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An Improved Method for Milling Semolina in the Buhler Laboratory Mill and a Comparison to the Allis-Chalmers Laboratory Mill1
Can. Inst. Food Sci. Techncl. J. Vol. 15, No. 3, pp. 225-228, 1982 Pergamon Press Lld. Prinled in Canada.
RESEARCH NOTE
An Improved Method for Milling Semolina in the Buhler Laboratory Mill and a Comparison to the Allis-Chalmers Laboratory Mill i
J.E. Dexter, H.C. Black and R.R. Matsuo Canadian Grain Commission Grain Research Laboratory Winnipeg, Manitoba R3C 3G9
Abstract A mill flow is described which produces a 70% extraction of granulars (65% extraction semolina) from a sound durum wheat in the Buhler laboratory mill when used in conjunction with a laboratory purifier. Compared to the Allis-Chalmers laboratory mill, the Buhler laboratory mill was equally sensitive to variations in wheat semolina milling potential. A wide range of semolina and spaghetti quality tests revealed the Buhler laboratory mill to be an equally reliable predictor of semolina end use quality compared to the standard Allis-Chalmers laboratory mill.
Resume Ce rapport porte sur la description d'un courant de moulin qui produit une extraction a 70% de granules (65% de semoule) a partir d'un ble durum sain dans un moulin de laboratoire Buhler utilise conjointement avec un purificateur de laboratoire. Par comparaison au moulin de laboratoire Allis-Chalmers, le moulin Buhler a reagi aussi bien aux variations dans la possibilite de mouture de la semoule de ble. 11 a ete possible de demontrer sur une grande marge de qualite de semoule et de spaghetti que le moulin de laboratoire Suhler etait un moyen aussi viable que le moulin Allis-Chalmers pour prildire la qualite d'usage de la semoule.
Introduction The aim of durum wheat quality control laboratories is to provide information on which sound judgement can be based regarding milling properties and end use quality from a small quantity of durum wheat. The first and perhaps most important step in durum wheat quality evaluation is the development of a reliable laboratory scale milling procedure which yields semolina of comparable extraction and quality to that obtained from a commercial semolina mill flow. Recently we have developed
a modified milling flow using a three-stand Allis-Chalmers laboratory mill which, in conjunction with a laboratory purifier (Black, 1966), yields a semolina of comparable extraction, granulation and spaghetti making quality to commercial semolina (Dexter and Matsuo, 1978; Matsuo and Dexter, 1980a). The Grain Research Laboratory receives many requests from quality control labs around the world for assistance in development of durum wheat laboratory milling procedures. Unfortunately, the Allis-Chalmers laboratory mill is no longer available commercially. Since most quality control labs are equipped with a Buhler laboratory mill we felt it would be desirable to develop a scheme for milling durum wheat in the Buhler laboratory mill to yield semolina of comparable extraction and quality to commercial semolina. Previous reports (Black and Bushuk, 1967; Sollberger, 1970) have described how, with some minor modifications, the Buhler laboratory mill can be used to produce durum wheat semolina of good quality. However, in both cases the extraction rate of the semolina was much below the normal commercial semolina extraction range of 63-68%. In this communication we describe a method for obtaining a 65% extraction semolina from a Buhler laboratory mill (total extraction including flour of about 70%) and compare the quality of the product to that produced by the Allis-Chalmers laboratory mill system.
Materials and Methods Wheat Reproducibility of milling performance and quality characteristics were determined for each mill with composite samples of No. 1 Canada Western amber durum
lContribution No. 485 from the Grain Research Laboratory.
