# 6844 Physical, Chemical, and Dry-MillingProperties ofCorn ofVaryingDensity and Breakage 

# Susceptibility1



### A. 

### J. PEPLINSKI,2 M. R. PAULSEN,3 and A. 

### BOUZAHER4

ABSTRACT Cereal Chern. 69(4):397-400

Seven lots ofyellow dent corn varying in kernel density and breakage susceptibility were tested for chemical composition, physical properties, and dry-milling response. Whole-kernel nitrogen content varied among lots from 1.35 to 1.48%, fat content ranged from 4.3 to 5.6%, starch from 70 to 78%, and ash from 1.3 to 1.6%. Physical analyses showed
test weights of732-762 kg!mJ (56.9-59.21b!bu), IDO-kernel weights from 29.0 to 32.2 g, 11-64% floating kernels, and 14-33% broken kernels. Kernel breakage susceptibility correlated statistically (P:S0.05) with test weight, percentage offloating kernels, and percentage ofstress-cracked kernels. Percentage offloating kernels was a more precise indicator of

The importance of corn as a major food, feed, and export commodity is demonstrated by the average U.S. production of 178 million metric tons (seven billion bushels) peryearfrom 1977
to 1986 (USDA 1987). Corn varieties grown in the United States vary in kernel chemical composition and in physical characteristics, such as density and hardness (Peplinski et al 1989). Corn kernel characteristics can also be affected by sheller damage if grain is harvested at high moisture content, by postharvest handling, and by drying air temperatures (Peplinski et al 1975, 1982, 1989). Differences inkernelcharacteristicscausedbygenetic inheritance,environment, orhandlingcaninfluencetheprocessing and utilization ofcorn.

Corn breakage susceptibility and hardness have been studied for some years with varying success. Paulsen et al (1983) investigated breakage susceptibility of midwestern corn genotypes; Pomeranz et al (1984) looked at corn hardness as measured by density and near-infrared reflectance; Stroshine et al (1986) measured density and breakage susceptibility ofselected hybrids; and Kirleis and Stroshine (1990) checked the effect ofhardness

on corn breakage susceptibility and dry-milling response.

The broad objective of this work was to study how kernel density and breakage susceptibility are related to kernel chemical composition, physical characteristics, and dry-milling response.



### MATERIALS AND METHODS

Corn

Market-grade yellow dent corn was obtained from commercial elevators in Illinois and was segregated by incoming truckload before it was unloaded. Corn on each truckload was tested at the elevator for test weight and breakage susceptibility and was separated into four groups: high-test-weight kernels with low breakage susceptibility; low-test-weight kernels with medium breakage susceptibility; high-test-weight kernels with high breakage susceptibility; and low-test-weightkernels with highbreakage susceptibility (Paulsen and Hill 1985). Each truckload was sampled by probing. Samples were checked immediately for test

'The mention offirm names ortrade products does notimply that they areendorsed

orrecommended by the U.S. DepartmentofAgriculture overotherfirms orsimilar products not mentioned. 'National Center for Agricultural Utilization Research. Agricultural Research Service. U.S. Departme;t ofAgriCUlture. 1815 N. University

### St., Peoria, IL 61604. "Department ofAgricultural Engineering. University ofIllinois. Urbana 61801. 'Agricultural and Rural Development. Iowa State University, Ames 50011.

This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. American Association of Cereal Chemists, Inc., 1992. kerneldensity, breakage susceptibility, and hardness than wastestweight. Dry-milling response showed that first-break grit yield was higher for

corn withtestweight above 747 kg!mJ (58.0Ib!bu), percentage offloating kernels below 36%, and percentage of broken kernels below 16% as measured by the Stein breakage test. Hull (pericarp) yield was positively correlated (P:S0.05) with breakage susceptibility, stress cracks, floating kernels, and degermer throughput. The results indicate that corn is less susceptible to breakage when its density is high, as measured by low flotation and high test weight, and when the percentage ofstress-cracked kernels is low.

weight and breakage with a Wisconsin-type tester until 2,286-t (90,000-bu) lots were obtained for each commercial milling run.

