136 DOI:10.17957/JGIASS/3.4.722
http://www.jgiass.com
SINGLE KERNEL CHARACTERIZATION OF WHEAT VARIETIES IN RELATION TO MILLING QUALITY
Zafar Iqbal
1,*, Imran Pasha
2, Muhammad Abrar
3, Atta Muhammad Arif
4and Sharoon Masih
51Mango Research Institute, Multan, Pakistan, 2 National Institute of Food Science and Technology, University of Agriculture, Faisalabad, Pakistan, 3 Wheat Research Institute, Ayub Agricultural Research Institute, Faisalabad, Pakistan, 4Citrus Research Institute, Sargodha, Pakistan, 5 Food Technology Section, Post-Harvest Research Institute,
Ayub Agricultural Research Institute, Faisalabad, Pakistan
*Corresponding author’s e-mail: [email protected]
Single kernel characterization system swiftly measures important physical characteristics of wheat grain and provides forecast for milling quality. Two wheat varieties were tested from SKCS for physical grain parameters. Wheat variety AS 2002 showed higher mean score for kernel weight (32.79mg/kernel), kernel diameter (2.77mm) and seed length (6.47mm) than Inqulab 91 (30.04mg/kernel, 2.65mm and 5.93mm repectively for kernel weight, diameter and length). Kernel density (1.61 mg/mm3) and SKCS hardness index (85.65) was comparatively greater in Inqulab 91 than AS 2002 (1.54mg/mm3, 75.51, respectively). AS-2002 exhibited higher break (139.50g/kg), straight grade flour (681g/kg) yield and milling score (83.28) as compared to Inqulab 91 (107.50g/kg) break, (658.50g/Kg) SGF and (75.19) whereas reduction flour higher in Inqulab 91 (551g/kg) than AS 02 (541.50g/kg). Mean scores for moisture content, ash content, fat content, protein content, crude fiber and NFE ranged from 9.52 to 12.10, 0.84 to 1.14, 1.95 to 3.75%, 9.54 to 13.25%, 0.12 to 7.53% and 63.29 to 76.78% respectively in different milled fractions of both wheat varieties. Break flour yield showed significant correlation with physical grain characteristics like TKW (r=0.97), kernel diameter (r=0.99), milling score (r=0.99), seed length (r=1.00) and SKCS kernel weight (r=0.92) whereas SKCS hardness (r=-0.60) and kernel density (r=-0.54) were negatively associated with break flour. Wheat variety with greater TKW, SKCS KW, kernel diameter and seed length yield more break flour and higher milling score. However, such wheat variety had less SKCS hardness and kernel density.
Keywords: Chemical composition, Mill streams, quality, Single kernel characterization
INTRODUCTION
Traditional flour milling process produces refined flour.
Prime objective of milling is to separate endosperm without contamination of outer parts of grain especially bran and germ (Belderok, 2000; Edwards, 2010). During this process, the bran and germ layers of grain are removed in order to stabilize the raw material and increase the keeping quality (Fiˇsteˇ et al., 2014). Dry milling alters the nature and upsurges the edibility of products obtained from cereals (Delcour et al., 2012). Dry milling of wheat results in production of flour, bran and wheat germ (OECD, 2003).
Refined flour thus obtained is more acceptable and relishing food raw material (Delcour et al., 2012). However, with increase in palatability, the nutritive value of refined flour decreases (Delcour and Hoseney, 2010). Knowledge of kernel parameters can help in improving milling yields (Edwards, 2010). Milling behavior is predicted on the basis of many factors (Bechtel et al., 2009). Small improvements in flour yield are possible by manipulation of these factors.
Hardness and softness are the milling characteristics related to breakage pattern of endosperm (Hrušková and Švec, 2009). The wheat hardness is strongly associated with the semolina and flour yields (Hrušková et al. 2008). However, Vignaux et al. (2004) reported hardness as possible cause for reduction in flour yield. Soft-textured wheat genotypes
(Pina-D1a/Pinb-D1d) showed the least value for grain hardness and higher break flour and lesser reduction flour yield (Ma et al., 2009). Wheat lines with Pinb-D1b allele showed significant reduction in grain hardness, higher break flour yield and milling score and lower flour ash content than the Pina-D1b group (Martin et al. 2001, 2008). Pina- D1a/Pinb-D1b genotypes displayed better milling yield than Pina-D1b/Pinb-D1a (Eagles et al., 2006). Endosperm texture affects milling characteristics (Ramseyer et al., 2011).
