New Zealand Journal of Crop and Horticultural Science abstracts
Heat treatments increase sweetness and flesh colour of buttercup squash
BRUCE L. BYCROFT
VIRGINIA K. CORRIGAN
DONALD E. IRVING*
Food Industry Science Centre
New Zealand Institute for Crop & Food
Research Ltd
Private Bag 11 600
Palmerston North, New Zealand
*Present address: School of Land and Food, University of
Queensland, Gatton, Qld 4345, Australia. email:
d.irving@mailbox.uq.edu.au
Abstract Buttercup squash (Cucurbita maxima Duchesne
`Delica') fruit were heated to 30 or 33deg.C in air for up to 7 days, then
stored at 12deg.C for up to 7 weeks. Control fruit remained at 12deg.C
throughout. Sucrose and starch concentrations were measured in edible portions
of raw squash, and the perceived sweetness of the cooked fruit was evaluated
using a trained sensory panel. Enzymes of starch degradation and sucrose
metabolism were also extracted and assayed. Sucrose content, on a dry weight
basis, was as much as 250% higher in heat-treated fruit than in fruit kept at
12deg.C. Sucrose accumulated with increasing length of treatment and continued
to accumulate during subsequent storage. There was a strong correlation between
sucrose content and panel sweetness rating. Heat treatments also increased the
red/yellow colour of the flesh. Both increased sucrose concentration and redder
flesh colour appear to increase the acceptability of buttercup squash to
consumers. In a subsequent experiment, we found that extractable activities of
[[alpha]]-amylase, [[beta]]-amylase, starch phosphorylase, D-enzyme, sucrose
synthase, sucrose phosphate synthase, maltase, and maltose phosphorylase did
not differ in samples taken from heat-treated or non-heat-treated squash.
Keywords buttercup squash; Cucurbita maxima; flesh
colour; starch degradation; sucrose; taste
H98055
Received 19 November 1998; accepted 6 August 1999
PDF file of entire paper: medium quality (587K); (scanned from paper original: notes about this process)
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