures and the reduction theshows moisture Goneli etofal. projected area, surface-volume ratio of adzuki (2011) assessedfrom the unitary volumetric contraction beans relating to the moisture content. that it increased 26 to 28% depending on the reduction of the moisture content. Goneli et al. (2011) 3876 assessed the unitary volumetric contraction of fruits of castor bean and found a volume reduction of 46% Semina: Ciências Agrárias, Londrina, v. 37, n. 6, p. 3871-3880, nov./dez. 2016

with respect to the initial volume, with moisture content ranging from 71.4 to 11.5% (wb).


Figure 4. Unitary volumetric contraction (A) and volumetric contraction index (B) of the adzuki beans (Vigna relating to moisture content, with drying conditions 80 °C. Figureangularis 4. UnitaryWilld.) volumetric contraction (A) and volumetric contraction index at (B)40, of 60, the and adzuki beans (Vigna angularis Willd.) relating to moisture content, with drying conditions at 40, 60, and 80 °C.

A

B

Source: Sigma Plot programme.

Table 1. Equations adjusted to the values of sphericity (Sp), volume (Bv), surface area (S), projected area (Pa), surfacevolume ratio (SV), unitary volumetric contraction ), and volumetric contraction index (Iψu) of the adzukivolume, beans Table 1 illustrates the models adjusted(ψto circularity, u the experimental data of sphericity, (Vigna angularis Willd.) relating to moisture content, with drying conditions at 40, 60, and 80 °C.

unitary volumetric contraction, surface area, projected area, and surface-volume ratio of adzuki beans relating to the moistureSphericity content.(%)

Volume (m3) T (°C) Model R² (%) P (%) T (°C) Model R² (%) P (%) 40 Sph = –0.002 x2 + 0.051 x + 60.266 91.4 0.35 40 Bv = 0.041 x2 – 1.856 x + 114.25 65.2 4.75 2 2 60 Sph = –0.001 x – 0.021 x + 62.524 97.0 0.23 60 B = 0.032 x – 1.349 x + 101.46 62.2 7.12area Table 1. Equations adjusted to the values of sphericity (Sph), volume (Bv), surface area (S), projected v 2 2 Sph = –0.001 xratio + 0.024 x + 61.481 80.2 0.39 80 Bv ), = 0.044 x – 1.805 x + 124.76 87.1 3.03 (Pa),80surface-volume (SV), unitary volumetric contraction (ψ u and volumetric contraction index (I u) 2 2 Surface area (m ) Projected area (m ) of the adzuki beans (Vigna angularis Willd.) relating to moisture content, with drying conditions at 40, 60, T (°C) Model R² (%) P (%) T (°C) Model R² (%) P (%) and 80 °C. 40 S = 0.002 x2 – 0.087 x + 18.69 65.2 1.51 40 Pa = 0.010 x – 0.3797 x + 39.701 83.5 2.31 3 Sphericity (%) Volume (m ) 60 S = 0.001 x2 – 0.076 x + 18.08 82.9 0.96 60 Pa = 0.010 x2 – 0.393 x + 37.014 93.5 1.42 P T R² P T (°C) Model R² (%) 0.94 Model 80 S = 0.002 x2 – 0.087 x + 19.34 88.2 80 Pa = 0.013 x2 – 0.585 x + 44.414 92.9 1.76 (%) (°C) (%) (%) Surface-volume ratio (mm2 m-3) volumetric contraction (decimal) 2 2 0.35 40 Unitary 4.75 40 + 0.051 x + 60.266 R² (%) 91.4 P (%) - 1.856 x + 114.25 R² (%)65.2 Sph = -0.002 x T (°C) Model T (°C) Bv = 0.041 xModel P (%) 2 0.23 60 B = 0.032 2x2 - 1.349 x + 101.46 7.12 6040 Sph 62.524 65.2 97.0 2.86 SV==-0.001 –3E-05xx2 -+0.021 0.001 xx + + 0.1727 40 ψu =v 0.0003 x – 0.013 x + 0.883 65.262.24.75 0.39 6080 ψB= =0.0003 8060 Sph SV==-0.001 –3E-05xx22++ 0.024 0.001 xx++0.1844 x +x0.872 61.481 84.3 80.2 1.78 0.044x2x–2 0.011 - 1.805 + 124.76 81.787.13.113.03 u v 2 2 80 SV = –3E-05Surface x2 + 0.001 x + 0.1616 89.8 1.69 80 ψ = 0.0003 x – 0.012 x + 0.860 u area (m ) Projected area (m2) 87.1 3.03 Volumetric contraction P Tindex (%) R² P TT (°C) Model R² (%) Model Model (°C) R²(%) (%) (%) (%) (°C) x2 + 1.2961 x + 11.656 65.2 4040 S = 0.002 x2 - 0.087 x + 18.69 Iyu = –0.0290 65.2 2 1.51 40 Pa = 0.010 x - 0.3797 x + 39.701 83.5 2.31 60 Iyu = –0.0269 x + 1.1227 x + 12.734 81.7 1.42 60 Pa = 0.010 x2 - 0.393 x + 37.014 6080 S = 0.001 x2 - 0.076 x + 18.08 Iy = –0.0301 82.9 x2 0.96 + 1.2448 x + 13.971 87.193.5 u

80

2

= 0.002content x - 0.087 x beans, + 19.34 Note. x =Smoisture of the % wb.

