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The quality and protection of meat is now a critical concern of the food industry worldwide, as it is related to economic development and public health. The high demand for meat processing has led the meat industry to monitor the freshness and quality of the products as expected by the consumers. It is essential to reduce the spoilage of meat products caused by chemical compounds in a manner that is sustainable and healthy. Therefore, the development and implementation of analytical methods for determining the quality and protection of meat have increased over the years. The present review was carried out using inclusion benchmarks to classify the previous articles published between 2010 and 2020, specifically related to the analytical method for detecting freshness in various meat samples. In this study, the research addresses the microbial spoilage of meat products, the chemical compounds that lead to the spoilage of the meat, and the methods used to quantify the meat’s freshness. A large section covers current techniques to detect meat freshness, including electrochemical, electronic nose and gas sensors, as well as optical biosensors. The concluding section outlines the status of current challenges, identifies current issues, and discusses future views.

Organophosphorus pesticides (OPs) are used in crops to eradicate pests, but are of concern to the public, attributable to their potential toxicity to human health. In the present study, a biodegradable composite film containing citrate-stabilized gold nanoparticles (AuNPs) was developed to detect pesticides. The proposed composite film has distinctive structural and functional characteristics as a colorimetric recognition indicator for detecting OPs (malathion, fenthion, dimethoate, and chlorpyrifos). The developed film was morphologically and spectroscopically characterized through electron microscopy and UV–Vis spectrometry, respectively. The spherical-shaped and monodispersed AuNPs were obtained with an average particle size of 20 nm. The aggregation of the AuNPs composite film in the presence of pesticides led to a change in color from red to blueish purple, which could be visually observed on the surface of the vegetables. Under optimum conditions, the detection limit was 2.02 μM, 1.33 μM, 2.27 μM, and 11.77 μM for malathion, fenthion, dimethoate, and chlorpyrifos, respectively. The developed films demonstrated good biodegradability, and excellent storage stability, sensitivity and selectivity, with recovery values ranging from 99.60 to 103.68%, and relative standard deviation (RSD) values from 0.56 to 5.76%. The findings indicate a sensitive and selective sensing biodegradable colorimetric film, which is eco-friendly, biodegradable, considered to have promising low-costs, and a renewable source material for detecting pesticide residues.

Food additives can be used to enhance processability and/or nutritional properties of food. In this study, two type of additives, magnesium stearate (Mg-ST) powder (as a processing aid) and plant sterol (PS) powder (as a processing and nutritional aids) were added into grated chocolate in order to enhance its flowability during auger type extrusion-based 3D printing. The thermal and rheology data showed that the melting peak of chocolate with additives ranged from 31.4 ± 0.8 °C to 32.1 ± 0.1 °C and a rapid reduction in viscosity began between 31.1 ± 0.7 °C and 33.3 ± 0.2 °C. The addition of additives showed no significant difference (p > .05) in melting peak (Tp) temperature of control chocolate samples and 3D printed chocolate samples suggesting that Mg-ST and PS do not affect the melting behaviour of chocolate. However, the yield stress values of chocolates containing additives were relatively higher than that of control samples indicating the possible effect of particulates. The tribology curve did not represent the typical Stribeck curve with or without the addition of additives. The particles in the additive potentially influenced the lubrication behaviour of 3D printed chocolate as their addition increased the coefficient of friction of the chocolate samples reducing the slippage in auger extrusion.

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.

The effect of green peas (Pisum sativum) on the physicochemical and sensory properties of chicken nuggets was studied. Five formulations were developed in accordance to the incorporation of different percentages of green peas which include control formulations (GPC = 0%, GP3 = 3%, GP6 = 6%, GP9 = 9%, GP12 = 12%). The addition of green peas increases the total dietary fiber (TDF) in the chicken nugget formulation. The incorporation of fiber from green peas altering the physical properties of the sample as an increase in hardness was observed in treated sample with 12% wt/wt green peas (3.243 ± 0.490 N). Based on the sensory scores, there was no significance difference (p < .05) recorded for the attribute of texture. GP9 (9% green peas) was found to be the optimum formulation as it achieved the highest overall acceptance. Green peas are a potential ingredient that can enhance the dietary fiber, improve the texture, and produce appealing sensory properties of chicken nuggets.

