Characterisation of the arabinose-rich carbohydrate composition of immature and mature marama beans (Tylosema esculentum)

TY - JOUR

T1 - Characterisation of the arabinose-rich carbohydrate composition of immature and mature marama beans (Tylosema esculentum)

AU - Mosele, Minah Mmoni

AU - Hansen, Åse Solvej

AU - Engelsen, Søren Balling

AU - Diaz, Jerome Villarama

AU - Sørensen, Iben

AU - Ulvskov, Peter

AU - Willats, William George Tycho

AU - Blennow, Per Gunnar Andreas

AU - Harholt, Jesper

PY - 2011/8

Y1 - 2011/8

N2 - Marama bean (Tylosema esculentum) is an important component of the diet around the Kalahari Desert in Southern Africa where this drought resistant plant can grow. The marama bean contains roughly 1/3 proteins, 1/3 lipids and 1/3 carbohydrates, but despite its potential as dietary supplement little is known about the carbohydrate fraction. In this study the carbohydrate fraction of "immature" and "mature" marama seeds are characterised. The study shows that the marama bean contains negligible amounts of starch and soluble sugars, both far less than 1%. The cell wall is characterised by a high arabinose content and a high resistance to extraction as even a 6 M NaOH extraction was insufficient to extract considerable amounts of the arabinose. The arabinose fraction was characterised by arabinan-like linkages and recognised by the arabinan antibody LM6 and LM13 indicating that it is pectic arabinan. Two pools of pectin could be detected; a regular CDTA (1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid) or enzymatically extractable pectin fraction and a recalcitrant pectin fraction containing the majority of the arabinans, of which about 40% was unextractable using 6 M NaOH. Additionally, a high content of mannose was observed, possibly from mannosylated storage proteins.

AB - Marama bean (Tylosema esculentum) is an important component of the diet around the Kalahari Desert in Southern Africa where this drought resistant plant can grow. The marama bean contains roughly 1/3 proteins, 1/3 lipids and 1/3 carbohydrates, but despite its potential as dietary supplement little is known about the carbohydrate fraction. In this study the carbohydrate fraction of "immature" and "mature" marama seeds are characterised. The study shows that the marama bean contains negligible amounts of starch and soluble sugars, both far less than 1%. The cell wall is characterised by a high arabinose content and a high resistance to extraction as even a 6 M NaOH extraction was insufficient to extract considerable amounts of the arabinose. The arabinose fraction was characterised by arabinan-like linkages and recognised by the arabinan antibody LM6 and LM13 indicating that it is pectic arabinan. Two pools of pectin could be detected; a regular CDTA (1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid) or enzymatically extractable pectin fraction and a recalcitrant pectin fraction containing the majority of the arabinans, of which about 40% was unextractable using 6 M NaOH. Additionally, a high content of mannose was observed, possibly from mannosylated storage proteins.

U2 - 10.1016/j.phytochem.2011.03.027

DO - 10.1016/j.phytochem.2011.03.027

M3 - Journal article

C2 - 21543095

SN - 0031-9422

VL - 72

SP - 1466

EP - 1472

JO - Phytochemistry

JF - Phytochemistry

IS - 11-12

ER -