Note: Descriptions are shown in the official language in which they were submitted.
2 1 ~ 70 ~ o
ssi~
216702~
final yogurt product. (see United States patent nos. 3,946,657 and 4,800,809)
Generally, only the bottom portion of the tank is disturbed to change the
r~ milk from a f~m gel to a smooth highly viscous fluid.
In another method as disclosed in United States patent no. 3,269,842,the
5 coagulated milk is ~ulll~ed through a pipeline cont~inin~ st~inl~c~ steel screens
having a mesh size of belw~;ell 15 and 30 mesh. The screens break up the lumps
of curd into a liquid having a plastic con~ y. However, if the ~ ule is
stirred too vigorously, the gel structure is r~luced to a weak bodied fluid which
can be poured. This weak bodied fluid is undesirable unless m~nllf~rt~lring
10 drinkable yogurt product.
It has been previously proposed to use a high speed mixer which produces
a strong axial thrust wilhoul Cl~dlillg a vortex, to agitate the ferm~nte~ milk into
a yogurt. However, such pn~posal has not been accepted as conventional
production m~int~in~ the notion that strong ...~oc~ -ir~l mixingdamages sour milk
15 coagulate and decreases viscosity of the end product.
Summary of the Invention
The disadvantages of the prior art may be overcome by providing a method
of m~mlfa.-l...ing yogurt by passing the coagulated milk through an emlll~ifier
colll~lising a series of rokt~ g rotors and fixed stators which proglessively
20 ~mnl~ifi~s the coa~ t~l milk to produce a yogurt product having increased gel
stability and viscosity.
It is desirable to provide a process of m~nnf~Gtllrin~ sour milk products
using a single pass process to impart shear forces on the sour milk product to
exact a desired change to produce an end product having h~loved gel stability
- 216702C
and viscosity.
According to one aspect of the invention, there is provided a method of
making an ~ rovcd yogurt in an in-line single pass process. The method
co-ll"ises the steps of~ bA~ g a base coul~ g raw milk, bacteria, a
stabilizing agent and a protein CO11C~1111;A~C~ and emulsifying the base after
i...-,~lLAIion, by passing the base through a series of rotors and stators pairs. The
rotors rotate relative to said stators at a pl~dc~ Pd speed. The rotors and
stators each have precise gaps therein for passing the inr~bAtPd base ~l~.e~ Jugh
and Ul~_liLIg shear forces thereon.
According to one aspect of the invention, there is provided a method of
making an l~rovcd yogurt. The method co,l,l"ises the steps of: inrllbAting a
base COLLIP1iSiUg raw miLlc, bacl_lia, a stabilizing agent and a about 0.5 to 0.8%
protein co~ce.lllalc; lldl~rclliL~g the i~ lk~t~d base at about 42C to an
emlll~ifiPr; the Pmlll~ifier Colll~lisL.~g a series of rotor/stator pairs, each of the
rotors has a plurality of CollccLI~ic rims which rotate relative to a plurality of
conre~l1 ;r rims on a corresponding stator, the plurality of CO11CC11LIiC rims on the
rotor and the co". s~onding stator each have precise gaps therein for passing the
.lb~led base Illtlcl~ough and i u~lmg shear forces thereon, the precise gaps
d~PSCf n~ in size on each of the rotor/stator pairs, in a direction from an inlet
to an outlet of the emlll~ifir~r; emulsifying the base after inr~k~tion, by passing the
inrubatr~l base through the series of rotor and stator pairs wl",lcill the rotors are
~lalillg relative to the stators at a speed bclwccll 6.5 and 20 Hz; ll~r. l,i. g the
Ik~1 ;rl and Prmll~ifiP,rl base to a holding tank; and cooling the inr~l~bAteA and
emlll~ifiP~1 base to about 15C.The gaps are bclwcen 5.0mm and l.5mm.
216702~
Description of the D~ a~ D
In &awh~gs which illustrate embo l;",~"l~ of the invention,
Figure 1 is a sr-h~.,.A1ir view of the appalalus for undertaking the
method of the present invention;
Figure 2 is a P1ID~Je~ Ve view of the emnl~ifPr of the a~alalus of
Figure l;
Figure 3 is an exploded pe,~e~liv~; view of the series of rotors and
stators of the eml~l~if1Pr of Figure 2; and
Figure 4 is a sectional view of the series of rotors and stators of the
emlll~ifPr of Figure 2, in an assembled condition.
Description of the Invention
The a~alalus for undertaking the process of the present invention is
generally illuDlla~d in Figure 1. The ap~alalus 10 generally colll~lises a batch
tank 12, a delivery pipeline 14, an Pmlll~ifPr 16 and a holding tank 18.
ReÇ~llil,g to Figure 2, the emlll~ifPr 16 is more particularly illustrated.
F.mlll~ifPr 16 colll~lises a motor 20,housing 22 mounted on the motor 20. The
housing 22 has an inlet pipe 24 and an outlet pipe 26. Inlet pipe 24 has a flow
meter 28 for Ill~.A~ , the flow through inlet pipe 24. F.mlll~ifPr 16 has a
thPrm~l-syphon 30 for deli~ h~g lublicall~ and coolants to the journal bearing
20 supporting shaft 32.
