Effect of Extrusion Temperature and Feed Moisture Content on the Microstructural Properties of Rice-Flour Pellets and Their Impact on the Expanded Product

A Review on the Application of Animal-Based Materials Using Three-Dimensional (3D) Printing and Protein Restructuring Technologies

Production of alternative proteins is crucial for the development of future protein resources. This study explored the creation of sustainable animal resources by combining extrusion molding and three-dimensional (3D) printing technologies. Extrusion effectively organizes vegetable proteins at high temperatures and pressures to replicate meat-like textures, and high-moisture extrusion successfully mimics the fiber structure of conventional meat. However, many meat analogs products still differ from conventional meat in terms of sensory properties such as texture, juiciness, and flavor, indicating the need for quality improvement. Researchers have leveraged 3D printing technology to incorporate fat analogs and enhance the appearance and texture through muscle fiber simulation. This technology allows for precise arrangement of muscle fibers, formation of adipose tissue, and marbling, thereby improving the overall sensory experience. By combining extrusion and 3D printing, we can enhance the nutritional and organoleptic qualities of meat analogs, ultimately meeting consumer expectations and achieving a balance between plant- and animal-based materials.

Investigating extrusion impact on functional, textural properties, morphological structure, and molecular interactions in hulless barley-based extruded snacks supplemented with mung bean

The effect of varying extrusion conditions on the functional properties of hulless barley-mung bean (70:30) extruded snacks was investigated using response surface methodology with feed moisture (FM), barrel temperature (BT), and screw speed (SS) as process variables. Results revealed significant impacts on functional characteristics with varying extrusion conditions. Bulk density (BD) of extruded snacks ranged from 0.24 to 0.42 g/cm3, showing that lower FM and higher BT results in lower BD while it increased with increasing FM, SS, and BT. The expansion ratio (ER) of extruded snacks ranged between 2.03 and 2.33, showing BT and SS had a desirable positive effect, whereas increasing FM led to decreased ER. Increasing BT and SS depicted a negative effect on water absorption index, whereas FM showed positive effect, which ranged between 4.21 and 4.82 g/g. A positive effect on water solubility index was depicted by BT and SS, which ranges between 9.01% and 13.45%, as higher SS and BT led to starch degradation and increased solubility suggesting better digestibility. The hardness of extruded snacks ranged from 32.56 to 66.88 Newton (N), showing increasing FM increased hardness, whereas higher SS and BT resulted in lowering the hardness. Scanning electronic microscope (SEM) analysis revealed structural changes in extrudates in comparison with nonextruded flour, indicating starch gelatinization and pore formation affected by varying processing parameters. Shifts in absorption bands were observed in Fourier transform infrared spectroscopy (FT-IR), suggesting structural changes in starch and protein. Understanding the effects of extrusion parameters on product properties can help tailored production to meet consumers' preferences and the development of functional snacks with improved nutritional quality.

Formation of pores and bubbles and their impacts on the quality attributes of processed foods: A review

Pores and bubbles significantly influence the physical attributes (like texture, density, and structural integrity), organoleptic properties, and shelf life of processed foods. Hence, the quality of foods and their acceptance by the consumers could be influenced by the properties and prevalence of pores and bubbles within the food structure. Considering the importance of pores, this review aimed to comprehensively discuss the factors and mechanisms involved in the generation of pores and bubbles during the processing of different food products. Moreover, the characteristics and effects of pores on the properties of chocolates, cheeses, cereal-based foods (like cake, puffed grains, and pasta), dried, and fried products were discussed. The impacts of bubbles on the quality of foam-based products, foam creamers, and beverages were also explored. This review concludes that intrinsic factors (like food compositions, initial moisture content, and porosity) and extrinsic factors (like applied technologies, processing, and storage conditions) affect various properties of the pores and bubbles including their number, size, orientation, and distribution. These factors collectively shape the overall structure and quality of processed food products such as density, texture (hardness, cohesiveness, chewiness), and water holding capacity. The desirability or undesirability of pores and their characteristics depends on the type of products; hence, some practical hints were provided to mitigate their adverse effects or to enhance their formation in foods. For example, pores could increase the nutrient digestion and reduce the shelf life of the products by enhancing the risk of fat oxidation and microbial growth. In conclusion, this study provides a valuable resource for food scientists and industry professionals by discussing the effects of pores on food preservation, heat, and mass transfer (including oxygen, moisture, flavors, and nutrients). Understanding the dynamic changes in porosity during processing will be effective in customization of final product quality with desired attributes, ensuring tailored outcomes for specific applications.