0315-5463/82/030225-04$3.00/0 Copyright © 1982 Canadian Institute of Food Science and Technology
225
(CWAD), No. 2 CWAD and No. 3 CWAD from the 1980 Canadian new crop survey. Samples were milled in each mill ten times on ten different days. A further comparison between the two mills was performed from single millings of the following series of samples representing a wide range in milling potential and semolina properties: (a) a No. I CWAD sample sieved to yield a sample with very large kernels (weight/I ,000 kernels 54 g), (b) a No. 2 CWAD sample of low protein (10.1%), (c) a very poor quality (No. 5 CWAD) sample of low test weight (74.7 kg/hL), and (d) a No. I CW red spring (RS) wheat. Milling The laboratory purifier described by Black (1966) was used in conjunction with both laboratory mills. All samples were tempered to 16.5% moisture for 18 h prior to milling. The mill room was controlled for temperature (22°C) and humidity (RH 60%). The modified long milling flow for the three-stand Allis-Chalmers mill has been described previously (Dexter and Matsuo, 1978; Matsuo and Dexter, 1980a). The Buhler laboratory mill was modified as described by Black and Bushuk (1967), but the mill flow was lengthened to increase semolina extraction and roll gaps were changed to yield a more granular product. A flow sheet is shown in Figure I. Only the break system of the mill was used. Following passage of stock through the third break (B3), middlings were purified, branny purifier stock passed through the third break rolls again (B4), and middlings purified. This was followed by a final passage of rich branny stock through the third break rolls (B5) and final purification. The break rolls were run dull to dull with a 2: I speed differential (fast roll speed 500 rpm). Roll gaps were set at 0.086 cm, 0.030 cm and 0.020 cm for BI, B2 and B3, respectively. Production of middlings as measured by release of stock through a twenty wire sieve was about 18%, 69% and 80% for BI, B2 and B3, respectively, for a typical good quality durum wheat. Feed rate to BI was 40 g of wheat/cm of roll surface per min. When flour through the 10 XX rebolt is included in the final product (granulars), a milling yield of about 70% (clean wheat basis) is achieved for sound p,
P5
P9
.
.,
•2
20
40 ; IOXX
...
.3 PI
B3 24 24
.'8
5EMO
SEMO DISCARD
Fig. I. Milling flow sheet for semolina milling in the Buhler laboratory mill.
226IDexter et al.
durum wheat. Semolina yield (flour excluded) will be somewhat lower depending on the proportion of flour produced during milling. Cumulative ash curves were calculated by gathering streams following every second purification, the 10 XX overs and the 10 XX throughs, weighing each stream and determining ash levels. Quality Testing Wheat test weight, thousand kernel weight and semolina sieve analyses were performed as described by Matsuo and Dexter (1980b). Ash, wet gluten and yellow pigment were determined as described by Dexter and Matsuo (1978). Protein content (% N x 5.7 on a 14% moisture basis) was determined by a modified Kjeldahl method (Williams, 1973). The method of Irvine et al. (1961) was used for pasta dough farinograms. Mixing time was defined as the time required to reach maximum consistency. Tolerance index was the decrease in consistency 4 min past the peak, and bandwidth also was measured at that point. Semolina specks were determined as described by Dexter and Matsuo (1981). Spaghetti was processed by a micromacaroni method (Matsuo et al., 1972) and dried with a controlled decrease in relative humidity at 39°C over a 29 h period. Spaghetti colour was measured by the method of Daun (1978). Brightness is a measure of the amount of light reflected by a sample relative to the amount reflected by a near perfect white surface. Purity is a measure of colour intensity. Dominant wavelength is the wavelength of the pure spectrum colour which, in combination with a tungsten lamp source, produces the colour, and is thus a measure of colour hue. Textural characteristics of cooked spaghetti were evaluated on an apparatus described by Matsuo and Irvine (1969, 1971) at normal cooking time (about 12 min) and after overcooking 10 min. Tenderness index is a measure of shear rate under increasing force (firmness indicator), compressibility is a measure of deformation under constant force and recovery a measure of resilience.
Results and Discussion Based on single test results for each of the ten semolina samples milled in the Buhler laboratory mill and the Allis-Chalmers laboratory mill from the No. I CW, No. 2 CW and No. 3 CWAD composites, the reproducibility of quality evaluation was comparable for either mill. Results for the No. I CW sample are given as an example (Table 1). The majority of the variability in test results was due to real day to day variations in semolina properties, i.e., for each mill when semolina was milled more than once on the same day, quality test results were very similar (results not presented). Often the number of samples to be screened for quality exceeds the daily mill capacity. Where this is the case, day to day quality variations can be accounted for by milling a control sample each milling day. Comparative test results for single millings of four diverse wheats milled by each mill on the same day (Table 1) revealed the mills to be equally sensitive to variations in milling quality as reflected by both relative milling yield and semolina yield. The samples ranked in J. Insl. Can. Sci. Technol. Aliment. Vol. IS, No. 3, 1982
~
Table I. Comparison of important quality characteristics for a series of diverse wheats when milled by the Allis-Chalmers laboratory mill and the Buhler laboratory mill.
