Page 161 - IJB-7-4

Lee, et al.
Foams are a type of food that consists of a liquid or (IDDSI) framework. In addition, food foams generally
continuous phase in which air bubbles are dispersed . have a lower viscosity, making them harder to print than
[17]
They are widely applied to food products such as ice other food matrices.
creams, mousse, and baked goods [18,19] . The primary In this study, we used EW and alternative food
purposes for foam products are food density and caloric ingredients, Methocel F50 and Foam Magic, which are
density reduction, modification of texture, and improved commercial products available to create food foams. The
rheological properties . Foams are also used to enhance hydrocolloid included in this study is xanthan gum (XG). XG
[20]
sensory features, such as enhanced texture and flavors of is a thickener that is commonly used in food products, such
food. More importantly, food foams are used to deliver as mayonnaise and ice cream . XG provides high viscosity
[30]
liquid in a more easy-to-swallow form, especially for even at low concentrations . Its highly shear-thinning
[31]
dysphagic patients . For example, the aeration of water properties make it an ideal choice as a thickener to improve
[32]
[21]
or milk into foams changes their texture and improves the printability of low-viscosity food foams and enhance the
nutrients delivery to dysphagic patients. These foods stability of foams . XG was added to the foaming agent to
[33]
could stay in the mouth for a certain duration, thereby formulate printable food foam inks. The foam properties,
providing prolonged hydration for dysphagic patients . such as foaming ability, foam stability, foam density, and
[22]
The main characteristics of food foams are foaming syneresis, were studied to provide an in-depth understanding
ability, foam stability, and water leakage . The foaming of how the foam properties affect the printability of the
[23]
ability dictates how much the volume increases after respective foam inks. The rheological properties, printability,
foaming, and the foam stability measures how long the microstructures, and texture profiles of the food foams were
foam maintains its shape without disintegrating. The characterized extensively in this study. IDDSI tests were
[34]
water leakage (syneresis) determines the ability of the also conducted to examine the suitability of the foam inks for
foam to hold its shape. This provides an early indication hydration to dysphagic patients.
if the printed part is able to sustain its shape. The criteria
for the ideal ink for food foam should be decently high 2. Materials and method
foaming ability, high foam stability of more than an 2.1. Formulation of foam inks
hour (sufficient time for printing), and low/no syneresis.
Foaming ability indicates whether the food matrix is The materials used were commercially available
suitable for the creation of food foam. One of the most pasteurized eggs from a local supermarket (N & N Egg
widely studied food foams is egg white (EW) food foam. Story, Singapore), Foam Magic from Modernist Pantry
It is the most commercially used foaming ingredient due (SKU:1214-25), Methocel F50 from Modernist Pantry
to its high foaming ability and its ability to create an (SKU:1056-50), XG from Diabetic Food Delivery
irreversible semi-stable foam . Most of the foam-based Singapore - Better4U.sg and Honeydew Extract Powder
[24]
food, such as meringues, pavlova, macarons, and mousse, from RunDeKang BioTechnologies.
are made from EW food foams [25,26] . 3D printing of EW For the egg-based foams, the EW were separated
foam was demonstrated by Kouzani et al., achieved from the egg yolks and weighed. They were then beaten
through printing a pavlova using an EW foam-based using an electronic whip (Kenwood, 800W) for 5 min to
batter . However, the foam stability and rheological foam. 12.5 wt% of honeydew extract powder was then
[27]
properties, which were key properties to the printability added, and the mixture was whipped for another minute.
of foams, were not characterized and controlled. Food For eggless foams, 2 wt% of Foam Magic and/or 2
foams have yet to be studied in depth for 3DFP. Without wt% Methocel F50 were added to water, and the mixture was
the characterization of foam properties and rheological beaten using an electronic whip for 5 min. Foam Magic is
properties, it is unclear if these foams are suitable for a proprietary formulation of maltodextrin, methylcellulose,
patients with dysphagia. Therefore, there is a need to and XG designed to create foams when whipped with
study the foam inks for 3DFP. either a hand blender or iSi whipper. Methocel F50 is a
Foam stability is a unique aspect of food foam that food-grade hydroxyl propyl methylcellulose (HPMC).
is different from other types of food matrices and strongly The pH of EW is approximately 9.2 in the normal
influences printability. Unlike other food matrices, the state. The EW used in Inks 1 and 2 were not treated;
thermodynamic instability causes the disintegration of therefore, Ink 1 has a pH close to pure EW’s (Table 1).
foams, and it is vital to ensure that the foam remains The presence of XG brought down the pH of Ink 2. The
stable while undergoing printing. Therefore, it is crucial pH of XG in an aqueous solution is 7 which brought
to increase the foam stability for 3DFP purposes with down the overall pH of the solution. Tap water was used
additives such as hydrocolloids [28,29] while ensuring that to produce Inks 3 – 5. The pH of tap water was tested to
the texture meets the standard of the dysphagic diet set by be approximately 8.40. Therefore, the pH of Inks 3 – 5 is
the international dysphagia diet standardization initiative approximately similar to that of tap water.

International Journal of Bioprinting (2021)–Volume 7, Issue 4 157