3D food printing is an emerging technology with a potential to influence the food manufacturing sector. Rheological properties of food inks are critical for their successful 3D printing. However, the ...relationships between rheological properties and 3D printability have not been clearly defined in food systems. In this work, a gel model system composed of carrageenan-xanthan-starch was prepared for an extrusion-based 3D food printer. The 3D printing process was divided into three stages and the corresponding rheological properties of inks for each stage were determined, namely extrusion stage (yield stress, viscosity and shear-thinning behaviour), recovery stage (shear recovery and temperature recovery properties) and self-supporting stage (complex modulus G* and yield stress at room temperature). Finally, 3D printability of the model inks was systematically studied starting with printing lines/pentagram (one dimensional, 1D structure) to printing lattice scaffold (two dimensional, 2D structure) and finally printing cylinders (three dimensional, 3D structure). Results demonstrated that addition of starch and xanthan gum in k-carrageenan based inks increased inks' gelation temperature (Tgelation), viscosity (within shear rate of 0.01–100 1/s), yield stress, G*, enhanced shear-thinning (thixotropic) behaviour and reduced time-dependence of modulus (temperature recovery). Rheological responses of yield stress (cross-over point where G′ (elastic modulus) equals to G′′ (viscous modulus) in the stress sweep tests) and shear-thinning behaviour (viscosity decreased when shear rate increased) were closely related to ink's extrudability. Inks' gelation temperature (Tgelation) and time-dependent behaviour (gelation time, tgel) significantly affected their printability and shape retention performance. The mechanical strength of the ink is important to be self-supporting, especially for 3D structures. Insights achieved from this study could provide guidance on improving 3D printability of foods that use hydrocolloids as a printing aid.
Display omitted
•Thixotropic and thermo-reversible gel system was used as a model in 3D printing.•Ink's rheology and 3D printability was correlated in the whole printing process.•1D, 2D, 3D structures were fabricated and correlated with ink's rheology.
3D printing was used for printing mashed potatoes (MP) constructs with variable internal structures. The dimensional properties, textural and structural qualities of the printed objects were ...investigated as a function of infill levels (10, 40 and 70%), infill patterns (rectilinear, honeycomb and hibert curve), and number of shell perimeters (3, 5 and 7). The printed samples significantly matched the designed geometries. Hardness and gumminess were strongly related to infill levels and perimeters, but the printing paths being performed to fill the samples showed no effect on them. Firmness and Young's modulus were only affected by infill percentage but not by perimeters and printing paths. Further, comparative assessment of 3D printed and cast samples were also conducted on the textural properties and microstructure features. Microstructure analysis indicated a uniform internal structure was obtained for cast sample. In comparison, an obvious layered structure was observed in longitudinal-sectional direction while a porous structure was obtained in cross-sectional view of 3D printed samples regardless of infill levels. 3D printed samples, even at 100% infill, were significantly (p < .05) less hard, by up to 26.75% and 28.36% in terms of hardness and gumminess, compared to cast samples. The results suggest that 3D printing considerably changes the properties of printed samples, possibly offering a new way for tailoring textural properties of printed samples through creating their internal structure.
Display omitted
•Different internal structure of mashed potatoes was created by 3D printing.•3D printing offers a new way for tailoring textural properties.•Comparative assessment was made between 3D printed and cast samples.
Gel formation characteristics and physical properties of baking dough changes with different composition of water, sucrose, butter, flour and egg contents. This study aims to explore how these ...changes affect 3D printing of the dough through laser scanning confocal microscopy (LSCM), low-field nuclear magnetic resonance (NMR), torque rheometer and texture analyser. Results show a pseudoplastic gel with suitable level of physical properties such as relatively higher extrudability, gel strength, elasticity and relatively lower ductibility was required to obtain better shape of the extruded samples. In conclusion, the best shape of 3D printing baking dough which was retained with proper gel formation characteristics and physical properties was obtained with a recipe containing water (29g), sucrose (6.6g), butter (6.0g), flour (48g) and egg (10.4g) per 100g of formulation.
