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The Influence of Wheat-Hardness on Some Granulometric and Energetic Characteristics of Grinding
THE INFLUENCE OF WHEAT HARDNESS ON SOME GRANULOMETRIC AND ENERGETIC CHARACTERISTICS OF GRINDING VEHA, A.- GYIMES, E. UNIVERSITY OF HORTICULTURE AND FOOD, COLLEGE OF FOOD INDUSTRY, SZEGED DEPARTMENT OF FOOD TECHNOLOGY H-6725 SZEGED, MOSZKVAI KRT. 5-7. PHONE: + 36 62 456030 FAX: + 36 62 456034 Email: [email protected]@BIBL.SZEF.U-SZEGED.HU
The specific superficial grinding energy demand of the farinaceous softer GK Kata depending on the screen perforation and characterized by the confidence intervals was measured as er = 0,37 ... 0,53 '10.7 kWh/cm2 and it became cca. one third of that of GK c:'>thalom: 1,25 ... 1,41 . 10-7 kWh/cml only. At the same time the grits for GK Kata were always fmer, expressed by the particle mean size Id = 1,0 ... 1,6 mm than that ofGK Otbalom: Xd = 1,3 ... 1,9 mm at even lower specific grinding energy requirements: GK Kata, ed = 1,48 ... 3,46 kWh/t while with GK Otbalom 1,61 ... 5,86 kWh/t.
Background Hardness of wheat varieties is such a physical characteristic of the material which can also be defined by help of the " grinding resistance" ( in our case the specific superficial grinding energy requirement) instead of or beside the usual vitreousity per cent. Former investigations of the authors carried out with feed grains - like barley (BOLONI,1972j BOLONICSERMELY-SALAMON,1993; VEHA,1994) , corn (CSERMELY,1988), wheat (BOL(lNI-VEHAGYIMES,1996) pointed at the almost importance of the specific superficial grinding energy consumption ( er : kWh/cm 2) related to the newly created specific surface area of ground material and of the grit fmeness (BOu'lNI 1996, VEHA-GYIMES,1997) It was proved that er specific grinding energy demand is a characterizing physical property of the grain kernels.
Aim of the investigations Task of the examinations was to check: is there any significant difference between the specific superficial 2 ginding energy requirements ( kWh/cm ) of two freely chosen Hungarian aestivum wheat varieties: - GK Kata (vitreousity = 63% ) and - GK Otbalom (vitreousity = 89%) by grinding with hammennill when the mass related specific grinding energy consumption ed( kWhIt) remains constant.( see Table 1.)
Tested materials, measuring methods Place and time of investigations: University of Horticulture and Food, College of Food Industry. Szeged, Hungary from November 1995 to March 1996. Vitreousity was tested by diaphonoscope. Some important characteristics of the above wheat varieties are to be seen in Table 2. Type of laboratory hammennill applied KD 161 manufactured by SAUNA Ltd. , Pusztaszabolcs, Hungary. For sieve analysis a Ro - Tap machine, model AP - 20 having 10 sieves was used. Electric power requirement was measured by an electronic spectraregister, type Schlumberger A 12 .
161
The specific superficial grinding energy consumption e r was calculated by means of the following equation ( B()L()NI 1996. ): er ( kWh/cm 2 ) = 10-6 (t/g ) .
£d (
kWhIt) cm 2 /g)
~ad (
where ed = mass related specific grinding energy demand ( kWhIt) ~ad = specific surface area increase of grind ( cm2/g» while whereas
ad =mean specific surface area of ground material, Boa = mean specific surface area of the whole wheat kernels before grinding.
Results of investigations See Table 2.; 3. and Figure 1..