~
No. I CWAD' Allis-Chalmers2
i:
Sieved No. I CWAD' Buhler2
No. 2 CWAD'
AllisChalmers3
Buhler3
62.4 59.1
62.1 58.7
62.6 54.2
63.0 54.8
0.51 9.0 23.4 35 7.38
0.69 13.3 30.8 43 6.09
0.65 13.0 31.2 59 6.23
0.42 12.7 31.8 209 2.45
0.37 12.4 31.4 203 2.33
12.8 64.8 13.4 3.2 4.8
12.6 64.0 14.2 3.2 5.0
14.2 65.2 12.9 3.3 4.2
12.9 63.6 14.7 3.2 4.8
10.2 59.8 16.8 4.4 7.0
8.2 61.0 18.8 5.0 7.2
5 60 90
8.75 50 70
6.5 50 35
5.25 105 55
3.75 80 110
3.5 50 100
3.55 27.6
5.11 31.1
5.32 27.9
4.16 31.7
Property
Mean
SD
Mean
SD
AllisChalmers3
Buhler3
S.
Wheat Milling yield (%) Semolina yield (%)
69.35 65.99
0.51 0.50
68.53 65.32
0.43 0.33
70.9 67.9
71.1 68.5
69.8 65.7
70.3 65.8
0.665 12.45 31.18 13.5 5.60
0.009 0.10 1.29 7.3 0.099
0.628 12.29 31.35 16.5 5.611
0.14 0.07 1.31 7.5 0.114
0.65 12.2 32.8 14 4.92
0.61 12.1 32.5 27 4.90
0.55 9.2 23.2 28 7.42
12.78 66.47 12.75 3.08 3.73
0.74 1.07 0.34 0.29 0.26
12.05 65.07 15.07 3.13 3.85
0.62 0.76 0.39 0.28 0.25
12.9 65.1 13.1 3.1 4.0
11.8 63.7 15.0 3.1 4.7
4.78 72.5 89.5
0.38 9.8 5.0
4.68 64.0 90.0
0.29 8.4 7.8
5.25 55 105
4.090 27.02
0.254 3.67
4.213 24.95
0.229 2.82
3.14 36.2
~ :--
~
No. I CWRSl
Buhler3
~
;;l
No. 5 CWAD'
AllisChalmers3
Buhler3
AllisChalmers3
p; z
? :-'
:0 OD
....
0 ><
~
0...
~ l:l
-:-
N N -.I
Semolina Ash 4 (%) Protein4 (%) Wet g1uten4 (%) Specks/250 cm2 Pigment (ppm) Sieve analysis (%): held on #40 #60 #80 #100 throughs Farinograph: mixing time (min) tolerance index (BU') bandwidth (BU')
Spaghetti Pigment4 (ppm) Pigment loss (%) Colour: brightness (%) purity (%) dominant wavelength (nm) Cooking: compressibility (%) recovery (%) tenderness index (m/sec x 10- 6 ) Overcooking: compressibility (%) recovery (%) tenderness index (m/sec x 10- 6 )
5 110 50
4.45 28.6
1.73 29.4
1.81 22.3
46.60 57.57 577.81
1.09 1.99 0.11
47.36 57.93 577.64
0.70 2.11 0.13
47.8 53.0 577.8
48.5 54.3 577.6
50.2 60.5 577.4
51.0 60.0 577.4
44.3 55.6 578.2
44.4 56.8 578.2
42.8 43.2 579.1
46.7 43.3 578.3
73.0 36.4
2.4 4.4
72.6 35.1
1.7 3.2
73 36
79 35
82 20
89 12
69 43
75 35
76 30
74 24
42.4
3.9
40.4
1.7
45
46
52
54
45
44
40
41
69.3 47.2
1.9 4.5
70.2 45.6
1.7 3.4
71 48
70 44
lOO 0
75 32
77 35
69 43
71 39
69 43
52.0
3.2
53.1
4.1
54
54
69
64
55
52
54
50
'CW = Canada. Western; AD = amber durum; RS = red spring; SD = standard deviation; BU = Brabender units. 2Milled ten times on separate days. 3Results from single millings. 4Expressed on 14% moisture basis.
