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Innovations in Extrusion Cooking

Dr. Nancy Agnes, Head,

Technical Operations, FoodResearchLab

info@foodresearchlab.com

I. INTRODUCTION

There are dietary concerns among

consumers to choose a healthier lifestyle

and follow food trends to prevent

nutritional deficiency and long term

prevention of chronic diseases. Consuming

processed fast foods in large is leading to

different extremities, such as lack of

nutrition and aggravation of chronic

diseases such as obesity and hypertension.

Thus food scientists and manufacturers are

focusing on novel and sustainable ways for

selecting suitable processing methods to

create healthy and convenient foods.

Extrusion processing can serve this

purpose.

As explained in our previous blog,

extrusion cooking uses a blend of high

temperature, pressure and shear conditions

which results in biochemical changes in

the food materials. This leads to

inactivation of microorganisms,

denaturation of proteins and enzymes, lipid

modifications, gelatinization of starch, the

formation of volatile compounds and

increased availability of soluble fibers (1).

Moreover, the extrusion process has the

ability to retain the bioactive compounds

and provides a platform to enrich the

ingredients with protein, fibre,

antioxidants, vitamins and minerals. The

impact of extrusion on the levels of

bioactive compounds was evaluated.

Factors such as food structure, shear,

resonance time, temperature and moisture

content contribute to the overall

composition and potential release of

functional bioactive compounds (2).

II. EXTRUSION BASED 3-D PRINTING

3-D printed extrusion is a digitally

controlled extrusion process, and currently

being utilized to build products with

complicated design, geometry, food

structure with high surface to volume

ration and compositions etc during new

food product development. Food products

such as chocolates, processed cheese,

chocolates and sugar cookies have been

manufactured using 3D printing. The

robotic construction used computer

loading of food materials and extruding on

a layer by layer deposition. 3D printing

technology is gaining attention for older

adults with mastication and swallowing

difficulties. Moreover, 3D printed meals

can be served to people with dysphagia.

Table 1 NPD using 3D printing extrusion

technology. Table adapted from ).

There are a few critical parameters that

need to be controlled during 3D printing

extrusion to achieve a product with

excellent mechanical integrity and

stability. The temperature of the extrusion,

printing time and speed, rheological

properties of the food inks. Products do

not expand if the temperate is below

2

100C. Expansion rate increases with an

increase in temperature, with moisture

levels close to 20%. At lower extrusion

temperatures, starch is completely molten

and thus expansion is reduced. On

contrary, the gel formation is elastic at

higher temperatures with smaller uniform

cells. An increase in temperature should

reduce the overall viscosity of the material

by favoring bubble growth and resulting in

low density extrudes. Finally, post-

processing of 3D printed foods after

deposition is essential to enhance the

sensory appeal and palatability.

III. NOVEL MEAT ANALOGUES

In India, vegetables, pulses and

cereals are readily available to be used as

ingredients in meat analogues. Not only

from India, vegetables grown in other

countries such as Saudi Arabia the UK.

The nutritional and functional

characteristics can be improved. The final

product composition can be altered by

physical losses, such as evaporation of

water, leakage of oil and volatile

compounds. The common physiochemical

changes which occur during extrusion are

binding, loss of native conformation,

thermal degradation and fragment

recombination. Improved Extrusion

cooking technology (IECT) is a novel

method modified from a single screw

extruder for developing textured rice.

The texturization process by

extrusion can be used to replicate the

texture, taste and appearance of meat in

plant-based foods. Dry extrusion can be

applied to produce meat extenders and wet

extrusion for meat analogues (2). The

disulfide bonds in protein break and

reform during the extrusion process.

Enzymes also lose their activity during

extrusion due to high temperatures and

shear. The main application of extrusion

with protein foods is texturization. During

the extrusion process, starch degradation

results in reduction during expansion. The

amylose and amylopectin content are

hydrolyzed to maltodextrins. This implies

in highly expanded products may crumble

while dense products are too hard. Starch

gelatinization occurs at much lower

moisture contents (12-20%) in comparison

to conventional methods.

Figure 1 Starch modified extruded products

Lipid content above 5% in foods is

considerable for the reduction in the

expansion rate. The type of starch lipid

complex present in the raw material

influences the formation of the amylose-

lipid complex being more favorable than a

triglyceride.

The fibrous texture development is the

challenging part of the extrusion process.

Fibers form a viscous network to

determine the physiochemical conditions.

Soluble fibres are able to modify the pH

and microflora of the colon leading to the

modification of mutagenic agents.

It can be currently defended that extrusion

technology allows large scale production

for food product structuring. Moreover,

promising value addition in the foods such

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as added proteins, fibers and other

nutritional components are essential for

biochemical and physiological processes.

Table 2 List of meat analogue and fortified

extruded products. Table adapted from (3).

REFERENCES

1. Brennan, C., Brennan, M., Derbyshire, E., & Tiwari,

B. K. (2011). Effects of extrusion on the polyphenols,

vitamins and antioxidant activity of foods. Trends in

Food Science & Technology, 22(10), 570-575.

2. Akdogan, H. (1999). High moisture food extrusion.

International journal of food science & technology,

34(3), 195-207.

3. Prabha, K., Ghosh, P., Abdullah, S., Joseph, R. M.,

Krishnan, R., Rana, S. S., & Pradhan, R. C. (2021).

Recent Development, Challenges, and Prospects of

Extrusion Technology. Future Foods, 100019.