Relationship between microstructure formation and in vitro starch digestibility in baked gluten-starch matrices

Increased prevalence of diabetes prompts the development of foods with reduced starch digestibility. This study analyzed the impact of adding soluble dietary fiber (inulin-IN; polydextrose-PD) to baked gluten-starch matrices (7.5-13%) on microstructure formation and in vitro starch digestibility. IN and PD enhanced water-holding capacity, the hardness of baked matrices, and lowered water activity in the formulated matrices, potentially explaining the reduced starch gelatinization degree as IN or PD concentration increased. A maximum gelatinization decrease (26%) occurred in formulations with 13% IN. Micro-CT analysis showed a reduction in total and open porosity, which, along with the lower gelatinization degree, may account for the reduced in vitro starch digestibility. Samples with 13% IN exhibited a significantly lower rapidly available glucose fraction (8.56 g/100 g) and higher unavailable glucose fraction (87.76 g/100 g) compared to the control (34.85 g/100 g and 47.59 g/100 g, respectively). These findings suggest the potential for developing healthier, starch-rich baked foods with a reduced glycemic impact.

Effect of Starch Types on the Textural and Rehydration Properties of Extruded Peanut Protein Pore Gel Particles

In this study, the effect of different starches from corn, potato and pea containing varying amylose/amylopectin ratios on the textural and rehydration properties of extruded peanut protein gel particles were investigated. Results showed that textural and rehydration properties of peanut protein extruded with corn starch, potato starch and amylopectin are slightly inferior to those of peanut protein with pea starch extrudates. The addition of pea starch led to an increase in the pore structure of the peanut protein extrudates and improved their water absorption index, simultaneously reducing the hardness and density. Pea starch, as a natural water-absorbing expansion material, helped peanut protein to form cross-linked gel polymers that bind more water molecules, in addition to further polymerization with peanut protein, which made the protein secondary structure became disordered. These changes directly affected the textural properties of the extrudates. In addition, the blended system of starches and peanut protein tended to form more elastic solids, which affected the expansion of the extrudates. These findings indicate that starch can effectively improve the poor expansion of proteins, making it suitable for use in the production of plant protein-based foods.

Understanding the physical breakdown and catechin bioaccessibility of third generation extruded snacks enriched with catechin using the human gastric simulator

The nutritional quality of third-generation snacks prepared from rice flour by extrusion can be improved by the addition of polyphenols such as catechins, which are known to be more stable at high temperatures. However, the extrusion parameters can impact the breakdown and release of bioactive compounds and decrease the catechin bioaccessibility. Accordingly, this study investigated the impact of different extrusion parameters, including different extrusion temperatures (110, 135, and 150 °C) and moisture content prior to extrusion (27 and 31%), on the breakdown and bioaccessibility of catechin-enriched snacks during in vitro dynamic digestion using the Human Gastric Simulator (HGS). The extrusion parameters did not significantly impact most measured variables by themselves, indicating that within the tested ranges, any of the processing conditions could be used to produce a product with similar digestive behavior. However, the interaction of extrusion parameters (temperature and moisture content) played a significant role in the snack behavior during digestion. For example, the combination of 27% moisture content and 150 °C extrusion temperature had higher catechin bioaccessibility and higher starch hydrolysis than the other treatments. Overall, these findings suggest that the processing conditions of third generation snacks enriched with catechin can be optimized within certain ranges with limited modifications in the digestive properties.

Mechanochemical Degradation of Biopolymers

Mechanochemical treatment of various organic molecules is an emerging technology of green processes in biofuel, fine chemicals, or food production. Many biopolymers are involved in isolating, derivating, or modifying molecules of natural origin. Mechanochemistry provides a powerful tool to achieve these goals, but the unintentional modification of biopolymers by mechanochemical manipulation is not always obvious or even detectable. Although modeling molecular changes caused by mechanical stresses in cavitation and grinding processes is feasible in small model compounds, simulation of extrusion processes primarily relies on phenomenological approaches that allow only tool- and material-specific conclusions. The development of analytical and computational techniques allows for the inline and real-time control of parameters in various mechanochemical processes. Using artificial intelligence to analyze process parameters and product characteristics can significantly improve production optimization. We aim to review the processes and consequences of possible chemical, physicochemical, and structural changes.

