RELATIONSHIP BETWEEN FREE AND COMPLEXED FORMS OF COPPER IN MALT WHISKEY DISTILLERY SPENT WASH

The spent wash produced by an Irish malt whiskey distillery was sampled over a four-year period. Total soluble copper levels of up to 8·5 ppm were found; these varied with wash pH. No more than 6% of total soluble copper was present as the free ion; the level varied with wash pH as well as with its free amino acid and total soluble copper content. However, up to 83% of total spent wash copper was in an insoluble form associated with its suspended solids.     

Comparison of Industrial Scale Ethanol Production from a Palmyrah‐Based Carbon Source by Commercial Yeast and a Mixed Culture from Palmyrah Toddy

Palmyrah (Borassus flabellifer) based products were used as an alternative carbon source for industrial scale ethanol production. The fermentation medium was enriched with spent wash obtained from a distillation column. The performance of a commercially available baker's yeast in the media was compared with a ‘palmyrah toddy mixed culture’ where the organisms were obtained from the sedimentation of palmyrah toddy. In a laboratory scale study, the ethanol produced from a palmyrah fruit pulp extract, diluted with distilled water, was 16.5 gL^?1 (36 h) and 13.0 gL^?1 (48 h) with ‘palmyrah toddy mixed culture’ and baker's yeast respectively. The ‘palmyrah toddy mixed culture’ performed better than the baker's yeast with palmyrah fruit pulp extract, diluted either with distilled water or spent wash. Among the different palmyrah based carbon sources, both cultures preferred molasses diluted with spent wash and both performed best in the medium containing the spent wash supplemented with sucrose. In a 5,000 L industrial scale fermentation of 20° Brix molasses supplemented with 10 gL^?1 ammonium sulphate, 72 gL^?1 and 65 gL^?1 ethanol was produced by the ‘palmyrah toddy mixed culture’ (72 h) and the baker's yeast (90 h) respectively. As the performance of the ‘palmyrah toddy mixed culture’ was better than that of the baker's yeast, the former was selected for the industrial scale studies of molasses fermentation media diluted with spent wash. In these studies the temperature reached 42°C by 36 h and resultant cell death was observed. However ethanol production was higher and more rapid in the molasses diluted with spent wash, rather than in the molasses diluted with tap water and supplemented with (NH₄)₂SO₄. Cell recycle operation obviated the interruption in fermentation caused by temperature induced cell death and increased rates and efficiency of ethanol production were observed.     

Evaluation of whisky distillery by-products IV.—Evaporated spent wash as a supplementary food with low-quality roughages for cattle

Evaporated spent wash, a whisky distillery by-product, has been evaluated as a supplementary food with low-quality roughage for beef cattle. Three levels of the material were used, the two lower levels with small amounts of barley. None of the supplements produced a marked increase in intake of roughage. Digestibility of the diet was substantially increased when spent wash or spent wash and barley was included and an intake of metabolisable energy of approximately 80% of the animal's maintenance requirement was obtained. The spent wash was found to be rich in nitrogenous compounds, phosphorus and copper but very low in calcium and sodium.     

Palmyrah Distillery Spent Wash for Ethanol Production by a Thermotolerant Saccharomyces cerevisiae S1 at 40°C

Palmyrah distillery spent wash was used as an alternative to the predefined PYN medium (peptone, yeast extract, magnesium sulphate, potassium hydrogen phosphate and ammonium sulphate). In this study, the focus was on the utilization of spent wash from Sri Lankan palmyrah based distilleries to reduce the biological oxygen demand (BOD). To utilise the spent wash, it was supplemented with glucose and different nitrogen sources. Replacing PYN medium with spent wash and the increase in the glucose concentration led to a decrease in ethanol production. Hydrolysis of spent wash with a commercial protease (Neutrase) and supplementation with 200 gL^?1 glucose produced 73.4 gL^?1 ethanol. Among the different nitrogen sources supplemented 4.6 gL^?1 (NH₄)₂SO₄ increased ethanol production to 92.5 gL^?1 indicating that the spent wash could be economically used to produce ethanol, while decreasing the BOD from 25,000 to 4,000 mgL^?1.     