similar order of quality for all semolina and spaghetti tests performed when milled in either mill. The major difference in semolina quality between the two mills was the consistently lower ash for the Buhler milled semolina (Table 1). A plot of cumulative ash vs. cumulative semolina yield for both mills revealed a significantly lower semolina ash for Buhler milled semolina over the complete semolina yield range (Figure 2). The lower ash of the Buhler milled semolina led to the expected superior spaghetti colour characteristics (Matsuo and Dexter, 1980a) compared to Allis-Chalmers milled semolina (Table 1). These included a tendency to lower pigment loss during processing, higher brightness values and shorter dominant wavelengths (less tendency to brownness). As pointed out by Eva and Fisher (1957), the relative milling performance of different Buhler mills is quite variable, so there is no guarantee that the advantage of lower ash in Buhler milled semolina would be apparent for all Buhler laboratory mills. Nevertheless, based on the current study it is reasonable to assume that all Buhler laboratory mills would rank a series of samples of diverse quality in the same order. Results of the current study have demonstrated that the Buhler laboratory mill can be used successfully to yield semolina of comparable extraction and spaghetti making quality to the Allis-Chalmers laboratory mill. Being an automatic mill, the Buhler laboratory mill has the added advantage of not requiring the operator to possess as
0.70
o AlLlS-CHAlMERS • BUHlER
0.40 '--_........._ ........._---''---_....1.-_........._---''------' 70 10 30 50 SEMOLINA YIELD
(%)
Fig. 2. Cumulative semolina ash curves for a No. 1 CWAD sample milled in the Allis-Chalmers and Buhler laboratory mills.
228/Dexter et al.
much milling expertise as the Allis-Chalmers laboratory mill. However, whereas only one sample can be milled in the Buhler mill at one time, several samples can be milled simultaneously in a batch mill such as the AllisChalmers laboratory mill. Thus, although the time to mill single samples is comparable for both mills (about 45 min for a I kg sample), where large numbers of samples are being assessed the Allis-Chalmers mill has the ability to mill up to 50% more samples in a given day than the Buhler laboratory mill.
Acknowledgements The expert technical assistance of J.J. Lachance, R.W. Daniel, J.W. Bradley and D.C. Sobering is gratefully acknowledged.
References Black, H.C. 1966. Laboratory purifier for durum semolina. Cereal ScL Today 11:533. Black, H.C. and Bushuk, W. 1967. Modification of the BUhler laboratory mill for milling semolina. Cereal Sci. Today 12: 164. Daun, J .K. 1978. Mathematical model for estimating color of spaghetti and mustard flour. Cereal Chem. 55:692. Dexter, J.E. and Matsuo, R.R. 1978. Effect of semolina extraction rate on semolina characteristics and spaghetti quality. Cereal Chem. 55:841. Dexter, J.E. and Matsuo, R.R. 1981. Effect of starchy kernels, immaturity and shrunken kernels on durum wheat quality. Cereal Chem. 58:395. Eva, WJ. and Fisher, M.H. 1957. Studies on variance in Buhler mills, with a bibliography on experimental milling. Cereal Sci. Today 2:124. Irvine, G.N., Bradley, J.W. and Martin, G.C. 1961. A farinograph technique for macaroni doughs. Cereal Chem. 38: 153. Matsuo, R.R. and Irvine, G.N. 1969. Spaghetti tenderness apparatus. Cereal Chem. 46: 1. Matsuo, R.R. and Irvine, G.N. 1971. Note on improved apparatus for testing spaghetti tenderness. Cereal Chem. 48:554. Matsuo, R.R., Bradley, J.W. and Irvine, G.N. 1972. Effect of protein content on the cooking quality of spaghetti. Cereal Chem. 49:707. Matsuo, R.R. and Dexter, J.E. 1980a. Comparison of experimentally milled durum wheat semolina to semolina produced by some Canadian commercial mills. Cereal Chem. 57: 117. Matsuo, R.R. and Dexter, J.E. 1980b. Relationship between some durum wheat physical characteristics and semolina milling propenies. Can. J. Plant Sci. 60:49. Sollberger, H. 1970. Lab grinding test for durum semolina. The Miller (October):8. Williams, P.C. 1973. The use of titanium dioxide as catalyst for large-scale Kjeldahl determination of the total nitrogen content of cereal grains. J. Sci. Food Agric. 24:343. Accepted December 3, 1981
J. Insl. Can. Sci. Technol. Aliment. Vol. !S, No. 3, 1982
RESEARCH NOTE
An Improved Method for Milling Semolina in the Buhler Laboratory Mill and a Comparison to the Allis-Chalmers Laboratory Mill i
J.E. Dexter, H.C. Black and R.R. Matsuo Canadian Grain Commission Grain Research Laboratory Winnipeg, Manitoba R3C 3G9
Abstract A mill flow is described which produces a 70% extraction of granulars (65% extraction semolina) from a sound durum wheat in the Buhler laboratory mill when used in conjunction with a laboratory purifier. Compared to the Allis-Chalmers laboratory mill, the Buhler laboratory mill was equally sensitive to variations in wheat semolina milling potential. A wide range of semolina and spaghetti quality tests revealed the Buhler laboratory mill to be an equally reliable predictor of semolina end use quality compared to the standard Allis-Chalmers laboratory mill.
