Effect of Processing on Nutrient Composition, Antinutritional Factors, Protein Digestibility and Bioaccessibility of Selected Minerals of Lablab Purpureus (L.) Sweet Grown in Ethiopia
No Thumbnail Available
Date
2016-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Lablab purpureus is one of the under utilized and less studied legumes of arid and semi-arid lands. It is a
good source of protein and other nutrients. This study was conducted to determine the effects of some
commonly applied traditional processing methods on antinutritional factors, in vitro protein digestibility
and mineval bioaccessibility of Lablab purpureus seeds. Proximate composition was determined according
to AOAC method. Selected minerals (Co, Fe, Zn and P) were determined using Atomic Absorption
Spectrophotometer (AAS). In vitro protein digestibility and bioaccessibility of minerals were conducted
under simulated gastro-intestinal conditions using intestinal enzymes (pepsin and pancreatin). To
investigate the effects of traditional processing methods; soaking (for 6, 12 and 18h), dehulling, boiling
and germination (for 24, 36 and 48 hrs) were applied on the two varieties of lablab (black and red) seeds.
The black variety of lablab raw seeds had a mean of 7.1 % Moisture, 3. 4 % ash, 2.5 % fat, and 25.03 %
crude protein. There is no significance (p>0.05) difference among the two varieties in terms of the above
nutritional compositions. The crude fiber content was 13.7 % in black and 10.6 % in red varieties. The
total CHO content ofrenv seeds in black and red varieties was 55.37 % and 58. 77 %, respectively. The total
energy of 344.1 Kcal in black and 357.32 Kcal in red varieties was recorded. Among the traditional
processing methods, dehulled-boiled samples showed higher increment in protein content (22 %). The total
CHO and energy contents were higher in delwlled samples (65.75 and 389. 01 Kcal, respectively) over their
respective controls (55.37 and 344.1 Kcal).The mean of In vitro protein digestibility in raw samples was
70.91% in black and 71.9% in red varieties. All traditional processing methods applied in the current study
significantly (p<0.05) increased in vitro protein digestibility. Germination showed the higher increment
(6.8- 28.6 %). The mineral content of the black variety was 105.59 of Co, 3.72 of Fe, 3.89 ofZn and 432. 75
mgll00g of P in raw sample. There is no significance (p>0.05) difference among varieties in Fe and Zn
content. The red variety had Ca content of 102.06 IIIgII00g and P content of 461.15 mgl IOOg. Delwlling
and dehull- boiling samples significantly (p<0.05) decreased calcium content (50.49 and 56.03 II/g1I00g,
respectively in black). All traditional processing methods significantly (p<0.05) decreased Fe and Zn
contents. Dehulling and germination increased phosphorus cpntent up to 21 and 12% respectively.
Bioaccessibility of minerals in renv seeds of black variety was 45.39 % for Ca, 34.04 % for Fe and 54.27 %
for Zn. There is no significance (p>0.05) difference among varieties in bioaccessibility. All traditional
processing methods significantly (p<0.05) increased bioaccessibility of Ca, Fe and Zn. Dehulling sholVed
the highest increment in Ca bioaccessibility (up to 84 %). The phytic acid content of raw seeds in black and
red varieties was 320.83 and 338.33 I11g1100g, respectively. The tannin content was 1.32 in black and
1.48mgll00g in red varieties. The total alkaloid content was found to be 1.3% in black and 1.5% in red
varieties. All traditional processing methods significantly (p<O. 05) reduced antinutritional factors (2.16-20
% in phytic ocid, 38 %-un detected level in tannin and 13.33-54 % in total alkaloids). Boiling of unsoaked,
soaked and delwlled samples showed the highest reduction in phytic acid content (9-20%). The tannin
content was reduced to the extent of undetected level due to delwlling and dehulled-boiling. Boiling of
soaked and dehulled samples showed the highest reduction in total alkaloids (47-54%). Therefore, soaking,
delwlling, boiling and germinating hold a good potential for improving the nutritional value of lablab
seeds by reducing antinutritional factors such as phytic acid and tannins thereby enhancing its utilization.
Del1ll1ling and germination of seeds are suggested to be promoted for improved protein digestibility and
mineral bioaccessibility.
Key words: Lablab pUlpureus, traditional processlllg methods, nutrient composition,
antinutrional factors, protein digestibility, bioaccessibi li ty
Description
Keywords
Lablab purpureus, traditional processlllg methods, nutrient composition, antinutrional factors, protein digestibility, bioaccessibi li ty