Low Moisture Extrusion Research Articles

Investigating the Impact of Moisture Levels on Structural Alterations and Physicochemical Properties of Cassava Flour through Extrusion: A Comprehensive Study.

The extrusion process, a vital technique for starch modification, is notably influenced by the moisture content (MC). This study aimed to elucidate the effect of varying MC levels (18, 22, 26, and 30%) on the structural and physicochemical characteristics of cassava flour during extrusion. Extrusion resulted in the fraction of degree of polymerization 13‒24, degree of branching, and molecular weight increased with increasing MC, with values of above indexes being 32.29%, 1.05%, and 1.21 × 105 g/mol, respectively, at a MC of 18%. This suggested that the degradation of amylopectin and amylose. Additionally, there was an increase in rapidly digestible starch (RDS) and a decrease in slowly digestible starch (SDS) in the extrudates in comparison to the native cassava flour. The extrusion of cassava flour at 18% MC exhibited the highest levels of RDS and SDS, reaching 64.52% and 4.06%, respectively. These findings indicated that low moisture extrusion could be a more effective method for disrupting the structure of cassava starch and enhancing the digestibility of cassava flour, offering valuable insights for the optimized use of cassava extrudates in various applications.

Dietary fiber-rich Lentinula edodes stems influence the structure and in vitro digestibility of low-moisture extruded maize starches

Low-moisture extrusion (LME) can be used to improve the utilization of dietary fiber-rich Lentinula edodes stems (LES). The incorporation of dietary fiber can affect heat-induced interactions of starch molecules, which are critical for modifying starch characteristics via LME. In this work, a blend of LES and maize starch was extruded into a product at low moisture (30 %, w/v). The structure, physicochemical properties, and in vitro digestibility of extruded maize starches were investigated at different LES levels. The results showed that low levels (<7 %) of LES increased the crystallinity of LME-produced starch, while high levels (>7 %) did not. Because of the LES's soluble to insoluble dietary fiber ratios, the increased crystallinity of LES-added starch led to greater molecular ordering and the formation of an elastic gel after LME. At a suitable LES level (~3 %), highly crystallized starches were resistant to enzymolysis and had a high proportion of resistant starch. The obtained findings would contribute to a better understanding of how dietary fiber-rich LES affects starch extrusion and provide an alternative use for boosting the value of LES by-products.

A Comprehensive Review on Harnessing Soy Proteins in the Manufacture of Healthy Foods through Extrusion.

The global development of livestock production systems, accelerated by the growing demand for animal products, has greatly contributed to land-use change, greenhouse gas emissions, and pollution of the local environment. Further, excessive consumption of animal products has been linked with cardiovascular diseases, digestive system diseases, diabetes, and cancer. On the other hand, snacks, pasta, and bread available on the market are made from wheat, fat, salt, and sugar, which contribute to the risk of cardiovascular diseases. To counter these issues, a range of plant protein-based food products have been developed using different processing techniques, such as extrusion. Given the easy scalability, low cost of extrusion technology, and health benefits of soy proteins, this review focuses on the extrusion of soy protein and the potential application of soy protein-based extrudates in the manufacture of healthy, nutritious, and sustainable meat analogs, snacks, pasta products, and breakfast cereals. This review discusses the addition of soy protein to reformulate hypercaloric foods through extrusion technology. It also explores physical and chemical changes of soy proteins/soy protein blends during low and high moisture extrusion. Hydrogen bonds, disulfide bonds, and hydrophobic interactions influence the properties of the extrudates. Adding soy protein to snacks, pasta, breakfast cereals, and meat analogs affects their nutritional value, physicochemical properties, and sensory characteristics. The use of soy proteins in the production of low-calorie food could be an excellent opportunity for the future development of the soybean processing industry.

Ingredient Functionality of Soy, Chickpea, and Pea Protein before and after Dry Heat Pretreatment and Low Moisture Extrusion.

