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Mixability™
Definition
 Mixability™
is defined as the ability of a product to be distributed homogeneously
in a premix or a feed.
The Mixability™ depends on:
- The product to be incorporated.
- The carrier.
- The mixer.
Benefits
The results of the measurement of Mixability™ parameters
make it possible to choose carriers which are best suited
to the manufacture of a given premix and to specify the methods
of incorporation of the vitamin products. They also make it
possible to optimize the mixing parameters and to objectively
interpret analytical results.
Poor Mixability™ leads to heterogeneous mixtures or
to insufficient dispersions of the active material. It may
be the cause of erroneous interpretation of the analytical
results and of counter-productiveness in animal productions.
Parameters for assessing Mixability™
Assessment of practical Mixability™ of a vitamin product
is determined by three factors:
- Theoretical Mixability™ determined on the vitamin
product to test.
- Efficiency of the mixer.
- Analytical performances.
Theoretical Mixability™ determined
on the vitamin product to test
The theoretical Mixability™ of a vitamin product indicates
whether the number of active particles in the product is (or
is not) sufficient to yield an acceptable distribution in
the intended mix. The objective entails obtaining a sufficient
number of active particles per unit of volume, and to obtain
an homogeneous distribution in the mixture.
Total variance = Theorical mixability variance + Mixer
variance + Analytical variance + Residual variance
The theoretical Mixability™ is determined
in three steps:
- step one: determine the
particle size profile and of the specific density.
The particle size profile corresponds to the distribution
of the product by standard particle size classes. It is
measured by screening (ISO method 2591).
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Relationship
between the particle size profile
and the number of particles
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Size of Particles
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Particle number in
1.0 gram (specific gravity = 1.0) from D.E.Axe (1995)
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U.S Sieve series
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Diameter
microns (μm)
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Tyler equivalent designation
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N° 18
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1000
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16 mesh
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1,530
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N°
20
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841
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20 mesh
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2,580
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N° 25
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707
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24 mesh
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4,350
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N° 30
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595
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28 mesh
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7,460
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N° 35
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500
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32 mesh
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N° 40
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420
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35 mesh
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20,800
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N° 45
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354
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42 mesh
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N° 60
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250
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60 mesh
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84,700
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N° 80
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177
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80 mesh
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281,000
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N° 100
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149
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100 mesh
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392,000
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N° 120
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125
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115 mesh
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N° 140
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105
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150 mesh
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1,200,000
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N° 170
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88
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170 mesh
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N° 200
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74
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200 mesh
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3,260,000
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N° 230
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63
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250 mesh
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N° 325
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44
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325 mesh
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15,600,000
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| Bold letters: ISO recommendation |
The specific density is defined as the weight of a volume
of product excluding all of the interparticulate volume
(air). It is measured by fluid displacement methods such
as pycnometry. In practice, the specific density of a vitamin
is given in tables (K. Behnke 1995 (1)).
- step two: calculate the
number of active particles per gram of vitamin product (K.
Behnke - 1995 (2)).
- step three: statistically
calculate the theoretical Mixability™ according to
the method of Bruggeman and Niesar (1965). The result of
the theoritical Mixability™ calculation is expressed
by the variation coefficient, wich is representative of
the distribution of the product in the mixture.
This step requires the information from steps one and two
and also involves the unit size of the sample and the level
of incorporation of the product in premixes or feeds.
The concept of theorical mixability is used to:
- Determine the minimum size of feed or premix samples to
obtain a significant result of analysis (i.e. containing
sufficient active particles).
- Determine the valid tracer and the size of the sample
in the case of testing the efficiency of the mixer.
- Assess the validity of a tracer and the adequate sample
sizeto use in a de-mixing test.
Adisseo has developed a computer program for calculating
the theoretical Mixability™ of a vitamin product, as
well as scales for interpretation of the Mixability™
of vitamins in premixes and feeds.
Comment:
In practice, the electrostaticity and the dustiness of the
product, as well as the form of its particles, may modify
the theoretical Mixability™ measurement results.
RPAN vitamin Mixability™ interpretation scale
(Variation coefficient %)
Compatibility of the carrier
 A
carrier is compatible if two criteria are met:
- The particle size profile of the carrier encompasses that
of the vitamin product to be mixed.
- The density of the carrier (de)
is of the same order as that of the vitamin (dv)'
In practice, it is accepted that it is possible to obtain
a stable mixture when the ratio of the two components (dc
/ dv) is between 1 and 3.
Unstable mixture (magnesium oxide + ground corn):
de / dv
> 3
Stable mixture (Microvit™ A Supra + ground corn):
de / dv
< 3
Efficiency of the mixer
The efficiency of the mixer characterizes the ability of the
mixer to disperse the vitamin products homogeneously in the
premix or the feed. Measurement of the efficiency of the mixer
takes into account the effect of shear (energy transmitted
to the mixture) and the mixing duration.
The efficiency of the mixer is determined experimentally and
should be supplied by the manufacturer of the mixer.
Analytical performances
The analytical performance depends on the
product to analyze and the laboratories which carries out
the analyses. The laboratory must be able to provide its analytical
performance for each required product.
Conclusion
In order to obtain and verify good mixing of a vitamin product
in a premix, it is necessary to satisfy the following three
criteria:
- Theoretical Mixability™.
- Compatibility of the carrier.
- Efficiency of the mixer.
The vitamin producer can directly control only the theoretical
Mixability™ of the product. However, during the development
of its product, the vitamin producer should have taken into
account the standard conditions used in premix or feed plants
(encompassed by the other two elements).
Under specific conditions, the premix manufacturer will have
to choose the most suitable carriers and/or modify the mixing
parameters.
Solubility
Solubility and water dispersibility of vitamin products
Certain animal production programs require the distribution
of vitamins in drinking water. In this case, it is necessary
to use vitamin products either in the form of soluble or water-dispersible
powders or in liquid form (vitamin hydrosols).
The actual solubility of water-soluble B vitamins will vary
according to their chemical form.
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Solubility of
B vitamins
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Common
name
of vitamin
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Chemical
form
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Solubility
(mg/ml of water)
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B1
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Thiamin hydrochloride
Thiamin mononitrate
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1,000
27
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B2
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Riboflavin
Sodium
riboflavin-5-phosphate
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0.1
30
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B2
ou PP
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Nicotinic acid
Nicotinamide
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17
1,000
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B5
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Calcium pantothenate
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357
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B6
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Not hygroscopic /
Stable
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222
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B9
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Folic acid
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0.02
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H
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D - biotin
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0.2
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B12
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Cyanocobalamin
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12
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C
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Ascorbic acid
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330
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Source : V. Bulher, 2nd edition, 2001
The fat soluble (vitamins A, D3
and E) are not soluble in water. A suitable formulation allows
very fine suspensions to be produced when these products are
mixed in water. Water-dispersible complexes exist for vitamin
K3 (MSB).
The most soluble chemical forms for the B vitamins or formulations
specially adapted for the fat soluble vitamins will preferably
be chosen for the preparation of water-soluble vitamin complexes.
Adisseo has developed a method for measuring the water dispersibility
of fat soluble vitamins (RPAN - D 080).
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