DARSHANA LANKE
Age 16 | Saskatoon, Saskatchewan
Canada-Wide Science Fair 2018 Finalist | Saskatoon Regional Science Fair 2018 Senior Bronze Medallist
Wheat is a cereal grain, that has a great impact on human nutrition and health. It is a major source of proteins, carbohydrates, and dietary fibers. At present there is considerable interest in the ancient wheats that were present in the Fertile-crescent and then naturally hybridized to give rise to the modern day allohexaploid wheat
1
. The modern wheat varieties have been further improved by plant breeding techniques to develop varieties with improved agronomic traits such as yield and desirable bread making qualities
2
. However, easy availability of food and over-consumption has led to a high calorie intake. This combined with a less active lifestyle has resulted in obesity and associated non-communicable diseases such as type 2 diabetes and cardiovascular diseases
OBJECTIVE
To analyze the grain nutritional composition of ancient and modern wheat varieties.
HYPOTHESIS
The hypothesis of the present study is that ancient and modern wheats differ in their grain nutritional composition 4 .
METHODS
Wheat varieties were the materials used in this project. The materials were harvested from the 2016 crop year in the Plant Sciences, University of Saskatchewan research farm in Saskatoon. Table 1 shows the wheat varieties used.
This study was done at the University of Saskatchewan in the Plant Sciences department. Professor Chibbar and his team helped in the analysis of the different grain components.
Table 1. The modern wheat varieties (with registration year), and ancient wheat varieties used.
Total Starch: Total starch concentration was determined using enzymatic procedures 5 . Enzymes were used to convert starch to glucose which was measured using a spectrophotometer at 510 nm.
Total Dietary Fiber: The total dietary fiber (TDF) was determined by the enzymatic hydrolysis of wheat meal 6 . Enzymes were used to solubilize and depolymerize starch and protein. The residue was treated with ethanol and filtered. The dried residue was used to calculate the TDF.
Total Protein: A combustion method was used to determine protein concentration using LECO Protein analyser 7 . The protein analyser is a microprocessor based, software-controlled instrument that determines the nitrogen content in wheat. In the analyser the sample is purged, burned and nitrogen is separated. The nitrogen levels were used to determine the levels of protein.
Total Arabinoxylans: Arabinoxylans are a major component of dietary fiber in cereal grains. The Phloroglucinol colorimetric method 8 with slight modifications 9 was used to determine arabinoxylans (AX) content in wheat flour. Total arabinoxylans (TAX) content as xylose equivalents was determined by using an extraction reaction reagent that included acetic acid, hydrochloric acid and a coloring substance, phloroglucinol, that helped the UV spectrophotometer determine the levels of arabinoxylans. Reading of arabinoxylans were taken at 552 nanometers and 510 nanometers.
Digestibility of Wheat Grain: The digestibility of the wheat grain was determined by using an in vitro method 10 . Pancreatic enzymes such as a-amylase and amyloglucosidase were used to imitate the digestion of starch. In thirty minute intervals the levels of starch converted to glucose were measured at 510 nanometers by using a spectrophotometer. Levels of resistant starch, readily digestible starch, slowly digestible starch and hydrolytic index were determined.
Variables: The controls for all procedures were standards and blanks. The type of standard varied for each procedure. The independent variables were the wheat varieties. The dependant variable was the percentage of the nutritional composition for the specific nutrient.
Analysis: This study used principal component analysis (PCA) to analyze the data collected. Through PCA, a visualization of the relationships amongst the different grain nutritional components was created. PCA also determined the similarities between the different wheat varieties by grouping them together.
RESULTS
Nutritional Composition:
Figure 1. Representation of the different nutritional components.
Digestibility:
Figure 2. Resistant Starch (RS), Readily Digestible Starch (RDS),and Slowly Digestible Starch (SDS) for the wheat varieties.
Figure 3. Hydrolytic index (HI) of the wheat varieties.
Nutritional Composition:
There was little variation in the difference between maximum and minimum percentages of total starch, total protein and total arabinoxylans in both ancient and modern wheat. Higher variations were seen in the other nutrients.
