A small and brief presentation on Gluconic acid, production techniques, current trends and market and applications.

1. GLUCONICACID PRODUCTIONAND MARKET
Submitted by: Debanjan Kundu
Roll- 18011003
PhD 1st Semester
School of Biochemical Engineering
IIT BHU

2. Introduction
• Gluconic acid is used as mild acidulant in metal processing, leather tanning
and foods. Sodium Gluconate is widely used as a sequestering agent to
prevent the precipitation of lime soap scums on clean products. Calcium
Gluconate is widely used in calcium therapy.
• Gluconic acid is manufactured only by submerged fermentation process: The
fungus used is a strain of Apergillus niger. Inoculum consists of either a
sporulated culture or spores germinated in seed tanks.
• Gluconic acid is an organic compound with molecular formula C6H12O7 and
condensed structural formula HOCH2(CHOH)4COOH. It is one of the 16
stereoisomers of 2,3,4,5,6-pentahydroxyhexanoic acid.
• In aqueous solution at neutral pH, gluconic acid forms the gluconate ion.
The salts of gluconic acid are known as "gluconates". Gluconic acid,
gluconate salts, and gluconate esters occur widely in nature because such
species arise from the oxidation of glucose. Some drugs are injected in the
form of gluconates (Eg: Calcium gluconate)

3. Gluconic acid occurs naturally in fruit, honey, and wine. As a food additive it is
used as an acidity regulator. It is also used in cleaning products, where it
dissolves mineral deposits, especially in alkaline solution. The gluconate anion
chelates Ca2+, Fe2+, Al3+, and other metals. In 1929 Horace Terhune Herrick
developed a process for producing the salt by fermentation.

4. Production of Gluconic Acid
• As mentioned earlier the inoculum consists of either a sporulated culture or
spores germination in a seed tank. Each one has its own advantages. For
instance, the direct spore inoculation avoids the cost of installation and
operation of the seed tanks. On the other hand use of germinated spores
reduces the operating cycle for the main fermentor. The acid is quickly
neutralised using alkali upon extraction by fungus . Therefore the fermented
broth contains only calcium or sodium gluconate.
• The raw materials are D Glucose and oxygen. The glucose substrate may be
supplied as a solution of crystalline glucose. Alternatively it may be added
as a syrup or starch or crude starchy materials by the action of alpha amylase
followed by amyloglucosidase. The glucose concentration that can be
handled depends upon whether sodium or calcium salt is prepared. If
sodium gluconate is to be prepared, it is possible to use initial glucose
concentration as high as 28-30 per cent.

5. Pyrroloquinone quinone is a redox cofactor also called a s methoxatin. It is
found in soil, and food such as kiwifruit as well human breast milk. Enzymes
containing PQQ are called as quinoproteins. Glucose dehydrogenase one of
the quinoproteins is used as a glucose sensor.

6. The entire reaction
of conversion of
Glucose to
Gluconic acid
takes place in the
periplasmic space
of the
microorganism.

7. Gluconic Acid production medium as defined by Gastrock, Proges, Wells and Meyer
(1938)
Corn Steep Liquor 3.70 g/l
MgSO4.7H2O 0.17 g/l
KH2PO4 0.20 g/l
Urea 0.10 g/l
(NH4)2HPO4 0.40 g/l
H2SO4 to adjust pH at 4.5
Water to make 1 litre of the inoculation
Antifoam agent is needed
It is necessary to maintain the maximum concentration of oxygen dissolved in the solution.
This is achieved by the application of vigorous agitation with a turbomixer or by the action
of a cavitator. The greater the concentration of the consumption of the power by the agitator
motor, the more the dissolution of oxygen.
A study by May et al (1934) gives us an idea about the yield of gluconate with relation to the
air pressure;
Pressure Weight Yield
1 42.5%
3 80.4%
4 82.4 %
5 81.3 %
6 86.1%

8. Fermentation Conditions for Gluconic Acid
Temperature = 28-30 ⁰C
Aeration = 1-1.5 Volumes of air/volume of solution/minute
Agitation = Highly vigorous
Initial pH = 6.5
The pH is maintained is about 5.5-6.0 by the excess of CaCO3 in the production of the
calcium salt or at about 6.8-7.2 by NaOH in the production of sodium salt.
 In a study reported by Anastassiadis et al, fermentation of Gluconic acid was carried
out in a continuous mode in a 5 litre fermentor with or without biomass retention with
an agitation rate of 1000 rpm in chemostat. Vitamins and NH4Cl were added to the
sterile autoclaved media (121⁰C for 30-60 minutes) via filtration method. The
fermenters worked according to the principle of chemostat with delimitation of a
growth factor and a constant supply of nutritive solution into the fermentor so that a
stationary state can be achieved (2006).
 In another study reported by the same author, newer strains of A.niger and
G.suboxidans have been used in discontinuous mode of fermentation mainly because
although microbiological mode of fermentation is still the most common method, it
has major problems in areas of decreased productivity over time and contamination
(2007).
 Newer methods of Gluconic acid production without the use of fermentation involves
pure chemical conversion.