Resume Ce rapport porte sur la description d'un courant de moulin qui produit une extraction a 70% de granules (65% de semoule) a partir d'un ble durum sain dans un moulin de laboratoire Buhler utilise conjointement avec un purificateur de laboratoire. Par comparaison au moulin de laboratoire Allis-Chalmers, le moulin Buhler a reagi aussi bien aux variations dans la possibilite de mouture de la semoule de ble. 11 a ete possible de demontrer sur une grande marge de qualite de semoule et de spaghetti que le moulin de laboratoire Suhler etait un moyen aussi viable que le moulin Allis-Chalmers pour prildire la qualite d'usage de la semoule.
Introduction The aim of durum wheat quality control laboratories is to provide information on which sound judgement can be based regarding milling properties and end use quality from a small quantity of durum wheat. The first and perhaps most important step in durum wheat quality evaluation is the development of a reliable laboratory scale milling procedure which yields semolina of comparable extraction and quality to that obtained from a commercial semolina mill flow. Recently we have developed
a modified milling flow using a three-stand Allis-Chalmers laboratory mill which, in conjunction with a laboratory purifier (Black, 1966), yields a semolina of comparable extraction, granulation and spaghetti making quality to commercial semolina (Dexter and Matsuo, 1978; Matsuo and Dexter, 1980a). The Grain Research Laboratory receives many requests from quality control labs around the world for assistance in development of durum wheat laboratory milling procedures. Unfortunately, the Allis-Chalmers laboratory mill is no longer available commercially. Since most quality control labs are equipped with a Buhler laboratory mill we felt it would be desirable to develop a scheme for milling durum wheat in the Buhler laboratory mill to yield semolina of comparable extraction and quality to commercial semolina. Previous reports (Black and Bushuk, 1967; Sollberger, 1970) have described how, with some minor modifications, the Buhler laboratory mill can be used to produce durum wheat semolina of good quality. However, in both cases the extraction rate of the semolina was much below the normal commercial semolina extraction range of 63-68%. In this communication we describe a method for obtaining a 65% extraction semolina from a Buhler laboratory mill (total extraction including flour of about 70%) and compare the quality of the product to that produced by the Allis-Chalmers laboratory mill system.
Materials and Methods Wheat Reproducibility of milling performance and quality characteristics were determined for each mill with composite samples of No. 1 Canada Western amber durum
lContribution No. 485 from the Grain Research Laboratory.