R~r~lling to Figure 3, shaft 32 has rotors 34, 38 and 42 mounted thereon.
Rotors 34, 38 and 42 are fixedly attArhPJ~ to shaft 32 to rotate 11l.,~ . A series
of stators 36, 40 and 44 are mounted within housing 22. The outer ~ te. of
each of the stator is sized to slide into and frictionally fit inside of housing 22.
21~7~2~
_ach of rotors 34, 38 and 42 are made of st~inl~sc steel and geneMlly
co~ ise a central hub 46, a radially çxt~n-ling flange 48 and an axially ~ n~ g
inner rim 50, an i..~ Pd;~lr rim 51 and outer rim 52. _ach rim 50, 51 and 52
has axially çx~ lin~ slots 54 defining teeth. Slots 54 are precisely cut to
5 predçt~ ...i..~d widths.
_ach of stators 36, 40 and 44 are made of st~inles~ steel and generally
col~ ises an outer hub 60, a radially inwardly ex~rn~ -g flange 62 and axially
e~lellding rims 64, 66 and 68. Each rim 64, 66 and 68 has axially ext~n-1ing slots
70 defining teeth.
Each of the slots 54 and 70 of the rotors and stators are precisely cut to
define the teeth. In the pl~ felled embo-limlo-nt, the rotor/stator pairs 42-44,38-40
and 34-36 have precisely cut gaps in descen~ g sizes.
F.m~ ifi~r 16 also has a spacer 76 for spacing the stators 36, 40 and 44
within housing 22.
Inner rim 50, ill~.. ~;~e rim 51 and outer rim 52 have a ~i~m~ter and
thir~n.oss to travel in the ch~;ull~fele.llial grooves defined by rims 64, 66 and 68.
Upon rotation of shaft 32, inner rim 50, i,.t~ te rim 51 and outer rim 52 will
travel belweell and relative to rims 64, 66 and 68. The tolerances must be
sufficient for the rotor to be able to rotate relative to the stator and impart shear
20 forces on the product passing through the ~alalus. In the ~l. r~ ,d
embo lim~nt the tOlc.al ces b~,lw~e~ rims is about 0.0010".
ReÇ~,.li~g to Figure 4, the flow path through the stators and rotors is
illu~lla~d. The product to be ern~ ifi~l enters through inlet pipe 24 to an inlet
cavity 82. The product will radially pass through the first opposed rotor/stator
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pair 42 44 by passing through the first gap into first i,.l~ .",P~ e cavity 84.
Through flowp~ c, product moves axiallyand radially c~ulw~ldly. The product
will then radially pass through the second opposed rotor/stator pair 38-40 by
passing btlween the second gap into second i"l~ d;~le cavity 86. Through flow
5 ~ S~UlC, product moves axiallyand radially uulv~ar~ly. The product willradially
pass through the third opposed rotor/stator pair 34-36 by passing through the third
gap into outlet cavity 88. The product is then discharged through outlet pipe 26
to holding tank 18.
In the p~fellcd emborlimPnt a three rotor/stator em~ ifier has been
10 illustrated. It is readily understood that one rotor/stator sets and two rotor/stator
sets may also be used with similar results.
EXAMPLE 1
In this example, a three rotor/stator set has a gap size in the following
- order, first gap: 5.0 mm; second gap: 3.0 mm; and third gap: 1.5 mm. A raw miL~
15 base is provided with a protein collcelllldle of between 0.5 to 0.8 %, by weight or
volume, d~e,ldi~lg on the state thereof, of a ~ ." or calcium casehldlc. Other
protein collcellLI~les are also colllcl~lated within the scope of this invention.
Using a flowrate of 15,0001iters per hour, inlet lcl~.,lalul~ of 42Cand a speed
of 6.5 Hz, the Pmlll~ifier produced a yogurt product which is cooled to 15C. The
20 yogurt product had a viscosity of approximately 1,000 mPa.s higher than the
viscosity achieved using a collvclllional method.
It has been found that similar results can be achieved using settingc of 10
and 15 Hz, but less than 20 Hz. Trials have found that operation in excess of 20
to 25 Hz resul~s in a product having a very high viscosity similar to cottage cheese,
- 2l67n20
which is not desired in yogurt.
It is believed that the i ll~rovcd yogurt product results from an elongation
of the protein molecules wi~ul damage which i~ VCS the mouthfeel and
emnl~ifi~s the stabilizing agent to a more productive and stable form. Since the
5 protein molecule is longer, the surface of the protein chains are elongated,
i~cleasillg the llull~el of bonding areas. The gel structure is thus denser and
more tightly knit, ill~l~asi~g viscosity and ability to bind water.
It is readily lln(l~r~tood that the process and method as described herein
is also applicable to illl~lovillg other dairy products, including fresh cheese and
10 similar products such as cottage cheese, kafir and plld~ling~. The milk base is
mixed with a coagulant for making the cheese and then processed in a like
er as ~ c!~sed above.
It is now appal~ to a person skilled in the art that there are numerous
other mo-lir.~ ns and purposes of this invention. It is to be understood that
15 certain changes in design, size and components may be effective without a
dep~lulc from the spirit of the invention and within the scope of the appended
claims.
