Cholesterol-lowering effect of extruded amaranth (Amaranthus caudatus L.) in hypercholesterolemic rabbits
Introduction
Interest in amaranth has recently been aroused due to its high nutritive values. Its protein presents a high concentration of essential amino acids, especially lysine which is a limiting amino acid in other crops (Teutonico & Knorr, 1985). Amaranth has also a higher concentration of soluble fibre than many cereals, such as wheat, corn or oats.
Extrusion cooking has been recently optimized for the production of an amaranth snack (Chávez-Jáuregui, Silva, & Arêas, 2000) and this product was of a high acceptability compared with commercial brands. Nutritional evaluation of the snacks made in this laboratory showed that they exhibit a high nutritional value, measured by its protein biological value, bioavailability of minerals, especially calcium, and high content of fibre (Ferreira, 1999).
Some studies conducted with amaranth suggest that it offers cholesterol-lowering effects. In an experiment with rats, Grajeta (1997) observed a reduction of 37% and 33% of total cholesterol when the animals were fed diets with whole amaranth and defatted amaranth, respectively.
In the present study amaranth was used in its extruded form due to the fact that extrusion resulted in a highly nutritious product (Table 1) and is one of the best methods for obtaining the maximum nutritive value of several grains, including amaranth (Mendoza & Bressani, 1987). Our aim was to evaluate the cholesterol-lowering effect of extruded amaranth and amaranth oil in hypercholesterolemic rabbits.
Section snippets
Amaranth
The amaranth species employed was Amaranthus caudatus L., variety Oscar Blanco, provided by CICA—Centro de Investigación en Cultivos Andinos (Perú). The seeds were milled in a knife mill (Mod. Termomatic, Marconi, Brazil), and defatted with n-hexane in Soxhlet apparatus to a final lipid concentration lower than 1% for further extrusion. The defatted flour had its proximate composition determined by conventional methods for moisture, protein, ash, and lipids, as described by AOAC (1990).
Extrusion
The
Results
Growth rates of rabbits were similar in all groups. The body weight gain of all groups is illustrated in Fig. 1.
After a 21 day feeding period, the total cholesterol levels were lower in the group that was fed EAD than in the other two groups. The same was observed for the LDL-cholesterol levels. These results are presented in Fig. 2. However, no differences between the HDL-cholesterol levels were observed among groups. As for the VLDL-cholesterol levels and triglycerides, both the EAD and the
Discussion
After 21 days, the diet with extruded amaranth reduced total cholesterol levels in rabbits by 50% whereas the control diet and the diet with amaranth oil reduced total cholesterol by 14% and 18%, respectively. Qureshi, Lehmann, and Peterson (1996) verified a reduction of 10–30% in total cholesterol of chickens when these were fed amaranth. Grajeta (1999) observed a reduction of 14% in total cholesterol of rats fed a diet with 30% of amaranth. These results indicate that extruded amaranth is
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