Batch production of L(+) lactic acid from whey by Lactobacillus casei (NRRL B‐441)

The effects of temperature, pH, and medium composition on lactic acid production by Lactobacillus casei were investigated. The highest lactic acid productivity values were obtained at 37 °C and pH 5.5. The productivity was 1.87 g dm^?3 h^?1 at 37 °C in shake flasks. In the fermenter, a productivity of 3.97 g dm^?3 h^?1 was obtained at pH 5.5. The most appropriate yeast extract concentration was 5.0 g dm^?3. Whey yielded a higher productivity value than the analytical lactose and glucose. Initial whey lactose concentration did not affect lactic acid productivity. MnSO₄ ·H₂O was necessary for lactic acid production by L casei from whey. Product yields were approximately 0.93 g lactic acid g lactose^?1. Copyright © 2004 Society of Chemical Industry     

Large-scale production of a hypoallergenic preparation of F(ab′)2 fragments from bovine colostrum

A method for the production of bovine colostral F(ab′)₂ fragments at pilot-plant scale was developed. Optimum yield of immunoglobulins in colostral whey was obtained after rennet treatment of first milking colostrum. Pepsin digestion was carried out directly on the colostral whey at pH 3·8 for 4 h, which led to the complete digestion of immunoglobulins into F(ab′)₂ fragments. Elimination of β-lactoglobulin, the main immunogenic protein, was achieved by anion exchange on Duolite A560 at pH 6·0. The preparation was diafiltered with a 5000 Da membrane and the retentate spray-dried. The powder obtained contained approximately 34% F(ab′)₂ fragments, with an antibody activity three times higher than the initial colostrum.     

Oil production by fermentation of lactose and the effect of temperature on the fatty acid composition1

Strains of the yeastsCandida curvata andTrichosporon cutaneum were isolated that were able to ferment the lactose of cheese whey and ultrafiltered whey permeate to produce oil. Rapid fermentation rates and lactose utilization were achieved by the Gcurvata strains. The fermentation was more efficient on permeate than whey, because the organisms used whey protein very poorly. Methods of extracting the oil were compared, and the best results were obtained by sequential extraction with methanol and benzene or by ethanol and hexane. The fatty acid composition of the yeasts varied with the growth temperature, fermentation time, and medium. The oil was rich in 18:1, 16:0, and 18:0. The process is a technically feasible means of using whey permeate. 1journal Paper No. J-9135 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA. Project 2144.     

A modelling study on hydrolysis of whey lactose and stability of β-galactosidase

In the present study, the effect of process conditions on whey lactose hydrolysis and enzyme inactivation were investigated. The experiments were carried out in 250 mL of 25 mM phosphate buffer solution by using β-galactosidase produced from Kluyveromyces marxianus lactis in a batch reactor system. The degree of lactose hydrolysis (%) and residual enzyme activity (%) against time were investigated versus lactose concentration, enzyme concentration, temperature and pH. The mathematical models were derived from the experimental data to show the effect of process conditions on lactose hydrolysis and residual enzyme activity (in the presence and absence of lactose). At the optimum process conditions obtained (50 g/L of lactose concentration, 1 mL/L of enzyme concentration, 37 °C of temperature and pH 6.5), 81% of lactose was hydrolyzed and enzyme lost its activity by 32%. The activation energy for hydrolysis reaction (E _A ) and the enzymatic inactivation energy (E _D ) were calculated as 52.7 kJ/mol and 96.7 kJ/mol. Mathematical models at various process conditions have been confirmed with the experimental results.     

Effect of the Kinetics of Evaporation of Solvent on the Performance Characteristics of Ultrafiltration Membranes Made of Secondary Cellulose Acetate

Two methods are proposed for dry-wet formation of membranes from SCA for ultrafiltration of cheese whey: dry formation followed by modification in aqueous medium and spontaneous gelation on a calender followed by modification in aqueous medium, which significantly differ in the solvent evaporation rate (12 h and 3–5 min). It was shown that the solvent evaporation rate affects formation of the pore structure of the membranes. In formation with the spontaneous gelation method on a calender, membranes with a less developed pore structure and better permeability for water and cheese whey are obtained in comparison to membranes formed by the dry method. The pore structure of the membranes can be regulated with NaHCO₃ filler. Membranes from 5–7% solutions of SA at a 3–4 wt. % NaHCO₃ content are the most efficient.__________Translated from Khimicheskie Volokna, No. 2, pp. 58–61, March–April, 2005.     

