Sugar- and Starch-Based Biorefineries

Höfer, Rainer

doi:10.1016/b978-0-444-63453-5.00005-7

Cited by 17 publications

(8 citation statements)

References 62 publications

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“…Its molecular weight is 192.12 g/mol, which has three different values of pKa (3.13, 4.76 and 6.39) (2). Citric acid is the primary metabolic product formed in the Krebs cycle used by all aerobic organisms (3). The citric acid cycle is shown schematically in Figure 1.…”

Section: Introduction Introductionmentioning

confidence: 99%

Citric Acid Production of Yeasts: An Overview

Börekçi

Kaban

Kaya

2021

The EuroBiotech Journal

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Background Citric acid, an intermediate product of the Krebs cycle, has a wide usage area in the food industry since it has some functions such as acidulant, flavouring agent, preservative and antioxidant. Although molds are the most commonly used microorganisms in the citric acid production, it is known that there are significant advantages of using yeasts. Purpose and scope The microbial citric acid production mechanism needs to be well understood to make production more efficient. In this study, the yeasts used in the production, fermentation types and the factors affecting production were reviewed with studies. Methodology Although production of citric acid can be produced by chemical synthesis, the fermentation is preferred because of its low cost and ease of use. More than 90% of citric acid produced in the world is obtained by fermentation. Results Yarrowia lipolytica, Candida zeylanoides and Candida oleophila are evaluated for citric acid production with substrates such as molasses, glucose, sucrose and glycerol. On the other hand, there is great interest in developing processes with new substrates and/ or microorganisms. Conclusion Although the microbial strain is an important factor, the factors such as carbon, phosphorus and nitrogen sources, aeration, the presence of trace elements and pH are also parameters affecting the production.

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Section: Introduction Introductionmentioning

confidence: 99%

Citric Acid Production of Yeasts: An Overview

Börekçi

Kaban

Kaya

2021

The EuroBiotech Journal

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“…Currently, dicarboxylic acids (DCA) are produced from petrochemical routes or edible biomass fermentation, and find uses in the pharmaceutical industry, polymer synthesis, as a food additive, or used as chemical precursors of other compounds (Höfer, 2015). In the actual context of biomass valorisation, C 4 -DCA, which include succinic, fumaric, maleic and malic acids, were listed among the 12 building blocks to be produced via this synthetic route (Werpy and Petersen, 2004).…”

Section: Introductionmentioning

confidence: 99%

Catalytic wet peroxide oxidation of vanillic acid as a lignin model compound towards the renewable production of dicarboxylic acids

Vega-Aguilar

Barreiro

Rodrigues

2020

Chemical Engineering Research and Design

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Lignin can be depolymerised and used as a feedstock to obtain renewable raw-materials, providing a green alternative to fossil counterparts. Among others, C 4 dicarboxylic acids (DCA), like succinic, malic, maleic and fumaric acids, which can find applications in pharmaceuticals, food industry, and act as solvents, can be obtained from lignin oxidation. To investigate their formation, the oxidation of vanillic acid (VA), a lignin model compound, was studied under catalytic wet peroxide oxidation (CWPO) conditions, using titanium silicalite-1 (TS-1) as the catalyst. The effect of temperature, pH, and reaction time were studied. In a second phase, catalyst modification with transition metal oxides (Fe, Co, Cu) was tested. Results showed that oxidation under pH = 10.5 gives rise to complete VA conversion with hydroxylated DCA, namely malic (15 mol%) and tartaric (5 mol%) acids, as the main products. At pH = 4.0, the production of succinic acid was improved (7.4 mol%), with VA conversion achieving 78% after 2.0 h of reaction. At alkaline pH, H 2 O 2 reactivity is higher, leading to C 4-DCA degradation to low-molecular weight compounds. Catalyst desilication was observed, pointed out for the convenience of using neutral and acidic pH. In acidic pH, Fe and Cu catalysts enhanced VA conversion, and Fe catalyst was more selective towards succinic acid production.

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“…Depending on the feedstock and reaction conditions, this reaction also leads to the formation of bicyclic, aromatic dimer acids or mixture of saturated and unsaturated branched C 18 -carboxylic acids with pending chains to bring softness. 151,152 Dimerization of fatty acid can take place to lead to the production of cyclo-polyols (Priplast™, Croda Germany) or through polycondensation with glycol to form polyester polyols (Sovermol®, BASF Germany). 153,154 These polyols are also used to improve the hydrolytic stability and aging properties in PUs.…”

Section: Generalitiesmentioning

confidence: 99%