This study investigates the impact of dry heat pretreatment on the functionality of soy, chickpea, and pea protein ingredients for use in texturized vegetable protein (TVP) production via low moisture extrusion. The protein powders were heat-treated at temperatures ranging from 80 °C to 160 °C to modulate the extent of protein denaturation and assess their effects on RVA pasting behavior, water absorption capacity (WAC), and color attributes. The results indicate that the pretreatment temperature significantly influenced the proteins' functional properties, with an optimal temperature of 120 °C enhancing pasting properties and maintaining WAC, while a higher pretreatment temperature of 160 °C led to diminished ingredient functionality. Different protein sources exhibited distinct responses to heat pretreatment. The subsequent extrusion processing revealed significant changes in extrudate density and color, with increased density and darkness observed at higher pretreatment temperatures. This research provides insights into the interplay between protein sources, pretreatment conditions, and extrusion outcomes, highlighting the importance of controlled protein denaturation for developing high-quality, plant-based meat analogues. The findings have broad implications for the optimization of meat analogue manufacturing, with the aim of enhancing the sensory experience and sustainability of plant-based foods.

Understanding the mechanism for sodium tripolyphosphate in improving the physicochemical properties of low-moisture extrusion textured protein from rapeseed protein and soybean protein blends

Our previous experiments found that rapeseed protein (RP) has applicability in low-moisture textured proteins. The amount of RP added is limited to <20 %, but the addition of 20 % RP still brings some negative effects. Therefore, in order to improve the quality of 20%RP textured protein, this experiment added different proportions of sodium tripolyphosphate (STPP) to improve the quality of the product, and studied the physical-chemical properties and molecular structure changes of the product to explore the possible modification mechanism. The STPP not only improved the expansion characteristics of extrudates, but also increased the brightness of the extrudates, the rehydration rate. In addition, STPP increased the specific mechanical energy during extrusion, decreased the material mass flow rate. Furthermore, STPP decreased the starch digestibility, increased the content of slow-digesting starch and resistant starch. STPP increased the degree of denaturation of extrudate proteins, the proportion of β-sheets in the secondary structure of proteins, as well as the intermolecular hydrogen bonding interactions. The gelatinization degradation degree of starch molecules also decreased with the addition of STPP. STPP also increased the protein-starch interactions and enhanced the thermal stability of the extrudate. All these indicate that STPP can improve the physical-chemical properties of extrudate.

The proteomic evidence on protein oxidation in pea protein concentrate-based low-moisture extrudates and its inhibition by antioxidants derived from plant extracts

This study aimed to assess the antioxidant activity of golden chlorella (GoC) and grape pomace (GrP) extracts both in vitro and in pea protein-based extrudates. We hypothesized that GoC/GrP would limit oxidation of proteins in the extrudates compared with commercial antioxidants. The results showed that GoC extract was effective in metal chelation and GrP extract possessed excellent radical scavenging activity and reducing power. Protein oxidation inevitably occurred after low-moisture extrusion in terms of elevated level of protein carbonyls and the gradual loss of thiols. LC-MS/MS revealed that the monoxidation and 4-hydroxynonenal adduction were the major oxidative modifications, and legumin was the most susceptible globulin for oxidation. The GoC/GrP extracts effectively retarded the oxidation progress in extrudates by lower intensity of oxidized peptides, whereas protein electrophoretic profiles remained unaffected. This study highlighted the great potential of GoC/GrP as natural antioxidants in plant-based foods.

Effects of extrusion screw speed, feed moisture content, and barrel temperature on the physical, techno-functional, and microstructural quality of texturized lentil protein.