Conclusions
o
o o o o
o o
er ( kWh/cm 2) specific superficial grinding energy requirements of the two tested wheat varieties differ quite a lot. See confidence intervals in Fig. 1. and most important statistical characteristics in Table 3. This proves that vitreousity has significant influence on specific grinding energy consumption ( kWh I cm 2 ) The 11 grinding resistance 11 characterized by er specific superficial grinding energy demand has a normal probability distribution .Averages of the two varieties are very different, but the coefficient of variation ( C. = standard deviationl average) are close. Both the grit fmeness characterized by the particle mean size of grinds ( Id : mm) and the specific superficial grinding energy demand er ( kWhI cm 2) are probability variables. There is a well determined correlation between the wheat-hardness and specific grinding energy requirements er ( kWhI cm 2) . Those characteristics of GK-0thalom (89 % vitreousity) are about three times bigger than that of GK-Kata (63 % vitreousity). (see Fig .. l .). Between above characteristics and mass related specific grinding energy requrement ed ( kWhIt ) exists a two - variable relationship according to the following equation (BOLONI, 1996. )
v.
In order to adjust hamrnermills for a predetermined value of mass related specific grinding energy requirement the machine should be developped that is going on. In order to establish wheat - hardness grades expressed by ( kWh/cm 2) physical units more other wheat varieties has to be tested further on.
162
Table 1.
Sign
Important energetic and granulometric characteristics of Hungarian aestivum wheat varieties ground by hammermill
Screen diameter
Wheat variety
Jlitreousity
Grit's
Feedflow rate
particle mean size
Specific grinding enO'gy requirement related to
Specific surface area increase
mass unit
surface unit
Q.
Id
Aa d
kg/h 5.
mm 6.
cm2/g 7.
ed kWhlt 8.
er 10-7 ·kWhlcm2 9.
180•.• 280
1,0... 1,3
75•• .46
2,68 •.• 3,46
0,40••• 0,74
200.. .420
1,25... 1,45
60... 44
1,76•.. 2,26
0,32 •••0,47
1. 2.
03
3.
12.14
4.
12.15
250 ...470
1,45... 1,6
45 .•. 31
1,48... 1,85
0,34.•.0,58
5.
12.13
130•.• 210
1,3... 1,5
46 ... 25
5,86... 4,87
1,09... 2,31
6.
04
190... 390
1,5... 1,75
17...30
2,14 ... 2,39
0,69... 1,40
7.
05
200... 450
1,65... 1,9
15... 23
1,61. .. 2,19
3.
GK- Kata ( m.c.=1l,4%)
GK-()thalom (m.c.=1l,5°/.)
4.
63,0
89,0
i ,
dr mm 2.
0/0
i
----
-
0,88~.1~42_ _
Table 2.
Important characteristics of tested wheat varieties
Wheat variety Item Moisture content
1.
Unit
GK-Othalom
GK-Kata
%
12,4
12,5
89,0
63,0
43,0
43,5
1,41
1,22
33 ... 34
27 ... 30
kg! l00dm 3
80,9
81,0
mm
2,98
2,82
cm1/g
14,30
17,40
(wet base) 2.
Vitreousity
%
3.
Thousand kernel mass
g
True density
4. 5.
Wet gluten content
6.
Bulk density
7.
Kernel mean size
8.
Specific surface area
g!cm
3
%
Table 3. Important statistical characteristics of specific superficial grinding energy consumption er ( kWh/cml ) as a probability variable with two Hungarian aestivum wheat varieties
Si2n 1 2 3 4 5 6 7 8 9 10 11 12
Statistical characteristic 2 Sample size Average Median Mode Standard deviation Standard error Minimum Maximum Skewness Standardized skewness Coefficient of variation
Unit 3 10.7 kWh/ cm1 10.7 kWhI cm 1 10.7 kWh/ cm 1
10.7 kWh/ cm1 10.7 kWh/ cm1
%
164
Wheat variety GKKata GK Othalom 4 5 30 30 0,4512 1,3313 0,4302 1,2024 0,4116 1,1851 0,1147 0,4326 0,0209 0_~O789 0,3278 0,6914 0,7478 2,3059 1,28671 0,77179 2,87718 1,72579 25,43800 32,49400
ef [10. 7 kWb/cm 2 ]
1.5
1.2
1,41
I
1,33 1,25
0.9
0.6
. ! . . . . . . . . .. . . . .. .. . . . . .. . .. . . ..... -:. . . . . . . . . .. . .. .. ... . ..... . . . . .. . t
I
... _ • • • ••.••
0,53 0,47
.... .. ... ......... .. .. . 0,37
0.3
o
• ••
~------------~------------~------------~
GK-OTHALOM
GK-KATA
Fig 1. Average values and confidence intervals ( on &=0,05 probability level) of specific superficial grinding energy consumption for two Hungarian aestivum wheat varieties
165
References
Boloni,I.(1972) :
Grinding Mechanism and Operational Relationships of Hanunennill ( D. Sc. Theses in Hungarian) , Mewgawasagi Gepkiserleti lntez.et, GOdo1l6, 1 - 115 pp.