Oxidative stability of water/oil mixtures as influenced by the addition of free Cu or Cu–alginate gel beads

The formation of Cu–alginate complexes and the impact of free or bound copper on the oxidative stability of model water/oil mixtures containing edible sunflower or corn oil were examined. Equilibrium dialysis showed that copper binding capacity of alginate increased proportionally with copper concentration and the binding was rapid. The results indicated that 25 mM CuCl₂ was necessary in obtaining beads of spherical shape and adequate mechanical strength (0.45 N at 80% compression) to avoid rupture during mixing, whereas lower CuCl₂ concentrations resulted in weak gel beads (0.34 N) of irregular shape. When Cu–alginate beads were dispersed in the aqueous phase to give 0.5 mM copper, the peroxide value of water/corn oil mixtures was 3.7 mEq peroxide/kg oil after 7 days. Corn oil-containing mixtures with 0.5 mM free Cu²⁺ in the aqueous phase had a peroxide value ∼3 times higher (P < 0.001) after the same storage time. However, copper binding by alginate did not significantly reduce the peroxide values of the water/sunflower oil mixtures. Results indicated that the binding of pro-oxidant minerals, such as copper, in alginate beads can reduce the levels of oxidation in water/oil mixtures.     

Tannin fraction from Ampelopsis grossedentata leaves tea (Tengcha) as an antioxidant and α‐glucosidase inhibitory nutraceutical

Leaf of Ampelopsis grossedentata is a new resource of functional foods with healthful properties. Antioxidant and α‐glucosidase inhibitory activities of water extract (made in the style of drinking), tannin fraction (TF) and dihydromyricetin (DMY) from A. grossedentata leaves were evaluated. The main component of TF was identified as gallotannins. DPPH and ABTS radical scavenging activities and reducing power of TF were superior to those of water extract, however, inferior to those of DMY. In no PBS wash protocol of cellular antioxidant activity assay, DMY and TF exhibited similarly, while in PBS wash protocol, the value of TF was higher than that of DMY. In addition, TF possessed the highest α‐glucosidase inhibitory activities (IC₅₀ = 1.94 μg mL^?1), followed by water extract (IC₅₀ = 23.10 μg mL^?1) and DMY (IC₅₀ = 72.21 μg mL^?1). The strong α‐glucosidase inhibitory activity of TF may attribute to the binding capacity to enzymes, as confirmed by fluorescence analysis.     

Selective separation of the major whey proteins using ion exchange membranes

Synthetic microporous membranes with functional groups covalently attached were used to selectively separate β-lactoglobulin, BSA, and α-lactalbumin from rennet whey. The selectivity and membrane performance of strong (quaternary ammonium) and weak (diethylamine) ion-exchange membranes were studied using breakthrough curves, measurement of binding capacity, and protein composition of the elution fraction to determine the binding behavior of each membrane. When the weak and strong anion exchange membranes were saturated with whey, they were both selective primarily for β-lactoglobulin with less than 1% of the eluate consisting of α-lactalbumin or BSA. The binding capacity of a pure β-lactoglobulin solution was in excess of 1.5 mg/cm² of membrane. This binding capacity was reduced to approximately 1.2 mg/cm² when using a rennet whey solution (pH 6.4). This reduction in protein binding capacity can be explained by both the competitive effects of other whey proteins and the effect of ions present in whey. Using binary solution breakthrough curves and rennet whey breakthrough curves, it was shown that α-lactalbumin and BSA were displaced from the strong and weak anion exchange membranes by β-lactoglobulin. Finally, the effect of ionic strength on the binding capacity of individual proteins for each membrane was determined by comparing model protein solutions in milk permeate (pH 6.4) and a 10 mM sodium phosphate buffer (pH 6.4). Binding capacities of β-lactoglobulin, α-lactalbumin, and BSA in milk permeate were reduced by as much as 50%. This reduction in capacity coupled with the low binding capacity of current ion exchange membranes are 2 serious considerations for selectively separating complex and concentrated protein solutions.     

