Description:DESCRIPTION
Field of Invention:
The present invention relates to the optimization of extrusion cooking method to produce low moisture extrudates of quinoa flour containing ingredient mixture (soy protein isolate and wheat gluten) and to study the effect of quinoa flour incorporation on the quality of low moisture extrudates.
Background of Invention and Prior Art:
Non-meat protein is the major source of ingredients to produce vegan meat analogues. These plant proteins have the function of binding with water to stabilize and form emulsions and gels. Various plant-based proteins including soy protein, cereal protein, pea protein, mycoprotein, etc. have been explored to produce fibrous meat-like products. These protein-rich materials also possess excellent texturization capacity which ensures the production of fibrous chunks during the process of texturization.
Practically all plant proteins can be used for fabricating meat alternatives. However, soy protein, pea protein, wheat gluten, and oilseeds are the most utilized sources to produce plant-based meat alternatives because of their accessibility, cost, and dietary benefits. Plant-based meat proteins must be unfolded, cross-linked, and aligned themselves to form microscopic and macroscopic fibers (Ismail et al., 2020, J Anim Sci Technol, 62, 111). Different forms of plant proteins are employed in the formulation of meat which includes flours, isolates, concentrates, and hydrolysates that offer a complete range of functional attributes.
Soybeans in food applications became popular after the Food and Drug Administration (FDA) approved the “Soy Protein Health Claim” on October 26, 1999. The FDA confirmed that 25 g of soy protein a day, may lower cholesterol and reduce the risk of coronary heart disease (Asgar et al., 2010, Compr Rev Food Sci Food Saf, 9, 513–529). Soybeans vary widely in nutrient content based on the specific variety and growing conditions, but they typically contain 35% to 40% protein, 15% to 20% fat, 30% carbohydrate, and 10% to 30% moisture. However, soy protein isolates are preferred over soy flour for extrusion-assisted texturization, as the protein isolates of soybean has a reduced beany off flavour and bitterness which is distinctively present in soy flour that primarily affects the sensory acceptability of meat analogues.
Wheat gluten is unique among cereals and other plant proteins in its ability to form a cohesive blend with viscoelastic properties once it is plasticized. Vital wheat gluten is approved by FDA as Generally Recognized as Safe (GRAS) for use as a dough strengthener, formulation aid, nutrient supplement, processing aid, stabilizer, thickener, surface finishing agent, and texturizing agent (Asgar et al., 2010, Asgar et al., 2010, Compr Rev Food Sci Food Saf, 9, 513–529). Wheat gluten is the only vegetable protein with viscoelastic properties, allowing it to form a resilient gel during the extrusion process; upon elongation, Wheat gluten has the inherent ability to develop thin protein frameworks that could easily produce fibrous protein structures due to the disulphide bonding. Wheat gluten can be used alone or in combination with soy flour or soy concentrate to produce meat extenders. Based on instrumental and sensory research, meat alternatives containing soy protein and wheat gluten (30%w/w) displayed fibrous structure, chewiness, and hardness, with the highest degree of texturization (Chiang et al., 2019, Food Structure, 19,100102).
Quinoa, on the other hand, is a major source of protein which consists of carbohydrates as well. Quinoa protein is one of the suitable ingredients in texturized vegetable protein based products due to their binding/thickening characteristics (Kyriakopoulou et al., 2021, Foods, 10, 600). Incorporation of quinoa flour into protein isolates based extrudate is expected to result in a notable gelatinized structure inside the developed low moisture meat analogue products. This would result in improving the juiciness after cooking.
As a result, the functional and thermal properties of the protein-based products also improve during extrusion. However, there is limited research on quinoa flour incorporated meat analogue products. Their higher gelation properties can make them more suitable to produce low moisture meat analogue products with improved juicy internal structure.
Objectives of the Present Invention:
The primary objective of this invention is to develop a method for producing low moisture extrudates using a plant protein mixture incorporated with quinoa flour, which enhances both nutritional and functional properties. Another key objective is to ensure the extrudates achieve a moisture content of less than 8% w/w, thereby extending shelf life and ensuring stability. The invention also aims to optimize textural attributes such as hardness and fracturability, to improve consumer acceptance and versatility. Additionally, the method seeks to ensure high water and oil absorption capacities, maintain a neutral pH, and achieve consistent production quality.