Milling performance is a complex quality parameter with kernel hardness being a highly significant component (Edwards, 2010). Milling efficiency is measured in terms of the purity of kernel fractions obtained at each step during milling (OECD, 2003). Commercial flour mills obtain refined flour as 80% of wheat kernel while remaining 20%
is utilized for animal feed and dietary fiber for human foods (Orth and Shellenberger 1988). Wheat varieties possessing distinctive bolting and sifting characteristics with typical flour recovery and ash content exhibit good milling quality (Maghirang et al., 2006). Milling score elucidates yield and ash content of flour and integrates it with break flour yield (Morris et al., 2004). Hard red spring (HRS) wheat showed more total flour and milling score than hard red winter (HRW) wheat. Moreover, HRS exhibited less break flour than HRW wheat (Maghirang et al., 2006).
Hardness Index measured from Single Kernel Characterization System (SKCS) is an arbitrary scale. It shows a histogram of the distribution of the hardness index values for 300 grains (Edwards, 2010). SKCS 4100 system provides rapid measurements of wheat physical properties important to miller for direct prediction of processing quality (Osborne and Anderssen, 2003). SKCS is the most suitable indicator of milling quality for small sample quantities (Edwards, 2010). Value of hardness index in SKCS is outcome of deformation curve resulting from force applied for grinding of individual kernels. Wheat grain moisture, kernel size and kernel weight are main factors affecting crushing force (Martin et al., 1993). Kernel hardness in wheat can be quantified by either NIR, SKCS hardness index and break flour yield (Morris et al., 1999).
Characteristics of wheat kernel are decisive factor in both the milling quality and final end-use of food wheat (Hrušková and Švec, 2009). Test weight measures bulk density of grain, envisages the grain size and used as rough indicator of flour yield potential of wheat varieties (Edwards, 2010; Khan et al., 2009). Higher sizing yield is favorable for a high yield of low ash flour (Li and Posner, 1989). The 1000 kernel weight is a useful tool for the assessment of the potential milling yield. The kernel size contributes directly towards the improvement of grain as well as milling yield. The wheat varieties with more grain weight showed better milling yield (Khan et al., 2009).
Flour milling alters the microstructure of the intact endosperm tissue (Souza et al., 2011). Wheat producing flour with low ash at high extraction rates possess good milling quality (Posner and Hibbs 1997). Ash content indicates milling performance by indirectly revealing the amount of bran contamination. Ash can affect color, imparting a darker color to finished products (Keran et al., 2009). Current study was planned to investigate milling performance of wheat varieties and its relation with physical characteristics of grain and chemical composition of flour.
MATERIALS AND METHODS
Wheat Milling: Two commercially available wheat varieties i.e. Inqulab-91 and AS-2002 were used as medium of experiment. Perten SKCS 4100 (Perten Instruments, Springfield, IL) was used to measure single kernel grain hardness, moisture content and diameter according to Approved Method 55-31 (AACC, 2002) on 300-kernels as described by Ma et al,. (2009). Clean wheat grains were tempered at 15.50% moisture content and kept in plastic containers at room temperature for 24 hours. Water quantity was calculated by AACC (2000) method No. 26-95. Wheat was milled through Brabender Quadrumate Senior Mill (C.W. Brabender Instruments, Inc.) following AACC (2000) method No. 26-95 to obtain different milling fractions i.e.
break, reduction flour, bran and shorts. Percent yield of break, reduction flour, bran and shorts were calculated based on weight recovered of each product divided by total material recovered according to AACC (2000) method No.
26-21A. Percent recovery of straight grade flour was
determined from combined yield of both break and reductions flours divided by total weight of all products, times 100 (Morris et al., 2004). All tests were conducted on straight-grade flour. Milling score was calculated by method developed by Martin et al. (2007).
[{100 - [0.50 × (16 - percent temper level) + (80 - flour yield) + 50 × (Percent flour ash - 0.30)]} × 1.117] - 3.675 Statistical analysis: The data obtained for each parameter were subjected to statistical analysis to work out effect of wheat varieties on SKCS parameters, milling fractions yield and chemical composition by using completely randomized design and mean values were compared according to Duncans Multiple Range test (Steel et al., 1997).
