pathways. Lactic, citric, malic, and the itaconic acids are subjected to be produced by
this method. The other group of acids like gluconic acids is synthesized by the direct
glucose oxidation method [11]. Also, the metabolic engineered gene of the various
microbial sources is concentrated in OA production. The global market is subsequently increased in the organic acid production by 4$ billion concerning the
demand of various chemicals in the market [12]. China was found to be the largest
producer of organic acids and is leading in the production of engineering plastics,
vinyl and polyester compounds. India is driving toward the organic acid production
by the growth of small- and medium-scale enterprises and found to grow at its
superior annual growth rate among the certain period. Though chemical process
produces organic acids, industries give preference to the microbial production of
numerous organic acids through fermentation methods, shown in Table 1. Citric acid
was mostly produced in the large quantity through submerged fermentation with
enhanced productivity and greater yield of about 1.6 million tons with annual
production by microbial processes. Next to citric acid, acetic acid is produced with
UNSATURATED
HYDROXYLIC
Organic acid classification based on the
functional group
PHENOLIC
MULTICARBOXYLIC
azelaic
Succinic
Benzoic
Salicylic
Citric
Lactic
Cinnamic
Sorbic
Fig. 1 Classification of organic acids based on the functional group
Organic acid classification based on the
carbon chain
Formic - HCOOH
Acetic - CH 3 COOH
Propionic - CH 3 CH 2 COOH
Butyric - CH 3 (CH 2 ) 2 COOH
Valeric - CH 3 (CH 2 ) 3 COOH
Enanthic - CH 3 (CH 2 ) 5 COOH
Caprylic - CH 3 (CH 2 ) 6 COOH
Pelargonic - CH 3 (CH 2 ) 7 COOH
Capric - CH 3 (CH 2 ) 8 COOH
Lauric - CH 3 (CH 2 ) 10 COOH
Myristic - CH 3 (CH 2 ) 12 COOH
Palmitic - CH 3 (CH 2 ) 14 COOH
Stearic - CH 3 (CH 2 ) 16 COOH
Caproic - CH 3 (CH 2 ) 4 COOH
SHORT CHAIN FATTY ACID
MEDIUM CHAIN FATTY ACID
LONG CHAIN FATTY ACID
Fig. 2 Classification of organic acids based on the carbon chain
70
D. Vishnu et al.
this method. The other group of acids like gluconic acids is synthesized by the direct
glucose oxidation method [11]. Also, the metabolic engineered gene of the various
microbial sources is concentrated in OA production. The global market is subsequently increased in the organic acid production by 4$ billion concerning the
demand of various chemicals in the market [12]. China was found to be the largest
producer of organic acids and is leading in the production of engineering plastics,
vinyl and polyester compounds. India is driving toward the organic acid production
by the growth of small- and medium-scale enterprises and found to grow at its
superior annual growth rate among the certain period. Though chemical process
produces organic acids, industries give preference to the microbial production of
numerous organic acids through fermentation methods, shown in Table 1. Citric acid
was mostly produced in the large quantity through submerged fermentation with
enhanced productivity and greater yield of about 1.6 million tons with annual
production by microbial processes. Next to citric acid, acetic acid is produced with
UNSATURATED
HYDROXYLIC
Organic acid classification based on the
functional group
PHENOLIC
MULTICARBOXYLIC
azelaic
Succinic
Benzoic
Salicylic
Citric
Lactic
Cinnamic
Sorbic
Fig. 1 Classification of organic acids based on the functional group
Organic acid classification based on the
carbon chain
Formic - HCOOH
Acetic - CH 3 COOH
Propionic - CH 3 CH 2 COOH
Butyric - CH 3 (CH 2 ) 2 COOH
Valeric - CH 3 (CH 2 ) 3 COOH
Enanthic - CH 3 (CH 2 ) 5 COOH
Caprylic - CH 3 (CH 2 ) 6 COOH
Pelargonic - CH 3 (CH 2 ) 7 COOH
Capric - CH 3 (CH 2 ) 8 COOH
Lauric - CH 3 (CH 2 ) 10 COOH
Myristic - CH 3 (CH 2 ) 12 COOH
Palmitic - CH 3 (CH 2 ) 14 COOH
Stearic - CH 3 (CH 2 ) 16 COOH
Caproic - CH 3 (CH 2 ) 4 COOH
SHORT CHAIN FATTY ACID
MEDIUM CHAIN FATTY ACID
LONG CHAIN FATTY ACID
Fig. 2 Classification of organic acids based on the carbon chain
70
D. Vishnu et al.