Tables
Starch
Tables
TM25-e
Composition of potato starch
|
Constituents |
Typical analysis |
|
Starch dry substance |
80% |
|
Water |
20% |
|
Ash |
0.3% |
|
Sand |
0.02% |
|
Protein |
0.09% |
|
Phosphor, P |
0.07% |
|
Calcium, Ca |
0.03% |
|
Iron, Fe |
3 ppm |
|
Cold water soluble |
0.1% |
Size distribution, potato starch.
|
Interval
mm |
% |
% less than |
|
|
140 |
87 |
3 |
97 |
|
87 |
53 |
24 |
74 |
|
53 |
38 |
17 |
24 |
|
28 |
22 |
9.1 |
15 |
|
22 |
17 |
7.7 |
6.8 |
|
13 |
10 |
0.9 |
2.6 |
|
10 |
8 |
0.5 |
2.0 |
|
6 |
0 |
2.0 |
0.0 |
Properties of starch
|
|
|
|
Surface of starch granules |
app. 30 ha/g |
|
Specific density |
app. 1.55 g/ml |
|
Specific heat |
1.22 J/g |
|
Bulk weight of starch 80% DS |
app. 0.7 g/ml |
|
DS of moist centrifugate |
app. 0.6 g/ml |
|
Brightness (MgO2 = 100%) |
app. 95 % |
Biosynthesis of starch
In the green leaves of plants carbon dioxide and water are transformed
into glucose and oxygen under the influence of sunlight and with the help
of chlorofyl. This process is known as photosynthesis. During the day this
starch is deposited as grains in the leaf, the so-called leaf-transition
starch. During the night this starch is partially broken down again into
sugars which are transported to other areas of the plant. From these
sugars the starch arises which is won in the familiar grain shape.
The build-up of the grain starts from a tiny bit of coagulated starch,
the core of the starch grain in the making. This origin of the starch
grain, the hilum, can be observed quite well with the help of a
microscope. The glucose building stones are incorporated into the starch
molecule ‘to be’ on the surface perpendicular to the surface of the grain.
Initially only branched starch molecules (amylopectine) are formed. During the growth phase of the grain more and more unbranched starch
(amylose) is formed.
Composition of the raw materials from which commercial starch is won.
|
source |
starch
% |
moisture
% |
protein
% |
fats
% |
fibres
% |
Starch (1)
% |
|
potatoes |
17 |
78 |
2 |
0.1 |
1 |
77 |
|
cassava |
26 |
66 |
1 |
0.3 |
1 |
77 |
|
maize |
60 |
16 |
9 |
4 |
2 |
71 |
|
waxy maize |
57 |
20 |
11 |
5 |
2 |
71 |
|
wheat |
64 |
14 |
13 |
2 |
3 |
74 |
(1) percentage of starch calculated on dry substance content
Conversion of units.
100 Pa = 1 mbar = 10.2 mm H2O = 0.0145 p.s.i.
3.6*106 J= 1 kWh = 860 kcal = 0.367*106 kpm
736 W = 75 kpm/s= 632 kcal/h = 1 hp (metric)
1000.000.000.000 J = 1000.000.000 kJ = 1000.000 MJ = 1000 GJ = 1 TJ
---------------------------------------------------------------------------------------
Determination of starch content in potatoes.
The starch content of fresh potatoes is correlated with potato density. A sample of 5050 g potato in a net basket is weighed above water and then again immersed in clean water of maximum 18 oC.
Wo =
weight of the potato sample
Wu =
weight of sample under water
Density dpotato =
Wo / (Wo - Wu) g/ml
Starch dry matter =
(dpotato -1,015059)/ 0,0046051 %
The calculated figure in per cent deviate less than 0.05 from values read
out of the EU-table enforced by the European Commission covering potatoes
with 13% to 23% starch dry matter. A short version of the table - as valid
per 1. July 1996 - is as follows:
|
Wo 1
g |
Wu 2
g |
Density d 3
g/ml |
Starch dry matter of potatoes 4
% |
Potatoes to produce 1 t commercial starch 5
kg |
EU-minimum price 6
ECU/t potato |
EU-subsidy I to the factory 7
ECU/t potato |
EU-subsidy II to the factory 8
ECU/t potato |
|
5050 |
352 |
1.075 |
13 |
6,533 |
32.110 |
3.405 |
13.31 |
|
5050 |
372 |
1.080 |
14 |
6,065 |
34.590 |
3.671 |
14.33 |
|
5050 |
392 |
1.084 |
15 |
5,664 |
37.040 |
3.924 |
15.35 |
|
5050 |
412 |
1.089 |
16 |
5,308 |
39.520 |
4.190 |
16.38 |
|
5050 |
430 |
1.093 |
17 |
5,000 |
41.960 |
4.456 |
17.39 |
|
5050 |
450 |
1.098 |
18 |
4,720 |
44.440 |
4.709 |
18.42 |
|
5050 |
470 |
1.103 |
19 |
4,467 |
46.960 |
4.987 |
19.46 |
|
5050 |
488 |
1.107 |
20 |
4,299 |
48.800 |
5.180 |
20.22 |
|
5050 |
508 |
1.112 |
21 |
4,234 |
49.550 |
5.253 |
20.53 |
|
5050 |
527 |
1.117 |
22 |
4,140 |
50.670 |
5.373 |
21.00 |
|
5050 |
545 |
1.121 |
23 |
4,056 |
51.720 |
5.482 |
21.43 |
1) Weight of potato sample above water. 2) Weight of sample
immersed in water. 3) Calculated density = (Wo /
(Wo -Wu)). 4) Starch content according to
the official table. 6) The minimum price to be paid by the
manufacturer directly to the farmer in order to qualify for a subsidy.