RESULTS AND DISCUSSION
SKCS characteristics: Wheat variety AS 2002 with lower hardness index (75.51) represented higher break flour yield than Inqulab 91 having greater score for hardness index (85.65). SKCS hardness index showed insignificant relationship with break flour yield and explained only 27.90 percent variation in break flour yield. In regression analysis SKCS hardness could not provide valuable prediction of break flour yield, however Hogg et al., (2005) revealed that SKCS kernel hardness might be a larger factor for predicting break flour. Ma et al. (2009) recorded hardness index 67.9 to 75.5 in seven near isogenic lines of wheat while 6.4 to 73.7 in Hi-line Hard red spring wheat and transgenic isolines (Martin et al., 2008). Based on SKCS hardness classification, both wheat varieties in current studies are of medium hard type. Hard wheats have SKCS hardness scores greater than 50 while soft wheats have scores less than 50 (Edwards, 2010). Wheat variety AS- 2002 having less mass to diameter3 ratio (1.54mg/mm3) exhibited significant higher break flour yield than Inqulab 91 (1.61 mg/mm3). Mean for kernel density in current studies is lower than Souza et al., (2011) who reported SKCS mass/dia3 vary from 1.88 to 2.39mg/mm3. Ratio of mass to diameter3 (kernel density) alone elucidated over 50% variation in break flour yield and its value in SKCS forecasts break flour yield (Campbell et al 2007).
Mean value for kernel weight was significantly higher in wheat variety AS-2002 (32.79mg/kernel) as compared to Inqulab 91 (30.04mg/kernel). SKCS kernel weight ranged from 33.6 to 35.4mg/kernel in Hi-line Hard red spring wheat and transgenic isolines (Martin et al., 2008) and 34.9- 35.3mm (Martin et al., 2007). Souza et al. (2011) recoded mean for SKCS kernel weight in range of 29.1mm to 37.4mm in different wheat varieties. Diameter of single kernel measured from SKCS was considerably higher for AS-2002 (2.77mm) than Inqulab 91 (2.65mm). Martin et al.
(2007) reported SKCS kernel diameter with lower mean (2.41-2.45mm) than current studies which might be due to different genetic make up of wheat varieties. Wheat variety AS 2002 exhibited significant higher seed length (6.47mm) than Inqulab 91 (5.93mm). Mean values for seed length in present investigation are in accordance with findings (5.54- 6.29mm) of Souza et al., (2011). Seed length, kernel
diameter and kernel weight illustrated inverse relationship with break flour yield. The results of current studies are contradictory to those reported by Souza et al., (2011). This might me due to different wheat varieties,tempering and milling conditions and different mill type as quadrumate senior is used in current in opposition to Malto Miag in their studies. Inverse relationship between flour protein contents and kernel weights or sizes (Park and Chang, 2007).
Milling fractions yield: Wheat varieties showed significant impact on flour yield. Break flour yield was significantly higher for AS 02 (139.50g/kg) as compared to Inqulab 91 (107.50g/kg) while it was reverse in case of reduction flour (Fig. 1) i.e. higher in Inqulab 91 (551g/kg) than AS 02 (541.50g/kg). Straight grade flour yield for was higher for AS 02 (681g/kg) as compared to Inqulab 91 (658.50g/Kg) which might be due to difference in tempering requirements for hard and soft wheats. Martin et al., (2007) reported higher break (430g/Kg) and total flour yield (674g/Kg) in soft wheat as compared to hard wheat varieties with 387g/Kg break flour and 661g/Kg total flour yield. Mean values for break in our studies are similar to Anjum et al.
(1993) (65.7 to 70.00%), Ma et al. (2009) (12.4 to 15.5%) and Randhawa et al. (2002) (11.41 to 19.72%) while lower
than Souza et al. (2011) who recorded break flour yield from 20.3 to 25.5g/100g in soft red winter and soft white winter wheats. Hard NILs yield more flour at break stage than reduction stage (Greffeuille et al., 2006). The difference might be due difference in wheat varieties and type of mill or tempering conditions. Mean score for reduction flour in current studies is higher than Ma et al.
(2009) (61.0 to 63.2%) and Randhawa et al. (2002) (40.88- 54.21%). This migh be due to different wheat varieties, tempering moisture content and mill type and settings.