Effect of wheat dextrin on corn flour extrusion characteristics

Wheat dextrin is a modified wheat starch, classified as water-soluble. This study investigated the effect of wheat dextrin as an ingredient in corn flour blends on extrusion characteristics. Blends were prepared at 0, 10 and 20 % fibre content. DOE was used to design experiments and investigate the effects of variables selected to be studied. Feed moisture content was set at 18-25 %, temperature at 110-150 °C and specific feeding load at 0.100-0.150kg/rev. Moisture content, water absorption and solubility indices, color, sectional expansion index, density, hardness, crispiness (work (Wc) and number of spatial ruptures (Nsr)) and specific mechanical energy were evaluated. A regression model was established using response surface methodology, and processing conditions for optimal quality were generated (e.g., WSI: 96.9 %, SME: 96.9 %, final MC: 93.9 %). Wheat dextrin solubility characteristics for moisture content, WAI and WSI were inconclusive, showing a high tendency to insoluble behavior. For expansion, lightness and SME characteristics depended on processing conditions, especially temperature. Crispness was highest at low MC (18.87 %) x high fiber content (20 %) (e.g., Nsr: 1.2-1.5/mm), whereas values were the lowest at high MC (25.70 %) x low fiber content (0 %) (e.g., Nsr: 0.5-0.7/mm). Optimal conditions were set at 12 % fiber content, 19 % feed moisture content, 130 °C and a specific feeding load of 0.146 kg/rev. This study showed that it is impossible to classify wheat dextrin as acting strictly according to soluble fiber characteristics based on extrudate characteristics.

Structure and Texture Characteristics of Novel Snacks Expanded by Various Methods

The aim of this work was to evaluate the structure of novel potato-based snack foods supplemented with various levels of fresh carrot pulp by using X-ray micro-computed tomography, texture profile, and sensory analysis. Three different methods of extruded snack pellets expansion were used to obtain ready-to-eat crisps: deep-fat frying, microwave, and hot-air toasting. The obtained results revealed that the pellets expansion method affected the porosity, size of pores and wall thickness, texture properties, and notes of sensory analyses of the obtained crisps. Deep-fat frying had a similar influence to microwave heating on ready-to-eat crisps properties, and both methods were significantly different in comparison to hot-air toasting. Crisps based on snack pellets supplemented with the addition of fresh carrot pulp in the amount of 10 to 30% expansion through hot-air heating showed unsatisfactory expansion and texture, but it is highly advisable to use deep-fat frying and microwave heating to achieve attractive potato-carrot crisps.

Effect of the Addition of Soybean Residue (Okara) on the Physicochemical, Tribological, Instrumental, and Sensory Texture Properties of Extruded Snacks

An extrusion process was used to improve the physical and textural characteristics of an extruded snack supplemented with soybean residue (okara). An extreme vertices mixture design with a constraint for okara flour (0−50%), mung bean flour (20−70%), and rice flour (20−80%) resulted in the production of eleven formulations. The color, radial expansion index (REI), bulk density, tribological behavior, and instrumental and sensory texture of the extruded snacks were evaluated. Increasing the quantity of okara resulted in an extrudate with a darker, redder color, decreased REI, increased bulk density, and decreased crispness. The tribological pattern of the snack was determined by its dominant composition (protein, starch, or fiber) in the flour mixture, which contributed to the stability of the lubricating film under rotational shear. A principal component analysis of sensory data captured a total of 81.9% variations in the first two dimensions. Texture appeal was inversely related to tooth packing (r = −0.646, p < 0.05). The optimized formulation for texture preference had an okara content of 19%, which was 104% crispier and 168% tougher than an okara content of 40%. This by-product of soybean milk processing can thus be used to develop gluten-free snacks with desirable physical characteristics and texture.

Twin-Screw Extrusion of Oat: Evolutions of Rheological Behavior, Thermal Properties and Structures of Extruded Oat in Different Extrusion Zones

Further investigation of material properties during the extrusion process is essential to achieve precise control of the quality of the extrudate. Whole oat flour was used to produce low moisture puffed samples by a twin-screw extruder. X-ray diffraction (XRD), Scanning electron microscopy (SEM), infrared spectroscopy (FTIR), thermal analysis, and rheological experiments were used to deeply characterize changes in the structure and cross-linking of oats in different extrusion zones. Results indicated that the melting region was the main region that changed oat starch, including the major transformation of oat starch crystal morphology and the significant decrease of enthalpy representing the starch pasting peak in the differential scanning calorimeter (DSC) pattern (p < 0.05). Moreover, the unstable structure of the protein increased in the barrel and then decreased significantly (p < 0.05) after being extruded through the die head. The viscosity of oats increased in the cooking zone but decreased after the melting zone. A transformation occurred from elastic-dominant behavior to viscoelastic-dominant behavior for oats in the melting zone and after being extruded. This study provides further theoretical support for the research of the change of materials during extrusion and the development of oat-based food.