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Potential of Canavalia gladiata as a food ingredient: Nutritional and Functional aspects

Författare:
  • Sagarika Ekanayake
Publiceringsår: 2005
Språk: Engelska
Sidor:
Dokumenttyp: Doktorsavhandling
Förlag: Applied Nutrition and Food Chemistry, Lund University

Sammanfattning

The tender fruits of the leguminous plant Canavalia gladiata (Sinhala awara, sword beans) are consumed in Sri Lanka as a green vegetable. The mature seeds are also utilized in a variety of ways but not very frequently, in spite of desirable agronomical properties, for cultivation in the country. This study was performed with the intention of developing methods for increasing utilization of the sword bean for human consumption.



Flour of the whole mature seed and cotyledon contained higher crude protein than other legumes, with starch as the major nutrient. The total dietary fibre of whole seed was thrice the amount in cotyledon. Sucrose represents the highest fraction of low molecular weight carbohydrates in both types of flour. In comparison with the recommended dietary intake for adults the seeds contained K, Mg and P in considerable quantities.



The essential amino acid profile compared well with the FAO/WHO recommended pattern except for the sulphur-containing amino acids. Heat processing increased the true digestibility of the cotyledon grits and flour when compared to raw and soaked grits. Soaking decreased the digestibility of cooked or uncooked seeds. The biological value of the processed samples was lower than that of raw sample except for soaked and cooked grits. The NPU values of (i) cooked and (ii) soaked and cooked grits were higher than those of other heat-processed samples, and also of raw seed flour, while not different from each other. The correlation between the in vivo and in vitro digestibility values was poor suggesting that the in vitro method was not a good predictor of changes in in vivo digestibility due to processing.



Starch granules were elliptical in shape. A well-defined cross, typical of ungelatinized starch, was seen under polarized light in raw and dry-heat treated samples. Wet-processed samples had lower water solubility, higher water absorption and lower gelatinization enthalpies than the raw bean flour, whereas the dry-heat-treated samples showed higher water solubility and higher gelatinization enthalpies. The starch molecular size distribution pattern indicated a higher amount of high molecular weight carbohydrates in dry heat-treated samples and a large fraction of intermediate molecular weight carbohydrates in the wet-processed samples. The low molecular weight carbohydrate content was low in wet-processed samples.



The content of canavanine, a potentially toxic amino acid, was quantified successfully using HPLC. The highest decrease in canavanine content was seen when soaked overnight and boiled in excess water followed by decanting. Boiling and decanting excess water was the other effective processing method for reducing canavanine. Roasting and autoclaving were less effective in decreasing the canavanine content.



The chemical composition and the protein nutritional quality evaluation indicate sword beans to be a good complement to be introduced as a new food to a cereal-based diet. The decrease in canavanine content was highest in wet-processed samples. The decorticated seed grits once soaked and cooked or cooked would have the best nutritional quality and the lowest anti-nutritional factors and thus could be used as a thickener in food preparations or be incorporated into dough.

Disputation

2005-06-01
10:15
Lecture Hall E, Centre of Chemistry and Chemical Engineering, Getingevägen 60, Lund Institute of Technology
  • Ulf Svanberg (Professor)

Nyckelord

  • Nutrition and Dietetics
  • Canavalia gladiata
  • Sword beans
  • Nutritional quality
  • Functional properties
  • Näringslära
  • Nutrition

Övriga

Published
  • Nils-Georg Asp
  • ISBN: 91-7422-085-3

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