Sorption and desorption of perchlorate and U(VI) by strong-base anion-exchange resins

This study investigated the sorption affinity and capacity of six strong-base anion-exchange (SBA) resins for both uranium [U(VI)] and perchlorate (ClO4-) in simulated groundwater containing varying concentrations of sulfate (SO4(2-)). Additionally, desorption of U(VI) from spent resins was studied to separate U(VI) from resins with sorbed ClO4- for waste segregation and minimization. Results indicate that all SBA resins investigated in this study strongly sorb U(VI). The gel-type polyacrylic resin (Purolite A850) showed the highest sorption affinity and capacityfor U(VI) butwasthe least effective in sorbing ClO4-. The presence of SO4(2-) had little impact on the sorption of U(VI) but significantly affected the sorption of ClO4-, particularly on monofunctional SBA resins. A dilute acid wash was found to be effective in desorbing U(VI) but ineffective in desorbing ClO4- from bifunctional resins (Purolite A530E and WBR109). A single wash removed approximately 75% of sorbed U(VI) but only approximately 0.1% of sorbed ClO4- from the bifunctional resins. On the other hand, only 21.4% of sorbed U(VI) but approximately 34% of sorbed ClO4- was desorbed from the Purolite A850 resin. This study concludes that bifunctional resins could be used effectively to treatwater contaminated with ClO4- and traces of U(VI), and dilute acid washes could minimize hazardous wastes by separating sorbed U(VI) from ClO4- prior to the regeneration of the spent resin loaded with ClO4-.     

Electrocoagulation for the removal of copper from distillery waste streams

Electrocoagulation, an electrochemical technique used to remove heavy metals from wastewaters, was explored in relation to its potential to remove copper from distillery waste streams. An initial laboratory‐scale study demonstrated that copper in spent lees could be reduced by up to 95% using electrocoagulation. Copper could not be removed from caustic washwater, as passivation of the electrodes meant that no floc was formed. However, the washwaters could be treated if mixed with spent lees, with an 80% reduction in copper being obtained. The electrocoagulation system was scaled up and its performance evaluated in a trial at a large Scotch malt whisky distillery. Copper reductions of 88% were achieved at low power consumption (34 W h/m³), while at 112 W h/m³ residual copper levels were reduced by 96%. This trial was carried out at a flow rate of 1000 L/h, demonstrating that the technology could readily handle the volumes and flow rates required in practice. Both the capital and running costs of an electrocoagulation system are low, while the technique presents other advantages over the existing copper removal technologies currently in use in the distilled spirits sector. Copyright © 2014 The Institute of Brewing & Distilling     

Feasibility of the SPME method for the determination of the aroma retention capacity of proteose–peptone milk protein fraction at different pH values

The work aimed to develop a “true headspace-SPME–GC” method for evaluating the aroma retention capacity of the proteose–peptone (PP) milk protein fraction. The SPME analytical conditions were optimized in aqueous solution to which was added a blend containing seven aroma compounds from different chemical classes. The following parameters were tested: sample equilibrium time, fibre coating and fibre exposure time. The optimal equilibrium time was found to be 4 h and the DVB/CAR/PDMS fibre offered the highest sensitivity and repeatability. Finally, a 1 min fibre exposure time was chosen in order to avoid aroma competition and extraction phenomena. This method was then employed to evaluate the flavour binding capacity of PP aqueous systems at different pH values (6.8, 5.0 and 3.8). For all the pH conditions the retention capacity of the PP fraction gradually increased with hydrophobic chain length or overall hydrophobicity of the aroma compounds. Higher aroma binding capacity was found at pH 3.8.     

