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Subcritical water mediatedhydrolysis of cider lees asaroute for recovery of high value compounds

Bahari, Alireza (2012)
Ph.D. thesis, University of Birmingham.

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Spent cider lees(yeast), a by-product of the cider industry, was subjected to subcritical water in a batch process over a temperature range of 100 °C to 300 °C. The efficacy of subcritical water to convert the waste biomass into a mixture of valuable compounds was investigated by studying formed products in the extracts.

At milder temperatures (up to 150°C), yeast intracellular contents such as proteins were released. Also, phenolic compounds which were previously adsorbed on cell walls during fermentation start to release, which was shown for
the first time, leading to an increase in the antioxidant activity of the extracts (maximum 80g ascorbic acid equivalent in 100 ml). The release of phenolics was compared to organic solvent extraction and the same level of extraction was observed in subcritical water treatment.

At higher temperatures, polymers of the yeast cell wall started to solubilise producing monosaccharides which later were converted to hydroxymethyl furfural (HMF). Kinetics of HMF synthesis were determined using first order kinetics suggesting that milder conditions are required for HMF production when compared to the same process using
cellulose as substrate. Results support the potentials of the studied feedstock as a substrate for numerous bio-based chemicals.

Type of Work:Ph.D. thesis.
Supervisor(s):Santos, Regina and Leeke, Gary
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Chemical Engineering
Subjects:TP Chemical technology
Institution:University of Birmingham
ID Code:3574
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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