Document Detail

Submerged citric acid fermentation on orange peel autohydrolysate.
MedLine Citation:
PMID:  18321055     Owner:  NLM     Status:  MEDLINE    
The citrus-processing industry generates in the Mediterranean area huge amounts of orange peel as a byproduct from the industrial extraction of citrus juices. To reduce its environmental impact as well as to provide an extra profit, this residue was investigated in this study as an alternative substrate for the fermentative production of citric acid. Orange peel contained 16.9% soluble sugars, 9.21% cellulose, 10.5% hemicellulose, and 42.5% pectin as the most important components. To get solutions rich in soluble and starchy sugars to be used as a carbon source for citric acid fermentation, this raw material was submitted to autohydrolysis, a process that does not make use of any acidic catalyst. Liquors obtained by this process under optimum conditions (temperature of 130 degrees C and a liquid/solid ratio of 8.0 g/g) contained 38.2 g/L free sugars (8.3 g/L sucrose, 13.7 g/L glucose, and 16.2 g/L fructose) and significant amounts of metals, particularly Mg, Ca, Zn, and K. Without additional nutrients, these liquors were employed for citric acid production by Aspergillus niger CECT 2090 (ATCC 9142, NRRL 599). Addition of calcium carbonate enhanced citric acid production because it prevented progressive acidification of the medium. Moreover, the influence of methanol addition on citric acid formation was investigated. Under the best conditions (40 mL of methanol/kg of medium), an effective conversion of sugars into citric acid was ensured (maximum citric acid concentration of 9.2 g/L, volumetric productivity of 0.128 g/(L.h), and yield of product on consumed sugars of 0.53 g/g), hence demonstrating the potential of orange peel wastes as an alternative raw material for citric acid fermentation.
Beatriz Rivas; Ana Torrado; Paolo Torre; Attilio Converti; José Manuel Domínguez
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Publication Detail:
Type:  Journal Article     Date:  2008-03-06
Journal Detail:
Title:  Journal of agricultural and food chemistry     Volume:  56     ISSN:  0021-8561     ISO Abbreviation:  J. Agric. Food Chem.     Publication Date:  2008 Apr 
Date Detail:
Created Date:  2008-04-02     Completed Date:  2008-07-10     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0374755     Medline TA:  J Agric Food Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2380-7     Citation Subset:  IM    
Departmento de Ingeniería Química, Universidad de Vigo (Campus Ourense), Edificio Politécnico, As Lagoas, 32004 Ourense, Spain.
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MeSH Terms
Calcium Carbonate / pharmacology
Citric Acid / metabolism*
Citrus sinensis / metabolism*
Fruit / chemistry,  metabolism*
Industrial Waste
Methanol / pharmacology
Reg. No./Substance:
0/Industrial Waste; 471-34-1/Calcium Carbonate; 67-56-1/Methanol; 77-92-9/Citric Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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