9. To overcome disadvantages of microbiological fermentation process new catalytic
oxidation processes have been proposed wherein Gluconic acid is produced under
high pressure and alkaline conditions with glucose and molecular oxygen reacting in
presence of noble metal catalysts like such as platinum or palladium (Japanese Patent
Publication No 7620/1958).
On a similar scale, an European patent publication have reported to have modified
the process by use of Palladium- bismuth adsorbed on activated charcoal which
eventually increased the glucose conversion of 99.8% and an yield of Gluconic acid
of 99.5% at a catalytic activity of 1450 g per gram Palladium used per hour of
reaction time.
Different types of microbial species and strain producing gluconic acid.
Filamentous Fungi - Aspergillus niger; Penicillium glaucum; P. amagasakiense;
Penicillium luteum purpurogenum; P. chrysogenum;
Bacteria- Pseudomonas savastanoi; Gluconobacter oxydans (obligate aerobic
bacterium); Acetobacter diazotrophicus; Acetobacter methanolicus; Pseudomonas
ovalis; Pseudomonas fluorescens; Zymomonas mobilis.
Yeast- Aureobasidium pullulans

10. Recovery of Gluconic acid
 At the end of the fermentation, fungal mycelium is filtered off from the solution. The
mycelium is used for the recovery of glucose aerodehydrogenase. On the other hand the
filtrate is used to recover calcium or sodium gluconate, gluconic acid and glucono –d-
lactone. Recovery of calcium gluconate is achieved by heating the filtrate with a slight excess
of calcium hydroxide followed by decolorizing with carbon and filtering.
 On cooling to a temperature below 20 ⁰C and seeding with calcium gluconate crystals, the
compound readily gets crystallised. A second crop of crystals of calcium gluconate is
recovered by evaporation of mother liquor through heating to about 10-15% volume followed
by treatment with carbon, filtration and chilling. On the other hand sodium gluconate is
recovered by concentrating the filtrate to about 42-45% of the solids. Therefore the pH of the
concentrate is adjusted to 7.5 with NaOH and the salt is drum-dried.
 To recover the Gluconic acid and its delta lactone, calcium is precipitated by addition of
stoichiometric quantity of sulphuric acid. Calcium sulphate is filtered off and the filtrate is
decolorized by carbon. After removal of carbon, the acid solution is subjected to a
concentration of 50% acid strength. The product thus obtained is a mixture of free Gluconic
acid and its gamma and delta lactones. Crystals separating from the solution at a temperature
of below 30 ⁰C and near about 0 ⁰C are principally of Gluconic acid, between 30- 70⁰C are
delta lactone and the gamma lactone crystallizes at a temperature above 70⁰C.

11. GluconicAcid Production flow chart

13. Other factors Governing Fermentation of Gluconic Acid
1) Effect of Oxygen- Oxygen supply is the most common and widely known factor
influencing the production of Gluconic acid and also the most important limiting factor in
the production of Gluconic acid by fungal processes by directly affecting the Gluconic acid
production and specific fermentation parameters. Continuous Gluconic acid production by
yeast like mold Aureobasidium pollulans has also been reported to be strongly influenced
by the DO concentration with a high oxygen demand for glucose concentration similar to
Aspergillus and Penicillium species.
2) Temperature- Similar to many fungi processes yeast like Aureobasidium pollulans process
operate at temperatures between 24- 32 ⁰C and in particular 29-30 ⁰C. Higher production of
Gluconic acid takes place with increase in temperature due to higher enzymatic activity and
higher biomass obtained at lower temperatures.
3) Glucose concentration- Fungal fed batch fermentation is carried out for the industrial
production of Gluconic acid. Glucose is fed to the inoculum at the end of the growth phase
while aeration is maintained. A.pollulans has been able to produce very high amount of
Gluconic acid up to 600 g/l and glucose conversion rate up to 100%.
4) Effect of Trace elements- The appropriate concentration of trace elements such as iron,
manganese and magnesium in the feed are a function of the concentration of nitrogen. The
concentration of iron is ion the range of 0.5-3.0mM, about 2.5- 5.0mM for manganese and
about 1mM to about 2mM for magnesium ions.

