FATTY ACID ANALYSIS OF PECAN IN LOW & HIGH INPUT ENVIRONMENTS Tom Warren September 21, 2017
Introduction High energy food source Lipid content up to 75% Carbohydrate content up to 18% Triglycerides - up to 95% of total lipids
Introduction LIPIDS PHOSPHOLIPIDS FATS STEROLS MONOGLYCERIDES DIGLYCERIDES TRIGLYCERIDES FREE FATTY ACIDS OMEGA-3 OMEGA-6 OMEGA-9 ALA DHA ELA
Introduction Considerable Health Benefits OMEGA-3 Lowering Cholesterol Altering Depression Decreasing Macular Degeneration Decreasing Inflammation Positive Impact on Nervous System ALA Cardiovascular Health
Introduction Fatty acids are an important quality parameter for pecans that lead to: Better Taste lower content = more rancid taste Longer Shelf Life Higher Price at Market
Introduction Ideal Fatty Acid Content = 50% to 75% < 50% = less valuable < 30% = unmarketable
Study Set-up Between 1996 1999 pecan cultivars were grafted to mature trees at E.V. Smith Research Station in either a high or low input environment All cultivars were grafted in a random design within each plot
Study Set-up High Input Characteristics: Irrigation Pesticide Treatment Herbicide Treatment Fungicide Treatment Fertilizer, as needed Trees spaced at 40 feet between rows & 30 feet within rows
Study Set-up Low Input Characteristics: Initial fertilizer treatment based on soil test recommendations No irrigation No chemical treatments Trees spaced at 30 feet between rows & 40 feet within rows
Study Set-up Study aimed to examine two factors in relation to nutrient input: Total Lipids Fatty Acid Content of Triglyceride Triglyceride Analysis
Study Set-up Fall 2014 Nuts from 5 cultivars were collected between high & low input orchards Desirable Gafford McMillan Elliott Syrup Mill Nuts stored at -20 o C to prevent rancidity until analysis could be completed
Study Set-up
Lipid Analysis 3 groups of 3 nuts from each cultivar in both environments were selected at random Weighed to calculate average weight Ground to powder consistency
Lipid Analysis Powder was defatted via the Bligh Dyer method of lipid extraction Mixed with MeOH:cholorform Vortex, then spun in centrifuge Allowed to sit
Lipid Analysis
Lipid Analysis Upper layer discarded Process was repeated Dried in oven to evaporate chloroform Weighed fat tissue samples
Results of Lipid Analysis Desirable high had the highest total weight, total lipid, and percent lipid Gafford and Elliott had minimal change between high and low input Syrup Mill had the greatest response when comparing high & low input for total weight and total lipid
Results of Lipid Analysis Cultivar and input average weight in grams and percentages of total weight and total lipid weight of pecan cultivars E.V. Smith Research Center. z CULTIVAR & INPUT KERNEL WEIGHT AVERAGE (g) TOTAL LIPID WEIGHT AVERAGE X PERCENT LIPID SOLUTION AVERAGE DESIRABLE HIGH 5.63 a 3.82 a 0.68 a DESIRABLE LOW 4.40 ab 2.39 ab 0.54 ab ELLIOTT HIGH 4.20 ab 2.34 ab 0.56 ab ELLIOTT LOW 3.57 ab 2.20 ab 0.62 ab GAFFORD HIGH 4.40 ab 2.50 a 0.57 ab GAFFORD LOW 4.50 ab 2.49 a 0.55 ab MCMILLAN HIGH 4.36 ab 2.39 ab 0.55 ab MCMILLAN LOW 2.30 cd 1.51 bc 0.66 ab SYRUP MILL HIGH 3.90 b 2.49 a 0.63 ab SYRUP MILL LOW 0.73 d 0.37 d 0.51 b z Tukey s HSD test. Difference shown by different letters p=0.05. y Mean of total weight of kernel (g). x Total lipid weight in kernel (g).
