using nirs to predict palmitic fatty acid in peanut seeds barry l. tillman and george person
TRANSCRIPT
Why are oleic, linoleic, and palmitic acid important?
• Dominant fatty acids in peanut oil
– High oleic acid• US Patent- 6,063,984, Knauft, Gorbet, Norden• Trait is simply inherited- two recessive genes
Oleic acid
(18:1)
Linoleic acid (18:2)
Palmitic acid
(16:0)
Normal 50-60% 20-30% 8-12%
High Oleic 74-84% 2-8% 5-7%
Relationship among Palmitic, Linoleic, and Oleic Acids
y = -0.1389x + 172.49
R2 = 0.8532n = 13856
y = -0.8685x + 727.76
R2 = 0.9806n = 13856
0
50
100
150
200
250
300
350
400
350 450 550 650 750 850
Oleic acid (g kg-1)
Co
nte
nt
(g k
g-1
)
Palmitic acid Linoleic acid
High oleic peanuts have commercial and health benefits.
• Commercial benefits– High oleic peanuts have 5x-15x the shelf life of normal peanuts
• Maintain flavor– Oil quality similar to olive oil
• Health (have more of what makes normal peanuts healthy)
– High in monounsaturated fats• Lowers total cholesterol • Lowers bad LDL cholesterol • Maintains beneficial HDL cholesterol • Lowers triglycerides
– May reduce risk of heart disease when eaten regularly
Developing high oleic (HO) peanut varieties is a priority
At Least 18 High oleic acid peanut cultivars have been released.
• SunOleic 95R• SunOleic 97R• GK7• VC-2• AT1-1• AT201• Flavor Runner• Georgia HiOL• Georgia 02C
• Olin• Tamrun OL01R• ANorden• Hull• Tamrun OL02R• AT3085RO • McCloud• York• Florida-07
How do we measure fatty acid content?
• Gas chromatography (GC)– Accurate– Always destructive/injurious– Time consuming (15-20 min./sample)
Can we reliably measure oleic, linoleic and palmitic acid content with NIR and replace GC? • We test about 800-900 samples per year using GC• Need to test 3-4 times that number
– Near infrared reflectance spectroscopy (NIR)• Less accurate• Can be non-destructive• Fast (3-5 min./sample)
NIR Calibration - Fatty Acids in Peanut
• Previous Calibration & Validation – Predicts Oleic and Linoleic acids– Misclassifies 4-5% of single seeds tested
(Crop Sci. 46:2121–2126 (2006))
• Goals of New Calibration– Predict Oleic, Linoleic and Palmitic acids– Reduce % misclassified seeds
300350400450500550600650700750800850900
300 350 400 450 500 550 600 650 700 750 800 850 900
NIR predicted Oleic Acid (g kg-1)
GC
me
as
ure
d O
leic
Ac
id (
g k
g-1)
Previous calibration- Oleic AcidAgreement between NIR and GC is very good
R2=0.98y = 1.01x – 4.4slope: p>|t|<0.0001intercept: p>|t|=0.6059n =132
GC
NIR
350400
450500
550600
650700
750800
850900
350 400 450 500 550 600 650 700 750 800 850 900
NIR predicted Oleic Acid (%)
GC
Me
as
ure
d O
leic
Ac
id (
%)
Previous validation- Oleic Acid4 out of 43 HO (4/94 total) kernels were misclassified by NIR
R2=0.84y = 1.01x – 2.0slope: p>|t|<0.0001intercept: p>|t|=0.9475n =94 GC
NIR
NIR Calibration - Fatty Acids in Peanut
• Previous Calibration & Validation – Predicts Oleic and Linoleic acids– Misclassifies 4-5% of single seeds tested
(Crop Sci. 46:2121–2126 (2006))
• Goals of New Calibration & Validation– Predict Oleic, Linoleic and Palmitic acids– Reduce % Misclassified seeds
New Model Oleic Acid Calibration(single seeds)
y = 0.9822x + 12.749
R2 = 0.851n = 243
360
440
520
600
680
760
840
380 430 480 530 580 630 680 730 780 830 880NIRS predicted Oleic acid (g kg-1)
GC
mea
sure
d O
leic
aci
d (
g k
g-1
)
New validation- Oleic Acid1 out of 43 HO (1/94 total) kernels were misclassified by
NIR
y = 1.0034x - 8.4905
R2 = 0.8882n = 94
360
440
520
600
680
760
840
400 450 500 550 600 650 700 750 800 850NIRS predicted Oleic acid (g kg-1)
GC
mea
sure
d O
leic
aci
d (
g k
g-1
)
New Model Palmitic acid calibration(single seeds)
y = 0.9541x + 3.2758
R2 = 0.7244n = 243
45
55
65
75
85
95
105
115
125
45 55 65 75 85 95 105 115NIRS predicted Palmitic acid (g kg-1)
GC
mea
sure
d P
alm
itic
aci
d (
g k
g-1
)
New Model Palmitic acid validation(single seeds)
y = 1.0383x - 5.0642
R2 = 0.804n = 94
45
55
65
75
85
95
105
115
125
45 55 65 75 85 95 105 115NIRS predicted Palmitic acid (g kg-1)
GC
mea
sure
d P
alm
itic
aci
d (
g k
g-1
)
NIR Calibration - Fatty Acids in Peanut
• Previous Calibration & Validation – Predicts Oleic and Linoleic acids– Misclassifies 4-5% of single seeds tested
(Crop Sci. 46:2121–2126 (2006))
• Goals of New Calibration & Validation– Predict Oleic, Linoleic and Palmitic acids– Reduce % Misclassified seeds
• Results- New Calibration & Validation– Predicts Oleic, Linoleic and Palmitic acids– Misclassifies 1 % of single seeds tested
Old Model Oleic acid validation(average of 5 spectra)
y = 1.1065x - 66.78
R2 = 0.8938n = 434
360
440
520
600
680
760
840
400 450 500 550 600 650 700 750 800 850NIRS predicted Oleic acid (g kg-1)
GC
mea
sure
d O
leic
aci
d (
g k
g-1
)
715
740
New Model Oleic acid validation(average of 5 spectra)
y = 1.016x - 15.107
R2 = 0.9115n = 434
360
440
520
600
680
760
840
400 450 500 550 600 650 700 750 800 850NIRS predicted Oleic acid (g kg-1)
GC
mea
sure
d O
leic
aci
d (
g k
g-1
)
725
740
Previous Model - Oleic acid validation(average of 5 seeds)
y = 1.1083x - 69.289
R2 = 0.89n = 434
360
440
520
600
680
760
840
400 450 500 550 600 650 700 750 800 850NIRS predicted Oleic acid (g kg-1)
GC
mea
sure
d O
leic
aci
d (
g k
g-1
)
720
740
% Misclassified (average of spectra)
0
2
4
6
8
10
12
14
655 675 695 715 735 755
NIRS cutoff value (g kg-1 predicted Oleic acid)
% M
iscl
assi
fied
New model Old model
725