3D food printing (3DFP) is an emerging novel technology in food fabrication, capable of creating food constructs with a layer-by-layer technique based on the desired design. The flexibility of this new technology offers the freedom to customise any preferred design. Among various type of 3D printing techniques, extrusion method is favourable to print the majority of fresh and edible foods. This method allows fresh foods in a paste, or liquid form to be extruded through the nozzle. Understanding the food material characteristic is the major factor that needs to be considered in choosing substrates for 3DFP. Dark chocolate was used as the main material in this work. It composed of cocoa butter (fat), cocoa solids, sugar, and lecithin. The important constituent in chocolate is cocoa butter (fat) containing the stable b-crystals in the chocolate matrix. These crystal fats help the chocolate to retain its quality such as glossy appearance, smooth texture and will set even after its being partially melted maintaining the b-crystal nuclei during printing. Extrusion method (auger) was applied in this work as the primary method to print the chocolate in powder form. Also, the addition of additive in auger extrusion is required to act as a flow enhancer, minimising the occurrence of slip-effect. Various physical properties, including analysing the effect of food additives, modification of internal structure, sensorial and potential consumersr perception and acceptance of 3D printed chocolates, were evaluated during this research work.At the beginning of this work, several modifications to a commercial 3D printer were required. The modification included developing a new 3D printer bed, water re-circulating system and the attachment of an air blower. A custom stainless steel printer bed (200 mm x 200 mm x 10 mm) was designed with an in-built water recirculation system (flow rate of 6.3 mL/s and maintain the temperature at ~16 oC).n Also, the printer bed was supported by a custom stabiliser printed by 3D filament printer using a plastic filament (Acrylonitrile Butadiene Styrene ABS). Additionally, an air blower was attached to avoid condensation that may occur on the printer bed due to cooling below room temperature. These modifications were done to ensure that the extruded chocolate solidifies efficiently upon extrusion. The optimisation of printing parameters was executed to determine the nozzle height and printing temperature. A series of comprehensive analysis including thermal properties, flow properties and tribological properties of printed chocolate was conducted. The original chocolate and the printed chocolate had a similar thermal melting profile (average melting peak of 32.9 p 0.3 dC) as analysed by DSC suggesting that the printed chocolate had similar crystal forms. Food grade additives, magnesium stearate (Mg-ST) and native plant sterol (PS) were investigated for their suitability as a flow enhancer to reduce the slip-effect of the powdered chocolate movement in the auger extrusion. The findings suggested that Mg-ST and PS did not influence the thermal and flow properties of the printed chocolate. However, tribology analysis indicated that chocolate samples with additives showing a higher coefficient of friction, possibly due to the effect of particle size.The 3D printer has the capability of modifying the internal structure of a food construct. In this study, 3D food printer was utilised to alter the internal construct structure (5%, 30%, 60% and 100%) infill percentage-IP (star, Hilbert curve and honeycomb infill patterns) to modify the textural properties of 3D printed chocolate. The void fraction of the printed constructs become lesser as IP increased from 5% to 100%. A higher force (N) was required to break the constructs with high IPs. Chocolate printed with Hilbert curve pattern required less force to break the samples (regardless of infill percentages, from 5% to 60% IP) ranging from 1.9 p 0.1 N to 11.7 p 0.7 N. For the same variation of infill percentages, the force required to break the samples printed with star pattern and honeycomb pattern ranged from 6.1 p 0.2 N to 45.3 p 1.4 N and 9.0 p 0.3 N to 47.4 p 0.5 N, respectively. Honeycomb and star infill pattern exhibited more interlayer bonding zones than that of Hilbert curve infill pattern producing a tougher 3D printed chocolates. The mechanical strength of the cast sample was higher (required g110 N) as compared to printed chocolate (100% IP). The results demonstrate that IPs influence the mechanical strength of 3D printed chocolate, indicating a textural change of the chocolate. In the sensorial perspective, texture modified chocolate (printed in a honeycomb pattern with various infill percentage 25%, 50% and 100%) was given to panellist (age between 28 and 55 years) to assess their preferences based on appearance and texture of the printed chocolate. The panellist suggested that the appearance of 3D printed chocolate (100% IP) was favourable and indicated their preferences for chocolate printed in 25% IP. A similar preference of cast chocolate and 3D printed chocolate samples in 100% infill percentage was obtained. Consumer perception was obtained by the 3D printer and printed chocolate samplesr display and using a survey questionnaire to assess their knowledge, perceived benefit and their attitudes towards 3DFP. The finding prominently indicated that most of the consumers in the investigated community (University of Queensland premises) were aware of 3D food printing technology. The display of 3D food printing contributed positive feedback from consumers as 3D printed dark chocolate samples were visible to the participants of the survey. These results demonstrated the positive attitudes of consumers toward 3D food printing technology.