After sampling, the corn was transferred to holding bins, conveyed to a commercial dry-milling plant (Lauhoff Grain Co., Danville, lL), cleaned on 6.35-mm sieves, and sent to degermers. Each corn lot was sampled at lO-min intervals before and after cleaningtoprovideone2-kgsampleevery30min. Arepresentative 45.4-kg (lOO-lb) portion of the pooled 2-kg samples from each lot was retained for testing at the Northern Regional Research Center, Peoria, IL The corn was further blended and cleaned by aspiration and screening over a 4.76-mm (l2/64-in.) roundhole-perforated sieve to remove fine materiaL This cleaning removed I% orless fine material from each lot.

Analytical Procedures and Calculations

Ash, fiber, nitrogen, and starch contents of whole corn were determined by AACC-approved methods (AACC 1983). The fat
content ofwhole corn and germ fractions was determined from pentane-hexane extraction by the Butt procedure (AACC 1983), andthefat contentoftheotherroller-milledfractions was assayed by gas chromatography (Blacket al 1967) as modified by Nielsen
et al (1979). Moisture contents were determined gravimetrically after lO-g ground samples were dried at 130°C for 60 min in

a forced-air oven. Yield ofrecoverable oil was calculated based

on yield of recovered germ fraction and its fat and moisture contents and assuming that residual germ cake contained 5% oil (db) (Reitmeier and Prusa 1990). Dry-millingproductyields were calculated with samples air-dried at 25°C and 50% relative humidityto9

### ± 1.0% moisture. Atthis humidityandtemperature, the final water content of the dry-milled fractions ranged from 8to 10%.

All physical tests were done on whole, sound corn kernels equilibrated to 9 

### ± 0.5% moisture. Test weight was determined inaccordancewithUSDAOfficialGrainStandards(USDA 1977). Weight per 100 kernels was determined for sound kernels visibly free from chips, cracks, and other defects. Stress-cracked kernels (sum ofsingle, multiple, and checked kernels) were counted for 50-g samples of whole corn by the method of Thompson and Foster(1963) under X3 magnification. Kernel breakage susceptibility was tested with a Stein breakage tester (model CK2) on 100-g portions ofwhole corn impacted for 2 min; breakage was determined as the percentage ofsample passing through a 4.76-

mm (l2/64-in.) round-hole-perforated sieve. Kernel hardness index was determined on 150-g samples by the "floaters test" (Wichser 1961) with a sodium nitrate solution ofspecific gravity 1.275 (Peplinski et al 1989); the hardest kernels were assigned

a value of 9 and the softest kernels a value of I. Kernel size

was determined by hand-screening of 200-g samples for 2 min

on0.33-m(l3-in.)-square round-hole-perforated screens. Alltests

were replicated two ormore times.

Vol. 69, No.4, 1992 397

### Statistical Analysis Samples from corn lots A-G were tested with two or more replications for every chemical and physical characteristic and everyroller-millingproductyieldandfatvalue. Thegenerallinear models (GLM) procedure was used to obtain least significant difference values, and correlation analyses were run to obtain Pearson correlation coefficients between all pairs of variables listed in Tables I-IV. Statistically significant coefficients (P ::; 

### 0.05) are listed in Table VI. Analysis ofvariance with the GLM procedure was used to compare values for corn lots with low, medium, and high breakage susceptibility (Table V).