Composition and nutritional evaluation of microbial biomass grown on whiskey distillery spent wash

Microbial biomass produced from malt whiskey distillery spent wash, composed of a mixture of the filamentous fungus Geotrichum candidum and the yeasts Hansenula anomala and Candida krusei, had crude protein contents of 48 and 52 g 100 g^?1 and ‘true protein’ contents of 38 and 42 g 100 g^?1 when grown in batch and continuous culture respectively. Analyses of amino acid composition showed that the essential amino acid content was between 45 and 49 g 16 g^?1 N and the essential amino acid index between 0.66 and 0.70. The sulphur-containing amino acids were limiting, being between 49 and 59% deficient compared with the requirements of the growing rat. In rat feeding trials the biomass had a biological value of 0.53, a net protein utilisation value of 0.40 and a digestibility of 0.75 based on its crude protein content. Supplementation of the biomass with methionine and admixture in a ratio of 1:9 with distillers spent grains raised the NPU values to 0.49 and 0.55 respectively. Comparison of the composition and nutritional quality with that of distillers' dark grains demonstrated that the biomass was of a higher quality, and when either supplemented with methionine or mixed with distillers' spent grains was comparable with soya-bean meal.     

Removal efficiency and binding mechanisms of copper and copper-EDTA complexes using polyethyleneimine

Copper is used extensively in semiconductor circuits as the multilayer metal. In addition to copper, waste streams often contain chelating agents like EDTA, which is widely used in the process to enhance solubility of copper, and it tends to form copper-chelated complexes. PEI--agarose adsorbents in a packed-bed column are capable of removing these anionic complexes, but the competitive binding between this chelating agent and PEI for copper is not well understood and needs to be explored.The current work focuses on investigating copper sorption by PEI-agarose adsorbent in the presence of EDTA. The pH of the column is fixed at 5.5 using 0.1 M acetate buffer. The ratio of chelator to copper ions is varied. Copper binding capacity and copper breakthrough curves are compared and contrasted to results without additional chelator present. An excess of EDTA leads to an increase in the fraction of free dissociated (anionic) ligand that competes for electrostatic attraction on protonated amine groups and therefore leads to a decrease in sorption capacity in the column. However, this waste treatment technique is still feasible for the semiconductor industry as large volumes of copper-contaminated solutions from actual waste can be concentrated 12-fold. When equimolar (copper to EDTA) or higher concentrations of EDTA are present, acetate can be utilized to recover the metal; for low ratios of copper to EDTA, metal recovery is achieved using hydrochloric acid.     

Investigation of the peptides with calcium chelating capacity in hydrolysate derived from spent hen meat

Calcium peptide chelates are developed as efficient supplements for preventing calcium deficiency. Spent hen meat (SHM) contains a high percentage of proteins but is generally wasted due to the disadvantages such as hard texture. We chose the underutilized SHM to produce peptides to bind calcium by proteolysis and aimed to investigate chelation between calcium and peptides in hydrolysate for a sustainable purpose. The optimized proteolysis conditions calculated from the result of response surface methodology for two-step hydrolysis were 0.30% (w_enzyme/w_meat) for papain with a hydrolysis time of 3.5 h and 0.18% (w_enzyme/w_meat) for flavourzyme with a hydrolysis time of 2.8 h. The enzymatic hydrolysate (EH) showed a binding capacity of 63.8 ± 1.8 mg calcium/g protein. Ethanol separation for EH improved the capacity up to a higher value of 68.6 ± 0.6 mg calcium/g protein with a high association constant of 420 M⁻¹ (25°C) indicating high stability. The separated fraction with a higher amount of Glu, Asp, Lys, and Arg had higher calcium-binding capacity, which was related to the number of ─COOH and ─NH₂ groups in peptide side chains according to the result from amino acid analysis and Fourier transform infrared spectroscopy. Two-step enzymatic hydrolysis and ethanol separation were an efficient combination to produce peptide mixtures derived from SHM with high calcium-binding capacity. The high percentage of hydrophilic amino acids in the separated fraction was concluded to increase calcium-binding capacity. This work provides foundations for increasing spent hen utilization and developing calcium peptide chelates based on underutilized meat.     