Kinetic modelling of lactic acid production from whey by Lactobacillus casei (NRRL B‐441)

The biomass growth, lactic acid production and lactose utilisation kinetics of lactic acid production from whey by Lactobacillus casei was studied. Batch fermentation experiments were performed at controlled pH and temperature with six different initial whey lactose concentrations (9‐77 g dm^?3) in a 3 dm³ working volume bioreactor. Biomass growth was well described by the logistic equation with a product inhibition term. In addition, biomass and product inhibition effects were defined with corresponding power terms, which enabled adjustment of the model for low‐ and high‐substrate conditions. The Luedeking‐Piret equation defined the product formation kinetics. Substrate consumption was explained by production rate and maintenance requirements. A maximum productivity of 2.5 g dm^?3 h^?1 was attained with an initial lactose concentration of 35.5 g dm^?3. Copyright © 2006 Society of Chemical Industry     

Novel whey protein‐based aqueous polymer‐isocyanate adhesive for glulam

Whey, a by‐product of cheese making, contains whey proteins, lactose, vitamins, and minerals. Whey and whey proteins are still not fully used. In this study, whey protein‐based aqueous polymer‐isocyanate (API) adhesives were developed and characterized by bond test, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscope (SEM) for bond strength, chemical structures, and morphology. The optimized whey protein‐based API adhesive for Glulam had a 28‐h boiling‐dry‐boiling wet strength of 6.81 MPa and a dry strength of 14.34 MPa. Results indicated that the addition of polyvinyl acetate emulsion can prolong the work life of the API adhesive. Addition of crosslinker polymeric methylene bisphenyl diisocyanate (P‐MDI) not only increased the cohesive strength of the cured adhesive by crosslinking whey proteins but also resulted in strong chemical bonds via urethane linkage in wood bondlines. Addition of polyvinyl alcohol (PVA) further increased the crosslinking density of the cured adhesive due to its capability of crosslinking whey proteins through the reaction with P‐MDI. Nanoscale CaCO₃ powder (3.5 wt %) as filler significantly improved bond strength due to its mechanical interlock with the polymers in the adhesive. SEM examinations confirmed that both PVA and nanoscale CaCO₃ improved the compatibilities of the components in the optimized whey protein‐based API adhesive. FTIR results revealed that P‐MDI reacts mainly with the residual amino groups rather than the hydroxyl groups of whey proteins. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

A MODELING STUDY ON HYDROLYSIS OF LACTOSE RECOVERED FROM WHEY AND β-GALACTOSIDASE STABILITY UNDER SONIC TREATMENT

In the present study, the aim was to investigate the effect of ultrasonication on the kinetics of hydrolysis of lactose recovered from whey. The effects of the duty cycle, acoustic power of sonifier, reaction volume, and the hydrolysis products on hydrolysis degree as well as on enzyme stability were studied. The hydrolysis reactions were carried out in 25 mM phosphate buffer solution by using a commercial β-galactosidase produced from Kluyveromyces marxianus lactis under the conditions of 37°C, pH 6.5, and processing time of 30 min. Under ultrasonic treatment, 92% of lactose charged was hydrolyzed and the residual enzyme activity was 77% under the optimum operational conditions: acoustic power of 20 W, duty cycle rate of 10%, and reaction volume of 250 mL. The corresponding values of hydrolysis degree and residual enzyme activity without ultrasonic irradiation were 81% and 68%, respectively. These results show that sonication was beneficial for hydrolysis of lactose recovered from whey. The mathematical models were derived by using the experimental data of residual lactose concentration and residual enzyme activity depending on the operating conditions. In addition, an exponential equation was used for reflecting the ultrasonic energy regarding the hydrolysis and enzyme inactivation. After evaluation of the data, the activation energy required for hydrolysis of lactose recovered from whey (E _H ) and the inactivation energy for β-galactosidase enzyme (E _D ) were found as 0.0489 and 0.0804 J mL^?1, respectively.     