Table 2. Averages of wheat types nutritional components. Maximum and minimum percentages for each wheat type.
Principal Component Analysis (PCA):
To study the relationship between different grain parameters and the wheat varieties, PCA analysis was done for grain constituents and wheat types. The total dietary fiber was related to readily and slow digestible starch and hydrolytic index. Whereas proteins and arabinoxylan concentrations were related to each other. Among the wheat varieties, Spelt and Emmer formed one group, while Einkorn wheat turned out to be in the same group as modern wheat varieties.
Figure 4. Principal component analyses to group grain nutritional constituents and wheat varieties to study their relationship.
CONCLUSIONS
The results have shown that there are variations in the wheat varieties nutritional composition with no substantial change in grain composition of wheat over time and not specific to the wheat type. The grain nutritional components such as protein, dietary fiber and starch of ancient wheats are comparable to modern wheats. The principal component analysis demonstrates that there is not a strong correlation between the variations seen and the wheat types. The implication of this study is, it gives consumers an idea about ancient and modern wheat varieties nutritional composition in comparison to each other.
ACKNOWLEDGEMENTS
I would like to sincerely thank Professor Ravindra N. Chibbar, his knowledgeable and helpful team and the department of Plant Sciences at the University of Saskatchewan.
REFERENCES
1. Feldman, M. 2000Origin of cultivated wheat In The World Wheat Book – A history of wheat breeding. Eds Bonjean, A.P. and Angus, W.J. Intercept Lavoisier publishing Londonres, Paris, New York.
2. Hucl, P., Briggs, C., Graf, R.J. and Chibbar, R.N. (2015) Genetic gains in agronomic and selected end-use quality traits over a century of plant breeding of Canada Western Red Spring wheat. Cereal Chemistry 92: 537 - 543
3. Shewry, P.R. and Hey, S.J. @016) Do we need to worry about eating wheat? Nutrition Bulletin 41: 6 – 13.
4. Davis, WR (2011) Wheat Belly: Lose the wheat, Lose the Weight and find your path back to health. Rodale Books: Emmaus , PA, USA
5. AACC International. (1999). Approved Methods of Analysis, 11th Ed. Method 76–13.01. Total Starch Assay Procedure (Megazyme Amyloglucosidase/alpha-Amylase Method) St. Paul, MN, U.S.A: AACC International.
6. AOAC International. (2003). Total, soluble and insoluble dietary fiber in foods and food products, enzymatic Gravimetric Method. In “Official Methods of Analysis of AOAC International”. 17th ed. 991.43. William Horwitz ed. Gaithersburg, MD, U. S. A.
7. AACC International. (1999). Approved Methods of Analysis, 11th Ed. Method 46-30.01. Crude protein—Combustion method. Approved November 8, 1995; reapproved November 3, 1999.
8. Douglas, SG (1981) A rapid method for determination of pentosans in wheat flour. Food Chemistry 7: 139-145.
9. Finnie, S.M., Bettge, A.D., and Morris, C.F. (2006) Influence of cultivar and environment on water soluble and water insoluble arabinoxylans in soft wheat. Cereal Chemistry 83: 617 – 623. et al., (2006)
10. Goñi, I., Garcia-Alonso, A., & Saura-Calixto, F. (1997). A starch hydrolysis procedure to estimate glycemic index. Nutrition Research, 17(3), 427–437. https://doi.org/10.1016/S0271-5317(97)00010-9
11. Hotelling, H. (1936). Relations Between Two Sets of Variates. Biometrika, 28(3/4), 321. doi: 10.2307/2333955
DARSHANA LANKE
My name is Darshana Lanke. I am a grade 10 student in the French Immersion Program at Walter Murray Collegiate. I love learning languages and can speak 4 different languages (English, French, Hindi and Marathi). Some of my hobbies include singing, cooking, and knitting. Currently I am working on my level 6 Royal Conservatory Voice Exam. I also have an interest in social justice. Debate, Math, Mock Trials, Badminton and French speaking competitions are some of the activities I take part in. I have a passion for learning, especially in the field of science. I have been participating in science fairs since grade 7. I am a Canada-Wide Science Fair participant and medalist.