Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE
A method of producing snack products.
DESCRIPTION
This invention relates to the production of snack products
utilising reversibly modified extrusion equipment normally applied in the
manufacture of pasta shapes. Desirable dough rheology and sophisticated shape
formation is executed in such equipment and this is followed by a steaming
process in which the specific objective is to physically modify the dough to
give the required final product characteristics.
PRIOR ART
It is known from the prior art that equipment for extruding
pasta can be used to form snack half products and snack products. In our prior
proposal (GB Patent Specification No 2063643) we disclose a method of
producing a rapidly rehydratable pasta which inclwdes preparing a mixture of
semolina and/or wheat flour and water, having a moisture content between 28
and 40%, extruding the mixture through a die to form a product having a thick-
ness between 0.3 and 0.7 millimetres, and subjecting the product to super-
heated steam at a temperature between 106C and 1~0C for from 9 to 14
minutes to reduce the moisture content sufficient to give a shelf stable
product.
It has also been suggested to make a careful selection of raw
materials having desirable characteristics with the specific object of
avoiding the gelatinisation of nati.ve starch during extrusion, since this is
seen as having detrimental effects with regard to process stability and
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the effect on product quality. Although this method is seen as an advantage
it does nevertheless require Kighly specific and sophisticated raw materials.
STATEMENT OF INVENTrON
According to the present invention there is provided a method of
producing starch-based snack products for subsequent expansion prior to
consumption, which includes preparing a starch-based mixture having a moisture
content between 26 and 40~, extruding the mixture through a die to form a
product having a thickness of between 0.35 and 2.0 millimetres at a pre-die
temperature within thc range 40 to 75C and at a pre-die pressure within the
range 50 kg/cm2 to 140 kg/cm2 at which conditions gelantinisation is inhibited;
and partially gelatinising the starch by the use of a steam process for from
4 seconds to 25 minutes at a temperature of 85 and 140 C.
GENERAL DESCRIPTION
lt is recognized in the manufacture of snack products utilising
extrusion equipment that it is usual for some gelatinised starch to be
present in the final product. Frequently, the gelatinised starch is added as a
raw material, but proposals have been made for the use of high temperature
extrusioll for snacks, this equipment being specifically designed to cause
gelatinisation in the extruder. A conventional pasta extruder is unable to
operate under these conditions particularly when a high degree of shape
definition and sophistication is a prime requisite in the product.
The present invention, however, uses reversibly modified pasta
extrusion plant in order to blend the wet and dry raw materials and to yield
carefully defined shapes. These pellets are then subjected to steam within a
chamber for a specific time and at a specific temperature in order to achieve
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the required degree of gelatinis.ation. Different textures and eating
qualities are achieved through the selection of raw materials; the degree of
subsequent processing, and the processing conditions within the steam
chamber. This particular technology was developed to meet the need in the snack
market for products with more continuous crunch and cleaner eating character-
istics. It is a suprising feature of the process that very short steaming
times cause dramatic improvements in these textural properties. rt is
hypothesised that this observed change is a result of the non-homogenous
distribution in the pellet of gelatinised and ungelatinised starch; this
could cause variations in the distribution of water and ionic salts, leading
to a change in the expansion characteristics.
The present invention can be applied using saturated steam, steam/
air mixtures and super-heated steam (i.e. steam elevated to a temperature in
excess of 100C at atmospheric pressure).
It will be clearly apparent, therefore, that the full flexibility
of the pasta extrusion equipment can be used to give carefully defined shapes
since extremes of extrusion conditions are not necessary.
Factors which effect this invention may be itemised as follows:-
1. Conventional pasta extrusion equipment, reversibly modified.
2. A wide range of raw materials may be selected, including those
manufactured from tubers, roots, pulses, cereals, native starch and
pregelatinised/modified starches. The use of ionic salts in such
products is well recognized.
3. The versatility of a pasta extruder can be fully utilised.
4. Mix moisture content is 26 to 40%. The preferred range is 2~ to 36%.
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5. Extrusion pressures 50 to 140 kg/cm ; pre-die temperatures 40
to 75 C.
6. Dies of aperture size Q.35 to 2 mm.
7. Generally a pre-drying/cooling s-tage.
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8. Steaming process; preferred temperature range 85 C to 110 C;
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overall range 85`C to 140 C.
9. Steaming residence time 4 sec. to 25 minutes.
10. Moisture of pellet ex-steamer 8 to 40% moisture.
ll. Optional further reduction of moisture to give a final moisture of
6 to 20%. Products with higher moisture contents may be produced,
but these tend to exhibit characteristics which are less desirable
when expanded.
12. Such pellets may be fried or otherwise processed immediately or
subsequent to a stabilisation period to give the expanded final
product.
DRAWINGS
~igure 1 of the accompanying drawings is a flow diagram showing
typical routes for carr~ing out the method of the present invention,the numbers
referring to the examples ~erein;
Figure 2 is a graph produced when testing a product made by a
conventional method; and
Figure 3 is a graph produced when testing a product made according
to example 6 herein.
