Search

Efforts to optimize bioethanol production were made by modifying culture condition of the yeasts used. Two commercial yeast (New Aule alcohol yeast and New Aule baker's instant dry yeast) were grown in sugarcane molasses under different condition with and without aeration in order to compare the productivity of both yeast. The fermentation processes were carried out in batch condition for 72 hours incubation time. Aeration rate of 0.3 vvm were provided for four hours at the early stage of the aerated cultures. The level of ethanol produced by New Aule Alcohol Yeast was 74.8 g/L with ethanol productivity of 2.078 g/L/h and yield (Yp/s) was at 0.378 g/g. Aeration of 0.3 vvm did not affect the level of ethanol produced, yielded 0.338 gram of ethanol per gram of substrate used. Interestingly, the result showed that the New Aule baker's instant dry yeast produced higher ethanol compare to that of its alcohol yeast. Without aeration, New Aule baker's instant dry yeast produced 102.854 g/L. Meanwhile, the aerated culture of this yeast increase the ethanol production to the level of 120.917 g/L with productivity 3.359 g/L/h and ethanol yield 0.669 g/g, indicating the differences in oxygen sensitivity of both commercial yeast. [ABSTRACT FROM AUTHOR]

Jackfruit seed is a potential local food source, which can be derived as flour. However, this seed contains several oligosaccharides such as raffinose and stachyose, which can cause flatulence for humans, and these substances will also create a darker color during flour processing. Effort to reduce this type of oligosaccharides is reported here by introducing fermentation technique using Lactobacillus plantarum . The aim of this study is to determine the physical and chemical characteristics of jackfruit seed flour fermented by fermentation process for 32 hours incubation time. The results showed that the jackfruit seed flour after fermentation processes have different characteristics compare to that of non-fermented one. The degree of whiteness of jackfruit flour produced under longer time of incubation during fermentation were higher compare to that of shorter duration. Based on the result of FTIR analysis, starch structure differences could not be seen between flour produced from fermentation process and without fermentation. It means that the fermentation process by L. plantarum were not able to change the structure or the degree of polymerization of the starch molecules. The only changes observed were the differences of the oligosaccharides content. The more incubation time assigned, the higher the amount of raffinose detected in the flour, followed by the decrease of the bigger oligosaccharides content such as stachyose and verbascose, as has been shown by HPLC chromatogram, which indicate that enzyme produced by L. plantarum during fermentation process is able to degrade bigger oligosaccharides rather than raffinose. [ABSTRACT FROM AUTHOR]