Utilizing lentil protein as a novel ingredient for producing texturized vegetable proteins (TVPs) can provide new opportunities for the production of next-generation hybrid meat products. TVPs from lentil protein isolate were manufactured using low-moisture extrusion cooking at different combinations of screw speed (SS), feed moisture content (MC), and barrel temperature (BT) profile. In total, seven different combinations of processing treatments were tested, and the resulting TVPs were characterized for their physical (rehydration ratio, texture profile analysis, color, and bulk density), techno-functional (oil and water holding capacities), and microstructural properties. The processing conditions of higher SS and lower MC resulted in increased values of several textural profile attributes (springiness, cohesiveness, and resilience), increased water holding capacity (WHC), and decreased bulk density. Compared to raw lentil protein, TVPs showed enhanced oil holding capacity, though WHC either decreased or remained constant. The extrusion response parameters (die pressure, torque, and specific mechanical energy) showed positive correlations with several physical properties (texture, WHC, and total color change), revealing their potential for serving as important TVP quality indicators. TVPs produced at SS, MC, and BT of 450rpm, 30%,and 140°C, respectively, showed relatively better overall physical and techno-functional quality and can be used as meat extenders in hybrid meat patties. Overall, this research evidenced the viability of lentil protein as a potential ingredient for producing low-moisture TVPs.

Comparative structural, digestion and absorption characterization of three common extruded plant proteins

Extruded plant proteins, also known as textured vegetable proteins (TVPs), serve as vital components in plant-based meat analogue, yet their structural and nutritional characteristics remain elusive. In this study, we examined the impact of high-moisture (HM) and low-moisture (LM) extrusion on the structures, digestion and absorption of three types of plant proteins. Extrusion transformed plant proteins from spherical to fibrous forms, and formed larger aggregate particles. It also led to the disruption of original disulfide bonds and hydrophobic interactions within protein molecules, and the formation of new cross-links. Intriguingly, compared to native plant proteins, TVPs’ α-helix/β-sheet values decreased from 0.68 to 0.69 to 0.56–0.65. Extrusion increased the proportion of peptides shorter than 1 kD in digesta of TVPs by 1.44–23.63%. In comparison to unextruded plant proteins, TVPs exhibited lower content of free amino acids in cell transport products. Our findings demonstrated that extrusion can modify protein secondary structure by diminishing the α-helix/β-sheet value, and impact protein tertiary structure by reducing disulfide bonds and hydrophobic interactions, promoting the digestion and absorption of plant proteins. These insights offer valuable scientific backing for the utilization of extruded plant-based proteins, bolstering their role in enhancing the palatability and nutritional profile of plant-based meat substitutes.

Effects of rapeseed protein addition on soybean protein-based textured protein produced by low-moisture extrusion: Changes in physicochemical attributes, structural properties and barrel flow behaviors

This study investigated the potential of rapeseed protein as a novel alternative protein source in meat analogs produced by extrusion cooking technology. To study the substitutability of rapeseed protein to soybean protein, the addition ratios of rapeseed protein to soybean protein in the extrusion experiment were 0:50, 10:40, 20:30, 30:20, 40:10 and 50:0 (w/w), respectively. The results showed that adding 0–20% rapeseed protein not only decreased the specific mechanical energy and mass flow rate of the mixture during extrusion, but also enhanced the hardness and chewiness of the extrudates while reducing their elasticity and resilience. In addition, increasing the amount of rapeseed protein may lead to decreased expansion characteristics, internal pore structure, and water absorption rate of the extrudates, as well as a decrease in brightness and an increase in redness on the surface. Weibull model could well describe the rehydration behavior for dynamic fitting of the extrusion rehydration process. Moreover, with the increase of rapeseed protein substitution, the content of disulfide bonds, and the proportion of relatively ordered protein secondary structures with high stability increased, and the degree of protein denaturation decreased. Besides, the degree of starch gelatinization reduced and the thermal stability of extrudates improved. Interaction analysis indicated that disulfide bonds are the primary force maintaining protein-mediated interactions in the extrudates. The incorporation of rapeseed protein shortened the mean residence time of molten feedstock and shifted the flow state to plug flow. Overall, our investigation suggests that within low levels of addition (≤20%, w/w), rapeseed protein has the potential to partially substitute for the soybean protein-based textured proteins. High substitution levels or complete substitution are not feasible due to the relatively low expansion and rehydration rates.

