This work characterized the most cultivated and consumed yam (
Dioscorea ) cultivars within the Ghanaian yam germplasm based on their
biochemical and cell wall constituents to assess their potential
alternative food and industrial processing applications. Samples were
analyzed for their biochemical composition - starch, amylose,
amylopectin, total sugars, reducing sugars and non-reducing sugars
along the head, middle and tail regions of each tuber using standard
analytical methods. Cell wall constituents - acid detergent fibre,
neutral detergent fibre, acid detergent lignin, cellulose and
hemicellulose of each tuber were also determined using standard
analytical methods. The results showed no significant differences at
p<0.05 in biochemical compositions along the length of the studied
cultivars. D. cayenensis (Pure-yellow), D. rotundata (Pona) and D.
alata (Matches) were found to have high starch contents
(63.16-65.69%, 63.54-65.30% and 63.24-65.17% respectively). Amylose
content was observed to vary along the length of the tubers for the
varieties studied. D. alata (Matches) was observed to contain the
highest amylose content of 19.66-20.64%. No identifiable trend was
however, observed for the amylopectin content along the length between
the varieties investigated. D. bulbifera recorded the lowest
amylopectin content of 41.29%, 43.59% and 44.63% while D. esculenta
had the highest with 49.84%, 50.24% and 50.13% along the tail, middle
and head sections respectively. Total sugar content varied
significantly (p<0.05) along the lengths of all the varieties
investigated. It was higher at the tail portions for all the varieties
studied than the head regions; the middle portions recorded the least.
D. bulbifera recorded highest total sugar contents (4.74-4.84%) and
total sucrose (3.58-3.64%). There were significant differences
(p<0.05) in the cell wall constituents of the yam varieties.
Cellulose was found to be the most common cell wall component with D.
rotundata having the highest level of 3.36% whilst D. dumetorum had
the least (1.56%). Hemicellulose content ranged between 0.42 g/100g in
D. alata to 4.58 g/100g in D. esculenta whiles lignin content ranged
from 1.56 g/100g in D. dumetorum to 2.87 g/100g for D. praehensalis
There were significant differences (p<0.05) in the neutral detergent
fibre found in Dioscorea esculenta and the other yam species. It ranged
from 1.18 g/100g in D. alata to 5.46 g/100g in D. esculenta. Less than
1% of acid detergent fibre was identified in the yam varieties,
suggesting varied levels of biochemical composition and cell wall
constituents in the different yam varieties. Key words: Biochemical
quality, cell wall composition, yam