Degermation

Each corn lot at 9-12% moisture was tempered by addition of water to 16% moisture, held for 16 hr, further tempered to

TABLEI Chemical Composition ofWhole Corn (db) 

### 21% moisture, and held for 1.75 hr. Finally, to loosen the hulls (pericarp), kernelmoisturewas increasedto 24% for 15 min. Corn

was then ground in a horizontal rotor degermer (HRD). The temperingstepsallowadequatemoisturepenetrationwithminimal internal stress-crack formation in the endosperm. Corn was fed
to the HRD while it operated at 1,750 rpm, and the net motor load was kept constant at 0.26 kW. Corn throughputs from the HRD ranged from 1.54to 1.93 kg/min. Details ofthe tempering process and of the design and use of the HRD and the drymillingflowwerepublishedpreviously(BrekkeetaI1972, Peplinski et al 1984). The degermer throughput (broken pieces of endosperm, germ, and hull) was dried with 38°C (100°F) air in a forced-air, flow-through tray dryer to 17 

## ± I% moisture. The throughputwasfurtherprocessedbyrollermillingtolow-fatfoodgrade products (prime products), feed products, and corn germ (Peplinskiet al 1982, 1984, 1989). Alltemperingand rollermilling

were done at 25°C and 50% relative humidity.

RESULTS AND DISCUSSION

'HTW and LTW indicate high and low test weight, respectively. LB, MB, and HB indicate low, medium, and high breakage susceptibility, respectively. bLeast significant difference at P:::; 0.05. Corn Lot
A B C D E F G
LSDb Type'

HTW-LB HTW-LB HTW-LB LTW-MB HTW-HB LTW-HB LTW-HB Nitrogen Fat Starch Ash (%) (%) (%) (%)
1.39 4.9 76 1.3 1.48 4.3 78 1.4 1.40 5.6 75 1.6 1.45 5.0 75 1.4 1.40 4.4 70 1.3 1.40 4.6 76 1.4 1.35 5.0 74 1.3
0.06 0.1 2 0.1 Fiber (%)
2 2 2 2 2 2 2
0.1 

### Chemical Composition ofWhole Corn Corn lots differed in composition (Table I). Nitrogen content ranged from 1.35% for lot G to 1.48% for lot B, a difference of 10% based on lot G. Fat content varied from 4.3% for lot B to 5.6% for lot C, a 30% difference based on lot B. Starch ranged from 70 to 78% and ash from 1.3 to 1.6%. Fiber was unchanged at 2%. These chemical composition data are similar to previously reported values (Peplinski et al 1982, 1984, 1989).

Physical Analyses ofWhole Corn

Corn test weights ranged from 732 to 762 kg/m3 

### (56.9-59.2 Ib/bu) (Table II). Breakage susceptibility of these corn lots increased sharply as test weight fell to 747 kg/m3 

### (58 Ib/bu) or

TABLE II Physical Analysis ofWhole Corn'

Test Weight Weight per Stress Stein Corn 100 Kernels Floaters Hardness Cracks Breakage Lot Typeb (kg/m3) (Ib/bu) (g) (%) Index' (%) (%)

A HTW-LB 762 59.2 32.2 16 8 8 14 B HTW-LB 754 58.6 30.9 36 6 24 15 C HTW-LB 754 58.6 31.7 16 8 33 16 D LTW-MB 740 57.5 31.7 II 9 19 22 E HTW-HB 747 58.0 29.9 52 4 62 33 F LTW-HB 733 57.0 29.0 64 3 59 31 G LTW-HB 732 56.9 29.9 62 3 61 33
LSDd 8 0.6 1.5 4 2 3 3
'9

### ± 0.5% moisture. bHTW and LTW indicate high and low test weight, respectively. LB, MB, and HB indicate low, medium, and high breakage susceptibility, respectively. '9 = hardest. I = softest. dLeast significant difference at P:::; 0.05.