Extrusion as pretreatment for complexation of high-amylose starch with glycerin monostearin: Dependence on the guest molecule

Low-moisture extrusion (LME) can modify starch structures and enrich their functionality. These LME-made starches may efficiently form inclusion complexes (ICs) with hydrophobic guest molecules, which is profoundly impacted by the guest molecule concentration. In this work, the influence of glycerin monostearin (GMS) concentration on the structure and in vitro digestibility of pre-extruded starch-GMS complexes was investigated. The results showed that LME pretreatment increased the complex index of high-amylose starch with GMS by 13 %. The appropriate GMS concentrations produced ICs with high crystallinity and excellent thermostability. The presence of IC retarded amylose retrogradation and dominated bound water in starches. In addition, highly crystallized ICs were resistant to enzymolysis and had a higher proportion of resistant starch. The acquired knowledge would provide a better understanding of the LME-modified starch and GMS concentration-regulated IC formation.

Texturized vegetable protein from a faba bean protein concentrate and an oat fraction: Impact on physicochemical, nutritional, textural and sensory properties

Texturized vegetable protein (TVP) from a blend of faba bean protein concentrate and an oat beta-glucan rich fraction was produced by low-moisture extrusion to combine nutritional benefits of both ingredients. The effect of extrusion conditions (temperature in zone 6 (HZ6), feed rate (FR) and moisture content (MC)) on physicochemical, nutritional, textural, and sensory attributes was studied. Overall, effect of the FR and MC of the blend showed greater impact on TVP properties rather than the temperature. TVPs produced at 28.5%, 5 Kg/h and 150⁰C and at 30.8%, 4 Kg/h and 160⁰C for MC, FR and HZ6, respectively, presented improved properties to be further formulated into a meat analogue product. The beta-glucan content of TVP (5.6g/100g dm) was high enough to reach >1 g beta-glucan per serving in a final food product (e.g., vegan burger), which qualifies for the health claim “reduces low-density lipoprotein (LDL)-cholesterol” approved by the European Food Safety Authority. The combination of these ingredients resulted simultaneously in an improved composition of essential amino acids and increased the protein quality of the blend as the calculated digestible indispensable amino acid score (DIAAS) improved from 72.2 (beta-glucan rich fraction alone) or 76.1 (faba bean protein concentrate alone) to 90.2 (blend).

Low moisture extrusion of soybean protein isolate: Effect of β-glucan on the physicochemical properties of the product

In this study, β-glucan(BG) was mixed with soy protein isolate (SPI) according to mass ratio of 0%, 1%, 2%, 3%, 4% and 5%, and the BG-SPI blends were subjected to low moisture extrusion (36%). The apparent properties, functional properties, and structural properties of BG-SPI extrudates were investigated. The results showed that the hardness decreased and then increased with the increase of BG addition, which was mainly influenced by the enhancement of HY-QY-DI (interactions between hydrogen bonds, hydrophobic interactions, and disulfide bonds). The addition of 5% BG promoted the formation of disulfide bonds (DI) and hydrogen bonds (HY), and thus increased the oil holding capacity (OHC) and cooking yield (CY) of BG-SPI extrudates. It also promoted the formation of HY and disrupted QY-DI (interactions between hydrophobic interactions and disulfide bonds), which reduced the water solubility index to increase nutrient retention during subsequent processing. In addition, BG and SPI in the extruder formed a compound with a large molecular weight, and the main forces that maintain this compound were DI and HY.