3D printing is a new promising technology capable of creating intricate food shapes. To stabilize the mechanical properties of the complex printed food it may require support structures. The 3D shape of chocolate was designed with different support structures (cross support, parallel support and no support) and its effect on the snapping properties was investigated. This study also determined the relationship between the physical properties of chocolate used for printing and the quality of the printed 3D constructs. The dimensions (wall thickness, height, and diameter), weight as well as physical properties (melting properties, flow behaviour, snap ability) of the 3D printed chocolate were evaluated. The nozzle temperature before deposition was maintained at 32 °C in order to extrude the melted state of the sample as the flow behaviour curves indicated that the melting of chocolate started between 28 °C to 30 °C. Incorporation of Magnesium Stearate (MgST) in the chocolate formulation aid in material lubrication and increase flow efficiency during deposition. Results showed that there was a minor difference between the predetermined diameter and the actual output diameter for each sample suggesting similarity between the printed 3D structure and the pre-designed 3D model. Wall thickness of printed item varied along the height due to uneven deposition of chocolate as the layer height increased. The breaking strength of the sample was strongly related to the additional support structure, with 3D chocolate with cross support structure requiring the highest force (N) to break the sample. Industrial relevance The development and production of food with 3-Dimensional printing (3DP) technology has potential to create and produce food in a more advanced format that will be a new paradigm shift in the food industry. Through 3D printing, personalised food can be created in terms of shape and nutritional composition. To firmly establish this promising technology as a powerful tool for engineering food it is required a thorough understanding of the supply ingredients and strategies to enhance printability. This study demonstrates the use of flow enhancer and inclusion of support structure in the designed shape were key factors influencing printability capacity of chocolate (edible ink chosen as a model).

This study aimed to assess the preferences and perceptions of texture-modified 3D printed chocolate through three measures, two tasting tests and one survey. In the first test, 30 semi-trained panellists ranked their overall preference from among the three samples of chocolate printed in a honeycomb pattern with infill percentages of 25%, 50% and 100%. The panellists ranked the samples based on appearance and hardness. In the second test, the same panellists nominated one preference between a 3D printed sample (100% infill percentage) and a cast commercial chocolate sample. Friedman test indicated that there was no significant difference in overall preferences for hardness although the panellists significantly preferred the appearance of samples with 25% and 50% over the 100% infill. Further, there was no significant difference in preference between the cast and 100% infill samples. The texture data of the chocolate samples showed that a higher force was required to break the chocolate samples as the infill percentage increased from 25% (20.4 ± 1.1 N) to 100% (54.4 ± 1.5 N). Also, the 3D printed chocolate (printed in 100% infill percentage) was found to be less hard than that of casted chocolate. In the survey of consumer perceptions, a total of 244 participated and assessed the samples for their intricate design and novel technology concept through a questionnaire. While there was a general awareness of 3D printing technology among these participants, many were impressed with the application of 3D printing to chocolate, as this was the first time they had seen this. The results obtained from the sensory tests and consumer survey provided a useful insight into consumers' perception of 3D food printing and the 3D products design. This awareness will be beneficial to promote this technology in the food industry. This article is protected by copyright. All rights reserved.

The 3D printing technology has been applied to directly to construct physical model from 3D modelling without any aid of mold. Several industries such as automobile, aerospace including and recently food industry has utilize this technology to manufacture a complicated and intricate part required in the industry. It is foreseeable that 3D food printing (3DP) are possible to produce complex food model with unique internal pattern. A 3D food printing technique is composed of an extrusion-based printing, selective laser sintering and inkjet (liquid binding) printing. The food materials such as sugar, gelatin-based chocolate, and are used to create designed shape based on layer-by-layer method. This paper presents a review of 3D food printing techniques. This review is to categorize, printability, productivity, properties of printable material and mechanism of 3D food printing techniques, as well as to propose the future direction of this novel technology.

This study aimed to create an intricate internal structure of 3D printed chocolate by varying the infill construction. Three intricate infill patterns designed were star, Hilbert curve and honeycomb with infill percentage of 5%, 30%, 60% and 100%. Cadbury dark chocolate (Choc-1) and Callebaut bittersweet dark chocolate (Choc-2) powders were used by incorporating magnesium stearate (Mg-ST) and plant sterol (PS) powders as food additives. Printing parameters were set up with an extrusion temperature of 32 °C, nozzle size of 0.78 mm and printing speed of 70 mm/s. The results showed that voids in printed samples of all three pattern with 5% infill density ranged from 60.8 ± 2.1% to 72.2 ± 1.8%. Voids in samples with 30% infill density ranged from 20.9 ± 2.1% to 49.2 ± 3.6% while with 60% infill density it ranged from 11.6 ± 2.3% to 19.4 ± 4.2%. Additionally, star and honeycomb infill pattern produced the most stable and tough structure at 60% infill as indicated by a higher normal force (N) to break the printed sample. Moreover, even at 100% infill percentage, 3D printed chocolate were found less hard (ranged from 82.2 ± 2.2 N to 92.2 ± 1.3 N) as compared to cast samples (>110 N) in the snap test. The results obtained in this study provide a useful insight in creating various internal structures of 3D printed dark chocolate with different textural characteristic and physical stability.