Means for SGF in current investigation are in line with Randhawa et al. (2002) SGF in range of 52.79 to 70.00%
and Morris et al., (2004) 67.4 to 70.00% while lower than Souza et al., (2011) who recorded straight grade flour yield from 71.6 to 76.5g/100g in soft red winter and soft white winter wheats. The difference is due to different type of mill used. Maghirang et al. (2006) recorded significantly higher flour yield for HRS wheat (67.0%) than to HRW wheat (65.9%). Higher flour yields may result from kernels with higher endosperm weight (Edwards, 2010). Larger wheat kernels produce higher break releases (Li and Posner, 1987).
Soft wheat gives almost the same percentage of break and reduction flour whereas break flour forms only quarter of the reduction flours yield in hard wheat (Edwards, 2010).
Table 1. Milling yield of different flour fractions of wheat varieties
Wheat Varieties Break Flour (%) Reduction Flour (%) SGF (%) Bran (%) Shorts (%) Milling score Inqulab-91 10.75±0.80b 55.10±0.42a 65.85±0.57b 33.49±1.18a 5.62±0.24a 75.19±1.24b AS 2002 13.95±0.80a 54.15±0.42a 68.10±0.57a 28.45±1.18b 4.64±0.24b 83.28±1.24a LSD (0.05) 2.27 2.27 1.70 2.27 0.57 2.27
SD 1.97 1.04 1.40 2.90 0.58 3.04
Table 2. SKCS quality parameters of wheat varieties Wheat
varieties
Moisture content (%)
Kernel hardness index
SKCS Kernel weight (mg/kernel)
SKCS Diameter (mm)
Seed length (mm)
Kernel density mass/dia3 (mg/mm3) Inqulab 91 11.31±0.40a 85.65±2.52a 30.04±0.63b 2.65±0.03b 5.93±0.13b 1.61±0.02a AS-2002 11.98±0.40a 75.51±2.52b 32.79±0.63a 2.77±0.03a 6.47±0.13a 1.54±0.02b LSD (0.05) 2.27 6.8 0.9 0.11 0.34 0.06
SD 0.27 13.49 7.51 0.3 0.32 0.04
Table 3. Chemical characteristics of mill streams of wheat variety AS 2002 Milling Fractions Moisture content
(%) Ash content
(%) Fat content
(%) Protein content
(%) Fiber content
(%) NFE content (%)
Break Flour 10.90±0.20ab 0.84±0.06b 2.96±0.19ab 10.57±0.32c 0.12±0.77e 74.62±1.21ab Red. Flour 10.30±0.20bc 0.57±0.06c 2.69±0.19bc 9.54±0.32d 0.15±0.77d 76.78±1.21a SGF 9.52±0.20c 0.50±0.06c 1.95±0.19c 11.46±0.32b 0.14±0.77c 76.41±1.21a Bran 11.35±0.20a 1.05±0.06a 2.65±0.19bc 12.54±0.32a 7.53±0.77a 64.89±1.21c Shorts 11.00±0.20ab 0.60±0.06c 3.75±0.19a 9.57±0.32d 2.84±0.77b 72.26±1.21b LSD (0.05) 0.91 0.18 0.91 0.64 0.02 2.66
SD 0.79 0.23 0.73 1.23 2.98 4.67
Table 4. Chemical characteristics of mill streams of wheat variety Inqulab 91 Milling Fractions Moisture content
(%) Ash content
(%) Fat content
(%) Protein content
(%) Fiber content
(%) NFE content (%)
Break Flour 11.75±0.18ab 0.92±0.05b 3.33±0.13b 11.13±0.35c 0.12±0.75d 72.77±1.11b Red. Flour 11.60±0.18b 0.69±0.05c 2.85±0.13c 9.98±0.35d 0.14±0.75c 74.75±1.11a SGF 10.23±0.18c 0.60±0.05c 2.96±0.13bc 12.45±0.35b 0.13±0.75cd 73.64±1.11ab Bran 12.10±0.18a 1.14±0.05a 2.88±0.13bc 13.25±0.35a 7.35±0.75a 63.29±1.11d Shorts 11.65±0.18ab 0.68±0.05c 4.00±0.13a 10.11±0.35d 2.61±0.75b 70.96±1.11c LSD (0.05) 0.45 0.14 0.45 0.64 0.02 1.70
SD 0.70 0.21 0.50 1.36 2.91 4.30
Table 5. Correlation coefficients physico-chemical and milling characteristics of wheat varieties Parameters Break
Flour NIR
hard PSI Red.
Flour SGF TKW TW Ash KD SKCS hard K.
