Optimization of lipase production by solid-state fermentation of olive pomace: from flask to laboratory-scale packed-bed bioreactor.

Lipases are versatile catalysts with many applications and can be produced by solid-state fermentation (SSF) using agro-industrial wastes. The aim of this work was to maximize the production of Aspergillus ibericus lipase under SSF of olive pomace (OP) and wheat bran (WB), evaluating the effect on lipase production of C/N ratio, lipids, phenols, content of sugars of substrates and nitrogen source addition. Moreover, the implementation of the SSF process in a packed-bed bioreactor and the improvement of lipase extraction conditions were assessed. Low C/N ratios and high content of lipids led to maximum lipase production. Optimum SSF conditions were achieved with a C/N mass ratio of 25.2 and 10.2% (w/w) lipids in substrate, by the mixture of OP:WB (1:1) and supplemented with 1.33% (w/w) (NH4)2SO4. Studies in a packed-bed bioreactor showed that the lower aeration rates tested prevented substrate dehydration, improving lipase production. In this work, the important role of Triton X-100 on lipase extraction from the fermented solid substrate has been shown. A final lipase activity of 223 ± 5 U g-1 (dry basis) was obtained after 7 days of fermentation.

Ferulic acid transformation into the main vanilla aroma compounds by Amycolatopsis sp. ATCC 39116.

The wild strain Amycolatopsis sp. ATCC 39116 was explored in ferulic acid-based media to produce naturally the aroma components of the cured vanilla pod, namely vanillin,vanillic acid, and vanillyl alcohol. Other phenolic compounds(4-vinyl guaiacol, guaiacol, and protocatechuic acid) were also evaluated. The influence of medium composition,fermentation technology (batch or fed-batch), supplementation with vanillic acid, and inoculum concentration on ferulic acid biotransformation were evaluated. The results postulate the initial concentration of cell mass as the variable with the strongest impact on ferulic acid metabolization under the studied conditions. The highest amounts of vanillin and vanillic acid were achieved at intermediate values of cell mass.Vanillyl alcohol and protocatechuic acid were more closely linked to high cell mass concentrations. Conversely, 4-vinyl guaiacol reached its highest amount at the lowest amount of cell mass. Guaiacol was not detected in any case. Therefore,the initial cell concentration must be considered a critical parameter when using Amycolaptosis sp. ATCC 39116 for the production of vanillin and related compounds.

Use of Vine-Trimming Wastes as Carrier for Amycolatopsis sp. to Produce Vanillin, Vanillyl Alcohol, and Vanillic Acid.

Raw vine-trimming wastes or the solid residues obtained after different fractionation treatments were evaluated for their suitability as Amycolatopsis sp. immobilization carriers during the bioconversion of ferulic acid into valuable phenolic compounds such as vanillin, vanillyl alcohol, and vanillic acid, the main flavor components of vanilla pods. Previously, physical-chemical characteristics of the materials were determined by quantitative acid hydrolysis and water absorption index (WAI), and microbiological characteristics by calculating the cell retention in the carrier (λ). Additionally, micrographics of carrier surface were obtained by field emission-scanning electron microscopy to study the influence of morphological changes during pretreatments in the adhesion of cells immobilized. The results point out that in spite of showing the lowest WAI and intermediate λ, raw material was the most appropriated substrate to conduct the bioconversion, achieving up to 262.9 mg/L phenolic compounds after 24 h, corresponding to 42.9 mg/L vanillin, 115.6 mg/L vanillyl alcohol, and 104.4 mg/L vanillic acid. The results showed the potential of this process to be applied for biotechnological production of vanillin from ferulic acid solutions; however, further studies must be carried out to increase vanillin yield. Additionally, the liquors obtained after treatment of vine-trimming wastes could be assayed to replace synthetic ferulic acid.

Green sustainable process to revalorize purple corn cobs within a biorefinery frame: Co-production of bioactive extracts.