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EXAMPLES
1. Potato granules 35.0%
Native potato starch ~farina~ 55.0%
Pregelatinised starch 6.5%
Salt 3.5%
A mix moisture of 33%; extruded through a shell die with aperture
size 0.5 mm and processing conditions of 95 kg/cm2 pre-die
pressure and a pre-die temperature of 55 C. Steamer process
conditions 107 C for 10 mins. Moisture content of pellet ex-
steamer 17%.
This product was fried immediately at 200 C for 12 seconds and
yielded a desirable light but crunchy textured product, with clean eating
characteristics.
2. As in 1 above, but further dried down to 10% moisture on discharge
from steamer. The product was fried at 200 C for 7 seconds and yielded a more
expanded, lighter textured, crunchy and lower bulk density product.
In both cases excellent shape identity o:E the product was retained.
3. Potato granules 25.0%
Farina 65.0%
Pregelatinised starch 6.5%
Salt 3.5%
The processing conditions were as in 2 above and the texture of
the product was somewhat lighter and the product less substantial
with a more porous structure. Shape identity was still good.
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4. Formulations as in 2 above but util~sing a gr~lle die with
aperture size 1.3 mm. Steamer conditions llZ ~ for 12 mins. Pellet moisture
ex-steamer 15%. The pellet was then dried down in conventional pasta equip-
ment at controlled temperature and humidity yielding a shelf stable pellet
at 9.5% moisture. The product was fried at 200 ~ for 10 seconds and yielded
a well expanded crisp crunchy product which was more substantial than those
given in the Example above,
5. Potato granules 27.0%
Farina 60.0%
Pregelatinised starch 10.0%
Salt 3.0%
The product was exkruded at a mix moisture of 37% through a
Hoop * die having an aperture size of 0.85 mm. The pellet was
extruded under conditions of 77 kg/cm2 pressure and a pre-die
temperature of 5~ C. The product was passed through a conventional
pasta pre-drier at 30 C for 3 mins. The pellet was then steamed
under super-heated conditions at 115 C for 20 mins. The product
from the steamer had a moisture content of 10% and was in a shelf
stable form. On frying at 200 C for 6 seconds a firm, well expanded
product was achieved.
6. Potato granules 25,0%
Farina 65.0%
Pregelatinised starch 7.0%
Salt 3.0%
A mix moisture of 33%; extruded as a grille die with aperture
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size 1.3 mm and process~ng conditions of 9O kg/cm2 pre-die
pressure and a pre-die temperature of 5e C. The product ex-extruder
was cooled to 18 C using a shaker pre~drier to give a moisture
content of 32%. The product was steamed (93C for 4 seconds)
increasing the moisture content to a~out 35%. This was progressively
reduced to 33%, 29% and 12% by three drying stages. On frying this
yielded a product substantially similar to that in Example 4.
7. As in Example 6, but with a residence time in the steamer of 6
minutes. On frying this yielded a product substantially similar to that in
Example 4.
8. Crushed flake yellow maize 30.0%
Farina 30.0%
Potato granules 30.0%
Pregelatinised starch 7.0%
Salt 3.0%
The product was extruded at a mix moisture of 35% through a
large shell die having aperture size of 0.9mm. The pellet was
extruded under conditions of 100 kg/cm2 pressure and a pre-die
temperature of 57 C. The subsequent process conditions were as in
Example 2 above and the product on frying at 200 C for 12 seconds
yielded a crisp and crunchy product with clean eating characteristics.
9. Ground rice flour 30.0%
Farina 30.0%
Potato granules 30.0%
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Pregelatinised starch 7~Q%
Salt 3~0%
The product was extruded at a mix moisture of 35% through a
large shell di~e having an aperture size of 0.9mm. The pellet was
extruded under condi~tions of gO ~g/cm2 pressure and a pre-die
temperature of 53C. The subsequent process conditions were as in
Example 2 above and the product on frying at 200~ for 10 seconds
~ielded a light but crisp and crlmchy product.
All the above examples give products with clean eating character-
istics, i,e. it does not adhere to the teeth or palate. These can be
demonstrated by comparing the sounds made and the forces required when an
instrument is used to simulate the molar bite. The acoustic prints and
force curves shown were produced using an Instron * 1122 and compare the
product manufactured according to example 6 ~Figure 3) with a product that is
identicàl except that the 4 second steaming stage is omitted ~Figure 2).
They show that the new product is distinctly different, requiring less force
to bite through it, and having a much more even fracture pattern; both these
factors are relevant to the perceived difference in texture.
In all the above examples, the percentages are by weight. It
should be noted that the products of the above processes may be expanded in `~
hot o~l or by the use of microwaves~ a fluidised salt bed, hot air, micro-
nisation and the like.
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