Den. MS SL SKCS KW NIR Hard 0.55
PSI 0.53 1.00
Red. Flour -0.06 0.81 0.81
SGF 1.00 0.57 0.56 -0.03
TKW 0.97 0.34 0.33 -0.28 0.97
TW 0.54 1.00 1.00 0.81 0.56 0.34
Ash -0.40 0.55 0.56 0.94 -0.38 -0.60 0.55 KD 0.99 0.65 0.64 0.07 1.00 0.94 0.64 -0.28 SKCS Hard -0.60 0.34 0.35 0.83 -0.58 -0.77 0.34 0.97 -0.50
Ker. Den. -0.54 0.41 0.42 0.87 -0.52 -0.72 0.41 0.99 -0.43 1.00 MS 0.99 0.39 0.38 -0.23 0.98 1.00 0.39 -0.55 0.96 -0.73 -0.68
SL 1.00 0.51 0.49 -0.10 1.00 0.98 0.50 -0.44 0.99 -0.64 -0.58 0.99 SKCS KW 0.97 0.32 0.30 -0.30 0.96 1.00 0.31 -0.62 0.93 -0.78 -0.73 0.99 0.98
Protein -0.08 0.79 0.80 1.00 -0.06 -0.31 0.79 0.95 0.04 0.84 0.88 -0.25 -0.13 -0.33 NIR Hard= NIR hardness; Red. Flour=Reduction flour PSI=Particle Size Index; SGF=Straight grade flour TKW=Thousand kernel weight;
TW=Test Weight; KD=Kernel Diameter; SKCS Hard. =SKCS hardness, K. Den. =Kernel Density; MS=Milling Score; SL=Seed length;
SKCS KW= SKCS kernel weight
Wheat variety Inqulab 91 (5.62%) showed higher mean for shorts than AS 2002 (4.64%). Randhawa et al. (2002) recorded similar yield of shorts (3.01 to 5.89%). Mean value for bran was significantly higher in Inqulab 91 as compared to AS 2002. The amount of bran from Quadrumate senior mill ranged from 28.48 to 47.45% (Randhawa et al. 2002).
Mean value for milling score was higher for wheat variety AS 2002 (83.28) as compared to Inqulab 91 (75.19). Martin et al., (2007) reported similar results for hard PinA-D1b (80.00) and soft PinB-D1b (82.40) wheats. Hard wheats exhibit more ash content and less flour yield resulting decrease in milling score than soft wheats. Morris et al.
(2004) recorded 84.3 to 85.8 milling score in soft wheat varieties which support the findings of current studies.
Chemical composition of milling fractions: Mean value for moisture content ranged from 9.52 to 12.10 in different milling fraction of wheat varieties. Maximum mean for moisture was recorded in bran (12.10, 11.35) while minimum in SGF (10.23, 9.52) respectively for Inqulab 91 and AS-2002. Mean for ash content varied between 1.05 to 1.14, 0.50 to 0.68, 0.84-0.92, 0.57 to 0.69, 0.50-0.60%
respectively in bran, shorts, break, reduction and straight grade flours which are well supported by findings of Saeed et al. (2011). Fat content of different milled fraction assorted between 3.75-4.00, 2.65 to 2.88, 2.96-3.33, 2.69-2.85, 1.95- 2.96% respectively in shorts, bran, break, reduction and straight grade flours. Shorts exhibit higher mean for fat content while lowest value recorded in SGF. Statistical mean values for protein concentration of wheat varieties ranged between 12.54-13.25, 9.57-10.11, 10.57-11.13, 9.54- 9.98, and 11.45-12.46% respectively for bran, shorts, break, reduction and straight grade flours. The range of means for crude fiber content varied between 7.35 to 7.53, 2.61 to 2.84, 0.12, 0.14-0.15, 0.13-0.14 respectively in bran, shorts, break, reduction and SGF flours. NFE content in different milling fractions differed from 74.75 to 76.78, 73.64 to 76.41, 72.77 to 74.62, 70.96 to 72.26 and 63.29 to 64.89%
respectively for reduction, SGF, break flour, shorts and
bran. AS 2002 Milled fractions revealed higher mean for fiber and NFE contents while means for all other chemical constituents were higher in mill streams of Inqulab 91. The results for chemical composition of milling fractions of wheat varieties in current are indistinguishable to findings reported by Saeed et al., (2011) and Akhtar et al., (2005).
