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A. Sultana and U. Ghosh
1 Introduction
Amaranth leaves are nutritious leafy vegetables. They grow in the lowland tropics of
Asia and Africa. They are of two types, namely, green amaranth and red amaranth.
Red amaranth looks wonderful with purple or fully red in color. It is a rich source of
calcium, iron, vitamin C, and protein (Khandaker et al. 2008). Because of these it acts
as a natural antioxidant to fight against infectious diseases like heart disease, cancer,
serious eye disease, and muscular degeneration (Dasgupta and De 2007; Kumar et al.
2017). Bioactive compounds are present in red amaranth leaves. Bioflavonoid was
the most important topic for recent research mainly for their beneficial effects on
human health and applications as potential sources of natural food dyes. Natural
pigments are used as an eco-friendly alternative to synthetic dyes and also in textile
industry. In recent years, color plays an important role in the consumer acceptability
of food. Colorants are being used in food industry since centuries to enhance or at least
restore original appearance of foods and ensure uniformity as an indicator of food
quality. Color is the first characteristic perceived by the senses. Synthetic colorants
have always been a question of controversy regarding their safety. Consumers prefer
natural colorants than the synthetic ones, as they are increasingly concerned with
the safety of synthetic colorants. Therefore, interest in natural colorants has significantly increased because of both legislative action and consumer awareness (Yousuf
et al. 2016). The present study deals with aqueous extraction of color from red
amaranth leaves and identification of the potent pigment by high-performance liquid
chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS).
2 Materials
Red amaranth leaves were purchased from market. HPLC grade acetonitrile,
methanol, acetone, acetic acid, 36% pure hydrochloric acid, Millipore, and ferric
chloride (FeCl 3 ) were purchased from Merck. 2,2-azinobis (3 ethylobenzothiazoline6 sulphonate) (ABTS), triphenyltriazine (TPTZ), 2,4,6-tris(2-pyridyl)–1,3,5triazine, 1,1-diphenyl-2-picrylhydrazyl (DPPH), 6-hydroxy-2,5,7,8-tetramethyl-2carboxylic acid (trolox), sodium peroxy disulfate, Folin–Ciocalteu reagent, and gallic
acid were purchased from Sigma-Aldrich. Laboratory-grade de-ionized water was
used. All reagents were of analytical grade.
A. Sultana and U. Ghosh
1 Introduction
Amaranth leaves are nutritious leafy vegetables. They grow in the lowland tropics of
Asia and Africa. They are of two types, namely, green amaranth and red amaranth.
Red amaranth looks wonderful with purple or fully red in color. It is a rich source of
calcium, iron, vitamin C, and protein (Khandaker et al. 2008). Because of these it acts
as a natural antioxidant to fight against infectious diseases like heart disease, cancer,
serious eye disease, and muscular degeneration (Dasgupta and De 2007; Kumar et al.
2017). Bioactive compounds are present in red amaranth leaves. Bioflavonoid was
the most important topic for recent research mainly for their beneficial effects on
human health and applications as potential sources of natural food dyes. Natural
pigments are used as an eco-friendly alternative to synthetic dyes and also in textile
industry. In recent years, color plays an important role in the consumer acceptability
of food. Colorants are being used in food industry since centuries to enhance or at least
restore original appearance of foods and ensure uniformity as an indicator of food
quality. Color is the first characteristic perceived by the senses. Synthetic colorants
have always been a question of controversy regarding their safety. Consumers prefer
natural colorants than the synthetic ones, as they are increasingly concerned with
the safety of synthetic colorants. Therefore, interest in natural colorants has significantly increased because of both legislative action and consumer awareness (Yousuf
et al. 2016). The present study deals with aqueous extraction of color from red
amaranth leaves and identification of the potent pigment by high-performance liquid
chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS).
2 Materials
Red amaranth leaves were purchased from market. HPLC grade acetonitrile,
methanol, acetone, acetic acid, 36% pure hydrochloric acid, Millipore, and ferric
chloride (FeCl 3 ) were purchased from Merck. 2,2-azinobis (3 ethylobenzothiazoline6 sulphonate) (ABTS), triphenyltriazine (TPTZ), 2,4,6-tris(2-pyridyl)–1,3,5triazine, 1,1-diphenyl-2-picrylhydrazyl (DPPH), 6-hydroxy-2,5,7,8-tetramethyl-2carboxylic acid (trolox), sodium peroxy disulfate, Folin–Ciocalteu reagent, and gallic
acid were purchased from Sigma-Aldrich. Laboratory-grade de-ionized water was
used. All reagents were of analytical grade.