Quality and chemical stability of long-term stored soy, canola, and sunflower cold-pressed cake lipids before and after thermomechanical processing: A 1H NMR study

Oilseed cakes obtained by cold-pressing are rich in lipids susceptible to degradation, which could challenge their handling and nutritional, safety, and sensory requirements, especially during long-storage. Although extrusion is effective at reducing antinutritional factors, its effect on the lipid stability of oilseed cakes remains unknown. In this work, a comparative 1H-NMR-based investigation of the lipid quality in terms of lipid composition, hydrolysis, and oxidation status, as well as their stability after long-term storage was performed on soybean, canola and sunflower cold-pressed cakes before and after low-moisture extrusion. Soybean cake was rich in linolenic and linoleic groups, whereas canola and sunflower mostly contained linoleic and monounsaturated acyl groups and fatty acids. Extrusion did not modify lipid quality immediately after processing. Nevertheless, lipid stability was significantly reduced after 12 months, especially in cakes subjected to extrusion, evidenced by the degradation of their polyunsaturated acyl groups and fatty acids, and the increase of primary and secondary oxidation products. Since lipid quality was retained immediately after extrusion (no storage), results indicated that any action to avoid the enzymatic lipid degradation must be performed immediately after cold-pressing. Moreover, long-term storage should be carefully considered as the lipid stability/quality of extruded cakes was compromised after extrusion.

Use of legume flours and fiber for tailoring structure and texture of pea protein-based extruded meat alternatives.

The overall objective of this study was to understand texturization of pea protein isolate (PPI) using low moisture extrusion, and investigate protein interactions, functionality, and cross-linking with the inclusion of different levels of pea fiber (5-15%) and different types of starch-containing legume flours (20% chickpea flour or pea flour). PPI/ legume flour raw formulations had 18-27% lower water absorption capacity (WAC) as compared to the PPI control. However, WAC increased by 8-16% with the addition of pea fiber to a PPI/ legume flour control. Rapid Visco Analysis trends mirrored these results with peak viscosity shifting to higher temperatures with the addition of legume flour and lower temperatures with the addition of pea fiber. The role of starch in interfering with protein hydrophilic interactions and that of fiber in decoupling this effect were discussed. These interactions determined extruded textured protein properties, with more layering and denser products (174-229% higher bulk density as compared to control) observed with the addition of legume flours leading to lower water hydration capacity (WHC), as opposed to more cellular and porous microstructure (55-58% lower bulk density as compared to control) with the addition of fiber. Bulk density and WHC trends due to these porosity and layering effects impacted the instrumental texture characteristics of ground hydrated product, including hardness that increased from 475g to 837-2334g with the higher layering caused by starch, but decreased from 1295g to 534-1050g due to the porosity induced by fiber. To summarize, the use of legume flours and fiber can allow flexibility in targeting specific qualities while reducing costs and increasing sustainability of plant-based meats. PRACTICAL APPLICATION: Health, environment, and animal welfare concerns are creating a growing movement toward plant-based meat. Pea protein isolate and concentrate have become popular ingredients for texturized plant protein. Understanding of the role of starch and fiber in the structuring of textured pea protein could lead to use of legume flours and co-products of protein isolation to reduce cost and increase sustainability and nutrition of meat alternatives while targeting desired textural attributes.

Effect of screw speed and die temperature on physicochemical, textural, and morphological properties of soy protein isolate-based textured vegetable protein produced via a low-moisture extrusion.

The online version contains supplementary material available at 10.1007/s10068-022-01207-8.