15. Concentration of Glucose and Gluconate measured by OD in continuous
fermentation method by free growing cells.

16. Fig. 1- DCW (a), CER (b) and microphotographs (c, d, and e, 40 x ) of the three A. niger
seeds after 18 h cultivation in 15-L bioreactors using different agitation strategies (Lu et
al (2015)

17. Market for GluconicAcid
In the global market of fermentation organic acid estimated to be third largest
market preceded by antibiotics and amino acid. The key driver to the growth of
the gluconic acid market is its application in the food industry as a food and
beverage additives (acidity stabilizer) and pharmaceutical industry and increase
in demand for biodegradable acid. Moreover, its ability to bind it with sodium,
iron, and calcium gives a boost to gluconic acid market owing to support the
effect of antioxidant as well as thickening and gelling agent. Gluconic acid
outperforms as an antimicrobial property due to its derivative sodium gluconate
which is widely used in textile dyeing, a chelating agent for plating and cement,
metal surface water treatment and printing which is a potential driver for the
growth of the gluconic acid market. Another derivative of gluconic acid that
outperforms in the pharmaceutical industry is calcium gluconate which is another
potential factor for the growth of the gluconic acid market. This is due to its
application for treating calcium deficiency such as hypocalcemia and
hypocalcemic tetany in pregnant women.

18. Organic acids represent the third largest category after antibiotics and amino acids
in the global market of fermentation. The total market value of organic acid was up
to $3 million in 2009. Citric acid dominates the market of organic acids due to its
application in various fields.
The market of gluconic acid is comparatively smaller. However, 60000 tonnes are
produced world wide annually and it is available in the market as 50 % technical
grade aqueous solution (by mass). The main product among the gluconic acid
derivatives is the sodium gluconate due to its properties and applications.
Manufacturers of gluconic acid and its salt in the United States are Pfizer Inc.,
New York, Bristol-Meyers Co., New York, Premier Malt Products Inc., Wisconsin.
European gluconate producers include Roquette Frères in France, Pfizer in Ireland,
Benckiser in Germany. Fujisawa and Kyowa Hakko are the manufacturers of
gluconate in Japan. Calcium gluconate is also an important
product among the derivatives of gluconic acid and it is available as tablets,
powder, and liquid for dietary supplements.

19. Over the last two decades consumption of gluconic acid has increased steadily up
to 60,000 tonnes per year. Market researcher Global Industry analysts predicts
that the global market for organic acids will have reached 1 billion Euro by 2017,
driven by demand more in the developing economies, stable demand for meat
and meat and meat products from the developing countries along with a growing
global population. Use of gluconic acid and the derivatives is currently restricted
as well in many cases because of high prices of around 1.20-8.50/kg US$ due to
the costly substrate of glucose and the stringent requirements of fermentation
conditions. However with the increasing demand of the organic acid in various
industries, it has created an interest in developing an effective and viable
economic system for the consistently.

20. Based on application Gluconic acid market is segmented into-
Acidification in food and beverages
Processed fruits and vegetables
Baked goods
pH adjuster
Hygiene products
Based on component: Gluconic acid market is segmented into
Gluconic acid
Glucono delta-lactone
Sodium salt of gluconic acid
Calcium salt of gluconic acid
Iron slat of gluconic acid
Based on industry: Gluconic acid market is segmented into
Food and Beverage
Pharmaceutical Products

21. Gluconic Acid Market: Region Wise Outlook
The global gluconic acid market is divided into seven regions, namely North America,
Latin America, Asia Pacific excluding Japan (APEJ), Western Europe, Eastern Europe,
Japan and the Middle East and Africa (MEA).
Europe holds major share of global gluconic acid market, factors that holds dominant
position of Europe is due to major player such as Roquette Frères and BASF SE in the
global gluconic acid market. Moreover the derivative of gluconic acid is high in
dietary supplements, thus the dietary supplement market is expected to boost the
demand for gluconic market in the region.
North America holds second major share in the global gluconic market. Established
players such as Sigma-Aldrich and Bristol-Myers Squibb strengthen the growth of
global gluconic acid market. Thus Europe and North America is estimated to witness
healthy CAGR in the forecast period.
APEJ is said to be most attractive region for gluconic acid market. Thus APEJ is
estimated to witness high CAGR during the forecast period of gluconic acid market.
This is due growing demand and rising application of gluconic acid in food and
beverage that will boost the market and technological production that has created
opportunities for global gluconic acid market.