TABLEIII Degermer Throughput' and Yield ofRoller-Milled Productsb

Low-Fat High-Fat Degermer First-Break Second- and Third- Meal and Prime Meal and Degermer Bran Corn Throughput Grits Break Grits Flour Products Flour Fines Meal Hull Germ Lot Type' (kg/min) (%) (%) (%) (%) (%) (%) (%) (%) (%)
A HTW-LB 1.54 10 31 14 55 13 4 5 8 15 B HTW-LB 1.67 12 33 14 59 12 4 6 7 12 C HTW-LB 1.77 9 31 16 56 13 4 5 8 14 D LTW-MB 1.60 7 32 16 55 13 4 5 8 15 E HTW-HB 1.93 6 31 14 51 15 4 6 9 14 F LTW-HB 1.78 6 30 14 50 15 4 6 9 15 G LTW-HB 1.74 7 30 15 52 15 5 6 9 13
LSDd 0.2 1.5 2 1.4 3.3 1.2 0.5 1.2 I.l 1.9
'22.5 

### ± 1.0% moisture. b9

### ± 1.0% moisture. 'HTW and LTW indicatehigh and low test weight, respectively. LB, MB, and HB indicate low, medium, and high breakage susceptibility, respectively. dLeast significant difference at P:::; 0.05.

398 CEREAL CHEMISTRY

### less. We therefore used 747 kg/m) (58 Ib/bu) as the test weight dividing high- and low-test-weight corn in this study. According to this measure, lots A, B, C, and Efall into the high-test-weight category. Paulsen and Hill (1985) suggested adividingtestweight ofabout 733 kg/m) (57 Ib/bu) in their work on kernel breakage and density.

Weight per 100 kernels was above 30 g for lots A-D. The percentage offloating kernels was lowest (::; 36%) for these four lots. Corn with a low percentage offloaters is denser than corn with ahigh percentage offloaters and tends to have more horny, vitreous endosperm, which is harder and more resistantto breakage than less dense, softer, floury endosperm. The floaters test rated lots A, C, and D as hard, lots Band E as intermediate, and lots F and G as soft. Stress-crack values for lots A-D were 33% or less, whereas lots E-G each contained 59-62% stresscrackedkernels. Stress-crackedkernelstendtobreakorchipmore readilyduringhandlingthan kernels withoutstress cracks. Kernel breakagesusceptibility, assessedbytheSteinbreakagetest,ranged from 14-16% for lots A-C to 22% for lot D and 31-33% for lots E-G.

Degermation, Roller Milling, and Grading of Degermed Corn

Degermer throughputs from the HRD and yields of rollermilled products from the grinding and gradingprocess are shown in Table III. Throughput, or the output of ground corn from the HRD at a constant net motor load of0.26 kW, ranged from

a low of 1.54 kg/min for lot A (corn with the highest test weight and lowest stress-crack and breakage percentages) to 1.93 kg/ min for lot E. Throughput is influenced by kernel density, hardness, stress cracks, hull (pericarp) thickness, shape, size, and percentage ofhorny endosperm.

First-breakgrityield, an indicatorofendospermhardness, was highest for lots A and B (10-12%), intermediate for lot C (9%), and lowest for lots D-G (6-7%). Prime products were highest from lots A-D (55-59%) and lower from lots E-G (50-52%). The prime products are a mixture of low-fat grits, meal, and flour used by cereal, malted beverage, and other related food processors. Yields of first-break grits and prime products were directly correlated with density as measured by the floaters test andnegativelycorrelatedwithbreakagesusceptibilityasmeasured by the Stein breakage test.

The germ fraction containing the oil varied little among corn lots; yields ranged from 12 to 15%. The remaining fractions are generally high in fat content and have less economic value than the lower-fat fractions; they are generally used in animal feed products. Their yields were as follows: high-fat meal and flour, 12-15%; degermerfines, 4-5%; bran meal, 5-6%; and hull, 7-9%.