Biosurfactants Production Using Permeate from Whey Ultrafiltration and Bioproduct Recovery by Membrane Separation Process

The management of whey is a challenge for dairy products where the volume produced is remarkable. This problem is minimized through membrane separation processes (MSP) to obtain whey protein concentrate, which has high added value. However, a permeate effluent stream is still generated that is composed of lactose, vitamins, and minerals, which can serve as raw material for the production of biotechnological compounds. Thus, this study aimed to produce biosurfactants using the permeate from whey ultrafiltration as part of the culture media of the bioprocess, to recover the biosurfactant produced using MSP, and to identify the biocompound. The production was carried out using Bacillus methylotrophicus and Bacillus pumilus. The variables nitrogen source (urea or ammonium sulfate), nitrogen source concentration (0.5% or 1.0%), inducer (soybean oil or biodiesel), inducer concentration (1% or 2%), and the addition of micronutrients (with our without) were studied using a fractional factorial experimental design 2^5-1_IV. In the fermentation processes, it was possible to verify the biosurfactant production through the reduction of surface tension, obtaining a minimum value of 35.07 mN/m for B. methylotrophicus and 26.02 mN/m for B. pumilus. Recovery via MSP was an efficient strategy for biosurfactant purification, which was concentrated in the fraction of the retentate. We produced a high-value-added biocompound identified as surfactin, valuing the permeate residue from whey ultrafiltration.     

Production of 2,3-butanediol from diverse saccharides via fermentation

The present study aimed to evaluate the potential use of whey to produce 2,3-BD via the fermentation of lactose and its monosaccharides, glucose and galactose, in a synthetic culture medium (medium 9, M9) using a modified strain of Escherichia coli K12 MG1655 (E. coli JFR12) at a 0.1 L/L (10 vol%) inoculum ratio, 37 °C, atmospheric pressure, an initial pH 7.4, and 100 rpm for 72 h varying the saccharide concentration from 12.5, 25, and 50 g/L. The 2,3-BD yield was ∼80 % of the theoretical yield using 25 g/L of glucose and lactose, corresponding to 0.38 g/g saccharides at a fermentation time of 48 h (glucose) and 72 h (lactose). However, the 2,3-BD yield was halved (0.19 g/g galactose), fermenting 25 g/L of galactose at 48 h. Taking into account these results, two important conclusions were determined: i) E. coli JFR12 could transform galactose into 2,3-BD although its yield was half of the yield observed with glucose at 48 h; and ii) E. coli JFR12 was as efficient as other natural 2,3-BD producers such as Klebsiella species fermenting lactose. However, the E. coli strain has the advantage of being an innocuous strain. To the best of our knowledge, there is no other study presenting the production of 2,3-BD from galactose and lactose with a genetically modified E. coli strain.     

Feed supplement recovered from dairy wastewater by biological and chemical pretreatment

A continuous process for treatment of dairy wastewater with immobilized lactic acid bacteria has been demonstrated at pilot scale. A strain of Lactobacillus plantarum was selected on the basis of a high conversion rate of lactose at low pH, a high affinity of lactose at low concentrations, and the ability to retain activity for a long time immobilized in alginate beads. Lactose was converted to lactic acid, which lowered the pH and precipitated milk proteins. The proteins were separated together with milk fat by flotation with carboxy methyl cellulose (CMC) or chitosan and gave a solid phase of approx. 10% dry matter (23% protein and 68% fat). The total chemical oxygen demand (COD_t) removed varied from 65 to 78% for CMC and 49 to 82% for chitosan. The precipitated material was used as a feed supplement for pigs to provide up to 30% of the total energy intake. No adverse effects on the pig's performance were observed. The energy feed value of the precipitate was estimated to be 2·0 feed units (FUs) per kg dry matter. © 1998 Society of Chemical Industry     

Recovery and purification of lactose from whey

One of the main problems associated with the manufacturing of cheese is the production of whey, which causes environmental pollution due to its high concentration of dissolved organic substances, mostly proteins, fat and lactose. The search for economically viable and appropriate alternative uses of whey proteins and lactose is of fundamental importance. This work investigated four integrated processes, incorporating microfiltration, ultrafiltration, ion exchange, reverse osmosis and spray-drying, for the separation and purification of lactose from whey. The recovery and the purity of the final lactose product recovered were evaluated. It was shown that the process comprising of microfiltration (nominal pore size 0.2 μm), ultrafiltration UF3 (molecular weight cut-off 5 kDa), ion exchange and reverse osmosis, a lactose purity of 99.8% (including 4.2% of galactose/glucose) and an overall lactose recovery of 74% were obtained. The lactose left over in the retentate and trapped in the membrane modules and ion exchange columns could be further recovered to improve the overall recovery.     