Summary of the invention
The present invention discloses a method for producing low moisture extrudates from a plant protein mixture incorporating quinoa flour, soy protein isolate, and wheat gluten. The method comprises the following steps: preparing an ingredient mixture with specific proportions of the mentioned components, adding 30% w/w water to the mixture, and kneading. The moistened mixture is pre-conditioned by keeping it under a cloth at 4ºC for 15 minutes. The pre-conditioned mixture is then extruded using a co-rotating twin-screw extruder under precise conditions: feeder speed between 20-25 rpm, screw speed between 220-250 rpm, cutter speed between 90-100 rpm, residence time of 25-30 seconds, and specific temperature settings for different sections of the extruder. The extrudates are subsequently cooled at ambient conditions for 10 minutes and dried at 105ºC for 1 hour to achieve a final moisture content of less than 8% w/w.
The invention further details the composition of the ingredient mixture (60% w/w soy protein isolate, 20% w/w wheat gluten, and 20% w/w quinoa flour) and optimal extrusion processing conditions. The resulting extrudates have a final moisture content of 8-8.5% w/w, initial water activity decreasing from 0.9411 to 0.6751, pH of 7.36 ± 0.12, water absorption capacity of 2.08 ± 0.21 g/g, oil absorption index of 1.15 ± 0.05 g/ml, hardness of 3774.84 ± 125.5 g, fracturability of 0.72 ± 0.06 mm, and a denaturation peak of proteins at temperatures exceeding 160ºC.
This invention offers a commercially viable technique for producing high-quality, protein-rich meat analogues with improved hydration, texture, and extended shelf life.
Brief description of drawings
Figure 1- represents the flow diagram of the optimized production process- low moisture extrudates of soy protein isolate, wheat gluten and quinoa flour mixture
Figure 2- represents the components of the twin screw extrusion cooker
Wherein,
201 – Feeder
202 – Screws
203 – Feeding section
204 – Compression section
205 – Metering section
206 – Die head section
207 – Cutter
208 – Die
209 – Tray drier
Detailed description of the invention
The invention follows the approach for the production of low moisture extrudates (Figure 1), which has the following processing steps. (a) Preparation of ingredient mix, (b) Moistening and kneading of ingredients, (c) Pre-conditioning, (d) Hot extrusion, (e) Cooling at ambient conditions for 10 min, (f) Drying to a final moisture content of less than 8% w/w on wet basis.
According to first aspect the present invention provides a method of manufacturing a textured low moisture extrudate comprising the steps of
Preparation of ingredient mixture
i) The dry matter which comprises of
1. 60% w/w of soy protein isolate,
2. 20% w/w of wheat gluten,
3. 20% w/w of quinoa flour
ii) The ingredient mixture further comprising of water (30% w/w on wet basis)
Cooking the ingredient mixture in a twin-screw extrusion cooker and extruding it to form the low moisture extrudates
Preferably, the share of soy protein isolate is chosen as the major fraction due to their excellent texturization and fibrous structure forming capacity. The share of wheat gluten is chosen as another major fraction due to their ability to form a cohesive blend with viscoelastic properties once it is plasticized.
The share of starch containing quinoa flour is chosen as another fraction of the ingredient mixture to improve the degree of gelatinization inside the textured extrudate, which can improve the juiciness of the developed low moisture extrudates.
Cooking of ingredient mixture through hot extrusion results in a textured food product having a major fraction of protein. It is also a ready-to-cook meat alternative product which can be processed further into various products such as vegan keema, vegan meat balls, vegan meat patties, etc.
Further advantages of the method are that the porous texture will be developed, and that the water absorption rate and hydration level of the textured food product will be improved as the result of the share of quinoa flour fraction. These improvements in the structure of the textured food protein improve the acceptability of the textured food product by consumers. The incorporation of quinoa flour also eliminates the beany off flavour and slight bitter taste developed as the result of the major fractions of the ingredients.
The cooking is performed at the following process conditions. Feeder speed: 20- 25 rpm, screw speed: 220- 250 rpm, cutter speed: 90- 100 rpm, residence time: 25- 30 s, feeding section temperature: 40- 50ºC, Compression section: 80- 90ºC, Metering section: 100-110ºC and in Die head section: 130- 140ºC. Then the obtained extrudates were allowed to cool down for a period of 10 min under ambient conditions, in order to ensure that the extrudates does not absorb moisture when they are packed or further processed without cooling them down.