Purple corn (Zea mays L.) is used for the preparation of traditional drinks and desserts, generating great quantities of residues. The scarce information about purple corn cob (PCC) is encouraging an interest in exploring its potential as a valuable source of bioactive compounds with benefits for human health. In this study, a green method based on hydrothermal processing was used for the simultaneous extraction of oligosaccharides and phenolic compounds from PCC. For this purpose, the effects of three factors (time, temperature and pH) on the oligosaccharide content (OSC), total phenolic content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC), as well as on the antioxidant activity measured with three different methods (DPPH, ABTS and FRAP) were evaluated. The bioactive extract obtained under optimal conditions presented a high content of bioactive compounds exhibiting a notable antioxidant capacity and moderate inhibitory activities towards xanthine oxidase. This extract was also structurally characterized by FTIR, HPAEC-DAD, MALDI-TOF-MS and TGA, and the HPLC-ESI-MS analysis led to the tentative identification of 15 antioxidant phenolic compounds. Thus, this research demonstrated that this residue from the food industry has a high potential for obtaining several bioactive compounds that can be utilized as multi-functional ingredients in the food and pharmaceutical industries.

Inhibitory substances production by Lactobacillus plantarum ST16Pa cultured in hydrolyzed cheese whey supplemented with soybean flour and their antimicrobial efficiency as biopreservatives on fresh chicken meat.

Cheese whey, the main byproduct of the dairy industry, is one of the most worrisome types of industrial waste, not only because of its abundant annual global production but also because it is a notable source of environmental pollution. However, cheese whey can serve as a raw material for the production of biocomposites. In this context, in this study, we assayed the production of a bacteriocin-like inhibitory substance (BLIS) and lactate by culturing Lactobacillus plantarum ST16Pa in hydrolyzed fresh cheese whey. The process was improved by studying the enzymatic hydrolysis of cheese whey as well as its supplementation with soybean flour under microaerophilic or anaerobic conditions. Thus, the highest values of BLIS (7367.23 arbitrary units [AU]/mL) and lactate yield (Ylactate/lactose=1.39g/g) were achieved after addition of 10g/L soybean flour in microaerophilia. These conditions were successfully scaled up in a bioreactor because during complete anaerobiosis at 150rpm, L. plantarum ST16Pa attained considerable cell growth (3.14g/L), lactate concentration (14.33g/L), and BLIS activity (8082.56AU/mL). In addition, the cell-free supernatant resulting from this bioprocess showed high biopreservative efficiency in chicken breast fillets artificially contaminated with Enterococcus faecium 711 during 7days of refrigerated storage, thus indicating the potential use of this BLIS as a biopreservative in the food industry.

Cell-free supernatants obtained from fermentation of cheese whey hydrolyzates and phenylpyruvic acid by Lactobacillus plantarum as a source of antimicrobial compounds, bacteriocins, and natural aromas.

Cheese whey hydrolyzates supplemented with phenylpyruvic acid (PPA) and commercial nutrients can be efficiently metabolized by Lactobacillus plantarum CECT-221 to biosynthesize some compounds with attractive applications in the food market. The main metabolites of cell-free extracts were antimicrobial compounds such as phenyllactic acid (PLA) and lactic acid (LA). The production of PLA by L. plantarum CECT-221 was evaluated in the Man-Rogosa-Sharpe broth supplemented with two biosynthetic precursors: phenylalanine or PPA. Using 30.5 mM PPA, the microorganism increased sevenfold the concentration of PLA producing 16.4 mM PLA in 46 h. A concentration of 40 mM PPA was a threshold to avoid substrate inhibition. The biosynthesis of whey hydrolyzates as a carbon source was enhanced by fed-batch fermentation of PPA; the average productivity of PLA increased up to 45.4 ± 3.02 mM after 120 h with a product yield of 0.244 mM mM(-1); meanwhile, LA reached 26.1 ± 1.3 g L(-1) with a product yield of 0.72 g g(-1). Cell-free fed-batch extracts charged in wells showed bacteriocin activity with halos of 7.49 ± 1.44 mm in plates inoculated with Carnobacterium piscicola and antimicrobial activity against Staphylococcus aureus (11.54 ± 1.14 mm), Pseudomonas aeruginosa (10.17 ± 2.46 mm), Listeria monocytogenes (7.75 ± 1.31 mm), and Salmonella enterica (3.60 ± 1.52 mm). Additionally, the analysis of the volatile composition of the headspace of this cell-free extract revealed that L. plantarum is a potential producer for natural aromas, such as acetophenone, with high price in the market. This is the first report of PLA production from cheese whey and PPA. The extracts showed bacteriocin activity and potential to be applied as an antimicrobial in the elaboration of safer foods.