MSc

A study on "Value addition and evaluation of nutritional quality in taro
(Colocasia esculenta (L.) Schott)" was carried out in the Department of
Processing technology, College of Agriculture, Vellayani,
Thiruvananthapuram during the period 1999- 2001. The objectives of the
study were to evaluate four cultivars of colocasia for nutritional quality, to
examine the potentiality of developing value added products using colocasia
and to assess the storage and shelf life of the colocasia products.
The nutritional quality of four cultivars ie., Pathanamthitta local,
Vellayani local, Thamarakannan and Sree Rashmi were evaluated. Corms of
Pathanamthitta local had the highest starch and calcium oxalate content.
Vellayani local exhibited the highest protein and vitamin C content while
Thamarakannan had the highest total sugar content. The crude fibre contents
of all the four cultivars were on par. Sree Rashmi recorded the maximum
organoleptic quality. In case of leaves protein content and organoleptic
quality were high in Sree Rashmi while total sugars was maximum in



Pathanamthitta local.


Vitamin C content was high in leaves of



Thamarakannan while Vellayani local recorded the highest calcium oxalate
content.

Value addition was done through preparation of chips and traditional
snack items viz., Murukku, Wafers and Papads.
Chips were prepared by two techniques ie. by freshly frying and by
parboiling and frying. Oil uptake was the highest in chips of Vellayani local
and it was seen that oil uptake increased with increasing thickness. Parboiling
helped to reduce the oil uptake significantly almost by half. Freshly fried
chips had a higher moisture content than parboiled fried chips. Chips of Sree
Rashmi recorded the greatest score for organoleptic quality presumably due to
its low acridity. Thinner chips score higher for organoleptic quality than
thicker chips while parboiled chips scored higher than freshly fried chips.
Evaluation of flour prepared from colocasia revealed that with
increasing temperatures and drying periods moisture content decreased. The
flour dried at 7SoCfor 18 hours was judged the best because it had low
moisture content and good colour.
The evaluation ~f secondary products prepared viz., Murukku, Wafers
and Papads revealed that products made from flour of Sree Rashmi and
Thamarakannan had higher organoleptic quality.
Storage studies of the primary and secondary products evaluated the
changes in starch, total sugars, moisture content and organoleptic quality. In
case of chips while starch content did not change significantly, the total sugar
and moisture content increased slightly on storage. The organoleptic quality

declined on prolonged storage. Glass and PET bottles gave better storage
results than LDPE bags. The moisture and total sugar content in stored flour
increased more rapidly in LDPE bags than in glass and PET jars while
changes in starch content were not significant. Murukku and Wafers stored in
LDPE bags showed a decrease in starch content. The total sugars and moisture
content of murukku increased over the period of storage in all containers,
though those in LDPE bags showed the maximum increase. The murukku and
wafers stored in glass and PET jars had higher organoleptic quality than those
stored in LDPE bags. Pappads had a shelf life of only 30 days after which
they were subject to mould attack.