Development of Instant Acetic Acid Bacteria Model for Pineapple Cider Production

Abstract

         The objectives of this research were to develop pineapple cider production technology in the form of instant acetic acid bacteria powder. Two types of acetic acid producing bacteria, Acetobacter aceti TISTR354 and Acetobacter pasteurianus TISTR521, were selected and grown in GYE broth with 3 days incubation at room temperature. It was found that A. pasteurianus was more suitable for cell growth and proliferation than A. aceti. Substrates tested to support the bacteria were rice starch, cassava starch and skim milk. The number of bacterial cells that survived on rice flour (5.97 x 10⁷ CFU/g) was comparable to the number that survived on cassava starch (4.65 x 10⁷ CFU/g). However, the particle size of the rice starch (2-5 microns) was smaller and more uniform than that of cassava starch (5-20 microns). The smaller particle size of rice starch meant that it was better homogenized and thus would be more soluble in fermented vinegar. In addition, the results showed that the temperature and time of drying of the supporting material could affect the survival of the bacterial cells. The work indicated that the cell survival concentration after drying with hot air dryer (at 35^OC for 4 hr.) and that of the non-dried control were 7.80 x 10⁷ and 1.15 x 10⁸ CFU/g, respectively. After a storage time of at least 2 weeks, the number of surviving cells of bacteria was high enough for fermented vinegar and pineapple cider production.