Amaranth (Amaranthus hypochondriacus) as an alternative crop for sustainable food production: Phenolic acids and flavonoids with potential impact on its nutraceutical quality

Abstract

The demand for food is increasing, not only to meet food security for growing populations, but also to provide more nutritious food, rich in good quality proteins and nutraceutical compounds. The amaranth (Amaranthus hypochondriacus) plant, in addition to its high nutritive and nutraceutical characteristics, has excellent agronomic features. The objective of the present study was to analyze some physical and proximal-nutritional properties of amaranth seeds obtained from different varieties grown in arid zones and characterize their phenolic acids and flavonoids. Two commercial (Tulyehualco and Nutrisol) and two new (DGETA and Gabriela) varieties of A. hypochondriacus were grown at the Mexican Highlands zone. Tulyehualco and DGETA varieties had higher seed yield of 1475 and 1422 kg ha⁻¹, respectively, comparable to corn and soybean production in agricultural areas. Gabriela had the highest protein content of 17.3%, but all varieties had an adequate balance of essential amino acids. Polyphenols as rutin (4.0–10.2 μg g⁻¹ flour) and nicotiflorin (7.2–4.8 μg g⁻¹ flour) were detected. Amaranth can be cultivated in arid zones where commercial crops cannot be grown; the seeds besides their well known nutritive characteristics could be a source of phenolic compounds of high antioxidant properties.

Introduction

The challenge for agricultural practices to increase food production to obtain food security still persists after 40 years of the Green Revolution (Hobbs, 2007). The first Millennium Development Goal is to reduce hunger and poverty by 2015 (Dixon et al., 2006). The demand for food is increasing, not only because of the growing population, but also to provide more nutritious food with high protein quality and nutraceutical compounds.

Water resources, especially surface and ground water will be more limited as domestic and industrial needs increase just as it is limited in semi-desert zones with low precipitation, and so future crops must be more suited to low water use. Amaranth (Amaranthus hypochondriacus) is a crop naturally resistant to water deficit and is a good source of nutritious seeds; the seeds have high amounts of protein containing essential amino acid such as lysine and methionine; also significant levels of squalene, an important precursor for all steroids (He et al., 2002), were reported in amaranth oil. Since the beginning of the 1980s, amaranth has been rediscovered and several reports have tried to promote it as a basic crop (Kauffman, 1992). In addition to nutritional characteristics, amaranth plants have agronomic features identifying it as an alternative crop where cereals and vegetables cannot be grown (dry soils, high altitudes and high temperatures) (Omami et al., 2006). In general, the selection of promising genotype in a breeding program is based on various criteria, with the most important being final crop yield and seed quality (Kozak et al., 2008).

The aim of the research presented in this paper was to analyze four amaranth varieties and select the most promising for growing in arid zones like the Mexican Highlands or arid zones of Southern Europe. Variety selection was carried out on the basis of seed yield and proximal quality. The presence of a range of phytochemical compounds that contribute to nutraceutical properties of the seeds was determined as well.