Platform chemicals production from food wastes using a biorefinery concept

According to the Food and Agricultural Organization (FAO), one-third of food produced globally for human consumption (nearly 1.3 billion tons) is lost along the food supply chain. Food waste has often been incinerated with other combustible municipal wastes for possible recovery of heat or other forms of energy, and the residual ash is disposed of in landfills. However, incineration is not cost-effective, and can potentially cause air pollution. Therefore, green technology is urgently needed for appropriate management of food waste with a focus on material recovery. Due to its organics- and nutrients-rich nature, food waste could be viewed as a useful resource for production of high-value platform chemicals through fermentation. Compared with animal feed or traditional fuel for transportation, platform chemicals obviously have higher economic value, i.e. more profitable. Recently, technologies for production of value added bio-products (e.g. organic acids, biodegradable polymers, etc.) from various kinds of food wastes have gained more and more interest. This review attempts to examine the state of the art of the fermentation technologies of food waste for production of platform chemicals, with emphasis on the Asia-Pacific region

Glucoamylase production from food waste by solid state fermentation and its evaluation in the hydrolysis of domestic food waste

In this study, food wastes such as waste bread, savory, waste cakes, cafeteria waste, fruits, vegetables and potatoes were used as sole substrate for glucoamylase production by solid state fermentation. Response surface methodology was employed to optimize the fermentation conditions for improving the production of high activity enzyme. It was found that waste cake was the best substrate for glucoamylase production. Among all the parameters studied, glucoamylase activity was significantly affected by the initial pH and incubation time. The highest glucoamylase activity of 108.47 U/gds was achieved at initial pH of 7.9, moisture content of 69.6% wt., inoculum loading of 5.2×105 cells/gram substrate (gs) and incubation time of 6 d. The enzyme preparation could effectively digest 50% suspension of domestic food waste in 24 h with an almost complete saccharification using an enzyme dose of only 2U/g food waste at 60°C

Developing novel biorefineries using food waste as substrate (Technical report 3)

The project is progressing smoothly on schedule as shown below. The projected milestones and deliverables have all been achieved as detailed in Section 'Results and Discussion'. As of July 2014, we have completed the optimization of in-house enzyme production. The saccharification of food wastes from cafeteria was investigated with in-situ produced enzymes, while the conditions were optimized. In addition, the solid residuals after saccharification were further used for anaerobic digestion

Optimizing the conversion of food waste to sugars using fungal enzymes

Food waste (FW) generally has high starch content and is rich in nutritional compounds, including lipids, proteins and acids. It is therefore potentially a renewable resource and its utilization for value-added product development is gaining interest. In this study, FW from a cafeteria was used as sole substrate for glucose production, and the fermentation conditions for optimum glucose yield were firstly optimized using response surface methodology. It was found that glucose yield was significantly affected by α-amylase loading, solid loading and temperature. The optimal conditions were found to be an α-amylase loading of 12.15 U/g FW, a solid loading of 22.4% and a culture temperature of 83.8°C for 90 min, which resulted in a maximum glucose yield of 217 mg/g. Secondly, in order to increase the final glucose concentration, an in situ produced fungal mash rich in glucoamylase was obtained from Aspergillus awamori which resulted in a glucose concentration of 99.1 g/L. When a fungal mash rich in cellulase obtained from Trichoderma reesei was combined with glucoamylase, a maximum of 140 g/L of glucose was obtained. This study showed that FW is a suitable substrate for saccharification with high conversion yield, indicating the potential utilization of food wastes for value-added chemicals production

Microbial oil produced from biodiesel by-products could enhance overall production

Glycerol and rapeseed meal, two major by-products of biodiesel production, have been tested for possible use as low-cost raw materials for the production of microbial bio-oil using the oleaginous yeast Rhodosporidium toruloides. Using fed-batch fermentation with crude glycerol and a novel nitrogen rich nutrient source derived from rapeseed meal as feed, it was shown that 13 g/L lipids could be roduced, compared with 9.4 g/L when crude glycerol was used with yeast extract. When 100 g/L pure glycerol was used, the final lipid concentration was 19.7 g/L with the novel biomedium compared to 16.2 g/L for yeast extract. The novel biomedium also resulted in higher lipid yields (0.19 g lipid/g glycerol consumed compared to 0.12 g/L) suggesting it provides a better carbon to nitrogen balance for accumulating lipids. FAMEs produced from the microbial lipids indicated a high degree of unsaturation confirming that the fatty acids produced from the novel biomedium have potential for biodiesel production

Improvement of enzymatic xylooligosaccharides production by the co-utilization of xylans from different origins

This study aimed to improve XOs production by enzymatic hydrolysis of xylans from various lignocellulosic waste biomasses namely corn cob, cotton and sunflower stalks, rice hull, wheat straw by using two commercial xylanase preparations, Shearzyme 500L and Veron 191. Shearzyme 500L showed better xylan hydrolysis capacity with high amount of xylose liberation. Xylobiose was the main hydrolysis product in each case. Even though the enzymatic hydrolyses using Shearzyme 500L resulted higher reducing sugar production compared to those of Veron 191, the hydrolysis of complex xylan structures was improved and the production of undesirable xylose was lowered by the co-utilization of xylanase preparations. By the co-utilization of xylanase preparations, the reducing sugar production from wheat straw, corn cob and sunflower stalk originated xylans was increased by 36%, 33% and 13%, respectively, compared to the expected reducing sugar yields. The highest reducing sugar production was obtained from complex corn cob xylan. The depolymerization of cotton and sunflower stalk xylan was poorest even though they have simple structures. Poor utilization of these xylans might be related to their high residual lignin content which might hinder the accessibility of xylan by the xylanases. However, the utilization of sunflower and cotton stalk xylan was improved when they were hydrolyzed within a xylan mixture containing equal amounts of each of five different xylans. In short, XOs production efficiency from agricultural waste materials was improved by the co-utilization of suitable xylanase and/or xylan mixtures considering the heterogeneous structures of xylan and different substrate specificities of xylanases. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved

Microbial biodiesel production by direct methanolysis of oleaginous biomass

Biodiesel is usually produced by the transesterification of vegetable oils and animal fats with methanol, catalyzed by strong acids or bases. This study introduces a novel biodiesel production method that features direct base-catalyzed methanolysis of the cellular biomass of oleaginous yeast Rhodosporidium toruloides Y4. NaOH was used as catalyst for transesterification reactions and the variables affecting the esterification level including catalyst concentration, reaction temperature, reaction time, solvent loading (methanol) and moisture content were investigated using the oleaginous yeast biomass. The most suitable pretreatment condition was found to be 4 g L-1 NaOH and 1: 20 (w/v) dried biomass to methanol ratio for 10 h at 50 degrees C and under ambient pressure. Under these conditions, the fatty acid methyl ester (FAME) yield was 97.7%. Therefore, the novel method of direct base-catalyzed methanolysis of R. toruloides is a much simpler, less tedious and time-consuming, process than the conventional processes with higher FAME (biodiesel) conversion yield