Browsing by Author "Lin, Carol Sze Ki"

Now showing 1 - 3 of 3

Citation - WoS: 205
Citation - Scopus: 284
Analysing Global Food Waste Problem: Pinpointing the Facts and Estimating the Energy Content
(de Gruyter Open Ltd, 2013) Melikoglu, Mehmet; Lin, Carol Sze Ki; Webb, Colin; Energy Systems Engineering
Food waste is a global problem. Each year food worth billions of dollars is wasted by the developed economies of the world. When food is wasted, the problem does not end at that point. More than 95% of the food waste ends at landfill sites, where converted into methane, carbon dioxide and other greenhouse gasses by anaerobic digestion. The impact of food waste to climate change is catastrophic. Food waste problem tends to increase in next 25 years due to economic and population growth mainly in Asian countries. In addition, when food wastes buried at landfill sites their energy content is lost. Although food waste is a huge problem, its global size and extent has recently become a hot topic in the academic community. This paper summarises the size of the global food waste problem together with the estimation of the amount of energy lost when food wastes dumped at landfill sites. Calculations in this study also revealed that energy lost at landfill sites equals to 43% of the delivered energy used for the preparation of foods in the US, 37% of the hydroelectric power generation of Japan, and more than 100% of the current annual renewable energy demand of UK industries.
Citation - WoS: 60
Citation - Scopus: 68
Kinetic Studies on the Multi-Enzyme Solution Produced Via Solid State Fermentation of Waste Bread by aspergillus Awamori
(Elsevier Science Bv, 2013) Melikoglu, Mehmet; Lin, Carol Sze Ki; Webb, Colin; Energy Systems Engineering
The aim of this study was kinetic analysis of the multi-enzyme solution produced from waste bread via solid state fermentation by Aspergillus awamori. It was found that at normal temperature for hydrolysis reactions, 60 degrees C, the activation energies for denaturation of A. awamori glucoamylase, 176.2 kJ/mol, and protease, 149.9 kJ/mol, are much higher than those for catalysis of bread starch, 46.3 kJ/mol, and protein, 36.8 kJ/mol. Kinetic studies showed that glucoamylase and protease in the multi-enzyme solution should have at least two conformations under the two temperature ranges: 30-55 degrees C and 60-70 degrees C. Thermodynamic analysis showed that, deactivation of glucoamylase and protease in the multi-enzyme solution can be reversible between 30 degrees C and 55 degrees C, since Delta S is negative and Delta H is positive. On the other hand, for glucoamylase and protease, both Delta S and Delta H are positive between 60 degrees C and 70 degrees C. This means that the deactivation of both enzymes in the multi-enzyme solution is spontaneous in this temperature range. It was also found that the glucoamylase produced in the solid state fermentation of waste bread is more thermally stable than the protease in the mixture. Consequently, the protease had little or no effect on the stability of the glucoamylase. Furthermore, the half-life of the glucoamylase produced from waste bread pieces was much higher than that produced from wheat flour. This is an important finding because the mode of production, via solid state fermentation, appears to have increased the thermostability of the enzyme significantly. (C) 2013 Elsevier B.V. All rights reserved.
Citation - WoS: 72
Citation - Scopus: 88
Stepwise Optimisation of Enzyme Production in Solid State Fermentation of Waste Bread Pieces
(inst Chemical Engineers, 2013) Melikoglu, Mehmet; Lin, Carol Sze Ki; Webb, Colin; Energy Systems Engineering
When it is not consumed, bread presents a major source of food waste, both in terms of the amount and its economic value. However, bread also possesses the characteristics of an ideal substrate for solid state fermentation. Yet nearly all wasted bread ends up in landfill sites, where it is converted into methane by anaerobic digestion. Governments are finally taking action and, according to the EU Landfill Directive, for example, biodegradable municipal waste disposed into landfills must be decreased to 35% of 1995 levels, by 2020. Solid state fermentation of waste bread for the production of value added products is a novel idea, which could help with the achievement of this target. In this study, glucoamylase and protease production from waste bread pieces, via solid state fermentation, was investigated in detail. The optimum fermentation conditions for enzyme production were evaluated as, 20 mm particle size, 1.8 (w/w, db) initial moisture ratio, and duration of 144h. Under these conditions, glucoamylase and protease activities reached up to 114.0 and 83.2 U/g bread (db), respectively. This study confirms that waste bread could be successfully utilised as a primary raw material in cereal based biorefineries. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.