7) An EU-subsidy I- a production premium - is paid to the
manufacturer, if he pays the EU-minimum price or better. 8) A
subsidy II- an equalisation payment - is paid directly to the factory, if
he pays the EU-minimum price or better. The exchange rate 1. July 1996 was
1 ECU = 1,24 US$.
Unfavourable storage conditions however may cause enzymatic conversion of
starch to glucose affecting starch yield without changing the
under-water-weight and density of potatoes. Therefore the method only
applies to fresh potatoes.
|
Starch Slurry Concentration at 60 oF
(15,6oC) |
|
Béo |
Specific Gravity |
Starch Dry Substance (DS) % |
Starch DS kg/m3 |
Water kg/kg Starch DS |
Béo |
Specific Gravity |
Starch Dry Substance (DS) % |
Starch DS kg/m3 |
Water kg/kg Starch DS |
|
0,50 |
1,003 |
0,89 |
8,93 |
112,360 |
13,00 |
1,098 |
23,10 |
253,75 |
4,329 |
|
1,00 |
1,007 |
1,78 |
17,92 |
56,180 |
13,50 |
1,103 |
23,99 |
264,53 |
4,168 |
|
1,50 |
1,010 |
2,67 |
26,98 |
37,453 |
14,00 |
1,107 |
24,88 |
275,39 |
4,019 |
|
2,00 |
1,014 |
3,55 |
36,00 |
28,169 |
14,50 |
1,111 |
25,77 |
286,33 |
3,880 |
|
2,50 |
1,018 |
4,44 |
45,18 |
22,523 |
15,00 |
1,115 |
26,66 |
297,36 |
3,751 |
|
3,00 |
1,021 |
5,33 |
54,43 |
18,762 |
15,50 |
1,120 |
27,54 |
308,36 |
3,631 |
|
3,50 |
1,025 |
6,22 |
63,74 |
16,077 |
16,00 |
1,124 |
28,43 |
319,56 |
3,517 |
|
4,00 |
1,028 |
7,11 |
73,12 |
14,065 |
16,50 |
1,128 |
29,32 |
330,85 |
3,411 |
|
4,50 |
1,032 |
8,00 |
82,56 |
12,500 |
17,00 |
1,133 |
30,21 |
342,22 |
3,310 |
|
5,00 |
1,036 |
8,89 |
92,08 |
11,249 |
17,50 |
1,137 |
31,10 |
353,69 |
3,215 |
|
5,50 |
1,039 |
9,77 |
101,55 |
10,235 |
18,00 |
1,142 |
31,99 |
365,24 |
3,126 |
|
6,00 |
1,043 |
10,66 |
111,20 |
9,381 |
18,50 |
1,146 |
32,88 |
376,89 |
3,041 |
|
6,50 |
1,047 |
11,55 |
120,92 |
8,658 |
19,00 |
1,151 |
33,76 |
388,51 |
2,962 |
|
7,00 |
1,051 |
12,44 |
130,71 |
8,039 |
19,50 |
1,155 |
34,65 |
400,34 |
2,886 |
|
7,50 |
1,055 |
13,33 |
140,57 |
7,502 |
20,00 |
1,160 |
35,54 |
412,26 |
2,814 |
|
8,00 |
1,058 |
14,22 |
150,50 |
7,032 |
20,50 |
1,165 |
36,43 |
424,29 |
1,745 |
|
8,50 |
1,062 |
15,11 |
160,51 |
6,618 |
21,00 |
1,169 |
37,32 |
436,40 |
1,680 |
|
9,00 |
1,066 |
15,99 |
170,48 |
6,254 |
21,50 |
1,174 |
38,21 |
448,62 |
1,617 |
|
9,50 |
1,070 |
16,88 |
180,63 |
5,924 |
22,00 |
1,179 |
39,09 |
460,82 |
1,558 |
|
10,00 |
1,074 |
17,77 |
190,86 |
5,627 |
22,50 |
1,184 |
39,98 |
473,23 |
1,501 |
|
10,50 |
1,078 |
18,66 |
201,17 |
5,359 |
23,00 |
1,189 |
40,87 |
485,75 |
1,447 |
|
11,00 |
1,082 |
19,55 |
211,55 |
5,115 |
23,50 |
1,193 |
41,76 |
498,37 |
1,395 |
|
11,50 |
1,086 |
20,44 |
222,01 |
4,892 |
24,00 |
1,198 |
42,65 |
511,10 |
1,345 |
|
12,00 |
1,090 |
21,32 |
232,44 |
4,690 |
24,50 |
1,203 |
43,54 |
523,93 |
1,297 |
|
12,50 |
1,094 |
22,21 |
243,05 |
4,502 |
25,00 |
1,208 |
44,43 |
536,86 |
1,251 |
|
Specific gravity is the weight relative to water at 15.6
oC; weight of 100 ml water = 99.799 g |
|
Baumé modulus 145: Béo = 145 - 145/Specific gravity15.6/15.6 |
|
Ref.: J.E.Cleland, E.E.Fauser and W.R.Fetzer; Anal. Ed. Int. and
Eng. Chem. Vol. 15 page 334 (1943). |
|
Disclaimer.
The information contained in this publication is to the best
of our knowledge reliable. Users should, however, conduct
their own tests to determine the suitability of our products
and recommendations for their own specific purposes.
Statements contained herein should not be considered as a
warranty of any kind, expressed or implied, and no liability
is accepted for the infringement of any patents. |