0315-5463/82/030225-04$3.00/0 Copyright © 1982 Canadian Institute of Food Science and Technology
225
(CWAD), No. 2 CWAD and No. 3 CWAD from the 1980 Canadian new crop survey. Samples were milled in each mill ten times on ten different days. A further comparison between the two mills was performed from single millings of the following series of samples representing a wide range in milling potential and semolina properties: (a) a No. I CWAD sample sieved to yield a sample with very large kernels (weight/I ,000 kernels 54 g), (b) a No. 2 CWAD sample of low protein (10.1%), (c) a very poor quality (No. 5 CWAD) sample of low test weight (74.7 kg/hL), and (d) a No. I CW red spring (RS) wheat. Milling The laboratory purifier described by Black (1966) was used in conjunction with both laboratory mills. All samples were tempered to 16.5% moisture for 18 h prior to milling. The mill room was controlled for temperature (22°C) and humidity (RH 60%). The modified long milling flow for the three-stand Allis-Chalmers mill has been described previously (Dexter and Matsuo, 1978; Matsuo and Dexter, 1980a). The Buhler laboratory mill was modified as described by Black and Bushuk (1967), but the mill flow was lengthened to increase semolina extraction and roll gaps were changed to yield a more granular product. A flow sheet is shown in Figure I. Only the break system of the mill was used. Following passage of stock through the third break (B3), middlings were purified, branny purifier stock passed through the third break rolls again (B4), and middlings purified. This was followed by a final passage of rich branny stock through the third break rolls (B5) and final purification. The break rolls were run dull to dull with a 2: I speed differential (fast roll speed 500 rpm). Roll gaps were set at 0.086 cm, 0.030 cm and 0.020 cm for BI, B2 and B3, respectively. Production of middlings as measured by release of stock through a twenty wire sieve was about 18%, 69% and 80% for BI, B2 and B3, respectively, for a typical good quality durum wheat. Feed rate to BI was 40 g of wheat/cm of roll surface per min. When flour through the 10 XX rebolt is included in the final product (granulars), a milling yield of about 70% (clean wheat basis) is achieved for sound p,
P5
P9
.
.,
•2
20
40 ; IOXX
...
.3 PI
B3 24 24
.'8
5EMO
SEMO DISCARD
Fig. I. Milling flow sheet for semolina milling in the Buhler laboratory mill.
226IDexter et al.
durum wheat. Semolina yield (flour excluded) will be somewhat lower depending on the proportion of flour produced during milling. Cumulative ash curves were calculated by gathering streams following every second purification, the 10 XX overs and the 10 XX throughs, weighing each stream and determining ash levels. Quality Testing Wheat test weight, thousand kernel weight and semolina sieve analyses were performed as described by Matsuo and Dexter (1980b). Ash, wet gluten and yellow pigment were determined as described by Dexter and Matsuo (1978). Protein content (% N x 5.7 on a 14% moisture basis) was determined by a modified Kjeldahl method (Williams, 1973). The method of Irvine et al. (1961) was used for pasta dough farinograms. Mixing time was defined as the time required to reach maximum consistency. Tolerance index was the decrease in consistency 4 min past the peak, and bandwidth also was measured at that point. Semolina specks were determined as described by Dexter and Matsuo (1981). Spaghetti was processed by a micromacaroni method (Matsuo et al., 1972) and dried with a controlled decrease in relative humidity at 39°C over a 29 h period. Spaghetti colour was measured by the method of Daun (1978). Brightness is a measure of the amount of light reflected by a sample relative to the amount reflected by a near perfect white surface. Purity is a measure of colour intensity. Dominant wavelength is the wavelength of the pure spectrum colour which, in combination with a tungsten lamp source, produces the colour, and is thus a measure of colour hue. Textural characteristics of cooked spaghetti were evaluated on an apparatus described by Matsuo and Irvine (1969, 1971) at normal cooking time (about 12 min) and after overcooking 10 min. Tenderness index is a measure of shear rate under increasing force (firmness indicator), compressibility is a measure of deformation under constant force and recovery a measure of resilience.
Results and Discussion Based on single test results for each of the ten semolina samples milled in the Buhler laboratory mill and the Allis-Chalmers laboratory mill from the No. I CW, No. 2 CW and No. 3 CWAD composites, the reproducibility of quality evaluation was comparable for either mill. Results for the No. I CW sample are given as an example (Table 1). The majority of the variability in test results was due to real day to day variations in semolina properties, i.e., for each mill when semolina was milled more than once on the same day, quality test results were very similar (results not presented). Often the number of samples to be screened for quality exceeds the daily mill capacity. Where this is the case, day to day quality variations can be accounted for by milling a control sample each milling day. Comparative test results for single millings of four diverse wheats milled by each mill on the same day (Table 1) revealed the mills to be equally sensitive to variations in milling quality as reflected by both relative milling yield and semolina yield. The samples ranked in J. Insl. Can. Sci. Technol. Aliment. Vol. IS, No. 3, 1982
~
Table I. Comparison of important quality characteristics for a series of diverse wheats when milled by the Allis-Chalmers laboratory mill and the Buhler laboratory mill.