Boloni, 1.- Csermely - Salamon (1993): Warning up of barley grits in hanunennill ( OTKA) Hungarian Agricultural Engineering Hungarian Institute of Agricultural Engineering, Godollo NO.6 . 53-54 pp Boloni, I. (1996):
Analysis of Grinding's Basic Energetic Relationship, Hungarian Agricultural Engineering, Hungarian Institute of Agricultural Engineering, GOdollo, Vol 9, 44 -45 pp.
Boloni, I. - Veha, A. - Gyimes, E. (1996): Effect of Aestivum Wheat Varieties on Some Energetic Characteristics of Grinding Jubilee Symposium on Cereal Chemistry and Food Quality, Budapest Technical University, Budapest, June 17 - 18, ,Abstracts, 53 . p. Csennely,J (1988) :
Technical and Technological Relations of Wet-Corn Storage. ( D. Sc. Theses in Hungarian) , Mewgazdasagi Gepkiserleti lntez.et, Godollo, , 1 - 182 pp.
Veha, A. (1994):
Agricultural Feed Grinding with Hanunennill ( Ph. D. Theses in Hungarian ), Kertesz.eti es Elelmisz.eripari Egyetem, Elelmisz.eripari F6iskolai Kar, Sz.eged, I - lIS pp.
Veha, A - Gyimes,E (1997) : Detennination of Wheat-Hardness with Energeticallnvestigation of Grinding Tudomanyos Kozlemenyek KEE EFK Sz.eged, Vol.19 (in print)
166
The specific superficial grinding energy demand of the farinaceous softer GK Kata depending on the screen perforation and characterized by the confidence intervals was measured as er = 0,37 ... 0,53 '10.7 kWh/cm2 and it became cca. one third of that of GK c:'>thalom: 1,25 ... 1,41 . 10-7 kWh/cml only. At the same time the grits for GK Kata were always fmer, expressed by the particle mean size Id = 1,0 ... 1,6 mm than that ofGK Otbalom: Xd = 1,3 ... 1,9 mm at even lower specific grinding energy requirements: GK Kata, ed = 1,48 ... 3,46 kWh/t while with GK Otbalom 1,61 ... 5,86 kWh/t.
Background Hardness of wheat varieties is such a physical characteristic of the material which can also be defined by help of the " grinding resistance" ( in our case the specific superficial grinding energy requirement) instead of or beside the usual vitreousity per cent. Former investigations of the authors carried out with feed grains - like barley (BOLONI,1972j BOLONICSERMELY-SALAMON,1993; VEHA,1994) , corn (CSERMELY,1988), wheat (BOL(lNI-VEHAGYIMES,1996) pointed at the almost importance of the specific superficial grinding energy consumption ( er : kWh/cm 2) related to the newly created specific surface area of ground material and of the grit fmeness (BOu'lNI 1996, VEHA-GYIMES,1997) It was proved that er specific grinding energy demand is a characterizing physical property of the grain kernels.