Disinfection potential of ozone, ultraviolet-C and their combination in wash water for the fresh-cut vegetable industry

The purpose of this research was to investigate the disinfection efficacy of ozone (O₃) and UV-C illumination (UV), and their combination (O₃–UV) for reducing microbial flora of fresh-cut onion, escarole, carrot, and spinach wash waters collected from the industry. Furthermore, the influence of water physicochemical parameters on the decontamination efficacy and the effect of these technologies on physicochemical quality of wash water were analyzed. O₃, UV, and O₃–UV were effective disinfection treatments on vegetable wash water, with a maximum microbial reduction of 6.6 log CFU mL⁻¹ after 60 min treatment with O₃–UV. However, maximum total microbial reductions achieved by UV and O₃ treatments after 60 min were 4.0 and 5.9 log CFU mL⁻¹, lower than by O₃–UV treatment. Furthermore, turbidity of wash water was reduced significantly by O₃ and O₃–UV treatments, while UV treatment did not affect the physicochemical quality of the water. Conclusions derived from this study illustrate that O₃ and O₃–UV are alternatives to other sanitizers used in the fresh-cut washing processes. The use of these technologies would allow less frequent changing of spent water and the use of much lower sanitizer doses. Nevertheless, in specific applications such as carrot wash water, where levels of undesirable microbial and chemical constituents are lower than other vegetable wash water, UV treatment could be an appropriate treatment considering cost-effectiveness criteria.     

Potential sources of copper contamination of farm milk supplies measured by atomic absorption spectrophotometry.

A method was developed to use atomic absorption spectrophotometry for copper measurements in milk filtrates prepared from equal volumes of milk and 20% trichloracetic acid. Results are reported for 11 farms for water supplies, wash and rinse solutions, and milk. Copper below 10 mug/liter was found at the well for the 5 farms with their own spring supply. Averages and ranges for all 11 farms in mug/liter were 33 (0 to 156) at the cold water tap in the milk house, 220 (8 to 1,360) at the hot water tap, 246 (8 to 1,722) in the wash sink with added detergent and hot water, and 275 (9 to 1,823) after using the wash solution. Rinse solution with hypochlorite in cold water showed a rise from 31 (1 to 157) before use to 51 (5 to 206) after use. Copper in milk averaged 99 mug/liter (72 to 163). In spite of relatively high copper in wash solutions, copper in milk was not correlated postively, giving rise to question whether adsorbed copper from such solutions can contribute much copper to milk. Thorough rinsing with low copper cold water and a high dilution ratio in milk were seen as mitigating factors. Direct contact of milk with copper bearing metals presented a greater opportunity for contamination. Removal of substantial amounts of copper from pipe lines and bulk tanks with sulfamic acid was demonstrated.     

ETHYL CARBAMATE FORMATION IN THE PRODUCTION OF POT STILL WHISKY

The formation and distribution of ethyl carbamate (urethane) during pot still distillation was investigated. Formation only occurred if the distillation was carried out in the presence of copper. Removal or chelation of dissolved or suspended copper prevented ethyl carbamate formation. When copper was present, during and subsequent to distillation, formation of ethyl carbamate was time-dependent. The degree of formation was maximised between pH 4 and 6. During the second or low wines distillation only 1–2 per cent of the total available ethyl carbamate was collected with the potable spirit fraction. The remainder was distributed between the feints (15 per cent) and the spent lees (84 per cent).     

Separation of immunoglobulins and lactoferrin from cheese whey by chelating chromatography

Different adsorption and chelating chromatographic methods were used to isolate immunoglobulins and lactoferrin from cheese whey. Among three adsorption solid supports (silica, controlled pore glass, and alumina), controlled pore glass showed the highest adsorption of immunoglobulins; however, its capacity was low. 1,4-Butanediol diglycidyl etheriminodiacetic acid on Sepharose 6B was loaded with copper ion and used for the same purpose. Of the two peaks eluted using pH gradient, the first yellowish peak was rich in lactoferrin and the second was rich in Ig. The purity of IgG in the Ig rich fraction as indicated by radial immunodiffusion was 77.2 and 53.0% for acid whey and Cheddar cheese whey, respectively. The capacity of the column was high; a 25-ml copper charged column could absorb Ig from 1 L of cheese whey. Modification of histidine residues in Ig with diethyl pyrocarbonate almost completely eradicated the adsorption, implicating the coordination compound formation between histidine in Ig and Cu on the chelating column as the adsorption mechanism. Enzyme-linked immunosorbent assays of the Ig thus separated demonstrated their binding activity against lipopolysaccharides extracted from Escherichia coli, Salmonella typhimurium, and Bordetella parapertussis.     