~
No. I CWAD' Allis-Chalmers2
i:
Sieved No. I CWAD' Buhler2
No. 2 CWAD'
AllisChalmers3
Buhler3
62.4 59.1
62.1 58.7
62.6 54.2
63.0 54.8
0.51 9.0 23.4 35 7.38
0.69 13.3 30.8 43 6.09
0.65 13.0 31.2 59 6.23
0.42 12.7 31.8 209 2.45
0.37 12.4 31.4 203 2.33
12.8 64.8 13.4 3.2 4.8
12.6 64.0 14.2 3.2 5.0
14.2 65.2 12.9 3.3 4.2
12.9 63.6 14.7 3.2 4.8
10.2 59.8 16.8 4.4 7.0
8.2 61.0 18.8 5.0 7.2
5 60 90
8.75 50 70
6.5 50 35
5.25 105 55
3.75 80 110
3.5 50 100
3.55 27.6
5.11 31.1
5.32 27.9
4.16 31.7
Property
Mean
SD
Mean
SD
AllisChalmers3
Buhler3
S.
Wheat Milling yield (%) Semolina yield (%)
69.35 65.99
0.51 0.50
68.53 65.32
0.43 0.33
70.9 67.9
71.1 68.5
69.8 65.7
70.3 65.8
0.665 12.45 31.18 13.5 5.60
0.009 0.10 1.29 7.3 0.099
0.628 12.29 31.35 16.5 5.611
0.14 0.07 1.31 7.5 0.114
0.65 12.2 32.8 14 4.92
0.61 12.1 32.5 27 4.90
0.55 9.2 23.2 28 7.42
12.78 66.47 12.75 3.08 3.73
0.74 1.07 0.34 0.29 0.26
12.05 65.07 15.07 3.13 3.85
0.62 0.76 0.39 0.28 0.25
12.9 65.1 13.1 3.1 4.0
11.8 63.7 15.0 3.1 4.7
4.78 72.5 89.5
0.38 9.8 5.0
4.68 64.0 90.0
0.29 8.4 7.8
5.25 55 105
4.090 27.02
0.254 3.67
4.213 24.95
0.229 2.82
3.14 36.2
~ :--
~
No. I CWRSl
Buhler3
~
;;l
No. 5 CWAD'
AllisChalmers3
Buhler3
AllisChalmers3
p; z
? :-'
:0 OD
....
0 ><
~
0...
~ l:l
-:-
N N -.I
Semolina Ash 4 (%) Protein4 (%) Wet g1uten4 (%) Specks/250 cm2 Pigment (ppm) Sieve analysis (%): held on #40 #60 #80 #100 throughs Farinograph: mixing time (min) tolerance index (BU') bandwidth (BU')
Spaghetti Pigment4 (ppm) Pigment loss (%) Colour: brightness (%) purity (%) dominant wavelength (nm) Cooking: compressibility (%) recovery (%) tenderness index (m/sec x 10- 6 ) Overcooking: compressibility (%) recovery (%) tenderness index (m/sec x 10- 6 )
5 110 50
4.45 28.6
1.73 29.4
1.81 22.3
46.60 57.57 577.81
1.09 1.99 0.11
47.36 57.93 577.64
0.70 2.11 0.13
47.8 53.0 577.8
48.5 54.3 577.6
50.2 60.5 577.4
51.0 60.0 577.4
44.3 55.6 578.2
44.4 56.8 578.2
42.8 43.2 579.1
46.7 43.3 578.3
73.0 36.4
2.4 4.4
72.6 35.1
1.7 3.2
73 36
79 35
82 20
89 12
69 43
75 35
76 30
74 24
42.4
3.9
40.4
1.7
45
46
52
54
45
44
40
41
69.3 47.2
1.9 4.5
70.2 45.6
1.7 3.4
71 48
70 44
lOO 0
75 32
77 35
69 43
71 39
69 43
52.0
3.2
53.1
4.1
54
54
69
64
55
52
54
50
'CW = Canada. Western; AD = amber durum; RS = red spring; SD = standard deviation; BU = Brabender units. 2Milled ten times on separate days. 3Results from single millings. 4Expressed on 14% moisture basis.