The extrudates were then dried to bring the moisture content of the extrudates down to less than 8% w/w (wet basis). The process of extrusion reduced the moisture content of the ingredient mix from 30% to 18-20% w/w (wet basis). Further, the moisture content of the extrudates reduced to 8-8.5% w/w (wet basis) when dried. the extrudates after drying had a water activity of 0.6751 which is an indicative of no growth of major microorganisms, which helps in the extended shelf life of the extrudates. The extrudates was also found to possess a slight basic pH (7.36), with higher levels of water and oil absorption indices, representing their suitability for production of meat analogue- based products with improved sensory acceptability. It has been noted that the extrudates have shown formation of thread like fibers and have shown good levels of porosity in its cross-sectional structure. the extrudates represented the denaturation peak of proteins at >160°C. This implies that the proteins in the extrudates have been texturized and their formed secondary protein structures during extrusion increased their thermal denaturation temperature (Td). The change in enthalpy (?H) was observed to be decreasing during the wheat gluten incorporation. This represents the reduction in hydrophilicity in extrudates with higher protein levels.
Presence of starch in quinoa resulted in lower protein content at quinoa incorporated extrudates. The addition of quinoa flour only resulted in the incorporation of trace levels of fat. However, it was noted that the fat containing compositions represented a smooth flow in the process of extrusion, as the trace fat content acts as a lubrication for the flow of material supply in extrusion barrel.
The prepared extrudates were analyzed for their thermal, mechanical, functional, and microstructural properties. Extrudates with quinoa flour exhibited higher degree of water and absorption capacity as compared to wheat gluten incorporated extrudates. This may be due to the formation of smaller molecules during as a result of starch dextrinization during extrusion cooking. Incorporation of quinoa flour also exhibited reduction in hardness and fracturability. The formulations rich in quinoa flour has formation of non-continuous thread like structure.
The moisture content of the ingredient mix is optimized to be 30% w/w on wet basis to prevent puffing during high temperature, pressure assisted hot extrusion process. Sufficient water is added to the ingredient mix to reach the optimized moisture levels.
The combined ingredients were then fed into a powder or flour mixer, that mixes flour or powder for food extruder feed ingredients. In order to ensure proper mixing of the ingredients and evenly distributed moisture content throughout the batch of ingredients, water was gradually added through the provision for moisture incorporation located on top of the mixer. The methodical addition of water also ensures that no agglomerates, which can occasionally cause an extrusion line blockage, form in the feed.
The moistened ingredient mix is kept under a cloth at a refrigerated temperature for 15 min to allow the ingredient mix's individual particles to absorb moisture. This aids in uniform hydration of particles resulting in reduced wear on the extruder, lower overall energy consumption and higher throughput.
The ingredient mix is then fed to the co-rotating twin screw extruder unit (Figure 2) for the formation of low-moisture meat analogues. The optimized conditions of the extrusion process are given in Table 1.
Table 1. Optimized extrusion process conditions
Parameter Value
Feeder speed 25 rpm
Screw speed 250 rpm
Total residence time of the sample inside barrel 30 s
Temperature profile Feeding section – 50ºC
Compression section – 90ºC
Metering section – 110ºC
Die head section – 140ºC
Speed of the cutter 100 rpm

The obtained extrudates were allowed to cool down for a period of 10 min under ambient conditions, in order to ensure that the extrudates does not absorb moisture when they are packed or further processed without cooling them down.
The extrudates were then dried to bring the moisture content of the extrudates down to less than 8% w/w (wet basis). To achieve this, the cooled extrudates were placed in a tray drier and dried at a temperature of 105ºC for 1 h.
Yet another embodiment of the invention relates to determining the physical properties of the prepared low moisture extrudates (Given in Table 2). The process of extrusion cooking reduced the moisture content of the ingredient mix from 30% to 18-20% w/w (wet basis). Further, the moisture content of the extrudates reduced to 8-8.5% w/w (wet basis) when dried for 1 h using the tray drier. No shape change (such as shrinkage) was observed during drying and the extrudates have retained their structure after drying. The extrudates has an initial water activity (Aqualab 4TE, Decagon Devices Inc., Pullman, WA, USA; sensitivity ± 0.001) of 0.9411 which has reduced to 0.6751 after drying. This decrease in water activity helps in increasing the shelf life of the extrudates. The extrudate also possessed a basic pH (7.36) due to the presence of protein isolates which increased the ionic strength of extrudates. The results of color revealed that the extrudates turned slight brown (lower L*) due to the protein-carbohydrate interactions during heating.
