This study investigated sweet potato peel waste as the main carbon source and determine the effect of media components and operating conditions on citric acid (CA) production by Aspergillus niger under submerged fermentation. The sweet potato peel waste is of low-cost readily-available and serve as hydrolysate for CA production. Two sets of experiments were performed using experimental design technique. The first set was designed using a low resolution 2-level factorial which was deployed for parameter screening. The other set of experiments was designed using 3-level design algorithm and was deployed for model development and optimization. The results from parameter screening showed that carbon source (CS), nitrogen concentration (NC), fermentation time (FT) and pH were the “heavy hitters” with significant impact on CA production. The developed model is predictive (R2 = 0.948) with optimum CA (3.22 mg/mL) obtained at CS (97.25%), NC (1.25%w/v), FT (7 days), and pH (6.5). This setting was validated experimentally and resulted in CA yield of 4.36 ± 006 mg/ml, representing a 135%-fold increase over the predicted yield. The present investigation shows that sweet potato peels hydrolysate is a viable and sustainable substrate for CA production.

Optimization of media components and fermentation conditions for citric acid production from sweet potato peel starch hydrolysate by Aspergillus niger

Objectives Response surface methodology coupled with statistically designed experiments has been found to be very useful in optimising multivariable processes. The aim of this study was to evaluate the influence of two independent variables, a ratio of permeation enhancers/antioxidants (transcutol and ethanolic extract of tetracarpidium conophorum EETC) and stirring rate, on the flux and permeation of gentamicin hydrogel. Materials and methods A modification of free radical initial polymerization was used to formulate the gentamicin hydrogel. A 32 factorial CCD was then used to investigate the effect of independent variables of the permeation enhancer transcutol: EETC (X1), stirring speed (X2) via 14 formulation batches, which were evaluated for dependent variables flux (Y1) and amount of drug permeated after 12 hours (Y2) ex vivo. Results The results of ANOVA performed to determine the fit of the models revealed that the models were statistically significant (p 0.80). The regression equation generated for flux was Y1=19.35 - 25.82X1 - 0.044X2 + 0.0097X1X2 + 11.86X21 and for cumulative permeation of gentamicin in 12 hours Y2=315.50 - 189.67X1 + 0.28X2 -1.29X1X2 + 123.55X21. The validity of the statistical models used for predicting flux and drug permeation was confirmed by conducting three confirmation experimental runs at the identified optimum conditions. The results showed that there was no significant difference between the experimental results and those predicted by the statistical models. Conclusion The excellent correlation between the predicted and measured values shows the validity of statistical models (R2=0.95). An antioxidant and permeation enhancer has been used for the first time to investigate the influence on dependent variables. Optimization of gentamicin hydrogel using central composite statistical design is valid for the prediction of drug permeation and flux using variables in formulation.

Formulation and Optimization of Gentamicin Hydrogel Infused with Tetracarpidium Conophorum Extract via a Central Composite Design for Topical Delivery.

Among organic acids, citric acid (CA) features the highest production volume and the greatest economic potential. The steadily increasing demand for CA necessitates the improvement and diversification of the corresponding production techniques via the incorporation of more environmentally friendly and less costly processes such as the bioconversion of agroindustrial by-products. Musa paradisiaca, known as plantain, is a food product of global importance; however, the related by-products are scarcely utilized. Herein, we investigate CA production from M. paradisiaca peels via fermentation with Aspergillus niger. Compositional analysis shows that the above peels contain 623 g·kg−1 total carbohydrates, 374 g·kg−1 starch, and 91 g·kg−1 protein and therefore are rather rich in carbon, with other elements contained in substantial amounts corresponding to K (28 g·kg−1), N (10 g·kg−1), Fe (39 mg·kg−1), Na (71 mg·kg−1), Zn (16 mg·kg−1), and Cu (18 mg·kg−1). Evaluation of solid-substrate fermentation conditions (pH and inoculum loading) reveals that CA production is maximized (29 g·kg−1) at 10% consistency, 30°C, pH 1.4, and inoculum loading = 20 mg, demonstrating that pH is the most important parameter determining fermentation efficiency. As a result, M. paradisiaca peels are concluded to be a suitable substrate for CA biosynthesis via fermentation with A. niger under optimal nutritional conditions.