The fat content of roller-milled products did not appear to be related to 

### corn hardness or breakage (Table IV). Fat content ofthe first-break grits, prime products, and germ fractions was highest in lots B, E, and G and much lower in lots A, D, and F; lot C had low fat content in the first-break grits and prime products but high fat content in the germ fraction. Recoverable oilyieldfromthegermfractionvarieddirectlywiththepercentage offloating kernels and inverselywithtestweightand ranged from 1.8 to 2.3 kgofoilper 100kg ofcorn. Theseyields arecomparable
to thosepreviouslyreported (Peplinskiet al 1989). Thecalculated recoverable oilyields are an indicatorofthe oil that can theoretically be extracted from the germ by commercial oil processors.

Kernel Breakage Susceptibility

The seven corn lots were divided into three groups with low, medium, and high mean breakage susceptibility for statistical evaluation. Corns with low and high breakage susceptibility were significantly different (P ::; 

### 0.05) in all variables listed in Table V. Test weight, 100-kernel weight, hardness index, and yields offirst-break grits and prime products increased as breakage susceptibility decreased. Corns with low breakage susceptibility had the highest mean values for test weight (757 kg/m), 58.8 Ib/bu), IDO-kernelweight(31.6g),first-breakgrityield(10.6%), andprime product yield (57.0%). Corns with high breakage susceptibility had the highest mean values for percentage offloating kernels

Yield' TABLEIV Fat Content ofRoHer-Milled Products"
Second- and Low-Fat High-Fat First-Break Third- Meal and Prime Meal and Degermer Bran Calculated Corn Grits Break Grits Flour Products Flour Fines Meal Hull Germ Recoverable Oil Lot Typeb (%) (%) (%) (%) (%) (%) (%) (%) (%) (kg/l00kg ofcorn)
A HTW-LB 0.45 0.56 0.54 0.53 1.17 0.71 3.64 1.58 20.9 1.8 B HTW-LB 0.80 0.89 1.07 0.91 2.08 1.30 4.50 2.78 24.6 2.1 C HTW-LB 0.47 0.49 0.40 0.46 0.69 0.69 3.08 2.08 23.1 2.0 D LTW-MB 0.39 0.46 0.36 0.42 0.73 0.37 1.89 1.36 21.0 2.0 E HTW-HB 0.84 0.88 1.39 1.02 0.84 0.77 2.64 3.38 24.8 2.2 F LTW-HB 0.55 0.63 0.62 0.62 0.97 0.88 2.28 2.07 21.4 2.2 G LTW-HB 0.76 0.81 0.94 0.84 1.46 0.94 2.05 3.42 24.5 2.3
LSD' 0.2 0.2 0.3 0.14 0.5 0.15 1.6 1.5 2.5
"Moisture-free basis. bHTW and LTW indicate high and low test weight, respectively. LB, MB, and HB indicate low, medium, and high breakage susceptibility, respectively. 'Least significantdifference at P-:500.05.

TABLE V Characteristics ofCorn Lots with Low, Medium, and High Breakage Susceptibility'
Weight Breakage per 100 Stress Degermer First-Break Prime Susceptibilityb Test Weight Kernels Floaters Hardness Cracks Throughput Grits Products Hull (%) (kg/ml ) (Ib/bu) (g) (%) Index' (%) (kg/min)d (%) (%) (%)
14.9 757 a 58.8 31.6 a 22.9 a 7.2 a 21.8 a 1.66 a 10.6 a 57.0 a 7.5 a 22.4 739b 57.4 31.6 a 10.8a 8.5a 18.8a 1.60 a 7.0b 54.3 a 7.8a 32.3 738 b 57.3 29.6 b 59.4 b 3.5 b 60.8 b 1.81 b 6.4 b 51.0 b 9.4 b

aMeans in a column followed by different letters are significantly different (P-:50 0.05) as determined by protected (0.05) least significant difference. Corn lots were tested at9

### ± 0.5% moisture unless otherwise indicated. bCorn lots A-C (average breakage susceptibility 14.9%) were classified as low in breakage susceptibility; lot D (22.4%) was classified as medium; and lots E-G (32.3%) were classified as high. '9