Triglyceride Analysis 3 nuts from each cultivar in both environments were selected at random Weighed to calculate average weight Sent to Vanderbilt School of Medicine for triglyceride analysis
Triglyceride Analysis Fatty acid content for each cultivar in high and low input settings were examined using gas chromatography-mass spectrometry (GC-MS)
Triglyceride Analysis What is GC-MS? GC: separation of compounds Hypothetically, think of different size balls being blown with a blower. Each will go different distances which are measurable MS: identification of compound Hypothetically, MS can identify the type of ball based on the distance traveled (e.g., baseball, football, etc.)
Triglyceride Analysis Total triglyceride identified by weight Fatty acids expressed as a percent of the total triglyceride weight
Results of Triglyceride Analysis High input Desirable & Gafford had the largest amounts of total triglyceride (g) Despite having the lowest amount of triglyceride (g), Syrup Mill low input had the highest percentage of palmitic acid, omega-3, & omega-6
Results of Triglyceride Analysis Syrup Mill had the greatest response in total triglyceride content when comparing high and low input environments Syrup Mill low also had lower omega-9 when compared to the other cultivars
Results of Triglyceride Analysis Cultivar and input total triglyceride average and fatty acid content of pecans grown at E.V. Smith Research Center. z CULTIVAR & INPUT TOTAL TRIGLYCERIDE y PALMITIC ACID (16:0) X STEARIC ACID (18:0) X OLEIC ACID (OMEGA-9) (18:1W9) X VACCENIC ACID (18:1W7) X LINOLEIC ACID (OMEGA-6) (18:2W6) X ALPHA LINOLENIC ACID (OMEGA-3) (18:3W3) X DESIRABLE HIGH 1.52 a 5.6 b 4.1 a 73.4 a 1.1 a 14.50 c 0.9 b DESIRABLE LOW 1.39 ab 6.1 b 3.5 a 73.4 a 1.1 a 15.00 c 0.8 b ELLIOTT HIGH 1.34 ab 6.2 b 3.3 a 71.0 ab 1.2 a 17.30 bc 0.9 b ELLIOTT LOW 1.20 ab 6.3 b 3.2 a 64.0 ab 1.2 a 24.10 bc 1.1 b GAFFORD HIGH 1.50 a 5.4 b 3.5 a 69.5 ab 1.1 a 19.30 bc 1.1 b GAFFORD LOW 1.49 a 6.4 b 3.1 a 70.3 ab 1.0 a 18.20 bc 1.1 b MCMILLAN HIGH 1.39 ab 7.1 b 4.0 a 66.0 ab 0.9 a 20.90 bc 1.2 b MCMILLAN LOW 0.71 bc 7.1 b 4.3 a 55.5 bc 1.0 a 30.70 ab 1.4 b SYRUP MILL HIGH 1.46 a 7.0 b 2.9 a 66.8 ab 1.2 a 17.38 bc 1.1 b SYRUP MILL LOW 0.17 c 9.6 a 2.9 a 42.0 c 1.4 a 41.25 a 2.7 a z Tukey s HSD test. Difference shown by different letters p=0.05. y Total triglyceride average weight in grams. x Fatty acids are a percent of the total triglyceride.
Results of Triglyceride Analysis Highly significant correlation between the amount of omega-9 and omega-6 fatty acids. Fitted Line Plot Omega-9 = 90.46-1.156 Omega-6 75 70 S 1.52971 R-Sq 97.8% R-Sq(adj) 97.5% 65 Omega-9 60 55 50 45 40 15 20 25 30 Omega-6 35 40 45
Conclusions - Lipids Desirable and Gafford high had the highest total kernel weights and total lipid weights McMillan and Syrup Mill low had the lowest total kernel weights and lowest total lipid weights
Conclusions - Lipids Syrup Mill showed the greatest response when comparing high and low inputs for total weight and total lipid weight Gafford had the lowest response in relation to high and low inputs for total weight and total lipid weight Results for Gafford may be genetic
Conclusions - Triglycerides Majority of fatty acid components in pecan are comprised of omega-6 and omega-9 Strong correlation between omega-6 and omega-9 not fully understood
Conclusions - Triglycerides Between high and low input environments Syrup Mill had the greatest response Elliott had the lowest response Results for Elliott may be genetic
Conclusions It is still undetermined which component(s) of the high input orchard yield the highest fatty acid content Future research Isolate the individual component(s) of the high input orchard Genome mapping for quality characteristics
Questions?