Heating effect on nutritional value from two morphotypes (palmate and semi-palmate leaves) of Hibiscus sabdariffa

Abstract

Leafy vegetables play an important role by contributing to most nutrients intake for health and human wellbeing. Different varieties or morphotypes of Hibiscus sabdariffa leaves are cultivated for medicine and food. H. Sabdariffa leaves are cooked before consumption. However, studies on the variation of nutritional value in different varieties or morphotypes and the effect of heating are relatively limited. This research aimed to assess the variation in different morphotypes (palmate and semi-palmate leaves) and the effect of heating on nutritional value of H. sabdariffa leaves. To do that, fresh leaves were collected, air dried and divided into raw and cooked. The raw and cooked samples were analyzed to determine the proximate and phytochemical properties (pH, ash, sugars, polyphenols, tannins and proteins) and minerals (Nitrogen). There was variability in nutritional content among the morphotypes. Sugars, proteins and Nitrogen were present at significantly different levels among the morphotypes. The most abundant proteins (3.26 ± 0.08%) and Nitrogen (0.52 ± 0.01%) was found in semipalmate leaves and sugars (4751.64 ± 992.60 mg/100g) in palmate leaves. The heating effect on these compounds was not significant. However, the heating decreased ash, sugars, polyphenols and tannins from 2 to 46% and increased pH, N and proteins from 2 to 10%. H. sabdariffa leaves were an important source of nutritional value that could contribute to improve health and well-being.