similar order of quality for all semolina and spaghetti tests performed when milled in either mill. The major difference in semolina quality between the two mills was the consistently lower ash for the Buhler milled semolina (Table 1). A plot of cumulative ash vs. cumulative semolina yield for both mills revealed a significantly lower semolina ash for Buhler milled semolina over the complete semolina yield range (Figure 2). The lower ash of the Buhler milled semolina led to the expected superior spaghetti colour characteristics (Matsuo and Dexter, 1980a) compared to Allis-Chalmers milled semolina (Table 1). These included a tendency to lower pigment loss during processing, higher brightness values and shorter dominant wavelengths (less tendency to brownness). As pointed out by Eva and Fisher (1957), the relative milling performance of different Buhler mills is quite variable, so there is no guarantee that the advantage of lower ash in Buhler milled semolina would be apparent for all Buhler laboratory mills. Nevertheless, based on the current study it is reasonable to assume that all Buhler laboratory mills would rank a series of samples of diverse quality in the same order. Results of the current study have demonstrated that the Buhler laboratory mill can be used successfully to yield semolina of comparable extraction and spaghetti making quality to the Allis-Chalmers laboratory mill. Being an automatic mill, the Buhler laboratory mill has the added advantage of not requiring the operator to possess as
0.70
o AlLlS-CHAlMERS • BUHlER
0.40 '--_........._ ........._---''---_....1.-_........._---''------' 70 10 30 50 SEMOLINA YIELD
(%)
Fig. 2. Cumulative semolina ash curves for a No. 1 CWAD sample milled in the Allis-Chalmers and Buhler laboratory mills.
228/Dexter et al.
much milling expertise as the Allis-Chalmers laboratory mill. However, whereas only one sample can be milled in the Buhler mill at one time, several samples can be milled simultaneously in a batch mill such as the AllisChalmers laboratory mill. Thus, although the time to mill single samples is comparable for both mills (about 45 min for a I kg sample), where large numbers of samples are being assessed the Allis-Chalmers mill has the ability to mill up to 50% more samples in a given day than the Buhler laboratory mill.
Acknowledgements The expert technical assistance of J.J. Lachance, R.W. Daniel, J.W. Bradley and D.C. Sobering is gratefully acknowledged.
References Black, H.C. 1966. Laboratory purifier for durum semolina. Cereal ScL Today 11:533. Black, H.C. and Bushuk, W. 1967. Modification of the BUhler laboratory mill for milling semolina. Cereal Sci. Today 12: 164. Daun, J .K. 1978. Mathematical model for estimating color of spaghetti and mustard flour. Cereal Chem. 55:692. Dexter, J.E. and Matsuo, R.R. 1978. Effect of semolina extraction rate on semolina characteristics and spaghetti quality. Cereal Chem. 55:841. Dexter, J.E. and Matsuo, R.R. 1981. Effect of starchy kernels, immaturity and shrunken kernels on durum wheat quality. Cereal Chem. 58:395. Eva, WJ. and Fisher, M.H. 1957. Studies on variance in Buhler mills, with a bibliography on experimental milling. Cereal Sci. Today 2:124. Irvine, G.N., Bradley, J.W. and Martin, G.C. 1961. A farinograph technique for macaroni doughs. Cereal Chem. 38: 153. Matsuo, R.R. and Irvine, G.N. 1969. Spaghetti tenderness apparatus. Cereal Chem. 46: 1. Matsuo, R.R. and Irvine, G.N. 1971. Note on improved apparatus for testing spaghetti tenderness. Cereal Chem. 48:554. Matsuo, R.R., Bradley, J.W. and Irvine, G.N. 1972. Effect of protein content on the cooking quality of spaghetti. Cereal Chem. 49:707. Matsuo, R.R. and Dexter, J.E. 1980a. Comparison of experimentally milled durum wheat semolina to semolina produced by some Canadian commercial mills. Cereal Chem. 57: 117. Matsuo, R.R. and Dexter, J.E. 1980b. Relationship between some durum wheat physical characteristics and semolina milling propenies. Can. J. Plant Sci. 60:49. Sollberger, H. 1970. Lab grinding test for durum semolina. The Miller (October):8. Williams, P.C. 1973. The use of titanium dioxide as catalyst for large-scale Kjeldahl determination of the total nitrogen content of cereal grains. J. Sci. Food Agric. 24:343. Accepted December 3, 1981
J. Insl. Can. Sci. Technol. Aliment. Vol. !S, No. 3, 1982