Page 227 - IJB-10-5

International Journal of Bioprinting Effect of ingredient flow speed

citric acid. Approximately, 60 g of potato powder was mixed Table 1. Foodini printer settings optimized for 4.0 mm nozzle
with water at 100°C at three different mass ratios: 0.15, 0.2, diameter
and 0.25 wt/wt. The mixture was blended manually for 5 Printer settings Values
min until a puree-like consistency was attained and all the
lumps in the mixture had dissolved. Pre-printability tests Nozzle size (mm) 4
were conducted to determine if the MP ink is suitable for Print speed (mm/min) 14000
3D printing. Through this qualitative analysis, the ratio of Ingredient flow speed 1.65
dry potato powder to boiling water was determined to be Fill factor (%) 1
0.2 wt/wt. The MP inks were subsequently loaded into the First ingredient hold (mm) 4.2
Foodini capsule before 3D printing. First ingredient flow (mm) 6.25

2.2. Rheological characterization First layer nozzle height (mm) 3.4
An oscillatory rheometer (Modular Compact Rheometer, First layer speed (%) 100
Anton Paar, Austria) was utilized to examine the Ingredient hold (mm) 3
rheological properties of MP food ink with an aluminum Line thickness (mm) 3.4
parallel plate with a diameter of 25 mm and truncation Distance between layers (mm) 3.5
gap of 1000 μm. To prevent edge effects from affecting
the characterization profile of the inks, the rotating shaft
was descended to remove any overflowing food inks the model. For model extrusion, the uploaded files would
off the disc. To understand the rheology profile of the go through the Foodini in-built slicer software, which will
MP food ink at room temperature, viscosity tests were generate a set of printing instructions for the printer for dot
performed by exerting a stepwise shear rate increase extrusion. Unlike model extrusion, there is no conversion
from 1 to 1000 s . Triplicate measurements of the MP of models into codes for the 3D food printer since the only
−1
inks were recorded. input needed from the user is the extrusion volume.
2.3. Measurement of nozzle geometry 2.4.1. 3D printing using dot extrusion
A digital microscope (VHX-7000, Keyence, Japan) was The dot function in the Foodini Creator hub allows
deployed at ×20 magnification to analyze the nozzles from different amounts of MP food inks to be extruded at once.
different perspectives (interior, external, and side) and By allowing a set volume of food inks to be extruded freely,
identify any contrast between the different nozzles. the time taken for each extrusion and the mass of food
ink extruded can be studied. By setting the dot extrusion
2.4. 3D printing experiments at different volumes from 1 to 50 mL, three dots of MP
An extrusion-based 3D food printer, Foodini (Natural food inks were extruded on a glass slide and subsequently
Machines, Spain), was utilized to print 3D models using the weighed. By altering the amount of food ink extruded
print settings listed in Table 1. Three nozzles (0.8, 1.5, and from 1 to 10 mL, the time taken for each dot extrusion was
4 mm) were used in this study. The control parameters that measured thrice by finding the two frames of the video
would be studied were printing speed (V ) and ingredient where extrusion occurred. The average time taken was
PS
flow speed (V ). According to the knowledge database of then recorded (Table S1, Supporting Information).
IFS
Natural Machines, printing speed (mm/min) is defined as
the speed of the nozzle head moving in the horizontal axis. 2.4.2. 3D printing using model extrusion
Ingredient flow speed is defined as the material extrusion Three straight lines were 3D printed on a ceramic plate,
flow on the vertical axis and is a dimensionless parameter. where the line width served as a measure of the printing
Unlike the typical food printers which control the flow resolution, i.e., the standard of measurement. 23,43 The
using a volumetric flow rate, Foodini printers regulate model had a length of 100 mm and a width of 4 mm and
the flow via ingredient flow speed. A higher ingredient was created using the “line drawing’’ function in Foodini
flow speed would lead to a larger volume being extruded, Creator. The straight line was subsequently printed for
resulting in a larger printed width. This indicates that the different printing parameters, such as printing speed
ingredient flow speed is related to the volumetric flow rate and ingredient flow speed of 200–50,000 mm/min and
by an arbitrary value. 0.1–50, respectively. Resolution refers to the width of the
The extrusion process parameters were studied using 3D-printed straight line. Comparisons of the straight line
two printing modes available in the Foodini Creator hub, were made at three different printing speeds (3500, 14,000,
namely dot and model extrusions. The two printing modes and 25,000 mm/min) and three ingredient flow speeds
differ in terms of whether the slicer software is applied to (1.65, 3.3, and 5.0).

Volume 10 Issue 5 (2024) 219 doi: 10.36922/ijb.2787