The formulation of baking dough affected the modeling quality of printed samples. Thus, the optimized formulation of modified baking dough will contribute to the success in practical production.
•Baking dough formulation is invented specifically for 3D food fabrication.•3D printing modeling effect of different samples was studied.•Physical properties which are bond to the extruding behavior of printed samples in different compositions were assayed.•NMR was used to explore changes of water distribution.•LSCM was used to explore fat and protein distribution.
The use of 3-Dimensional (3D) printing, also known as additive manufacturing (AM), technology in food sector has a great potential to fabricate 3D constructs with complex geometries, elaborated ...textures and tailored nutritional contents. For this reason, 3D technology is driving major innovations in food industry. Here, we review the use of 3D printing techniques to design food materials. Our discussions bring a new insight into how essential food material properties behave during application of 3D printing techniques. We suggest that the rational design of 3D food constructs relies on three key factors: (1) printability, (2) applicability and (3) post-processing. Especial emphasis is devoted to how the advantages/limitations of 3D printing techniques affect the end-use properties of the printed food constructs.
•3D food printing technologies overview.•Design of new textures and tailored nutritional content.•Design of complex geometries of food structure.•How 3D printing techniques are influenced by material properties?•Rational choice of 3D printing technique to design food.
•Starch fine structures were measured by size-exclusion chromatography.•Amylopectin chain-length distribution was fitted in a biosynthesis model.•Hardness and stickiness of cooked rice grains were ...tested by texture analyzer.•Statistical correlation found between structural characteristics and rice texture.
Statistically and causally meaningful relationships are established between starch molecular structure (the molecular distribution of branched starch and the chain length distribution of debranched starch) and texture (hardness and stickiness) of cooked rice grains. The amounts of amylose chains with degree of polymerization (DP) 100–20,000, and of long amylopectin chains, positively correlated with hardness, while amylopectin chains with DP<70 and amylose molecular size both showed negative correlations with hardness (p<0.05). There was also a significant negative correlation between stickiness and the amounts of long amylopectin chains (p<0.01). For rices with similar amylose content, the amount of amylose chains with DP 1000–2000 positively correlated with hardness while size negatively correlated with hardness (p<0.05). This indicates for the first time that, regardless of amylose content, rice varieties with smaller amylose molecular sizes and with higher proportions of long amylose chains have a harder texture after cooking.
An air-fried 3D printed snack was developed to potentially provide consumer an alternative choice of potato snack with reduced oil. One cylindrical shape was firstly 3D printed with variable internal ...structures, followed by air-frying post-printing. The unfried printed samples well matched the designed geometry but with a slight shrinkage after air-frying process. Hardness and fracturability of air-fried potato snack, significantly affected by infill pattern, also significantly decreased when infill level decreased. The 100% infill printed and cast samples were observed with a serious puffing phenomenon during air-frying process. Finally, one kind of a food structure comprised of different parts illustrating multiple textures was developed by varying infill structure. The results suggested that the textural properties of the air-fried 3D printed potato snack could be modified by altering its internal structure, possibly offering a new way of oil reduction for potato-based snacks by creating customized internal structure by applying 3D printing.
•A new tribometer set up to study lubrication properties of dairy products.•Coefficient of friction of milks and cream cheeses with different fat levels determined.•The method differentiated the ...samples based on their different lubrication properties.
Tribology has a growing interest in oral texture and sensory research due to its ability to assess certain properties of the food during the complex oral processing that cannot be explained by its bulk texture and rheology. Developing a reliable, low cost and easy-to-use tribometer applicable to a wide variety of food products is still a big challenge to researchers. In this work, a simple method to measure lubricating properties (friction coefficient) of dairy products is presented using a newly introduced tribometer coupled with a widely used rheometer. Pasteurized milks (fat contents from 0.1% to 4.9%) and cream cheeses (fats content: 0.5%, 5.5%, 11.6%) were chosen as representative dairy products and their friction coefficients were measured as a function of entrainment speed of the tribometer. The friction coefficients of the samples at low entrainment speed generating low shear rate (similar to the shear rate in mouth) were significantly different between the samples at each fat levels. Thus, this method is capable of differentiating samples with different fat contents both in liquid or semi-solid forms. This suggests a promising application of this technique for a quick assessment of the sensory mouthfeel of various dairy products in relation to fat content.
