1 michael southan
TRANSCRIPT
Michael Southan, Mathew Rees, Robert Quodling, Daniel Skylas
John McCorquodale, Brian Osborne
Achieving NATA Accreditation of Laboratory Test Milling
Introduction
• Flour yield is the most important quality target for wheat breeders – large investment is at risk if milling potential is not accurately measured
• The Buhler MLU 202 laboratory mill is most commonly used to measure milling potential
• Samples are milled under constant settings• Allows direct comparisons of flour yields and
flour relevant for chemical analysis and end product testing
Introduction
• Laboratory milling is an analytical method that should, like any testing method, be subject to technical accreditation to ISO/IEC 17025:2005 standard which in Australia equated to NATA accreditation
Buhler Test Mills
• Direct correlation of Buhler test mill flour yields and commercial milling yields is difficult
• FMCA report by Greer et al 1977 observed that:– Buhler test mills have an inherent limited
reduction capacity - ie low flour yields.– Entoleters and bran finishers increased flour
yield and commercial relevance.
Buhler Test Mill
Break Rolls Reduction Rolls
1st 2nd 3rd 4th 5th A B C D E F G H
Buhler Test Mill
Commercial
Buhler Test Mill
Break Rolls Reduction Rolls
1st 2nd 3rd 4th 5th A B C D E F G H
Buhler Test Mill Bran Finisher Entoleters
Commercial
Sources of Error in Test Milling
• Sample non-homogeneity• Inadequate or excessive sample preparation
(cleaning)• Non-uniform conditioning• Variation in lab temperature and humidity• Poor maintenance of milling equipment• Sub-optimal mill settings, and• No standardisation of methods
Increasing Test Mill Efficiency
• Test Mill overhaul
Increasing Test Mill Efficiency
• New felt seals
Increasing Test Mill Efficiency
• Repairing wear
Increasing Test Mill Efficiency
• New bearings
Increasing Test Mill Efficiency
• Reduction rolls re-ground
Increasing Test Mill Efficiency
• Stainless steel stock trays for more efficient cleaning
Increasing Test Mill Efficiency
• Replacement of sieve chains with rubber sieve cleaners
• More efficient sieve cleaning - greater area of sieves cleaned
Increasing Test Mill Efficiency
• Plastic sheeting on sifter boxes for protection when cleaning
Increasing Test Mill Efficiency
• Fan exhaust outlet was repositioned to allow ducting and a sock to be added so that dust could be collected more efficiently
Increasing Test Mill Efficiency
• Reconfiguration of entoleters which were mounted on back of mill and controlled with a frequency inverter
Increasing Test Mill Efficiency
Measuring Test Mill Performance
Change in Roll Temperature with Wheat
22
24
26
28
30
32
34
36
0 7 14 23 30
Wheat Milled (kg)
Tem
per
atu
re (
Deg
rees
C)
B1 B2 B3 R1 R2 R3
Measuring Test Mill Performance
Change in Roll Temperatures without Wheat
22
24
26
28
30
32
34
36
0 2 3 4 5
Hours
Te
mp
era
ture
(D
eg
ree
s C
)
B1 B2 B3 R1 R2 R3
Measuring Test Mill PerformanceEffect of Break Roll Gaps on Hard and Soft Wheat Flour
Yield
0
10
20
30
40
50
60
70
80
0 0.25 0.5 0.75 1 1.25 1.5 1.75 2
Roll Gap (mm)
Flo
ur
Yie
ld (
%)
Janz - 1st break roll Janz - 3rd break roll Rosella - 1st break roll Rosella - 3rd break roll
Measuring Test Mill PerformanceEffect of Break Roll Gap on Hard and Soft Wheat Flour
Quality
0
1
2
3
4
5
6
7
8
0 0.25 0.5 0.75 1 1.25 1.5 1.75 2
Roll Gap (mm)
Bra
n S
pe
ck
s
Janz - 1st break roll Janz - 3rd break roll Rosella - 1st break roll Rosella - 3rd break roll
Measuring Test Mill PerformanceEffect of Break Roll Gap on Hard and Soft Wheat Flour Quality
0
10
20
30
40
50
0 0.25 0.5 0.75 1 1.25 1.5 1.75 2
Roll Gap (mm)
Mill
ing
Qu
alit
y In
de
x
Janz - 1st break roll Janz - 3rd break roll Rosella - 1st break roll Rosella - 3rd break roll
B1
B3
Measuring Test Mill PerformanceEffect of Reduction Roll Gaps on Hard and Soft Wheat Flour
Yield
72
74
76
78
80
82
0 0.025 0.05 0.075 0.1 0.125 0.15
Roll Gap (mm)
Flo
ur
Yie
ld (
%)
Janz - 1st reduction roll Janz - 3rd reduction roll
Rosella - 1st reduction roll Rosella - 3rd reduction roll
Measuring Test Mill Performance
B1 B2 B3 R1 R2 R3 Buhler 120 m 100 m 70 m 30 m FMBRA Normal1 1000 m 700 m 700 m 300 m
FMBRA Commercial2 600 m 400 m 300 m 200 m
BRI Optimised 460 m 100 m 100 m 100 m
Measuring Test Mill Performance
Uncertainty of Measurement
70
72
74
76
78
80
82
84
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170
Sample No.
Flo
ur
Yie
ld (
%)
Sunco Control Janz Control Sunco Av. Janz Av. Sunco av.+2SD Sunco av-2SD
Janz av.+SD Janz av-2SD Wedgetail Control Wedgetail av+2SD Wedgetail av-2SD Wedgetail Av.
AH Control AH Average AH av+2SD AH av-2SD
Conclusions
• The first ever NATA accreditation of laboratory test milling has been achieved
• Test mill maintenance and efficiency is critical for high performance and productivity
• Laboratory test mill optimum roll gaps need to be identified experimentally - a systematic approach to determining optimum roll gap settings has been developed
• Milling Quality Index provides a mechanism for determining the optimum balance between flour yield and flour quality irrespective of mill set up