Table 2. Physical properties of extrudates
Property Value
Moisture content (% on wet basis) before drying 20.2 ± 1.8
Moisture content (% on wet basis) after drying 8.15 ± 0.7
pH 7.36 ± 0.12
Colour 40.46 ± 1.25 (L*),
04.99 ± 0.65 (a*)
14.10 ± 1.02 (b*)
Water activity (aw) after drying 0.6751 ± 0.045
Yet another embodiment of the invention studies the proximate composition (AOAC, 2000) of the developed extrudates (given in Table 3). The levels of quinoa flour have an indirect influence on the total protein content. Presence of starch in quinoa resulted in lower protein content at quinoa incorporated extrudates. Addition of quinoa flour also resulted in trace levels of fat.
Table 3. Proximate composition of extrudates
Property Value
Protein (g/100 g) 68 ± 1.25
Fat (g/ 100 g) 0.178 ± 0.03
Ash (g/ 100 g) 3.09 ± 0.15
Yet another embodiment of the invention studied the functional properties and textural properties of the extrudates (given in Table 4). Extrudates with quinoa flour exhibited higher degree of water absorption capacity. When starch rich compositions are extruded, the gelatinized fractions tend to absorb more moisture, thus higher water holding capacity was achieved. Oil absorption index has a notable increase in the extrudates containing quinoa flour due to the formation of smaller molecules during as a result of starch dextrinization during extrusion cooking.
Table 4. Functional properties and textural properties of extrudates
Property Value
Water absorption capacity (g/g) 2.08 ± 0.21
Oil absorption index (g/ml) 1.15 ± 0.05
Hardness (g) 3774.84 ± 125.5
Fracturability (mm) 0.72 ± 0.06
Yet another embodiment of the invention studied the thermal properties of the extrudates. the extrudates represented the denaturation peak of proteins at >160°C. This implies that the proteins in the extrudates have been texturized and their formed secondary protein structures during extrusion increased their thermal denaturation temperature (Td).
The novelty of the present invention is
1. The process conditions were optimized for the quinoa flour incorporated ingredient mixture which contain carbohydrates in the mixture
2. The quantity of quinoa flour incorporated in the ingredient mixture without affecting the fibrous structure formation was optimized.
3. The quinoa flour incorporation improved the physical, functional, textural, and thermal properties of the prepared extrudates.
The following examples are given by the way of illustration of the present invention and should not be construed to limit the scope of present invention.
Example 1:
A trial was conducted with the ingredient mixture containing soy protein isolate (80% w/w) and wheat gluten (20% w/w) alone which is extruded under the same processing conditions. However, these extrudates possessed increased hardness which results in higher cooking time and lower water and oil absorption capacities of the extrudates that directly impacts their sensory acceptability.
Example 2:
Another experiment of extrusion was conducted with the ingredient mixture containing quinoa flour (30 and 40% w/w) and soy protein isolate (60 and 70% w/w). It was noted that, the extrudates obtained from formulations containing higher levels of quinoa flour (40% w/w), have shown less porous and highly denser extrudates as compared to extrudates that had wheat gluten in composition. This extrudate also shown to have slightly acidic pH which directly affects their sensory profile. The extrudates obtained from formulations with 30% w/w quinoa flour possessed a slightly higher levels of hardness. The absence of wheat gluten in the ingredient mixture composition resulted in reduced mechanical properties of the extrudate.
Example 3:
Another experiment on extrusion was conducted with ingredient mixture containing soy protein isolate (60% w/w), wheat gluten (20% w/w) and quinoa flour (20% w/w). This resulted in successful texturization of the ingredient mixture at the processing conditions as follows. Feeder speed: 20- 25 rpm, screw speed: 220- 250 rpm, cutter speed: 90- 100 rpm, residence time: 25- 30 s, feeding section temperature: 40- 50ºC, Compression section: 80- 90ºC, Metering section: 100-110ºC and in Die head section: 130- 140ºC. These extrudates possessed improved physicochemical and functional properties.
Advantages of the Invention
Enhanced Nutritional Profile: Incorporating quinoa flour, soy protein isolate, and wheat gluten provides a well-rounded nutritional profile with essential amino acids, making the extrudates a rich source of plant-based protein.
Low Moisture Content: Achieving less than 8% w/w moisture content extends shelf life and reduces the risk of microbial growth and spoilage.