•3D printed hydrocolloid-added cooked beef pastes are potential foods for dysphagia.•Cooked beef pastes may be used for ready-to-eat- and finger-foods for dysphagia.•3D shape stability over time can ...be related to the phase angle across frequencies.•Minimal dimensional deviancy detected at rather constant or declining phase angles.
The printability and textural attributes of cooked beef pastes with xanthan gum (XG), guar gum (GG), k-carrageenan (KC), and locust bean gum (LB) added individually or as blends (50:50 ratios) in concentrations of 0.5% and 1% were analysed. Pastes with ease of extrusion displayed viscosities at rest ranging from 108±11 Pa.s to 350±26 Pa.s and viscosities at the estimated shear of extrusion (~50/s) of about 4.3 ± 0.1 Pa.s to 11.6 ± 0.3 Pa.s. Samples with higher 3D printing dimensional deviation showed increasing phase angles across frequencies, reaching 21.3 ± 0.8° and 23±1° and denoting less shape stability over time. In contrast, those with minimal or negligible deviation displayed either constant or decreased phase angles with values ranging between 13.2 ± 0.2° and 17.4 ± 0.7° In addition, the textural attributes by Texture Profile Analysis (TPA) and the International Dysphagia Diet Standardisation Initiative (IDDSI) testing methods suggested the application of the different formulations as modified-texture foods, potentially categorising into levels 5, 6 and 7 of the IDDSI framework.
Display omitted
The stickiness of cooked rice is important for eating quality and consumer acceptance. The first molecular understanding of stickiness is obtained from leaching and molecular structural ...characteristics during cooking. Starch is a highly branched glucose polymer. We find (i) the molecular size of leached amylopectin is 30 times smaller than that of native amylopectin while (ii) that of leached amylose is 5 times smaller than that of native amylose, (iii) the chain-length distribution (CLD: the number of monomer units in a chain on the branched polymer) of leached amylopectin is similar to native amylopectin while (iv) the CLD of leached amylose is much narrower than that of the native amylose, and (v) mainly amylopectin, not amylose, leaches out of the granule and rice kernel during cooking. Stickiness is found to increase with decreasing amylose content in the whole grain, and, in the leachate, with increasing total amount of amylopectin, the proportion of short amylopectin chains, and amylopectin molecular size. Molecular adhesion mechanisms are put forward to explain this result. This molecular structural mechanism provides a new tool for rice breeders to select cultivars with desirable palatability by quantifying the components and molecular structure of leached starch.
•Rice texture was evaluated by sensory panellists and two instrumental methods.•Two instrumental methods showed strong correlation with sensory results.•Dynamic rheological testing can be used to ...replace the conventional TPA method.•Rheological behaviour is explained from starch structural differences.
Increasing demands for better instrumental methods to evaluate cooked rice texture is driving innovations in rice texture research. This study characterized cooked rice texture by descriptive sensory analysis and two instrumental methods (texture profile analysis (TPA) and dynamic rheological testing) using a set of 18 varieties of rice with a wide range in amylose content (0–30%). The panellists’ results indicated that hardness and stickiness were the two most discriminating attributes among 13 tested textural attributes. The consistency coefficient (K*) and loss tangent (tan δ) from a dynamic frequency sweep were used to compare with hardness and stickiness tested by TPA and sensory panellists, showing that using K* to express hardness, and tan δ to express stickiness, are both statistically and mechanistically meaningful. The instrumental method is rationalized in terms of starch structural differences between rices: a higher proportion of both amylose and long amylopectin branches with DP 70–100 causes a more elastic and less viscous texture, which is readily understood in terms of polymer dynamics in solution.
PDF