Aim of the investigations Task of the examinations was to check: is there any significant difference between the specific superficial 2 ginding energy requirements ( kWh/cm ) of two freely chosen Hungarian aestivum wheat varieties: - GK Kata (vitreousity = 63% ) and - GK Otbalom (vitreousity = 89%) by grinding with hammennill when the mass related specific grinding energy consumption ed( kWhIt) remains constant.( see Table 1.)
Tested materials, measuring methods Place and time of investigations: University of Horticulture and Food, College of Food Industry. Szeged, Hungary from November 1995 to March 1996. Vitreousity was tested by diaphonoscope. Some important characteristics of the above wheat varieties are to be seen in Table 2. Type of laboratory hammennill applied KD 161 manufactured by SAUNA Ltd. , Pusztaszabolcs, Hungary. For sieve analysis a Ro - Tap machine, model AP - 20 having 10 sieves was used. Electric power requirement was measured by an electronic spectraregister, type Schlumberger A 12 .
161
The specific superficial grinding energy consumption e r was calculated by means of the following equation ( B()L()NI 1996. ): er ( kWh/cm 2 ) = 10-6 (t/g ) .
£d (
kWhIt) cm 2 /g)
~ad (
where ed = mass related specific grinding energy demand ( kWhIt) ~ad = specific surface area increase of grind ( cm2/g» while whereas
ad =mean specific surface area of ground material, Boa = mean specific surface area of the whole wheat kernels before grinding.
Results of investigations See Table 2.; 3. and Figure 1..
Conclusions
o
o o o o
o o
er ( kWh/cm 2) specific superficial grinding energy requirements of the two tested wheat varieties differ quite a lot. See confidence intervals in Fig. 1. and most important statistical characteristics in Table 3. This proves that vitreousity has significant influence on specific grinding energy consumption ( kWh I cm 2 ) The 11 grinding resistance 11 characterized by er specific superficial grinding energy demand has a normal probability distribution .Averages of the two varieties are very different, but the coefficient of variation ( C. = standard deviationl average) are close. Both the grit fmeness characterized by the particle mean size of grinds ( Id : mm) and the specific superficial grinding energy demand er ( kWhI cm 2) are probability variables. There is a well determined correlation between the wheat-hardness and specific grinding energy requirements er ( kWhI cm 2) . Those characteristics of GK-0thalom (89 % vitreousity) are about three times bigger than that of GK-Kata (63 % vitreousity). (see Fig .. l .). Between above characteristics and mass related specific grinding energy requrement ed ( kWhIt ) exists a two - variable relationship according to the following equation (BOLONI, 1996. )
v.
In order to adjust hamrnermills for a predetermined value of mass related specific grinding energy requirement the machine should be developped that is going on. In order to establish wheat - hardness grades expressed by ( kWh/cm 2) physical units more other wheat varieties has to be tested further on.
162
Table 1.
Sign
Important energetic and granulometric characteristics of Hungarian aestivum wheat varieties ground by hammermill
Screen diameter
Wheat variety
Jlitreousity
Grit's
Feedflow rate
particle mean size
Specific grinding enO'gy requirement related to
Specific surface area increase
mass unit
surface unit
Q.
Id
Aa d
kg/h 5.
mm 6.
cm2/g 7.
ed kWhlt 8.
er 10-7 ·kWhlcm2 9.
180•.• 280
1,0... 1,3
75•• .46
2,68 •.• 3,46
0,40••• 0,74
200.. .420
1,25... 1,45
60... 44
1,76•.. 2,26
0,32 •••0,47
1. 2.
03
3.
12.14
4.
12.15
250 ...470
1,45... 1,6
45 .•. 31
1,48... 1,85
0,34.•.0,58
5.
12.13
130•.• 210
1,3... 1,5
46 ... 25
5,86... 4,87
1,09... 2,31
6.
04
190... 390
1,5... 1,75
17...30
2,14 ... 2,39
0,69... 1,40
7.
05
200... 450
1,65... 1,9
15... 23
1,61. .. 2,19
3.
GK- Kata ( m.c.=1l,4%)
GK-()thalom (m.c.=1l,5°/.)
4.
63,0
89,0
i ,
dr mm 2.