## =hardest, I 

## =softest. d22.5 

### ± 1.0% moisture. '9 ± 1.0% moisture.



### Vol. 69, No.4, 1992 399TABLE VI Correlation Coefficients' ofSelected Variables Weight Prime Test per 100 Hardness Stress Stein Degermer First-Break Products Variable Weight Kernels Floaters Index Cracks Breakage Throughput Grit Yield Yield Weight per

100 kernels 0.73 Floaters -0.65 -0.96** Hardness index 0.65 0.95** -0.99** Stress cracks -0.69 -0.90** 0.89** -0.86** Stein breakage -0.82* -0.85* 0.81* -0.77 0.90** Degermer

throughput -0.31 -0.69 0.63 -0.59 0.85* 0.67 First-break

grityield 0.73 0.59 -0.47 0.41 -0.70 -0.88** -0.55 Primeproduct

yield 0.69 0.69 -0.64 0.58 -0.78 -0.92** -0.56 0.95** Hull -0.71 -0.88** 0.86** -0.82* 0.95** 0.97** 0.75 -0.83* -0.92**

'* and ** denote statistical significance at P"'50.05 and P"'50.0I, respectively.



### (59.4%), percentage ofstress-cracked kernels (60.8%), degermer throughput (1.81 kg/min), and hullyield (9.4%).
Correlations Among Variables

Correlation coefficients were calculated for all variables reported in Tables 

### I-IV, and some statistically significant coefficients are listed in Table VI. Hull yield and Stein breakage

were each significantly correlated with seven ofthe otherparameters. Hull yield was positively correlated with percentage of floaters, stress cracks, and breakage and negatively correlated with 100-kernelweight, hardness, first-breakgrityield, and prime product yield. Stein breakage was positively correlated with percentage offloaters, stress cracks, and hull yield and negatively correlated with test weight, 100-kernel weight, first-break grit yield, and prime product yield. Paulsen et al (1983) showed a correlationbetween kernel thickness and density, and Kirleis and Stroshine (1990) noted that kernel hardness was correlated with breakage susceptibility.

Based on the strength of our data, we believe that the hull (pericarp), becauseofits amount, structure, oradherenceto endosperm or germ, has a large but unexplained influence on kernel hardness, breakagesusceptibility, and millingresponse. Theother variables with statistically significant correlation coefficients (P


### ::; 0.05) were stress cracks, related to six variables; floaters and 100-kernel weight, five variables each; and hardness, four variables. Kernel chemical composition, fat contents of dry-milled fractions, and the remaining fraction yields showed little or no significantstatisticalcorrelationwith othertested parameters and

are not shown in Table VI.

CONCLUSIONS
Seven corn lots varying in density and kernel breakage susceptibility differed extensively in chemical composition, drymilling response, and physical characteristics. Whole-kernel fat
content varied by up to 30% and nitrogen content by up to 10%.

Roller-milling response studies indicated that grit yield was significantlyhigherforcornlots withtestweightabove740kg/m3 

### (57.5Ib/bu), fewerthan36%floatingkernels, lessthan22% kernel breakage in the Stein test, and fewer than 34% stress-cracked kernels. Recoverable germ oil varied directly with percentage of floating kernels and inverselywith test weight.

Corn hardness is related to breakage, density, and dry-milling response and is very difficult to determine with present test methods. The percentage offloating kernels correlates with hardness and breakage susceptibility more precisely than does test weight. Corn kernels resist breaking and cracking when their densityis high, as measuredbyhightestweight and lowflotation, and when the percentage of stress-cracked kernels is low. Hull amount, structure, or adherence to endosperm or germ appears to have a large but unexplained influence on kernel hardness, breakage susceptibility, and milling response. LITERATURE CITED
AMERICAN ASSOCIATION OF CEREAL CHEMISTS. 1983.

