We developed a method to perform direct ink writing (DIW) three-dimensional (3D) printing of milk products at room temperature by changing the rheological properties of the printing ink. 3D printing ...of food products has been demonstrated by different methods such as selective laser sintering (SLS) and hot-melt extrusion. Methods requiring high temperatures are, however, not suitable to creating 3D models consisting of temperature-sensitive nutrients. Milk is an example of such foods rich in nutrients such as calcium and protein that would be temperature sensitive. Cold-extrusion is an alternative method of 3D printing, but it requires the addition of rheology modifiers and the optimization of the multiple components. To address this limitation, we demonstrated DIW 3D printing of milk by cold-extrusion with a simple formulation of the milk ink. Our method relies on only one milk product (powdered milk). We formulated 70 w/w% milk ink and successfully fabricated complex 3D structures. Extending our method, we demonstrated multi-material printing and created food with various edible materials. Given the versatility of the demonstrated method, we envision that cold extrusion of food inks will be applied in creating nutritious and visually appealing food, with potential applications in formulating foods with various needs for nutrition and materials properties, where food inks could be extruded at room temperature without compromising the nutrients that would be degraded at elevated temperatures.
We developed a method to 3D-print milk-based inks at room temperature by changing the rheological properties. The method is based on direct ink writing (DIW) and permits multi-material printing of 3D edible structures.
Three-dimensional food printing (3DFP) leads to advances in digital gastronomy by targeting consumers’ specific requirements for nutrition customization and visual appeal. Dysphagia, or difficulty ...swallowing, is prevalent in elderly people and patients suffering from debilitating illnesses. Dysphagic diets require textural modifications to render them soft and safe to swallow. Diets must be visually pleasing to enable a greater food uptake to prevent malnutrition in patients. 3DFP so far has mainly utilized freeze-dried vegetable powders for shaping 3D designs. Our work focuses on fresh and frozen vegetables having better nutritional profile and low costs. Three different categories of vegetables are identified based on the number of hydrocolloids required to render them printable. Garden pea, carrot and bok choy are chosen as representatives in each category, which requires no HC, one type of HC and two types of HCs, respectively. Food inks are prepared by the addition of HCs i.e. xanthan gum (XG), kappa carrageenan (KC) and locust bean gum (LBG) for texture modification. Rheological, textural, microstructural and syneresis properties of the inks are examined. International dysphagia diet standardisation initiative (IDDSI) tests are done to assess the potential of the inks for dysphagic diets. Optimized ink formulations display excellent 3D printability, minimal water seepage, and dense microstructures with minimal amount of HCs. Using fresh vegetables instead of freeze-dried foods serves the purpose of preserving flavour and nutrition like real food. This in turn may bring 3DFP closer to the hospital and nursing home kitchens.
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•Three-dimensional food printing of fresh vegetables for dysphagic patients.•Three vegetable categories defined according to the number of hydrocolloids required to prepare food inks.•Extensive characterization of food ink properties and its suitability for dysphagic patients.•3D-Printable food inks with no more than 2% hydrocolloids.•A method of quantifying syneresis in food inks.
3D printing has enabled modifying internal structures of the food affecting textural properties, but predicting desired texture remains challenging. To overcome this challenge, the use of response ...surface methodology (RSM) was demonstrated to develop empirical models relating 3D printing parameters to textural properties using aqueous inks containing cricket powders as a model system. Regression models were established for our key textural properties (i.e., hardness (H), adhesiveness (A), cohesiveness (C), and springiness (S)) in response to three 3D printing parameters: infill percentage (i), layer height (h), and print speed (s). Our developed model successfully predicted the 3D printing parameters to achieve the intended textural properties using a multi-objective optimization framework. The predicted limits for H, A, C, and S were 0.66–5.39 N, 0.01–12.43 mJ, 0.01–1.05, and 0–19.20 mm, respectively. To validate our models, we simulated the texture of other food using our model ink and achieved high accuracy for H (99%), C (82%), and S (87%). This work highlights a simple way to 3D-print foods with spatially different textures and materials, unlocking the full potential of 3D printing technology for manufacturing a range of customized foods.
