Abstract
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.
Highlights
In the cheese whey protein concentration process, it passes through a membrane filtration system, achieving a retentate product at the end, composed of proteins, fats, colloidal minerals, and a liquid that permeates through the membrane, originating the cheese whey permeate (CWP) (Andrade & Martins, 2002; Lagrange & Dallas, 1997; Zacarchenco et al, 2012)
In the first fermentation stage, besides the results showing a high conversion of the CWP lactose into ethanol, the K. marxianus CCT 4086 behavior regarding the consumption of the substrate lactose was elucidated, evidencing that the factors temperature, pH, and the CWP lactose concentration itself are significant in ethanol production by this yeast
While in the second fermentation, the ethanol from CWP could be used in the oxidation to acetic acid (AA) by A. aceti CCT 2565 reaching the AA content recommended by FAO, in addition to considerable process efficiency
Summary
In the cheese whey protein concentration process, it passes through a membrane filtration system, achieving a retentate product at the end, composed of proteins, fats, colloidal minerals, and a liquid that permeates (passes) through the membrane, originating the cheese whey permeate (CWP) (Andrade & Martins, 2002; Lagrange & Dallas, 1997; Zacarchenco et al, 2012). According to data provided by the Sooro Renner Nutrição S.A. company (2020), the cheese whey quantity used to obtain the protein concentrates ranges according to the protein quantity required in the final product. To produce WPC containing 35 % of protein, 26 kg of cheese whey or milk is necessary, resulting in 1 kg of WPC 35% and 2.3 kg of CWP, while the production of 1 kg of WPC 80% of protein, generates around 8 kg of CWP. Its composition on a dry basis is of approximately 85% lactose, 10% ashes, and > 3% protein (Illanes, 2016) Due to this composition, it is a favorable growth medium for biotechnological processes applications (Diniz, Silveira, Fietto, & Passos, 2012; Passos et al, 2021). Its action is reported as effective in weight loss, reduction of fatigue, and anti-cancer activity (Budak, Aykin, Seydim, Greene, & Guzel-Seydim, 2014; Chen, Chen, Giudici, & Chen, 2016; Lynch, Zannini, Wilkinson, Daenen, & Arendt, 2019)
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