Surface-volume ratio (mm2 m-3)

88.2

T (°C)

Model

R² (%)

40

SV = -3E-05 x2 + 0.001 x + 0.1727

65.2

60 80 T (°C) 40

2

SV = -3E-05 x + 0.001 x + 0.1844

84.3

0.94

80

1.78

60

Pa = 0.013 x2 - 0.585 x + 44.414 92.9 1.76 Unitary volumetric contraction (decimal) P T R² P Model (%) (°C) (%) (%) 2.86 40 ψ = 0.0003 x2 - 0.013 x + 0.883 65.2 4.75 u

ψu = 0.0003 x2 - 0.011 x + 0.872

1.69 80 ψ = 0.0003 x2 - 0.012 x + 0.860 SV = -3E-05 x2 + 0.001 x + 0.1616 89.8 u Volumetric contraction index (%) Semina: Ciências Agrárias, Londrina, v.Model 37, n. 6, p. 3871-3880, nov./dez. 2016

Iu = -0.0290 x2 + 1.2961 x + 11.656

81.7 3.11 87.1 3.03

3877 R² (%) 65.2


It is worth noting that in all the variables analysed, the second-order polynomial models exhibited a coefficient of determination (R2) of more than 80%, with the exception of the temperature of 40 °C for volume, surface area, surface-volume ratio, unitary volumetric contraction, and volumetric contraction index, and 60 °C for volume. With respect to the average relative error (P), the values were less than 10%. According to Mohapatra e Rao (2005), a value of the average relative error lower than 10% indicates good fit of the model to the experimental data. It should be noted that it is not possible to determine the average relative error for the index of volumetric contraction, because the value is zero with the highest moisture content. In this way, the models represented adequately the behaviour relating to the reduction of the moisture content.

Conclusion Drying conditions altered the physical properties of adzuki beans. With the reduction in moisture content, there was increase in sphericity and surface-volume ratio, and decrease in volume, unitary volumetric contraction, surface area, and projected area. The circularity was not influenced by the drying temperatures within the range of moisture content assessed.

References AFONSO JÚNIOR, P. C.; CORRÊA, P. C.; PINTO, F. A. C.; SAMPAIO, C. P. Shrinkage evaluation of five different varieties of coffee berries during the drying process. Biosystems Engineering, Londres, v. 86, n. 4, p. 481-485, 2003. AL MAHASNEH, M. A.; RABABAH, T. M. Effect of moisture content on some physical properties of green wheat. Journal of Food Engineering, Londres, v. 79, n. 4, p. 1467-1473, 2007. ALMEIDA, D. P.; RESENDE, O.; MENDES, U. C.; COSTA, L. M.; CORRÊA, P. C.; ROCHA, A. C. Influência da secagem na qualidade fisiológica do feijão adzuki. Revista Brasileira de Ciências Agrárias, Recife, v. 8, n. 2, p. 311-315, 2013.

