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Large amounts (at least 55%) of sugar (sucrose) are
required as the cosolute for gelation of high methoxyl
pectin (HMP). The effective replacement of sucrose by
other low-calorie replacers would be significantly favorable
to human health. However, besides gelation, sucrose also
provides sweetness, shelf life, and improves a number of
properties such as bulking and lowering water activity in
the gelled product. Therefore, several sugar replacers with
similar functional properties were selected to replace sucrose
in this study. The samples were formed by thermal gelation and
the substitute effects of individual sugar replacers were
evaluated by physical measurements including gel strength,
Hunter L, a, b values, and Instron texture profile analysis
(TPA). The results indicated that among the sugar bulking
agents tested, sorbitol and xylitol possessed more effects
on HMP gelation and significantly lowered the water
activity. In addition, there were higher lightness
and no browning reaction in the gels formed by
sorbitol and xylitol. Response surface methodology (RSM)
and a three-variable and three-level design were then used to
determine the optimum processing conditions of the HMP gelled
products based on the responses of physical measurements and
sensory evaluation. The optimum processing condition was found
to be citric acid 0.0025 M, sorbitol 28.6 %, and xylitol 32.5 %.
After storage at 4℃for three months, it was also found that
there was no significant change in water activity and appearance
except slight increases of hardness and springiness values, and
the products became more acceptable to the mass panel.
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