pH of the osmotically dehydrated with CaCl2 of purple sweet potatoes is shown
in Figure 4. pH of purple sweet potatoes was decreased continuously during storage
under room temperature and a low temperature (4˚C). The initial level of pH in the
potatoes that were prior to storage was 6.72. However, during the storage it tends to
decreased to 4.31 under room temperature storage and 6.15 under a low-temperature
storage. The pH of potatoes that were stored under low temperature fluctuated
throughout the storage (P≥0.05). pH of osmotically dehydrated purple sweet potatoes
during storage significantly differed among the different temperature storage. The
samples stored at room temperature was losing pH more quickly than at 4˚C. pH for
the samples, an indication of high acidity may confer longer keeping the quality of
plants (Nzeagwu OC and Undugwu AN, 2009). pH influences the chemical reaction and
the enzyme, as well as the growth of microorganisms. The storage at room
temperature was decreased of pH more quickly than at a low temperature, and it
could be due to the growth of microorganisms. For a low temperature, the pH was pH
gradually decreased because the in storage at a low temperature was slow down the
microbial growth.