Improved Textural Properties: The extrudates offer optimal hardness and fracturability, enhancing mouthfeel and consumer acceptance.
Controlled Water Activity: Water activity is effectively reduced from 0.9411 to 0.6751, improving stability and shelf life.
High Water and Oil Absorption Capacities: The extrudates feature high water absorption capacity (2.08 ± 0.21 g/g) and oil absorption index (1.15 ± 0.05 g/ml), enhancing their versatility in food applications.
pH Stability: A neutral pH of 7.36 ± 0.12 ensures compatibility with a wide range of food products without negatively affecting flavor.
Efficient Production Process: The precise extrusion process enables consistent production of high-quality extrudates with minimal variation.
Temperature Resilience: The extrudates maintain stability under high temperatures, with protein denaturation peaks above 160ºC, making them suitable for various cooking and baking processes.
Versatility in Applications: Suitable for use in meat analogues, snacks, and ready-to-eat meals, meeting the demand for plant-based and high-protein foods.
Scalability: The method is adaptable to industrial production, supporting commercial manufacturing of plant-based protein products.
Cost-Effective: Utilizing common plant proteins and quinoa flour, the method offers a cost-effective solution for high-quality extrudates, making it viable for large-scale production.
Environmental Sustainability: By reducing reliance on animal-based proteins, the method supports environmental sustainability and lowers the carbon footprint of food production.

, C , Claims:Claims
We claim,
1. A method for producing low moisture extrudates from a plant protein mixture, comprising:
a. Preparing an ingredient mixture comprising of soy protein isolate, wheat gluten, and quinoa flour;
b. Adding 30% w/w water to the ingredient mixture and kneading;
c. Pre-conditioning the moistened ingredient mixture by keeping it under a cloth at a refrigerated temperature of 4ºC for 15 minutes;
d. Extruding the pre-conditioned ingredient mixture in a co-rotating twin-screw extruder under the following conditions:
i. Feeder speed ranging between 20-25 rpm,
ii. Screw speed ranging between 220-250 rpm,
iii. Cutter speed ranging between 90-100 rpm,
iv. Residence time ranging between 25-30 seconds,
v. Feeding section temperature ranging between 40-50ºC,
vi. Compression section temperature ranging between 80-90ºC,
vii. Metering section temperature ranging between 100-110ºC, and
viii. Die head temperature ranging between 130-140ºC;
e. Cooling the extrudates at ambient conditions for 10 minutes;
f. Drying the cooled extrudates at 105ºC for 1 hour to achieve a final moisture content of less than 8% w/w (wet basis).
2. The method as claimed in claim 1, wherein ingredient mixture composition is 60% w/w of soy protein isolate, 20% w/w of wheat gluten and 20% w/w of quinoa flour.
3. The method as claimed in claim 1, wherein the extrusion processing conditions are: Feeder speed: 25 rpm, screw speed: 250 rpm, cutter speed: 100 rpm, residence time: 30 s, feeding section temperature: 50º C, Compression section: 90º C, Metering section: 110º C and in Die head section: 140º C.
4. The method as claimed in claim 1, wherein the cooled extrudates have a final moisture content of 8-8.5% w/w on a wet basis after drying.
5. The method of claim 1, wherein the extrudates have an initial water activity of 0.9411 which decreases to 0.6751 after drying.
6. The method of claim 1, wherein the extrudates have a pH of 7.36 ± 0.12.
7. The method of claim 1, wherein the extrudates exhibit a water absorption capacity of 2.08 ± 0.21 g/g and an oil absorption index of 1.15 ± 0.05 g/ml.
8. The method of claim 1, wherein the extrudates exhibit a hardness of 3774.84 ± 125.5 g and a fracturability of 0.72 ± 0.06 mm.
9. The method of claim 1, wherein the extrudates have a denaturation peak of proteins at temperatures exceeding 160ºC.
10. A low moisture extrudate produced by the method of any of the preceding claims, comprising of 60% w/w soy protein isolate, 20% w/w wheat gluten, and 20% w/w quinoa flour, characterized by moisture content of less than 8% w/w (wet basis), a water activity of 0.6751 ± 0.045, pH of 7.36 ± 0.12, water absorption capacity of 2.08 ± 0.21 g/g, oil absorption index of 1.15 ± 0.05 g/ml, hardness of 3774.84 ± 125.5 g, fracturability of 0.72 ± 0.06 mm, and denaturation peak of proteins at temperatures exceeding 160ºC.