The effects of pH, salt, heating and freezing on the physical properties of bacterial cellulose - nata

The effects of pH (2, 7 and 10), NaCl concentrations (0, 1, 3 and 5% w/w), and temperatures (-20, 25 and 100 degrees C) on the physical properties of nata, a bacteria cellulose produced by Acetobacter aceti ssp. xylinum, were evaluated in this study. The addition of NaCl was found to increase the hardness of nata but to decrease the water-holding capacity; however, no effect of NaCl on the hardness of nata was found when nata was acidified or alkalized. Compared to the texture properties of nata at 25 degrees C, freezing at -20 degrees C for 24 h gave a more elastic texture, but heating at 100 degrees C for 3 h had no significant effect on the textural properties. The results of this study indicated that acidification or alkalization was necessary to prepare salted nata products without increasing their hardness.