Three-dimensional food printing offers the possibility of modifying the structural design, nutrition, and texture of food, which may be used for consumers with special dietary requirements such as ...dysphagic patients. One of the food matrices that can be used for liquid delivery to dysphagic patients is food foams. Foams are widely used in different food products to adjust food density, rheological properties, and texture. Foams allow the food to stay in the mouth for sufficient time to provide hydration while minimizing the danger of choking. Our work studies the foam properties and printability of both egg white foams and eggless foams with a strong focus on their foaming properties, rheological properties, printability, and suitability for dysphagic patients. Food hydrocolloid, xanthan gum (XG), is added to improve foam stability and rheological properties so that the inks are printable. Rheological and syneresis properties of the pre-printed foam inks are examined. The texture profile and microstructure properties are studied post-printing. International dysphagia diet standardization initiative tests are carried out to assess the inks' potential for dysphagic diets. Inks with XG performed better with minimal water seepage, better foam stability, and excellent printability. This suggests that hydrocolloids lead to more stable food foams that are suitable for 3DFP and safe for hydration delivery to dysphagic patients.
Gelatin and transglutaminase (TG) ink is increasingly popular in direct ink writing three-dimensional (3D) printing of cellular scaffolds and edible materials. The use of enzymes to crosslink gelatin ...chains removes the needs for toxic crosslinkers and bypasses undesired side reactions due to the specificity of the enzymes. However, their application in 3D printing remains challenging primarily due to the rapid crosslinking that leads to the short duration of printable time. In this work, we propose the use of gelatin preheated for 7 days to extend the duration of the printing time of the gelatin ink. We first determined the stiffness of freshly prepared gelatin (FG) and preheated gelatin (PG) (5 – 20% w/w) containing 5% w/w TG. We selected gelatin hydrogels made from 7.5% w/w FG and 10% w/w PG that yielded similar stiffness for subsequent studies to determine the duration of the printable time. PG inks exhibited longer time required for gelation and a smaller increase in viscosity with time than FG inks of similar stiffness. Our study suggested the advantage to preheat gelatin to enhance the printability of the ink, which is essential for extrusion-based bioprinting and food printing.
We developed a method to perform direct ink writing (DIW) three-dimensional (3D) printing of coconut-based products with high oil content by varying compositions of the coconut oil and the coconut ...cream. The addition of oils is particularly crucial in providing energy, developing neurological functions, and improving the palatability of food. Despite the potential merits of high oil-content foods, there have been limited studies on 3D printing of high oil-content foods. In particular, the effect of oil content on the printability of food inks has not been studied to date. 3D printing of food inks with high oil contents is challenging due to oil separation that leads to unpredictable changes in rheological properties. In this work, we surveyed the behavior of the mixture of the coconut oil and the coconut cream and identified the appropriate conditions for the food inks that show the printability in DIW 3D printing. We initially formulated coconut cream inks added with coconut oil that did not exhibit oil separation, and characterized the rheological properties of such inks. We successfully 3D-printed coconut cream with additional coconut oil and successfully fabricated 3D structures with inks containing 25% water with an additional 10% (w/w) of coconut oil. Texture profile analysis (TPA) suggested that the hardness index and the chewiness index of mesh-shaped 3D-printed coconut cream decreased due to an increase in the water content of the ink. Overall, this study offered an understanding of the stability of the food inks and demonstrated the fabrication of 3D colloidal food with controlled oil content, which can be applied to formulating foods with tunable oil content to cater to individual nutritional needs without compromising the stability of the inks.
This paper describes a method for multi-material 3D food printing using a multi-channel nozzle in direct ink writing (DIW) with rapid ink switching. Existing methods for multi-material food printing ...rely on independently controlled syringes, posing challenges in (1) aligning more than one type of food inks and (2) creating a seamless continuous food filament with different materials. To overcome this limitation, we developed a method using a Y-junction nozzle for seamless ink switching. The use of two inks possessing different rheological properties may result in the backflow of the higher-yield-stress fluid into the channel of the lower-yield-stress fluid, which was addressed by designing the channel sizes to limit the backflow. We successfully demonstrated continuous printing of two food inks exhibiting a yield stress difference on the order of > 102. Real-time switching of the materials can delay deposition at the intended location, which was overcome by introducing an offset distance to the toolpath, resulting in a 74% reduction in print errors. Lastly, we demonstrated the Y-junction nozzle for co-laminar extrusion of two food materials, enabling anisotropic arrangements in 3D food objects. Our approach applies the Y-junction nozzle for multi-material 3D food printing, with broad applicability to various edible inks.
