mean value, \* black-hull oilseed, \*\*striped-hull oilseed

was increased from 4.6% d.b. to 17.7% d.b., representing a variation of 6.3%.

Table 6. Sphericity () of different seeds

equipment for the seed.

The sphericity varied between 65.8% and 67.6%, values higher than the data reported for sunflower and safflower seed, but lower

**Seed [Reference] Sphericity (%)**  Amaranth [24] 82 # Fenugreek[16] 60.79 – 64.06 Quinoa [22] 77 – 80 Rapeseed [28] 93 – 92 Safflower [17] 58 – 62 Sunflower\* [18] 49 – 52 Sunflower\*\* [18] 47 – 50 Soybean [23] 80.6 – 81.6

The high value thus suggests that the seeds tend towards a spherical shape. Thus, the value of the generally indicates a likely difficulty in getting the seed to roll. This tendency to either roll or slide should be necessary in the design of hoppers and dehulling

As can be seen in Figure 6, the equivalent diameter (*De*, mm) increased linearly from 1.28 to 1.36 mm when the moisture content

Since porosity depends on bulk and true densities, the magnitude of its variation depends mainly on these properties. Therefore, the porosity of each type of seed or grain could re‐ spond differently with increasing moisture content. This fact could be attributed to the seeds' morphological characteristics; the relative changes in their length, width, and thick‐ ness; and the associated bulk and true densities. Taking into account the high level of poly‐ unsaturated fatty acids, chia seeds can be easily affected by temperature. For this reason, aeration is an important process to maintain a low uniform temperature and prevent the moisture migration. The resistance to airflow or pressure drop is affected by different fac‐ tors, such as the bulk density, porosity, and moisture content. Due to the low bulk density and size of chia seeds, the grain bed will have an important pressure drop, requiring a high level of power for driving the aeration fans [25].

The variation of volume (*V*), equivalent diameter (*De*), thousand seed mass (*W1000*), and sphericity (*ϕ*) of chia seeds with moisture content (4.6 - 17.7 % d.b.) is shown in Figure 5.; the average values were 1.21 mm3 , 1.32 mm, 0.129 g and 66.7 % respectively. Statistical analysis revealed significant differences (*p* < 0.05) between seeds with different moisture content for *V, De* and *W1000*. Nevertheless, sphericity did not present significant differences (*p* > 0.05).

The sphericity varied between 65.8% and 67.6%, values higher than the data reported for sunflower and safflower seed, but lower than those of amaranth, quinoa, rapeseed and soy‐ bean seed (Table 6).


**Table 6.** Sphericity (ϕ) of different seeds

**Seed [Reference] Regression equation R2** Amaranth [24] 28 + 0.16 x 0.75 Cumin [13] 48 + 0.643 x 0.93 Flaxseed [27] 11.453 + 2.7621 x 0.99 Fenugreek [16] 42.987 + 0.555 x 0.95 Quinoa [22] 13.1 + 1.22 x 0.98 Rapeseed [28] 44.659 + 0.6656 x 0.99 Safflower [17] 39.53 + 0.342 x 0.93 Sunflower [15] 32.27 + 0.54 0.95 Sunflower\* [18] 36.99 + 0.58 x 0.92 Sunflower\*\* [18] 30.10 + 0.37 x 0.91 Soybean [23] 40.5 – 0.1365 x 0.98

\* black-hull oilseed, \*\*striped-hull oilseed

determination (R2) for porosity (ε, %).

390 Food Industry

Volume (mm3

1,00 1,05 1,10 1,15 1,20 1,25 1,30 1,35

Thounsan seed mass (g)

1,0

1,1

1,2

1,3

1,4

)

(1:4.6, 2:6.5, 3:8.7, 4:10.0, 5:12.5, 6:15,3, 7:17,7).

Moisture content (%d.b.) 1234567

Moisture content (%d.b.) 1234567

than those of amaranth, quinoa, rapeseed and soybean seed (Table 6).