乳清两步发酵法制取环保型融雪剂醋酸钙镁盐

为合理利用乳酪和乳酪素的副产品乳清,研究了一种新的厌氧发酵方法将乳清中的乳糖发酵成醋酸,以此醋酸与CaO/MgO反应制备得到环保型融雪剂醋酸钙镁盐（CMA）。第一步用植物乳杆菌将乳清中的乳糖发酵成乳酸,乳酸的转化率是47.47%;第二步用丙酸杆菌将乳酸发酵成醋酸与丙酸,用气相色谱法将二者分离,得到醋酸的转化率为5.643%;用红外光谱法验证了此醋酸与CaO/MgO反应制备得到的CMA的结构。该法既有效地利用了乳酪和乳酪素的副产品乳清,又降低了环保型融雪剂醋酸钙镁盐的生产成本,具有很好的应用前景。     

The influence of the ion content of whey on the pH-activity profile of the β-galactosidase from Aspergillus oryzae

The pH-dependence of the reaction kinetics of lactase (β-galactosidase) from Aspergillus oryzae in different reaction media is presented in terms of a two-parameter model. The lactase from A. oryzae seems to have replaced the A. niger lactase on the market owing to a better activity/price ratio and may be utilised for lactose hydrolysis in acid as well as in neutral milk products. Its pH optimum is around pH 4.5. However, in the neutral pH-range its activity depended strongly on the salt content of the substrate solution. For example, its activity in whey (pH 6.5) fell to only 30% of its expected activity in a pure lactose solution at the same pH. The whey effect was the same for both soluble and immobilised lactase. The two parameter kinetic model, which included a term for competitive product inhibition gave excellent agreement with experimental data, and may thus be useful for the prediction of reactor performance with this enzyme.     

Energy requirements and production cost of the spray drying process of cheese whey

The influence of spray drying conditions on the energy required, production cost, and physicochemical characteristics of cheese whey was researched. The factors investigated were the inlet air temperature (180–220°C), outlet air temperature (80–100°C), and silica and maltodextrin (DE-10) as additives at 2 and 5% (w/w), respectively. Analysis of variance revealed that the inlet and outlet air temperatures, and the addition of additives had significant effects (p?T_inlet of 180°C, T_outlet of 80°C, and the addition of 5% additive material. Under these conditions, 0.2165?kg/h of dried product was obtained, with a moisture content of 2.08% and water activity of 0.125, and the product cost was $17.06?kg with an energy consumption of 2.0490?kW?·?h/kg of dry product.     

Barley grain as carbon substrate for fungal protein production in a farm process

A simple, non-aseptic, submerged aerobic fermentation was sought in which microbial protein could be synthesised from non-protein nitrogen, at the expense of barley carbohydrate, to supplement the protein content of barley grain for non-ruminant feeding. Screening of 23 isolates of fungi in shake flask cultures showed that microbial protein could be successfully produced by a number of different species in a medium containing barley as a source of carbohydrate. Protein synthesis was markedly affected by the addition of different sources of non-protein N to the fermentation; and (NH₄)₂SO₄ or urea proved to be good N sources in this respect. Aspergillus oryzae was selected as the most suitable species for protein synthesis, based on its performance when supplemented with the various N sources. The growth rate of A. oryzae in stirred culture was such that high yields of mycelial protein could be achieved within 24 h from a culture inoculated with a spore suspension. Under the conditions of growth used in these experiments there appeared to be little advantage in adding more than 2% barley to the medium. Higher yields of protein could be achieved at barley concentrations in excess of 2%, but only if the incubation period was extended. The tolerance of A. oryzae to low pH values was exploited to enable fungal cultures to be grown under non-aseptic conditions. Good yields of protein were obtained in 40 litre cultures grown at pH 3.5 in a modified domestic washing machine. Although protein yields were poor, non-aseptic growth was also sucesssful at pH 3.5 in 1000 litre cultures grown in an agricultural feed-mixing vessel.     