0/0
i
----
-
0,88~.1~42_ _
Table 2.
Important characteristics of tested wheat varieties
Wheat variety Item Moisture content
1.
Unit
GK-Othalom
GK-Kata
%
12,4
12,5
89,0
63,0
43,0
43,5
1,41
1,22
33 ... 34
27 ... 30
kg! l00dm 3
80,9
81,0
mm
2,98
2,82
cm1/g
14,30
17,40
(wet base) 2.
Vitreousity
%
3.
Thousand kernel mass
g
True density
4. 5.
Wet gluten content
6.
Bulk density
7.
Kernel mean size
8.
Specific surface area
g!cm
3
%
Table 3. Important statistical characteristics of specific superficial grinding energy consumption er ( kWh/cml ) as a probability variable with two Hungarian aestivum wheat varieties
Si2n 1 2 3 4 5 6 7 8 9 10 11 12
Statistical characteristic 2 Sample size Average Median Mode Standard deviation Standard error Minimum Maximum Skewness Standardized skewness Coefficient of variation
Unit 3 10.7 kWh/ cm1 10.7 kWhI cm 1 10.7 kWh/ cm 1
10.7 kWh/ cm1 10.7 kWh/ cm1
%
164
Wheat variety GKKata GK Othalom 4 5 30 30 0,4512 1,3313 0,4302 1,2024 0,4116 1,1851 0,1147 0,4326 0,0209 0_~O789 0,3278 0,6914 0,7478 2,3059 1,28671 0,77179 2,87718 1,72579 25,43800 32,49400
ef [10. 7 kWb/cm 2 ]
1.5
1.2
1,41
I
1,33 1,25
0.9
0.6
. ! . . . . . . . . .. . . . .. .. . . . . .. . .. . . ..... -:. . . . . . . . . .. . .. .. ... . ..... . . . . .. . t
I
... _ • • • ••.••
0,53 0,47
.... .. ... ......... .. .. . 0,37
0.3
o
• ••
~------------~------------~------------~
GK-OTHALOM
GK-KATA
Fig 1. Average values and confidence intervals ( on &=0,05 probability level) of specific superficial grinding energy consumption for two Hungarian aestivum wheat varieties
165
References
Boloni,I.(1972) :
Grinding Mechanism and Operational Relationships of Hanunennill ( D. Sc. Theses in Hungarian) , Mewgawasagi Gepkiserleti lntez.et, GOdo1l6, 1 - 115 pp.
Boloni, 1.- Csermely - Salamon (1993): Warning up of barley grits in hanunennill ( OTKA) Hungarian Agricultural Engineering Hungarian Institute of Agricultural Engineering, Godollo NO.6 . 53-54 pp Boloni, I. (1996):
Analysis of Grinding's Basic Energetic Relationship, Hungarian Agricultural Engineering, Hungarian Institute of Agricultural Engineering, GOdollo, Vol 9, 44 -45 pp.
Boloni, I. - Veha, A. - Gyimes, E. (1996): Effect of Aestivum Wheat Varieties on Some Energetic Characteristics of Grinding Jubilee Symposium on Cereal Chemistry and Food Quality, Budapest Technical University, Budapest, June 17 - 18, ,Abstracts, 53 . p. Csennely,J (1988) :
Technical and Technological Relations of Wet-Corn Storage. ( D. Sc. Theses in Hungarian) , Mewgazdasagi Gepkiserleti lntez.et, Godollo, , 1 - 182 pp.
Veha, A. (1994):
Agricultural Feed Grinding with Hanunennill ( Ph. D. Theses in Hungarian ), Kertesz.eti es Elelmisz.eripari Egyetem, Elelmisz.eripari F6iskolai Kar, Sz.eged, I - lIS pp.
Veha, A - Gyimes,E (1997) : Detennination of Wheat-Hardness with Energeticallnvestigation of Grinding Tudomanyos Kozlemenyek KEE EFK Sz.eged, Vol.19 (in print)
166