Study of the proteic
quality of a non traditional source
Pallaro,
Anabel Nora (1)*, Fernández, Inés (1), Feliú, Maria Susana (1),
Vidueiros, Silvina Mariela (1), Slobodianik, Nora (1), Ayerza (h), Ricardo (2),
Coates, Wayne (2)
(1) Laboratorio de Nutrición Experimental.
Cátedra de Nutrición. Facultad de Farmacia y Bioquímica. Universidad de Buenos
Aires. Junín 956 -2° piso - (1113) -
Tel (fax): 54-11-4964-8243. Buenos Aires.
Argentina. apallaro@ffyb.uba.ar
(2)
Southwest Center for Natural Products Research and Commercialization,
Office of Arid Lands Studies, The University of Arizona, Tucson, Arizona 85706,
USA.
Introduction
Chía (Salvia hispanica L.) is grown in the rugged mountainous
areas extending from the Central West of Mexico to the North of Guatemala.
In the pre-Columbian times, chía was one of the basic
foods of the Central American civilizations, after corn and bean and before
amaranth. Tenochtitlán, the capital city of the Aztec Empire, received 5,000 to
15,000 tons per year as tribute of the conquered nations. Chía seed was used
not only as food but as offering to the Aztec gods as well.
Chía when used in the pagans religious ceremonies was the
reason it was eliminated by the Spaniard conquerors and replaced by species
brought from the
Usually, chía seeds were eaten as food, mixed with other
crops. They were also used as beverage mixed with water, ground as flour, in medicines
and pressed because the oil was used as a base for face and body paints.
Modern science has concluded that pre-Columbian diets
were superior to the diets consumed today in the same region.
Chía seed is a natural source of omega-3 fatty acids,
antioxidants and dietetic fiber.
Scientific research and technological development offer
an excellent opportunity to bring to the world a “new-old crop”, chía, with a
significant nutritional potential for the food industry.
Objective
Study the protein quality of a non traditional food
source, using different biological methods.
Materials and methods
Proteic quality evaluation was made with Net Proteic Relation
(NPR),
Relative Net Proteic Relation (RNPR)
and Net Proteic Utilization (UPN) in Wistar rats well nourished
when weaned, following standardized methodology.
NRP was determined by feeding the rats an experimental
diet based on chía prepared of 10% of protein for 10 days. It was also used a
reference diet of casein on 10 % supplemented with methionine to evaluate
maximum growth and another free of protein to evaluate protein total efficiency
to animal maintenance.
NPR value for each animal was calculated according to the
following formula:
NPR
= weight earning of the “test” animal + average weight loss of the lote LP
protein eaten by test animal
RNPR value of the diets is obtained as:
RNPR = “test” protein
NPR x 100
Caseine
+ methinine NPR
The UPN method was used to determine the modification in
the nitrogen content of the rats skeleton. The rats were fed an experimental
diet of 10 % of protein for 10 days.
This nitrogen content was evaluated indirectly after
determining body water content using a formula to relate the quotient between
both the body Nitrogen and the body water with animal age (Miller and Blender).
Once body Nitrogen was known, the UPN was calculated as:
UPN
= B- (Bk-Ik)/ I
with B and Bk corresponding
to body Nitrogen of the experimental lot and protein free lot respectively,
while I and Ik corresponded to the nitrogen intake of both the experimental lot
and protein free lot.
The protein concentration was determined by the Kjeldahl
method which obtains the total of all the sources of reduced Nitrogen, using
S04H2 conc, (proteins, free amino acids, urea, ammoniacal compounds, etc.) The
proteic concentration of the chía seeds was 19.96%.
Digestibility (D) was determined by triplicate and the
Biological Value (VB) as UPN/D x 100 (Pellet & Young 1980), (Morrison et
al., 1963), (Millar & Bender, 1955).
The obtained information was analyzed with the anova
test.
The Chemical Score of the protein was also calculated
using as reference protein the corresponding with the preschool.
Results
Biological methods
|
SOURCE |
RNPR |
UPN |
D% |
VB |
|
CHÍA |
75.11 ± 3.41 # |
56.90 ± 5.89 |
74.81 |
76.06 ± 7.88 # |
|
0 ± DE; # Significant difference
at p<0.001 level respect to the UPN group |
||||
Chemical Score calculation
|
|
HISTIDINE |
LEUCINE |
ISOLEUCINE |
LYSINE |
SULFURUTED |
THREONINE |
AROMATICS |
TRYPTOPHANE |
VALINE |
|
PROTEIN OF REFERENCE # (mg/g
of protein) |
19 |
66 |
28 |
58 |
25 |
34 |
63 |
11 |
35 |
|
CHÍA (mg/g de proteína) |
25.7 |
58.9 |
32.1 |
44.4 |
18.2 |
34.3 |
74.8 |
12.9 |
51 |
|
% PRESENCIA |
100 |
89.2 |
100 |
76.5 |
73.2 |
100 |
100 |
100 |
100 |
|
# Protein of reference for
1985 preschool; CS = 73.20 Deficient Sulfureted
Amino acid |
|||||||||
Discussion
RNPR and VB values were comparable
among and statistically different to the UPN (p<0.001) value. The
mathematical calculation of Chemical Score (CS=73.20) was comparable to the
RNPR and VB values.
Conclusion
The results indicate that CHIA is a
good quality protein source and suggests that it is important to consider the
incorporation of this non-traditional food source into the diet as complement
to other foods.
References
Bushway,
A.A., P.R. Belya, and R.J. Bushway.
1981. Chía seed as a source of oil, polysaccharide, and protein. J. Food Sci.
46:1349-1356.
Pellet
P.L. and V. Young Eds. 1980. “Evaluation of protein quality in experimental
animals”. En: Nutritional Evaluation of protein foods. The United
Pellet
P.L. and V. Young Eds. 1980. “Evaluation and choice of assay procedures”. En:
Nutritional Evaluation of protein foods. The United
Pellet
P.L. and V. Young Eds. 1980. “Some rat and human bioassay procedures”. En:
Nutritional Evaluation of protein foods. The United
Morrison
A.B., Z.I. Sabry, N.T. Gridgeman and J.A. Campbell. 1963. “Evaluation of
protein in foods. VIII. Influence of Quality and Quantity of Dietary Protein on
Net Protein Utilization”.
Miller
D.S. and A.E. Bender. 1955. “The determination of the net utilization of
proteins by shortened method”. Brit. J.Nutr. 9:382-388.
Weber,
C.W., H.S. Gentry, E.A. Kohlhepp, and P.R. McCrohan. 1991. The nutritional and
chemical evaluation of chia seeds. Ecology of Food and Nutrition,
26:119-125.