New Zealand Journal of Crop and Horticultural Science abstracts
Texture and the cell wall polysaccharides of buttercup squash `Delica'
(Cucurbita maxima)
R. M. SUNIL RATNAYAKE1*
PAUL L. HURST2
LAURENCE D. MELTON1*
1Department of Food Science
University of Otago
Dunedin, New Zealand
2New Zealand Institute for Crop & Food
Research Ltd
Private Bag 11 600
Palmerston North, New Zealand
*Present address:
Food Science Postgraduate
Programme
, University of Auckland, P. O. Box 92 019,
Auckland, New Zealand.
email: l.melton@auckland.ac.nz
Abstract Texture of buttercup squash `Delica' (Cucurbita
maxima D.) during storage, and the effect of cooking on the texture, have
been investigated using a penetrometer and an Instron Universal Testing
Machine. Firmness (measured by penetrometer) of uncooked and cooked squash
increased during the first 2 months of storage (P < 0.001). The
Texture Profile parameters of hardness, fracturability, and gumminess tended to
decrease during storage, whereas cohesiveness, chewiness, and springiness
remained unchanged. A procedure for isolating cell walls in tissues containing
high levels of starch has been developed. An initial extraction of the tissues
with HEPES buffer-containing mercaptoethanol was followed by grinding the
residue in a ball mill and a second HEPES buffer extraction. Any remaining
starch was gelatinised and then removed by [[alpha]]-amylase treatment.
Sequential fractionation of the cell wall polysaccharides was done. The cell
walls of buttercup squash at harvest were composed of 34% pectin, 26%
hemicelluloses, and 39% cellulose by dry weight.
Keywords buttercup squash; Cucurbita maxima; cell
wall; cell wall polysaccharides; texture; fruit firmness; postharvest
H98038
Received 10 August 1998; accepted 17 December 1998
PDF file of entire paper: medium quality (904K); (scanned from paper original: notes about this process)
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