Bioethanol Production from Pineapple Peel Juice using Saccharomyces Cerevisiae

Transcription

1 Advanced Materials Research Online: ISSN: , Vols , pp doi: / Trans Tech Publications, Switzerland Bioethanol Production from Pineapple Peel Juice using Saccharomyces Cerevisiae Jutarut Pornpunyapat 1,a Wilaiwan Chotigeat 1,b, Pakamas Chetpattananondh 2,c 1 Department of Molecular Biotechnology and Bioinformatics, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand 2 Department of Chemical Engineering, Faculty of Engineering Prince of Songkla University, Hat Yai Songkhla 90112, Thailand a jpornpunyapat@yahoo.com, b wilaiwan.c@psu.ac.th, c pakamas.p@psu.ac.th Keywords: bioethanol, pineapple peel, fermentation, Sacchromyces cerevisiae Abstract. Bioethanol is widely used as renewable resource due to its safe to produce and environmentally friendly. However, knowledge on ethanol production from pineapple peel juice (Pattawia spp) is far from sufficient. In this work, pineapple peel juice (initial ph at 5) was fermented at various yeast contents (1, 3 and 5% by wt.) and fermentation times (3, 5 and 7 days) in order to investigate ethanol production characteristics. Yeast, Sacchromyces cerevisiae was grown on pineapple peel juice. The squeezed juice contained 11% of total sugar and 5% of reducing sugar. The results indicated that the optimum ethanol production was yeast contents of 5% by wt. and fermentation times of 5 days which gave the ethanol production of 9.08g/l. The ethanol at a higher yeast content also had a higher ethanol concentration. Introduction Since the oil crisis in the 1970s, the ethanol, as an attractive alternative for replacement of fuel energy resource, has been a major of good interest [1]. Especially ethanol was produced from biomass. The obtained ethanol has a very low CO 2 so it can reduce the emission of greenhouse gas to environment. [2]. War and Singhs [3] reported that a gasoline produced from bioethanol can reduce pollution gas (CO 2 ) emission by 90%. The ethanol can also be produced from various residues of agro: crops, wheat, sugarcanes and fruits. Pineapple waste was one of fruit waste which most was used for ethanol production along with Saccharomyces cerevisiae because it is easy available and cheap in cost [4]. About 40% of pineapple was discarded as waste (peel, cores and crown) having high biochemical oxygen demand (BOD) and chemical oxygen demand (COD) values. This waste can be caused a pollution problem [5]. Various techniques have been used for ethanol concentration determination: GC, HPLC and refractometer. Each technique has particular advantages and disadvantage. Nevertherless, refractomter is simple, rapid, and inexpensive. Thus, it is especially suitable for applications [6, 7] The objective of this study is to investigate the effect of initial yeast content and fermentation time on ethanol production from pineapple peels using Saccharomyces cerevisiae. The ethanol concentrations were determined by refractometer. Materials and Methods Substrate Pineapple peels (Pattawia spp.) were obtained from local market in Hat Yai, Thailand. The peels were ground with a waring blender and pressed juice. The initial ph of the juice was 3.79, it was adjusted ph until the ph was 5.00 [8] with NaOH 0.1M before being fermented. The latter, it was sterilized by using autoclave at 121 C for 20 min. All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-08/05/16,20:46:40)

2 Advanced Materials Research Vols Yeast (Sacchromyces cerevisiae) obtained from commercial baker s yeast (Saf-Instant Yeast, Gold Lable) was used in this study. Fermentation experiments Air lock fermentation apparatus with 250 ml were used in this study. Each a sterile flask contains 30 ml of the juice. Fermentation was operated at room temperature (30 C) with various initial yeast weights: 1, 3 and 5% by weight of the juice. The fermented juice was measured ethanol concentration every 3, 5 and 7 days. Before measurement, the filtration and centrifugation was used to produce clear juice. Analytical Procedures Total sugar and reducing sugar were determined by Modified Lane-Eynon constant volumetric method and Dinitrosalicylic acid method [9] respectively. Ethanol concentrations were analyzed using the ABBE Refractometer (Model: Nar-1T liquid, ATAGO, Japan) Preparation of Ethanol standard Ethanol solutions with concentrations of 0, 5, 10, 15, 20, 25% (v/v) were prepared to set ethanol standard. The solutions were made by mixing appropriate volumes of absolute ethanol and distilled water. Place the solutions in the refractometer. Wait until the temperature is stable and make the measurements. Each concentration was measured three times. Results and Discussion The ethanol standard is shown in Fig.1. It was notable that the ethanol with high refractive index value presents higher concentration. The relationship of refractive index and ethanol concentration can be expressed as shown in Eq. (1) RI= x (1) where RI is refractive index; x is ethanol concentration (% v,v); the coefficients of linear correlation (R 2 ) is Fig. 1 Variation of refractive indices with various ethanol concentrations Total sugar and reducing sugar were 11% and 5% respectively. It could be used as a substrate for ethanol production [8]. The ethanol concentrations at various ratios of yeast to juice as a function of fermentation time are shown in Fig 2. And it could be converted to ethanol yield at various ratios of yeast to juice as functions of fermentation time are shown in Fig 3. The maximum ethanol concentration was 9.08g/l which optimum fermentation was 5% by weight of yeast and 5 days of fermentation time. At the same fermentation time, it was notable that the higher values of ethanol concentrations were notable at higher ratios of yeast to juice. It also was noticeable that the ethanol concentration increased rapidly during the initial fermentation (3 days to 5 days) and kept constant as fermentation varied from 5 days to 7 days especially the juice with 5% by weight of

3 244 Material Research and Applications yeast to juice. Thus it could be concluded that increasing the initial yeast inoculation could accelerate the fermentation rate while increasing the fermentation time could not be increased ethanol yield. Fig. 2 Ethanol concentrations at various ratios of yeast to juice and fermentation time Conclusions Fig.3 Yields of ethanol at various ratios of yeast to juice and fermentation time The ethanol fermentation from pineapple peels juice at 5% by weight of yeast gave optimum ethanol concentration of 9.08g/l in 5 day of fermentation time. The initial yeast content has effect on ethanol production at only initial fermentation time. Acknowledgements This work was supported by department of Molecular Biotechnology and Bioinformatics, Faculty of Science, Prince of Songkla University, Thailand.

4 Advanced Materials Research Vols References [1] F. Tao, J.Y. Miao, G.Y. Shi, K.C. Zhang. Process. Biochem. Vol. 4 (2005), p.183 [2] S. Oberthur, H. Ott. International climate policy for the 21st century. Springer-Verlag, Berlin (1999) [3] A. War and D. Singhs. Food Chem. Vol. 124 (2011), p [4] J. Mishra, D. Kumar, S. Samanta and M.K. Vishwakarma. J Yeast Fungal Res. Vol. 3 (2012), p13 [5] L. Ban-Koffi and Y.W. Han. World J Microbiol and Biotechnol. Vol. 6 (1990) p. 281 [6] R.C. R. Santos and R. B. Vieira Microchem. J. (2012), inpress [7] C. I. Owuama. Refractometric determination of ethanol Concentration. Food Chem. Vol. 48 (1993), p. 415 [8] C. Jongsomchai, A. Areesirisuk, A. Reungsang and S. Moonarmart. 1 st International Conference on Fermentation Technology for Value Added Agricultural Product (2005) [9] G. L. Miller. Anal. Chem. Vol. 31(1959), p. 426

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