Correlation studies: Kernel diameter was significantly associated with break flour (r=0.99), SGF (r=1.00), milling score (r=0.96), seed length (r=0.99), SKCS KW (r=0.93) and protein (r=0.93). SKCS kernel density showed significant positive relationship with reduction flour (r=0.87), ash content (r=0.99) and SKCS hardness (r=1.00) while negative correlation with break flour (r=-0.54), SGF (r=-0.52) and TKW (r=-0.72) showing that variety with high kernel density has less break flour yield, more reduction flour with high ash content. Wheat variety with higher TKW, seed length and kernel weight whereas less density and hardness yield more flour as evident from direct correlation of milling score with TKW (r=1.00), seed length (r=0.99) and SKCS KW (r=0.99) while inverse relationship with kernel density (r=-0.73) and SKCS hardness (r=-0.68).
Greater seed length provides assurance for higher flour recovery. Seed length depicted strong positive association with break flour (r=1.00), SGF (r=1.00) and TKW (r=0.99) while kernel density (r=-0.58) and SKCS hardness (r=-0.64) was negatively related with seed length.
Significant correlation of break flour yield with physical grain characteristics like TKW (r=0.97), kernel diameter (r=0.99), milling score (r=0.99), seed length (r=1.00) and SKCS kernel weight (r=0.92) is indication of higher break flour yield in wheat variety with soft texture as compared to hard wheat. Whereas SKCS hardness (r=-0.60) and kernel density (r=-0.54) were negatively associated with break flour recovery. SKCS kernel weight exhibited direct relationship with TKW (r=1.00), break flour (r-0.97), kernel diameter (r=0.93) and seed length (r=0.98) whereas it was negatively associated with ash content (r=-o.62), SKCS hardness (r=-0.78) and kernel density (r=-0.73). Seed length
of wheat grain significant correlation with TKW (r=0.98), kernel diameter (r=0.99), milling score (r=0.99) while negatively associated with kernel density (r=-0.58) and SKCS hardness index (r=-0.64). Wheat variety with greater TKW, SKCS KW, kernel diameter and seed length yield more break flour and higher milling score. However, such wheat variety had less SKCS hardness and kernel density.
PSI and NIR hardness index were highly (r=1.00) associated while both these parameters showed only weaker association with SKCS hardness and break flour yield.
Break flour yield and SKCS hardness were inversely related (r=-0.6) depicting that wheat variety with greater hardness and PSI value yield less break flour. Hardness index obtained from SKCS illustrated inverse correlation with most grain physical like kernel diameter (r=-0.5), SKCS KW (r=-0.78) and seed length (r=-0.64) and milling parameters; break flour (r=-0.6) and milling score (r=-0.73).
Protein content showed positive relationship with grain hardness; NIR hardness (r=0.79), PSI (0.80) and SKCS hardness (r=0.84). Wheat protein is often positively related with grain hardness within hard wheats (Giroux et al., 2000; Slaughter et al., 1992). Hardness was only weakly associated with absorption (r , 0.3) (Martin et al., 2007).
Grain hardness was negatively correlated with break flour yield, flour yield, and mixing score and positively correlated with flour ash (Martin et al., 2007). Hard wheats have smaller PSI scores than soft wheats due to their larger particle sizes not passing through the sieve (Edwars, 2010).
SKCS characteristics were significantly correlated with conventional wheat quality parameters such as kernel size, wheat protein content, and straight-grade flour yield (Edwards, 2010). Standard SKCS parameters, seed weight and diameter measurements made significant correlations with flour yield (Edwards et al., 2008). SKCS 4100 HI correlated well with particle size index (PSI) (Osborne et al., 1997; Williams et al., 1998; Psotka, 1999) and NIR hardness (Chung et al., 1999).
CONCLUSIONS
Wheat variety AS 02 possessing greater mean score for physical grain characters like kernel weight, kernel diameter and seed length and less kernel density and SKCS hardness index exhibited more break flour, straight grade flour and milling score but less reduction flour. Linear relationship between physical grain parameters and break flour yield is an indication that wheat variety with means for grain parameters yield higher break flour. Kernel density depicted positive association with reduction flour and negative with SKCS hardness and break flour. PSI and NIR hardness were strongly interrelated but these revealed weak connection with break flour and SKCS hardness index is a reliable prediction as less break flour is recovered from wheat variety with more hardness and PSI values.
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