Construction of rice protein-based meat analogues by extruding process: Effect of substitution of soy protein with rice protein on dynamic energy, appearance, physicochemical, and textural properties of meat analogues

Meat analogues are garnering significant attention as future food and a sustainable diet. This study demonstrates the possibility of using rice protein (RP) to create new meat analogues. Various RP substitution ratios [0, 25, 50, 75, and 100 % (w/w)] for soy protein (SP) were used to prepare the meat analogues based on a low-moisture extrusion cooking. The effect of its ratio on the meat quality characteristics was investigated via specific mechanical energy, expansion ratio, piece density, true density, porosity, water absorption capacity, rehydration kinetics, and texture profile (hardness, springiness, cohesiveness, chewiness, and resilience). The use of RP decreased some values (specific mechanical energy, porosity, expansion ratio, water absorption capacity, springiness, cohesiveness, chewiness, and resilience) while increasing others (piece density, true density, and hardness) depending on its substitution ratio. Three different models (Peleg, Weibull, and exponential) were used to describe the rehydration kinetics of the samples, and the Weibull model was the best-fitted one. Finally, twelve polynomial equations with RP mixing ratios (0–100 %) as variables were developed to predict the quality characteristics of meat analogues. These results suggested that RP can substitute the typical SP as an expansion or texture modifier in the production of SP-based meat analogue products, and a portion of SP (≤75 %, w/w) can be substituted with RP in the production of meat analogue products. Still, the full RP substitution was impossible due to the low porosity of the resulting meat analogue.

Physico-chemical characteristics of rice protein-based novel textured vegetable proteins as meat analogues produced by low-moisture extrusion cooking technology

Currently, active research is being focused on the development of future foods that can replace conventional meat. Meat analogues have been drawing considerable attention as possible alternatives to meat. In this study, the possibility of using rice protein isolate (RPI) to create meat analogues was investigated. Therefore, novel textured rice proteins (TRPs), which are meat analogues, were prepared from RPI and soy protein isolate (SPI) as primary raw materials by blending RPI and SPI at ratios approximately 25:75, 50:50, 75:25, and 100:0 (w/w). Meanwhile, corn starch and wheat gluten, minor ingredients, were added at 29% and 13% (w/w) of the total weight of the all ingredients, respectively, in all samples. Low-moisture extrusion cooking process using a twin-screw extruder was used for manufacturing TRPs. An analysis of physico-chemical characteristics showed that RPI replacement decreased specific mechanical energy, porosity, and water absorption capacity of the meat analogues. However, meat analogues made from combinations of RPI and SPI had better nutritional quality than commercial one, whose main ingredient is SPI without the addition of RPI and displayed desirable results pertaining to their soluble matter content during rehydration. Consequently, RPI exhibits potential to partially replace SPI in the manufacture of meat analogues.

Effect of Low Moisture Extrusion on the Physicochemical Properties of Mixtures of Β-Glucan/Soybean Protein Isolate

Effect of Low Moisture Extrusion on the Physicochemical Properties of Mixtures of Β-Glucan/Soybean Protein Isolate

Physicochemical, textural, and sensorial properties of fibrous meat analogs from oat-pea protein blends extruded at different moistures, temperatures, and screw speeds

This study investigated meat analogs produced using low-moisture extrusion from oat and pea protein blends at ratios 20:80, 30:70, 50:50, and 70:30. Response surface methodology was used to assess the effect of blend composition, screw speed (200–1200 rpm), barrel temperature (135–160 °C), and moisture content (25–35%) on the properties of extruded meat analogs. Blend composition had a relatively stronger effect on water holding capacity, water solubility index, bitterness, cohesiveness, and springiness, while extrusion conditions had more influence on hardness, fibrousness, and moistness. As the oat content increased from 20% to 70% the maximum sensory fibrousness increased from 7.2 to 8.6 on a scale of 0–9. Although the mean water holding capacity decreased from 2.1 to 1.4 g g−1, the mean sensory moistness remained around 4.1. Cereal taste dominated over legumes with the mean intensities 3.9 and 2.0, however, the differences between oat-pea blends were small. In general, the extruded meat analogs had a mild flavor and high fibrousness, and the developed response surface models can be used to tune the properties further. This confirms that oat protein in combination with pea is a practical alternative to soy and gluten proteins for the production of meat analogs.

Food for Thought: The Protein Transformation

Food for Thought: The Protein Transformation