30 temperature, the material took more time to be dried, therefore, contractile stresses occured in
the cellular become longer which may intensify the changes in volume. Nassiri and Heydari 2012 also stated that more shrinkage has been occured at lower temperature.
4.2.6 Texture of Dried and Rehydrated Bamboo Shoots
Texture is another important parameter which plays major role on quality attribute of both dried and rehydrated products. It gives information on the storability and resistance to
damage of the products during handling, transportation, and futher processing. Texture analyzer allows to measure mechanical properties objectively and to obtain profile which can
be used to estimate the textural attributes, i.e. hardness, adhessiveness, chewiness related to the elastic nature and cohessiveness, springeness related to the plastic nature Vega-Gàlvez
et al. 2008. Firmness hardness is one of mechanical properties defined as a force required to
deform food in mastication that is exerted by compressing the food between teeth or between tongue and mouth. Results of firmness of dried bamboo shoots were shown in Figure 17. The
results ranged between 107.653 N and 191.342 N. Drying temperature highly significant affected p0.01 the firmness of dried bamboo shoots, while blanching had no significant
effect p0.05 on the firmness. Firmness increased with increase in drying temperature. The highest firmness was found in sample dried at 70
⁰C, while the firmness samples dried at 50 ⁰C and 60 ⁰C had no significant difference p0.05. It may be explained that at higher
temperature, the surface structure of sample became more compact rigid, resulting in higher force required to deform the sample. Yet, it was observed that there were some data which
had overlapped standard deviation, as shown in Figure 17. Such result obtained because there was wrong in sampling of texture analysis. Before doing analysis, the sample was divided
into three portions, i.e. top, middle, and bottom parts. Each portion was analyzed and the values of the portions were directly averaged and resulting in much higher standard
deviations due to quite different firmness among the portions. Generally, the top part is softer than the others. When the shoot pierces the ground, critical bio-chemical processes started.
These lead to rapid growth as well as concurrent hardening. The amount of fibre increases from bottom to top of shoots in vertical direction NMBA
a
2009. Moreover, there was no possibility of significant grouping of data due to unidentified data of each sample portion,
whether it was belong to the top, middle, and bottom parts.
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Figure 17. Mean firmness dried bamboo shoots
On the contrary, the firmness of rehydrated bamboo shoots was not significantly affected p0.05 by drying temperature. Referred to Appendix 30 and Appendix 32, both
dried and rehydrated bamboo shoots were not significantly affected p0.05 by the concentration of sodium metabisulfite. As a dried product, the firmness of rehydrated product
is expected as well as the raw material. In this study, it was investigated that the firmness of raw material was 80.998 ± 25.796 N. It can be observed that the rehydrated sample was less
firm than the dried one and the raw material. The higher tissue softening occured during rehydration, which was related with the decrease in the strength of cellular adhesion and
increase in intercellular space that caused rehydrated sample had less firmness.
Figure 18. Mean firmness rehydrated bamboo shoots
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4.2.7 Total Residual Sulfites