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Fermentation of Musa paradisiaca Peels to Produce Citric Acid

This chapter presents the optimization of the hydrodynamic and chemical parameters of the FIA system in the determination of copper and manganese in wine samples by VIS spectrophotometry. This technique has been based on the injection of liquid samples in the non-segmented movement, within a continuous carrier current of a suitable liquid. The injected sample forms a zone that disperses on its way to a detector. The later continuously records the absorbance or other physical parameters, since it continuously passes the sample material through the flow cell, using the factorial designs PlackettBurman, Box-Behnken, and the factorial design 2^4. The methods have the advantages of low-cost, easy availability of chemicals, and instrumentation and straightforward application to real samples. Optimization of a Spectrophotometric Flow Injection: Method for Determination Copper and Manganese in Wines by Design Experiments

Optimization of a Spectrophotometric Flow Injection: Method for Determination Copper and Manganese in Wines by Design Experiments

Citric acid is one of the major constituents of citrus fruits and it is one of the most important organic acids produced through biotechnological means . As a result of the important properties of citric acid such as biodegradability, high solubility, low toxicity and palatability, it is widely employed in the food industry as an acidulant, antioxidant and as a flavouring agent. It also finds application in the pharmaceutical industry as a buffering, scavenging and chelating agent as well as in the cosmetic and textile industries . Traditionally, citric acid is produced via submerged fermentation of sugarcontaining substrates by Aspergillus niger. However, the global demand for citric acid is higher than its current rate of production. Furthermore, the high cost of chemical synthesis of citric acid has necessitated the need for more economical alternatives . Recently, a lot of attention has been given to solid state fermentation (SSF) as an alternative to submerged fermentation . Solid state fermentation has some important advantages when compared with submerged fermentation. It has a higher citric acid yield, lower energy and water requirements, less risk of bacterial contamination, less wastewater generation and less environmental concern regarding the disposal of solid waste . Several researchers have investigated SSF as a route to producing citric acid from abundantly available solid waste materials such as sugarcane bagasse , pineapple peels , apple pomace , banana peels , date palm , carob pod , and grape pomace . Watermelon rind is basically the left-over after the consumption of the juicy part of the watermelon pod. It is a waste material that has very little use. Hence it is mostly disposed off improperly, particularly in less developed countries and this has the potential to cause serious environmental problems.

Determination of Optimum Composition of Fermentation Medium for Citric Acid Production from Watermelon Rinds using Response Surface Methodology

Statistical experimental design was employed for the improvement of citric acid production from Madhuca indica through submerged fermentation process using mutant fungi Aspergillus niger MTCC 282. Efficient production of citric acid by mutant Aspergillus niger MTCC 282 grown on a sugar rich byproduct requires the supplementation of the optimized quantities of nutrients. Optimization of chemical parameters for the production of citric acid was done by Box-Behnken design. Box-Behnken design was used to statistically compare different combinations of four different nutrients, namely Ammonium sulphate ((NH4)2SO4), Magnesium (Mg2+), Ethylene diamine tetra acetic acid (EDTA) and Potassium phosphate (KH2PO4), for the maximum production of citric acid. The optimum nutrient concentrations obtained using the Box-Behnken design were Ammonium sulphate ((NH4)2SO4) 0.2138 g/l, Magnesium (Mg2+) 0.1896 g/l, Ethylene diamine tetra acetic acid (EDTA) 0.3968 g/l and Potassium phosphate (KH2PO4)3 g/l. Under the optimum conditions, mutant Aspergillus niger MTCC 282 produced the maximum citric acid of 75 g/l of citric acid/ kg substrate at pH 4.

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Ayyanna C

Papers

Optimization of Chemical Parameters for the Production of Citric acid using Box-Behnken Design