Cheese whey permeate valorization using sequential fermentations: case study performed in the Western Region of Paraná

Sooro Renner Nutrição S.A. company is found in the Western Region of Paraná/Brazil, which is highlighted nationally and in Latin America concerning the production of whey protein concentrate (WPC). During the production of WPC, performed in ultrafiltration membranes, the subproduct cheese whey permeate (CWP) is generated, which is rich in nutrients, such as lactose, minerals, and vitamins. This subproduct is reported as a potential culture medium to grow microorganisms. Thus, this research, performed in partnership with the Sooro company, aimed to develop biotechnological products employing sequential fermentations to fully use this subproduct bioconverting the ethanol obtained from CWP into vinegar employing the acetic bacterium Acetobacter aceti and different methods - Orleans, aerated, and stirred. The biotransformation into ethanol was performed by Kluyveromyces marxianus (alcoholic fermentation step) using a 2³ factorial experimental design to investigate the influence of lactose concentration, temperature, and pH. The maximum ethanol production was 47.18±0.05 g L-1, employing the conditions 88 g L-1 of lactose, 29 °C, and pH 4.5 in 45 h. Besides ethanol, probiotic cellular biomass, prebiotic galacto-oligosaccharides, and organic acids were also produced. In the oxidation stage, the Orleans method presented the best production: 42.30±0.08 g L-1 of acetic acid in 21 days. After this production, reductions of chemical oxygen demand and biochemical oxygen demand of the CWP were 60 and 65%, respectively. The results showed the great potential of CWP as a fermentation medium to obtain biotechnological products as a rentable and viable alternative to fully use CWP.

Upscale fermenter design for lactic acid production from cheese whey permeate focusing on impeller selection and energy optimization

This study focusses on the design and scale-up of industrial lactic acid production by fermentation of dairy cheese whey permeate based on standard methodological parameters. The aim was to address the shortcomings of standard scale-up methodologies and provide a framework for fermenter scale-up that enables the accurate estimation of energy consumption by suitable selection of turbine and speed for industrial deployment. Moreover, life cycle assessment (LCA) was carried out to identify the potential impacts and possibilities to reduce the operation associated emissions at an early stage. The findings showed that a 3000 times scale-up strategy assuming constant geometric dimensions and specific energy consumption (P/Vw) resulted in lower impeller speed and energy demand. The Rushton turbine blade (RTB) and LightninA315 four-blade hydrofoil (LA315) were found to have the highest and lowest torque output, respectively, at a similar P/Vw of 2.8 kWm−3, with agitation speeds of 1.33 and 2.5 s−1, respectively. RTB demonstrating lower shear damage towards cells (up to 1.33 s−1) was selected because it permits high torque, low-power and acceptable turbulence. The LCA results showed a strong relation between the number of impellers installed and associated emissions suggesting a trade-off between mixing performance and environmental impacts.

From cheese whey permeate to Sakacin-A/bacterial cellulose nanocrystal conjugates for antimicrobial food packaging applications: a circular economy case study

Applying a circular economy approach, this research explores the use of cheese whey permeate (CWP), by-product of whey ultrafiltration, as cheap substrate for the production of bacterial cellulose (BC) and Sakacin-A, to be used in an antimicrobial packaging material. BC from the acetic acid bacterium Komagataeibacter xylinus was boosted up to 6.77 g/L by supplementing CWP with β-galactosidase. BC was then reduced to nanocrystals (BCNCs, 70% conversion yield), which were then conjugated with Sakacin-A, an anti-Listeria bacteriocin produced by Lactobacillus sakei in a CWP based broth. Active conjugates (75 Activity Units (AU)/mg), an innovative solution for bacteriocin delivery, were then included in a coating mixture applied onto paper sheets at 25 AU/cm2. The obtained antimicrobial food package was found effective in reducing Listeria population in storage trials carried out on a fresh Italian soft cheese (named “stracchino”) intentionally inoculated with Listeria. Production costs of the active material have been mainly found to be associated (90%) to the purification steps. Setting a maximum prudential 50% cost reduction during process up-scaling, conjugates coating formulation would cost around 0.89 €/A4 sheet. Results represent a practical example of a circular economy production procedure by using a food industry by-product to produce antimicrobials for food preservation.

From Cheese Whey Permeate to Sakacin A: A Circular Economy Approach for the Food-Grade Biotechnological Production of an Anti-Listeria Bacteriocin

Cheese Whey Permeate (CWP) is the by-product of whey ultrafiltration for protein recovery. It is highly perishable with substantial disposal costs and has serious environmental impact. The aim of the present study was to develop a novel and cheap CWP-based culture medium for Lactobacillus sakei to produce the food-grade sakacin A, a bacteriocin exhibiting a specific antilisterial activity. Growth conditions, nutrient supplementation and bacteriocin yield were optimized through an experimental design in which the standard medium de Man, Rogosa and Sharpe (MRS) was taken as benchmark. The most convenient formulation was liquid CWP supplemented with meat extract (4 g/L) and yeast extract (8 g/L). Although, arginine (0.5 g/L) among free amino acids was depleted in all conditions, its supplementation did not increase process yield. The results demonstrate the feasibility of producing sakacin A from CWP. Cost of the novel medium was 1.53 €/L and that of obtaining sakacin A 5.67 €/106 AU, with a significant 70% reduction compared to the corresponding costs with MRS (5.40 €/L, 18.00 €/106 AU). Taking into account that the limited use of bacteriocins for food application is mainly due to the high production cost, the obtained reduction may contribute to widening the range of applications of sakacin A as antilisterial agent.