3D printing of gels based on xanthan/konjac gums

https://doi.org/10.1016/j.ifset.2020.102343Get rights and content

Highlights

  • Printability of syrup, xanthan, and konjac gels is affected by temperature.

  • Gels printed at 50 °C were less elastic and had greater fluidity.

  • Higher G′, G″, and η* were obtained with greater content of xanthan gum and KGM.

  • Mixture design can help in 3D food printing modelling.

Abstract

3D printing technology is a promising technology with the possibility of use for developing personalised food. To make this technology easier, and readily available for consumers, greater knowledge of the printing conditions and characteristics of food-ink is needed. This paper investigates the printability of gels based on syrup, xanthan, and konjac gums, while affecting printing variables. Those variables include the printing temperature (25 °C and 50 °C) and the composition of the product analysed using rheological and textural characterisation techniques. Also, the link between rheological and textural properties of gels, and printability was analysed. The higher values of G′, G″ and η* correlated to the mixtures with lower syrup concentration, and higher values of xanthan and konjac gum. Syrup, xanthan gum and konjac gum content influenced the textural properties. With the increase of syrup content, the Fmax, Fmean, Area, and slope showed reductions giving more weak gels. Rheological and textural values can define composition of formulations that give rise to valid 3D printed figures.

Industrial relevance

There is an increasing market need for customized food products. Three-dimensional (3D) food printing will be developed in the coming years. Undoubtedly, food printing can have many advantages, but whether the market is ready for such a big change and the technology will grow fast enough are the questions. Also it seems to be the right solution to meet the needs of today's consumers who increasingly have too little time to prepare meals on their own, especially in small or single-person households. In the future, ready, healthy meal, tailored to their individual needs, will be waiting when coming home. 3D printed gels can contribute to develop personalised food with specific nutritional characteristics. For example, this kind of gels can be used to manufacture soft foods for the elderly who have problems to swallow.

Introduction

Additive manufacturing (AM), referred to as 3D printing, has received a large amount of attention from industry, academia, and the public for its many advantages. AM offers shorter production time compared with traditional manufacturing methods. In addition, it can generate various complex shapes by using a limited mass of materials, with an enhancement of mechanical properties (Godoi, Prakash, & Bhandari, 2016; Wang, Zhang, Bhandari, & Yang, 2018). The potential advantages of 3D printing technology can be applied within the food sector, such as customized food design, personalised, and digitalised nutrition, simplifying supply chain, and expansion of source food material. Using this technology, some complex and fantastic food designs, which cannot be achieved by manual labour or conventional moulds, can be produced by ordinary people based on predetermined data files compromising culinary knowledge and artistic skills from chefs, nutrition experts, and food designers (Liu, Zhang, Bhandari, & Wang, 2017; Sun et al., 2015). The properties and composition of materials are considered the key factors for the 3D printing process. These materials should be homogeneous with appropriate flow properties, suitable for extrusion but able to support its structure during and after the printing process (Godoi et al., 2016; Yang, Zhang, Bhandari, & Liu, 2018). Zhang et al. (2015) used dual-responsive hydrogels to fabricate three-dimensional objects via extrusion from a nozzle in 3D printing. They found gels with a rapid and reversible modulus response to shear stress and temperature were suitable for direct-write 3D printing; they were easily extruded from nozzle tip during printing and could maintain sufficient mechanical integrity to support the next printed layer, without deformation (Zhang et al., 2015). Other researchers have come to similar conclusions (Wang et al., 2018). However, the correlation between the food material's rheological properties and 3D printing behaviour has not been widely investigated (Liu et al., 2017). Rheological properties of gels significantly affect the printability, therefore are important criteria to judge 3D printing materials (Liu et al., 2017; Yang et al., 2018). The effect of temperature on rheological properties can be a parameter to consider in 3D printing, meaning its control must be considered in the design of printers. During the extrusion process, rheological properties of materials are critical for providing proper extrudability, binding of different foodstuff layers, and to support the weight of deposited layers. In food printing, soft materials, such as dough and meat pastes have been utilised to print 3D objects (Godoi et al., 2016). Apparent viscosity is an important factor which should be low enough to allow for easy extrusion but high enough to adhere to previous deposited layers (Liu, Zhang, Bhandari, & Yang, 2018). Until last year, limited information on the effects of the printer variables such as temperature of food, travel speed, print speed, infill levels, and layer height, on the printing performances of the food were available (Severini & Derossi, 2016; Severini, Azzollini, Albenzio, & Derossi, 2018, however, has seen an increase in the number of investigations of rheological characteristics, and effect of printing conditions, on the properties of several printed food snacks, including, potato puree, lemon juice gel, surimi, vegetables, sauces and processed cheese (Derossi, Caporizzi, Azzollini, & Severini, 2018; Hamilton, Alici, & in het Panhuis, 2018; Holland, Foster, MacNaughtan, & Tuck, 2018; Le Tohic et al., 2018; Severini et al., 2018; Yang et al., 2018). These previous papers reveal the increasing interest in information of printing parameters and physicochemical properties of food, allowing improvement of food printers. 3D food printing is far more complex than it appears. There are several conditions that need optimising in 3D food printing, including proper application of mechanical force, careful design of the digital recipe, and suitable feeding ingredients. Different food formulations are necessary when different pressures are applied. Sometimes room temperature may also affect the food mixture flow rate through the food nozzle (Lipson & Kurman, 2013). While determining the food recipes, the properties of food materials should be considered; the materials should have high strength, to fit the needs of product printability (Yang, Zhang, & Bhandari, 2017). Concurrently, the temperature of the food during the printing process may be a key factor considering rheological properties. At present, there is little work that analyses the effect of printing temperature on the characteristics of final product rheological properties of 3D printed food (Diañez et al., 2019; Liu, Bhandari, Prakash, Mantihal, & Zhang, 2019). The aim of this paper was to study the printability of gels based on xanthan/konjac gums when affected by printing variables, such as, the printing temperature and rheological and textural properties, analysing the composition of the product.