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Orange peels are often discarded as food waste despite being a nutritious source of vitamins and antioxidants. These orange peel wastes (OPW) are produced in millions of tons globally every year; ...discarding them results in detrimental environmental and economical impacts. This paper discusses the application of 3D printing technology to effectively upcycle the OPW into edible, healthy snacks for consumption. We aimed to develop a method to enable OPW to formulate 3D-printable inks for direct ink writing (DIW). Using DIW 3D printing, we successfully created edible constructs of rheologically modified inks containing OPW. The formulated ink possessed an initial viscosity of 22.5 kPa.s, a yield stress of 377 Pa, and a storage modulus of 44.24 kPa. To validate the method, we conducted a biochemical analysis of the OPW at each stage of the fabrication process. This study suggested that our ink formulation and 3D printing process did not affect the content of bioflavonoids and antioxidants of the OPW. The cell viability test using human dermal microvascular endothelium (HMEC-1) suggested that the OPW did not exhibit cytotoxicity throughout the entire process of the ink manipulation. Overall, this study has highlighted a potential scenario to revalorize food waste into the food value chain using 3D printing toward more sustainable and circular food manufacturing and consumption.
Distributed Denial of Service (DDoS) attacks remain a daunting challenge for Internet service providers. Previous work on countering these attacks has focused primarily on attacks at a single server ...location and the associated network infrastructure. Increasingly, however, high-volume sites are served via content distribution networks (CDNs). In this paper, we propose two mechanisms to withstand and deter DDoS attacks on CDN-hosted Web sites and the CDN infrastructure. First, we present a novel CDN request routing algorithm which allows CDN proxies to effectively distinguish attacks from the requests from actual users. The proposed scheme, based on the keyed hash function, can significantly improve the resilience of CDNs to DDoS attacks. In particular, the resilience of a CDN, consisting of
n proxies, becomes O(
n
2) with the proposed approach, when compared to a site hosted by a single server. We present performance numbers from a controlled test environment to show that the proposed approach is effective. Second, we introduce novel site allocation algorithms based on the well-established theory on binary codes. The proposed allocation algorithm guarantees an upper bound on the level of service outage of a CDN-hosted site even when a DoS attack on another site on the same CDN has been successful. Together, our schemes significantly improve the resilience of the Web sites hosted by CDNs, and complement other work on countering DoS.
Three-dimensional food printing (3DFP) of multicomponent inks fortified with alternative proteins can help drive consumers towards easier and greater acceptance of alternative proteins by familiar ...nature of the final printed products with respects to taste, texture and appearance. Protein fortification is a well-established way of improving the nutritional and functional properties of foods and helping prevent malnutrition. This work focuses on the optimization of multicomponent food inks containing alternative proteins through response surface methodology (RSM) for 3D printing. RSM reduces the number of experiments required to robustly investigate the interrelationships between the desired response and composition of inks, thereby saving precious resources and time. A plant protein, three insect proteins, and an algae protein along with a traditional animal protein were chosen to fortify carrot powder. Usage of carrot as a vegetable food base to which different proteins and xanthan gum were combined served the purpose of adding the flavour and nutrition as well as providing desired rheological properties for printing. The six protein inks were optimised with the addition of hydrocolloid xanthan gum which worked as an excellent shear thinning and hydrating agent. Printability and syneresis were the targeted responses for optimization by RSM with the second order multiple linear regression model. The rheology, microstructure and textural profile of optimised protein inks were also studied. This RSM-based approach for multi-component food ink optimization is envisioned to be widely adopted in 3D food printing.
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•Three-dimensional food printing (3DFP) of food fortified with alternative proteins.•Insect, plant, algal and animal-based food powders utilised for 3DFP covering varied dietary habits.•Response surface methodology used for systematic optimization of multi-component protein inks.•Approach suitable for food ink optimization using responses including printability and syneresis.•Cricket, BSFL and sericin used as insect protein powders.
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