Agriculture Reference
In-Depth Information
In order to get more precise information of soybean cultivars, only USA varieties were
subjected to a discriminant analysis for differentiating among cultivars from different
American states. Seven different categories, corresponding to seven different American states
from where the soybeans were original, were established: Arkansas (2 varieties), Hawaii (3
varieties), Illinois (6 varieties), Indiana (5 varieties), Iowa (7 varieties), Minnesota (10
varieties), and Mississippi (2 varieties). Two discriminant functions with P-values less than
0.05 (at the 95% confidence level) enabled the correct classification of all varieties (97.1%)
with the exception of one Minnesota cultivar that was incorrectly classified as Illinois variety.
Figure 5 shows how those soybean cultivars original from the warmest regions such as
Mississippi, Hawaii or Arkansas were displayed in the left and up side of the diagram while
varieties grown in colder regions appeared in the right and down side.
3. Estimation of Different Chemical and Physical Characteristics
The chromatographic data collected from the protein profiles obtained from the 91
different soybean cultivars were compared with different chemical and physical
characteristics of cultivars in order to explore possible correlations. Thus, the area
percentages obtained were used for the estimation of the 7S and 11S globulin contents and the
ratio 11S/7S. These parameters vary among soybean cultivars and are very important for the
characterization of the seed since they affect significantly to the protein quality and food
processing properties. The estimation of 7S and 11S globulin fractions in every cultivar was
performed from the peak area percentages taking into account a previous research work [64]
in which peaks 1 to 7 were mainly identified as the 7S globulin fraction while peaks 12-14
were attributed to the 11S globulin fraction. Figure 6 shows the box-and-whisker diagram for
the 11S/7S ratio in the American, European, and Asian soybeans. Results confirmed the
variability of this ratio with the soybean cultivar. In fact, 11S/7S ratios ranged from 0.46 to
3.45 observing the highest 11S/7S ratios for Asian soybean cultivars while European varieties
presented the lowest ratios. Taking into account the characteristics of 7S and 11S globulin
fractions, European cultivars, in general, could be most suitable when certain functional
properties of soybean are required while Asian soybeans, in general, presented higher 11S
globulin contents and, therefore, could be more useful for their nutritional properties.
Moreover, trying to explore the possibilities of using protein profiles as “fingerprints” of
soybean cultivars, their capability for predicting different characteristics of soybean cultivars
was studied. Eleven different parameters including compositional parameters (contents in oil,
protein, linoleic acid, linolenic acid, oleic acid, palmitic acid, and stearic acid) and physical
ones (height of the plant from ground to stem tip, weight of 100 seeds, time needed by 50%
of the plants for flowering, and time needed by 95% of the pods for reaching its final color)
were studied. All these data corresponding to 64 of the 91 soybean cultivars employed in this
work were taken from the Agricultural Research Service from the United States Agricultural
Department (http://www.ars-grin.gov/npgs/urbana.html). Highest variability among soybean
cultivars were observed for the plant height (85.1 ± 16.8 cm), the 100-grain weight (2.45 ±
0.48 g), the linolenic acid content (1.51 ± 0.28 g/100g), the oleic acid content (4.12 ± 0.99
g/100g), the palmitic acid content (2.21 ± 0.48 g/100g), and the stearic acid content (0.62 ±
0.16 g/100g) while those parameters showing the lowest variability among the soybean
cultivars studied were the protein content (43.5 ± 2.5 g/100g), the oil content (19.4 ± 1.5
g/100g), the linoleic acid content (10.5 ± 0.9 g/100g), the flowering time (221 ± 15 days), and
the maturation time (290 ± 26 days).
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