22. Key Developments
February 2017 – Jungbunzlauer in collaboration with Green Biologics Inc.
announced to lead the production of bio-based plasticizers. The opportunity for
bio-based plasticizers in personal care, healthcare, bio-polymers, and many other
industrial applications is immense
Competitive Landscape
Major Players - AK Scientific Inc., Alfa Chemistry, AN Pharmatech, BASF,
Chembo Pharma, Evonik, Jungbunzlauer, Kerry, Merck Millipore, Novozymes,
Oxychem Co., PMP Inc., Roquette, R-Biopharm, Sigma Aldrich, TCI Chemicals,
among others.

25. Applications of Gluconic acid
1. Gluconic acid being a mild organic acid finds various applications in the food industry.
It is natural constituent in fruit juices and honey and is also used in pickling of food. It
contains ester glucono-d-lactone imparting initially sweet taste which with passage of
time becomes acidic. It is used in dairy products particularly in baked foods as a
leavening agent for preleavened products. It is also used as a flavouring agent and it
also finds application in reducing fat absorption in doughnuts and cones hence
foodstuffs containing D-glucono-d-lactone include bean curd, yogurt, cottage cheese,
bread, confectionery and meat.
2. It is also used in bottle washing preparations and also helps in the prevention of scale
formations and its removal from the glass. It is well suited for removal of calcareous
deposits from metals and other surfaces including beer and milk scaling galvanised on
iron or stainless steel.
3. It is also used in metallurgy for alkaline derusting as well as in the washing of painted
walls and removal of metal carbonate precipates without causing corrosion.

26. Components Applications
Gluconic acid Prevention of milkstone in dairy industry
Cleaning of aluminium cans
Glucono- d- lactone Latent acid in baking powders for use in dry cakes and
instantly leavened bread products
Slow acting acidulant in meat processing such as sausages
Coagulation of soybean protein in the manufacture of Tofu
In dairy industry for cheese curd formation and improvement of
heat stability of milk
Sodium salt of gluconic acid Detergent in bottle washing, metallurgy, additive in cement,
alkaline derusting, textile industry
Calcium salt of gluconic acid Calcium therapy, animal nutrition
Iron salt of gluconic acid Treatment of anemia, foliar feed formulations in horticulture

27. Conclusion
The production of gluconic acid is a simple oxidation process that can be
carried out by electrochemical, biochemical or a combination of both the
methods but production by fermentation process involving fungi and bacteria is
well established commercially as well as most accepted process. Although
considerable progress has been made in understanding the mechanism of
fermentation process by different microorganisms, by developing highly
efficient production process which dates back to quiet a long ago. However,
development of novel, more economical process for the conversion of glucose
to gluconic acid with longer shelf life would be promising. Future
investigations would enable a further acceleration of gluconic acid production
and the lowering of the production costs to minimum levels. Certain results
indicate the latent potential of nature regarding high producing microbial wild
strains, as a comparison to extensive publicity for genetic engineering research
and development.

28. References
1. S. Anastassiadis, A. Aivasidis, C. Wandrey, H.J. Rehm, Process optimization of
continuous gluconic acid fermentation by isolated yeast-like strains of
Aureobasidium pullulans, Biotechnol. Bioeng. 91 (2005) 494–501.
2. R.H. Blom, V.F. Pfeifer, A.J. Moyer, D.H. Traufler, H.F. Conway, Sodium
gluconate production – Fermentation with Aspergillus niger, Ind. Eng. Chem. 44
(1952) 435–440.
3. H. Saito, S. Ohnaka, S. Fukuda, US patent 4,843,173 (1989).
4. Ramachandran S, Fontanille P, Pandey A, Larroche C. Gluconic acid: properties,
applications and microbial production. Food Technol Biotechnol 2006; 44:185–
95.
5. Singh OV, Kumar R. Biotechnological production of gluconic acid: future
implications. Appl Microbiol Biotechnol 2007; 75:713–22.
6. Anastassiadis, S. and Rehm, H.-J. 2005. Continuous gluconic acid production by
biomass retention of Aureobasidium pullulans. Electron J Biotechnol 2006; 9 (5).
7. European patent disclosure 0142725.