Stoichiometric analysis of Kluyveromyces fragilis growth on lactose

This paper describes results of the application of simple metabolic model principles to aerobic growth of Kluyveromyces fragilis during the utilisation of a semi‐synthetic medium simulating dairy waste (whey). The theoretical yield coefficients (maximum, true and real) of biomass on lactose and oxygen, available electrons and ATP were determined and compared with experimental data. The experimental runs were performed in a B Brown fermenter (15 dm³ of operating capacity). The yeast K fragilis was cultured in semi‐synthetic medium containing lactose (40 g dm⁻³) as a main carbon and energy source and ammonia salts as a main nitrogen source (C/N = 8.74). The yeast growth is closely related to the concentration of oxygen in the media. The experimental yields of biomass on lactose and oxygen reached 94% and 88% of real maximum theoretical values, respectively. Calculated true biomass yield coefficients were closely correlated with the values resulting from the balance analysis of stoichiometric equations. The specific maintenance requirement (m_ATP) was 14.7 mmole ATP(g DM h)^‐1. Determination of the elemental composition of the biomass during the course of fermentation resulted in observations of the cellular C/N ratio changes. The conversion of lactose carbon to biomass and CO₂ was 74.3%–81.2%. The recovery of ATP reached 79%, and the recovery of oxygen 96.2%. © 2000 Society of Chemical Industry     

The use of CO2 for reversible pH shifting,and the removal of succinic acid in a polymer‐based two‐phase partitioning bioreactor

BACKGROUND: Succinic acid (SA) is an intermediate in the production of commodity chemicals, but SA bioproduction has not yet been commercialized due to end product inhibition and high product separation costs. Two‐phase partitioning bioreactors (TPPBs) can increase volumetric productivity through in situ product removal, although SA uptake by polymers requires a pH below the pK_A2 of SA (4.2). It was proposed to reversibly reduce the pH with CO₂ sparging for absorption of SA, followed by nitrogen stripping to allow continued bioproduction after returning to metabolic pH levels. RESULTS: At 1 atm CO₂ sparging lowered the pH of RO water to 3.8 but only to 4.75 in medium, requiring acid/base pH adjustment in subsequent experiments. Actinobacillus succinogenes was temporarily exposed to pH 4.2 for between 5 min and 4 h to observe the effect on subsequent growth; cells could grow after up to 4 h of low pH exposure, sufficient time for SA uptake. Because atmospheric CO₂ could not adequately lower the pH of medium, a TPPB was operated with the pH being shifted using strong acid/base; SA was recovered in situ, however, the accumulation of salts hindered further cell growth. CONCLUSION: Several key elements of this novel processing strategy were successfully demonstrated, and work is continuing with high pressure CO₂ to achieve the desired pH adjustment levels. Copyright © 2011 Society of Chemical Industry     

FERMENTATION OF CHEESE WHEY IN AN IMMOBILIZED-CELL FLUIDIZED-BED REACTOR

Batch and continuous fermentation of cheese whey to lactic acid were carried out in a fluidized bed reactor by using Lactobacillus bulgaricus immobilized in 3% (w/v)garose. Five batch fermentations conducted under uncontrolled pH conditions and initial lactose concentrations ranging from 40 to 60g/L gave an average final lactic acid concentration of 6·9 g/L in a 48 to 50 h period. Continuous fermentation under controlled pH conditions at four different dilution rates ranging from 0·043 to 0·428 h^-1 and a lactose inlet concentration of 43·5 g/L resulted in a lactic acid yield of 0·26mg/mg lactose consumed. The maximum lactic acid concentration was 10·0 mg/mL at a dilution rate of 0·086 h^-1 with a substrate utilization of 90·5∥. The mathematical model of the system for batch and continuous operations was developed and the model parameters were determined experimentally and by non-linear multiple regression analysis.     

Continuous alcohol production from whey permeate using immobilised cell reactor systems

The present paper reports the performance of a bioreactor packed with alginate-entrapped Kluyveromyces marxianus NCYC179 for continuous fermentation of whey permeate to ethanol. A maximum ethanol productivity as 28.21 gl^?1 h^?1 was attained at D=0.42h^?1 and 75% lactose consumption (substrate feed rate in the inflowing medium was 200 g lactose I^?1). However, the higher dilution rates (0.6-1.Oh^?1) resulted in poor productivities and higher substrate washout in the effluent samples. The maximum specific ethanol production (qpi) and maximum specific lactose uptake (qsi) of the immobilised Kluyveromyces marxianus NCYC179 was found to be 3.88g ethanol/g immobilised cell/hx10^?2 and 8.75g lactose consumed/g immobilised cell/hx10^?2 respectively. A bead size of 2.5 mm in diameter and activation period of 24h of alginate beads in lactose solution (10%) prior to their packing in column reactor were found to support the efficient working of the bioreactor. The immobilised cell bioreactor system was operated continuously at a constant dilution rate of 0.15h^?1 and 10% lactose for 562 h without any significant change in the efficiency (varied from 84 to 88% of theoretical) and viability of the entrapped yeast cells (dropped from 84 to 81%).