Section snippets

Raw materials

Xanthan gum was kindly provided by Solé Graells S.A. (Barcelona, Spain). Glucomannan (KGM), Calcium lactate hydrate (CLH), and calcium gluconate anhydrous (CGA) were supplied by Sosa Ingredients S.L. (Moià, Spain). Sugar was purchased from a local supermarket. Colourant, Brilliant Blue E133, was supplied by ROHA EPSA S.L. (Torrent, Spain).

Preparation of solutions

The food-inks were formulated as water solutions composed of different concentrations of xanthan gum, KGM and sugar syrup (100 mL water, 20 g of sugar, 2 g of

Rheological and viscoelastic behaviour

Fig. 3 shows the elastic modulus (G′), viscous modulus (G″), apparent viscosity (η*), and tan δ, as a function of temperature. For Fig. 3 the heating rate was 2 °C/min for a syrup-xanthan gum–KGM (97.975, 0.575, 1.45) mixture. Table 2 shows the values of the rheological parameters for all the mixtures evaluated in this work at 20 °C and 50 °C. In Fig. 3 the mixture shows a melting transition, with a sigmoidal reduction in apparent viscosity (η*), G′, and G″ moduli, with a sigmoidal increase in

Conclusions

In this investigation the printing temperatures studied (25 °C and 50 °C) strongly affect rheological characteristics of the gel as implies a different interaction type. Samples printed at 50 °C were less elastic and had greater fluidity than samples printed at 25 °C. Regarding the effect of composition on rheological properties; higher values of G′, G″, and η* were obtained in the mixtures with lower syrup concentration, and with greater content of xanthan gum and KGM. The textural properties

Funding sources

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of authors' contributions

V. García-Alcaraz: Methodology, Visualization, Formal analysis.

S. Balasch-Parisi: Formal analysis, Methodology, Visualization.

Purificación García-Segovia: Conceptualization, Supervision, Writing - Review & Editing.

Javier Martínez-Monzó: Conceptualization, Methodology, Formal analysis, Supervision, Writing - Original Draft, Writing - Review & Editing.

Declaration of competing interest

The authors confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome.

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