Study on utilizing solid food industry waste with brewers' spent grain and potato pulp as possible peroxidase sources

This study found that extracts containing ionically bound proteins, isolated from potato pulp and brewers' spent grain, were characterized by high peroxidase activities. The kinetic parameters, namely K_m and V_max values, were typical for plant peroxidases. Seven peroxidase isoenzymes in potato pulp and two isoenzymes in brewers' spent grain were obtained from their respective ionically bound fractions. Peroxidases from both potato pulp and brewers' spent grain displayed high storage stability, over a 90‐day‐long storage period, if stored at ?20°C with glycerol added to a concentration of 50% or as unsupplemented extracts at 4°C. Peroxidase activity was present in the covalently bound fraction of potato pulp, whereas it was absent in the respective fraction of brewers' spent grain. Covalently bound peroxidases from potato pulp displayed high activity, but low stability. Peroxidases extracted from brewers' spent grain and potato pulp, followed the ping‐pong mechanism and the sequence mechanism, respectively.

Practical applications

Plant peroxidases are widely applicable in various fields of biotechnology and diagnostics. These enzymes are used for biosensor and glucometer construction and in conjugation with antibodies for the purpose of enzyme immunoassays. Using waste products as a peroxidase source provides a cost‐friendly alternative to commercially available horseradish peroxidase and gives an opportunity to recycle waste from the food industry—processed plant biomass. Here, the properties of peroxidases from food waste products, namely potato pulp and brewers' spent grain are analyzed. The extracts were characterized by high storage stability and high enzymatic activity, which are two key traits necessary for the practical use of enzyme preparations.     

Evaluation of harvested mushrooms and viability of Agaricus bisporus growth using casing materials made from spent mushroom substrate

The present work evaluates of harvested mushroom and viability of Agaricus bisporus growth in several casing materials based on spent mushroom substrate. The experiment consisted of eight casing layer, which six were made with spent mushroom substrate. The results confirm the usefulness of reincorporating the spent substrate in new cultivation cycles as an ingredient of casing mixtures. In general, biological efficiency was high, three of the SMS based‐casings surpassing the threshold value of 100 kg 100 kg^?1 of compost. The high electrical conductivity of mixtures containing a large proportion of spent substrate limits the extent to which it can be used, although mixing it with other materials (such as peat) reduces these values to acceptable levels. In short, it makes economic and environmental sense to reuse spent mushroom substrate as an ingredient of alternative casing materials.     

Copper bioavailability from breakfasts containing tea. Influence of the addition of milk

The influence of drinking tea on copper bioavailability is unclear, particularly when tea is consumed with food. A breakfast meal containing white bread, margarine, strawberry jam, cheese and tea, with or without milk, was digested in; vitro and the dialysis of copper investigated. Reference breakfasts were prepared with water and water with milk. Copper dialysability (percentage of copper dialysed) was markedly increased by tea. The influence of adding milk to tea was not significant. A second study was carried out in rats using the breakfasts containing tea and water. They were spiked with ⁶⁴Cu and given orally to the animals in a single dose. Whole-body ⁶⁴Cu retention was measured over a 4-day period after administration. In order to determine the true absorption of ⁶⁴Cu a control group of rats received the dose intraperitioneally. The results in vivo indicate a tendency to higher absorption and retention of ⁶⁴Cu with tea. Liver ⁶⁴Cu retention was significantly elevated by tea. Therefore, the presence of tea in a breakfast meal favours the formation of soluble low-molecular-weight ligands which can be absorbed and retained by rats. The concomitant increase in liver copper retetition may be associated with higher bioavailability and/or lower copper mobilisation.