Approved Methods of the AACC, 8th ed. Method 08-16, approved May 1960, revised October 1976, reviewed October 1981; Method 30- 25, approved April 1961, revised October 1976 and 1981; Method 32- 10, approved October 1981, revised October 1982; Method 46-10, approved April 1961, revised October 1976 and September 1985; Method 76-20, approved May 1969, reviewed October 1982. The Association: St. Paul, MN. BLACK, 1.T., SPYRES, G. G., andBREKKE, O. 1. 1967. Determination

of oil contents of dry-milled corn fractions by gas-liquid chromatography. Cereal Chern. 44: 152. BREKKE, O. 1., PEPLINSKI, A. J., GRIFFIN, E. 1., JR., and ELLIS,

J. J. 1972. Dry-milling ofcorn attacked by Southernleafblight. Cereal Chern. 49:466. KIRLEIS, A. W., and STROSHINE, R. 1. 1990. Effects of hardness

and drying air temperature on breakage susceptibility and dry-milling characteristics ofyellow dentcorn. Cereal Chern. 67:523. NIELSEN, H. 

### c., WALL, J. S., and INGLETT, G. E. 1979. Flour

containing protein and fiber made from wet-mill corn germ, with potential food use. Cereal Chern. 56: 144. PAULSEN, M. R., and HILL, 1. D. 1985. Corn quality factors affecting

dry milling performance. J. Agric. Eng. Res. 31:255. PAULSEN, M. R., HILL, 1. D., WHITE, D. G., and SPRAGUE, G.

F. 1983. Breakage susceptibility ofcorn-belt genotypes. Trans. ASAE 26: 1830. PEPLINSKI, A. J., ANDERSON, R. A., and ECKHOFF, S. R. 1984.

A dry-milling evaluation oftrickle sulfur dioxide-treated corn. Cereal Chern. 61:289. PEPLINSKI, A. J., BREKKE, O. 1., GRIFFIN, E. 1., HALL, G., and

HILL, 1. D. 1975. Corn quality as influenced by harvest and drying conditions. Cereal Foods World 20:145. PEPLINSKI, A. J., ANDERSON, R. A., and BREKKE, O. 1. 1982.

Corn dry millingas influenced by harvest and dryingconditions. Trans. ASAE25:1114. PEPLINSKI, A. J., PAULSEN, M. R., ANDERSON, R. A., and

KWOLEK, W. F. 1989. Physical, chemical, and dry-milling characteristics ofcorn hybrids from various genotypes. Cereal Chern. 66: 117. POMERANZ, Y., MARTIN, C. R., TRAYLOR, D. D., and LAI, F.

S. 1984. Corn hardness determination. Cereal Chern. 61:147. REITMEIER, C. A., and PRUSA, K. J. 1990. Addition of dry- and

wet-milled corn germ flours to model system frankfurters ofthree fat levels. J. Food Qual. 13:283. STROSHINE, R. 1., KIRLEIS, A. W., TUITE, J. F., BAUMAN, 1.

F., and EMAM, A 1986. Differences in grain quality among selected

corn hybrids. Cereal Foods World 31:31 I. THOMPSON, R. A, and FOSTER, G. H. 1963. Stress cracks and

breakage in artificially dried corn. U.S. Department of Agriculture Marketing Research Report 631. U.S. Government Printing Office: Washington, DC. U.S. DEPARTMENT OF AGRICULTURE. 1977. Official Grain Standards ofthe United States. Consumer and Marketing Service, Grain Division. U.S. Government Printing Office: Washington, DC. U.S. DEPARTMENTOFAGRICULTURE. 1987. Agriculturalstatistics.

U.S. Government Printing Office: Washington, DC. WICHSER, W. R. 1961. The world ofcornprocessing. Am. Miller89:29.


### [Received March 19, 1990. Revision received October 10, 1991. Accepted October26, 1991.]

400 CEREAL CHEMISTRY