Aproveitamento de subprodutos da indústria de alimentos para produção de ácido propiônico por fermentação e purificação usando sistemas aquosos bifásicos

Abstract

Propionic acid is among the 30 best chemicals used as a component for products with various applications: food and animal feed preservatives, chemical intermediates in the synthesis of cellulose fibers, herbicides, perfumes and pharmaceuticals. Propionic acid can be produced by chemical synthesis and by fermentation. In fermentative processes, the cost of growing medium is on e of the factors to be reduced. In addition, conventional purification technologies are also great bottleneck of the entire production process in terms of complexity and high cost because they involve several steps of unit operations and therefore at each step some amount of target molecule is lost, resulting in a large global loss. In this sense, the use of by-products such as whey (carbon source) and corn steep liquor (CSL) (nitrogen source) and then purification using Aqueous Two-Phase System (ATPS), which is a simple technology, can be economically feasible. Thus, the objective of this work was to study the viability of the use of by-products of the food industry for propionic acid biosynthesis and purification of the same in the fermented medium using ATPS. The experiment was divided into three stages. Central Composite Rotational Design (CCRD) was used at all stages. In the first step, 2 3 complete factorial was used, where glucose and yeast extract were replaced by whey. Three factors (cell, lactose and CaCO3 concentration) were tested and mixed culture of Propionibacterium freundenreichii ATCC 6207 and Lactobacillus paracasei were used. Only lactose and CaCO3 were significant (p<0.05), and propionic acid at a concentration of 23.27 g L -1 was produced. Values between 20 and 45 g L -1 of lactose and above 26 g L -1 of CaCO 3 increased the biosynthesis of propionic acid. In the second step, a CCRD with 11 treatments, glucose and yeast extract replaced by whey and CSL, was used and mixed culture of Propionibacterium acidipropionicii NRRL B-3568 and Lactobacillus paracasei were used. In this case, the factors tested were lactose and CSL. Both lactose and CSL were significant (p<0.05) with the highest propionic acid production of 6.85 g L -1 . This value was obtained with the use of 40 g L -1 lactose and 65 g L -1 CSL. Finally, in the third step, 4 CCRD were conducted to evaluate the partition of pure propionic acid and the purification of propionic acid in a biphasic aqueous system with PEG and sodium citrate. The two independent variables were PEG and sodium citrate and 2 PEG molar masses (1500 and 4000) were tested. Partition coefficients and phase relations were determined in the partition and purification process of propionic acid. Still in the purification, the best results were analyzed for the efficiency of the process. The lowest propionic acid partition coefficients were obtained in the 24% w w -1 PEG and 15% w w -1 sodium citrate systems for both PEG1500 and PEG4000, with values lower than 0.4. The best systems for purification of organic acids, with the lowest total acid partition coefficients (K AT), were 16.7% w w -1 PEG and 13.5% w w -1 citrate, for PEG1500 with KAT equal to 0.21 with an efficiency of 58.03% and the system 24% w w -1 PEG and 15% w w -1 citrate with PEG4000, KAT of 0.15. The efficiency of the purification process for the latter system was 68.15%. The use of whey, CSL and CaCO3, for the biosynthesis of propionic acid with the use of the mixed culture of propionic and lactic bacteria is feasible. In the conditions tested, Propionibacterium freundenreichii showed better results in the production of propionic acid than Propionibacterium acidipropionicii.