The document discusses different types of extruders and expellers used in food processing. It provides information on: 1) Extruders that use shear and pressure to mix, cook, and form foods in a continuous process. They are used to make breakfast cereals, snacks, pet foods and more. 2) Classification of extruders including single-screw, twin-screw, and types based on shear stress levels. 3) Expellers that use compression to mechanically extract oil from seeds with higher efficiency than traditional methods. Modern expellers have improved recovery rates and product quality. 4) Research developing expeller technologies like a twin-screw expeller and an integral

1. EXTRUDERS AND EXPELLERS
Dr. R. T. Patil
Fmr Director
Central Institute of Post Harvest
Engineering & Technology, Ludhiana

2. • A single machine conveys, mixes, kneads,
cooks and forms in one continuous
process.
• The energy input comes mainly from the
conversion of mechanical to thermal
energy.
• Extruded food materials undergo various
transformations like starch gelatinization,
fragmentation and protein denaturation
• It is widely used to manufacture breakfast
cereals and snacks and other emerging
application to increase process efficiencies.
Extrusion Processing

3. • Low-shear (forming) extruders: used to increase
density of material that is generally high in moisture
(e.g. pasta) using low screw speeds.
• Medium-shear stress: used to process raw materials
with lower moisture content with higher energy
inputs (e.g. pet foods, aquatic feeds, texturized
vegetable protein).
• High-shear stress: where extrusion speeds and
energy inputs are high to process low-moisture raw
materials in a short length-to-diameter ratio barrel.
Highly expanded products are obtained (e.g. snacks,
breakfast cereals).
Classification of Extrusion Processes

4. Single-screw extruders
Consists of a rotating extruder shaft with screw elements (may be
segmented screws and shearlocks), a stationary barrel housing
(maybe segment sections), and a die and knife assembly.
Twin screw extruders
•Counter-rotating twin-screw extruders (screws move in opposing
directions, low speeds and long residence times) for production of
gum, jelly and licorice confections.
•Co-rotating twin-screw extruders(screws move in same direction,
high degree of heat transfer but not forced conveyance) for snack
products.
•An intermeshing screw producing a positive pumping
action, efficient mixing and self-cleaning.
•Non-intermeshing screws depend on friction for extrusion,
like single-screw extruders
Classification of Extruders

5. SINGLE SCREW EXTRUDER

6. TWIN SCREW EXTRUDER

7. DRY EXTRUDER

8. • Second generation snacks: are those that
expand when they come out of the extruder.
This is the most popular type of expanded
snack.
• Third generation snacks: or pellets do not
expand when they come out of the extruder.
After storage, the pellets are puffed by frying,
microwave heating or hot air puffing.
Expanded Snacks Produced
by Extrusion

10. • Have angled steam injector ports oriented in the
direction of material flow, along with a unique
screw profile that allows steam to be mixed into
the product and can utilize up to four times more
thermal energy than the average twin screw
machine.
• They translate thermal to mechanical energy
ratios of 14:1, lowering energy costs, less wear
and a lower environmental impact.
• Potential to produce specialty foods including up
to 90 percent fresh meat (as a percent of the dry
recipe) and up to 40 percent moisture without
changing the extruder configuration.
Thermal Twin Extrusion Systems

11. • Supercritical CO2 is injected into mixer and
extruder to provide proofing of the product.
• Rising of the dough is achieved by a
combination of hydrodynamic expansion of air
bubbles and diffusion of CO2 into these bubbles
without the need for yeast.
• The controlled acid hydrolysis of the starches in
the dough helps to produce reducing sugars
that add desirable flavor to the final product.
Super Critical Fluid Extrusion for
Breadlike Products

12. At CIPHET Ludhiana, we developed
• Ready-To-Eat snack foods from minor millet viz.,
foxtail millet, proso millet, little millet, barnyard millet
and kodo millet using low cost collet extruder.
• The retexturized fruit bars were prepared
incorporating dehulled bengal gram blended maize
extrudates with banana (Musa paradisaca L.), mango
(Magnifera indica L.) and papaya (Carica papaya L.)
fruit pulps. Using twin screw extruder
Extrusion of millets/fruit pulp
for health foods

13. Value Added Products from Rice Brokens
• High percentage of brokens is a
problem in summer rice due to
climate change (18-40%)
• Brokens fetch very low price
• Extrusion is a novel technology to
produce expanded blended products
under high temperature short time
regime
• CIPHET has modified the low cost
collet extruder to produce expanded
ready to eat snacks using rice and
pulse brokens.
• The cost of the unit is Rs 2 Lakh,
capacity 25 kg/h, cost of
accessories Rs. 2 lakh and thus earn
about minimum of Rs. 50,000 per
month

14. • More homogeneous and consistent cooking
process minimum waste.
• Extrusion is a very efficient and clean process,
since all steps can be done in-line: mixing,
cooking, forming, cooling, and cutting.
• Modular designs allow changing from one
product to another product, color, or shape to
be done within minutes—a significant process
efficiency.
• Twin-screw extruders are largely self-cleaning,
an advantage from the viewpoint of both
sanitation and labor savings.
Conclusion

15. Extractors
• Oil Seed Production of India is 30 million tonnes, losses are to
about 6%.
• Oil from by products
–Rice Bran
–Maize Germ
–Millet bran
• Oilseed processing is a major segment, an activity largely
concentrated in the cottage industry.
• 2.5 lakh ghanis and kolus which are animal operated oil
expellers (cake has 15% fat)
• 50,000 mechanical oil expellers (Cake 6-8%)
• 15,500 oil mills (Cake 5-6%)
• 725 solvent extraction plants (Cake/Meal <1%)
• 300 oil refineries and
• over 175 hydrogenated vegetable oil plants.

16. Oil Expelling Techniques

17. Double Chamber Modern Oil Expeller
•Provision for cooling the barrel by
passing water through water
jackets for temperature of the
barrel below 700C
•Pungent compounds present in
the oil are not escaped during
expelling.
•10 tpd capacity provides 5.8%
residual oil in mustard cake in
one-go crushing, as compared to
7.5% in conventional expeller
•Mustard cake is bright green
without any discolouration.
•Durability worm & cage bar
assemblies (10 week against 3
weeks conventional expellers)
•The plant requires less space for
installation.

18. Parameter Values
Throughput capacity 25 kg/h
Effective capacity for
extruded soy-sample
15 kg /h
Recovery 70%,
Single pass
Effective capacity for
soft seeds in 2 passes
15 kg/h
Recovery 80-85%
Compression ratio for
Primary section 5:1
Secondary section 3:1
Overall compression
ratio
15:1
L:D ratio
Primary section 5.1:1
Secondary section 4.5:1
Overall 9.6:1
Single Feed Multi Stage Oil Expeller

19. • Capacity 100 kg /h
• Oil recovery 65 – 70 % in
single pass
• Good quality MFSF (Protein
48 %, Fat 6-8 %, TI
Inactivation up to 70 %)
•Development of commercial
unit ( 250 kg /h) in progress
in collaboration with a
manufacturer
Integral Extrusion Expelling Unit

20. DESIGN OF TWIN SCREW OIL EXPELLER

22. REFERENCES

23. Thank You
Contact: ramabhau@gmail.com
Mob. No. 8964030701