ARAUJO, W. D.; GONELI, A. L. D.; SOUZA, C. M. A.; GONÇALVES, A. A.; VILHASANTI, H. C. B. Propriedades físicas dos grãos de amendoim durante a secagem. Revista Brasileira de Engenharia Agrícola e Ambiental, Campina Grande, v. 18, n. 3, p. 279-286, 2014. BANDE, Y. M.; ADAM, N. M.; AZNI, Y.; JAMAREI, O. Moisture-dependent physical and compression of bitter melon (Citrullus colocynthis lanatus) seeds. International Journal of Agricultural Research, Nova Iorque, v. 7, n. 5, p. 243-254, 2012. BART-PLANGE, A.; BARYEH, E. A. The physical properties of Category B cocoa beans. Journal of Food Engineering, Londres, v. 60, n. 3, p. 219-227, 2003. BARYEH, E. A.; MANGOPE, B. K. Some physical properties of QP-38 variety pigeon pea. Journal of Food Engineering, Londres, v. 56, n. 1, p. 39-46, 2002. CORRÊA, P. C.; RESENDE, O.; GARIN, S. A.; JAREN, C.; OLIVEIRA, G. H. H. Mathematical models to describe the volumetric shrinkage rate of red beans during drying. Engenharia Agrícola, Jaboticabal, v. 31, n. 4, p. 716-726, 2011. CORRÊA, P. C.; RIBEIRO, M. D.; RESENDE, O.; BOTELHO, F. M. Determinação e modelagem das propriedades físicas e da contração volumétrica do trigo, durante a secagem. Revista Brasileira de Engenharia Agrícola e Ambiental, Campina Grande, v. 10, n. 3, p. 665-670, 2006. FERREIRA, D. F. Sisvar: a computer statistical analysis system. Ciência e Agrotecnologia, Lavras, v. 35, n. 6, p. 1039-1042, 2011. GONELI, A. L. D. Variação das propriedades físicomecânicas e da qualidade de mamona (Ricinus communis L.) durante a secagem e o armazenamento. 2008. Tese (Doutorado em Engenharia Agrícola) – Universidade Federal de Viçosa, Viçosa, MG. GONELI, A. L. D.; CORRÊA, P. C.; MAGALHÃES, F. E. A.; BAPTESTINI, F. M. Contração volumétrica e forma dos frutos de mamona durante a secagem. Acta Scientiarum. Agronomy, Maringá, v. 33, n. 1, p. 1-8, 2011. GUARESCHI, R. F.; ARAUJO, M. J. C.; GAZOLLA, P. R.; ROCHA, A. C. Produtividade de feijão azuki em função de doses de potássio em cobertura. Global Science and Technology, Rio Verde, v. 2, n. 2, p. 67-72, 2009. KHRAISHEH, M. A. M.; MCMINN, W. A. M.; MAGEE, T. R. A. Quality and structural changes in starchy foods during microwave and convective drying. Food Research International, Essex, v. 37, n. 5, p. 497-503, 2004.



MOHAPATRA, D.; RAO, P.S. A thin layer drying model of parboiled wheat. Journal of Food Engineering, Londres, v. 66, n. 4, p. 513-518, 2005. MOHSENIN, N. N. Physical properties of plant and animal materials. New York: Gordon and Breach Publishers, 1986. 841 p. OLIVEIRA, D. E. C.; RESENDE, O.; SMANIOTTO, T. A. S.; SIQUEIRA, V. C.; JOSÉ NETO, C. A. Alterações morfométricas em grãos de soja durante o processo de secagem. Semina: Ciências Agrárias, Londrina, v. 34, n. 3, p. 975-984, 2013. OZARSLAN, C. Physical properties of cotton seed. Biosystems Engineering, Londres, v. 83, n. 2, p. 169-174, 2002. SACILIK, K.; OZTURK, R.; KESKIN, R. Some physical properties of hemp seed. Biosystems Engineering, Londres, v. 86, n. 2, p. 191-198, 2003. SANTOS, M. N. S.; OLIVEIRA, D. E. C.; RUFFATO, S.; PEREIRA, V. S. Cinética de secagem de grãos de milho da cultivar Pioneer P3646. Global Science and Technology, Rio Verde, v. 7, n. 2, p. 119-129, 2014. SIQUEIRA, V. C.; RESENDE, O.; CHAVES, T. H. Shape and size of jatropha beans (Jatropha curcas L.) during drying at different temperatures. Revista Ceres, Viçosa, MG, v. 60, n. 6, p. 820-825, 2013.

SIQUEIRA, V. C.; RESENDE, O.; CHAVES, T. H.; SOARES, F. A. L. Forma e tamanho dos frutos de pinhão manso durante a secagem em cinco condições de ar. Revista Brasileira de Engenharia Agrícola e Ambiental, Campina Grande, v. 16, n. 8, p. 864-870, 2012. TUNDE-AKINNTUNDE, T. Y.; AKINTUNDE, B. O. Some physical properties of sesame seed. Biosystems Engineering, Londres, v. 88, n. 1, p. 127-129, 2004. VARNAMKHASTI, M. G.; MOBLI, H.; JAFARI, A.; KEYHANI, A. R.; SOLTANABADI, M. H.; RAFIE, S.; KHEIRALIPOUR, K. Some physical properties of rough rice (Oryza Sativa L.) grain. Journal of Cereal Science, Londres, v. 47, n. 1, p. 496-501, 2008. VIEIRA, R. F. Comportamento de cultivares de feijãoazuki em diferentes épocas de plantio em Ponte Nova e Leopoudina, Minas Gerais. Revista Ceres, Viçosa, MG, v. 49, n. 286, p. 705-712, 2002. YOUSIF, A. M.; BATEY, I. L.; LARROQUE, O. R.; CURTIN, B.; BEKES, F.; DEETH, H. C. Effect of storage of adzuki bean (Vigna angularis) on starch and protein properties. Lebensmittel-Wissenschaft & Technologie, Zurique, v. 36, n. 6, p. 601-607, 2003.
