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Fermentation and distillation of cheese whey: Carbon dioxide-equivalent emissions and water use in the production of whey spirits and white whiskey

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Abstract

Whey disposal can be both an environmental and economic challenge for artisanal creameries. Lactose in whey can be fermented to produce ethanol and subsequently distilled. The objective of this study was to use a process-based life cycle analysis to compare carbon dioxide-equivalent (CO2e) emissions and water usage associated with the artisanal or craft production of clear, unaged spirits using whey or malted barley as fermentation substrate. Differences in production were assessed based on key process differences: energy used, water used, distillation by-product disposal, and mass of CO2 produced during fermentation. For this study, whey was assumed removed from the artisanal creamery waste stream. Quantifiable differences were evaluated per 750-mL (45% alcohol by volume) functional unit and expressed as mass-equivalent CO2 emissions (kg of CO2e) and mass of water (kg) used. The CO2e emissions and water usage were quantified using published data, thermodynamic calculations, and mass-balance calculations for a hypothetical distillation system. The process-based life cycle analysis estimated that distillation of fermented whey reduced overall CO2e emissions by 8.4 kg per functional unit and required 0.44 kg less water added into the production process compared with production of a similar clear, unaged spirit using malted barley as substrate. Our preliminary analysis suggests that conversion to distilled whey spirit is a more environmentally responsible approach compared with landfill disposal of whey.

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... The production of potable spirits from whey has the potential to reduce environmental impacts of cheese and spirit production [71]. The fermentation process reduces the environmental impact of whey. ...
... K. marxianus is classified as GRAS and can be used as feed for livestock. It has also illustrated that production of a spirit from whey destined to be land spread instead of a similar grain-based spirit can reduce net CO 2 -equivalent emissions [71]. This 2018 study also indicated that the production of a wheybased spirit required less water than a grain-based spirit [71]. ...
... It has also illustrated that production of a spirit from whey destined to be land spread instead of a similar grain-based spirit can reduce net CO 2 -equivalent emissions [71]. This 2018 study also indicated that the production of a wheybased spirit required less water than a grain-based spirit [71]. These factors indicate that the production of a spirit from whey may be beneficial to the whey producer, distiller and the environment. ...
... Galactose also acts as a precursor for galactooligosaccharides, which are well studied prebiotics (Torres et al., 2010). In addition, the feasibility of whey-based spirits has been addressed in various studies (Dragone et al., 2009;Gantumur et al., 2022;Hughes et al., 2019;Risner et al., 2018Risner et al., , 2019; such products began making their way into commercial markets starting in 1978 . This points to the partial fermentation of WP-i.e., the fermentation of its glucose but not its galactose-as a means of generating multiple products exhibiting diverse possibilities in terms of their incorporation into the food supply chain. ...
... Following the first stage of the distillation described in "Distillation" section, the alcohol content was approximately 16.0%v/v. After being further concentrated in the second Table 7 Concentrations of vitamins and minerals in the products obtained through the fermentation of whey permeate (WP) by B. claussenii OYL-201, followed by its distillation Each result is expressed as a mean ± standard deviation of 3 biological replicates; each result that includes a "less than" sign shows the highest measurement obtained among 3 replicates a n = 2; one replicate had a value < 31.6 µg/100 g (Dragone et al., 2009); 45.0, (Risner et al., 2018); and 28.5, (Gantumur et al., 2022)). Additionally, the spirit we obtained had minimal acetic acid (0.02 ± 0.02 g/L) and undetectable lactic acid. ...
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Under specific conditions of oxygen availability and lactose hydrolysis, Brettanomyces claussenii OYL-201 can convert glucose in dairy coproducts into ethanol, leaving the galactose almost untouched. This approach could be applied specifically to whey permeate (WP) to develop foods with low-glycemic loads and other potential health benefits. The aims of this research are to optimize the fermentation of WP by B. claussenii, to maximize the production of ethanol and galactose, and to characterize various products obtained with this approach. For this purpose, five fermentation factors were studied to determine their impacts on ethanol and galactose: temperature (20–40 °C), substrate concentration (5–15%TS), lactase enzyme/substrate ratio (0–40 IU/ g lactose), inoculation level (6–8 log cfu/mL), and time (6–30 days). Linear models, containing quadratic and interaction effects, were built for the optimization of both responses. Optimal levels were predicted for the maximum outputs of ethanol and galactose simultaneously, which utilized the following parameters: 15%TS, 37 IU / g lactose, 28 °C, 7.5 log cfu/mL, and 30 days, which together were predicted to produce 4.0%v/v ethanol and 51 g/L galactose in the final product. These parameters were applied to 18-L fermentations, and the fermentates were processed via distillation and freeze-drying. As a result, four product streams were obtained: a fermented product with 3.4%v/v ethanol and 56 g/L galactose, a 45%v/v ethanol distillate, a galactose-rich drink base (63 g/L), and a galactose-rich powder (55%w/w). These results demonstrate that it is possible to maximize the production of ethanol and galactose from WP and to develop novel, potentially functional bioproducts from this stream.
... Upon completion of the distillation's first stage, the ethanol concentration of the obtained solution was 22.4 ± 2.1% v/v, which increased to 48.4 ± 3.8% v/v at the end of the process. Dairy-based distillates have been investigated for years for their volatile compounds profile, as well as for the reduced carbon emissions and water use associated with their production [36][37][38][39][40]. Their manufacture results in aroma profiles mainly comprised of higher alcohols, esters, and acetaldehydes, with an overall good organoleptic character [36,38]. ...
... Dairy-based distillates have been investigated for years for their volatile compounds profile, as well as for the reduced carbon emissions and water use associated with their production [36][37][38][39][40]. Their manufacture results in aroma profiles mainly comprised of higher alcohols, esters, and acetaldehydes, with an overall good organoleptic character [36,38]. Additionally, Risner, et al. [40] concluded that the conversion of cheese whey to a distilled product is more environmentally responsible compared to the production of white whiskey or whey disposal through landfilling, which emphasized another advantage of producing ethanol from dairy coproducts. No studies have been published on distillates obtained through the fermentation of MP streams. ...
Article
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Previous studies highlighted Brettanomyces claussenii as a versatile yeast that produces ethanol or acetic acid from lactose, or selectively metabolizes glucose while leaving behind galactose, depending on different operational conditions. This flexibility enables the production of galactose-rich bioproducts from liquid dairy residues. The purpose of this study is to: (i) optimize the anaerobic fermentation of milk permeate (MP) by B. claussenii to maximize the yields of galactose and ethanol and minimize leftover glucose, and (ii) combine the optimized process with distillation and drying and characterize its multiple products. Response surface methodology was used for the optimization. Three fermentation parameters were chosen as input factors: temperature (25–35 °C), inoculation level (7.0–8.5 log cfu/mL), and time (4–40 days), with three metabolites as responses: galactose, glucose, and ethanol. The optimal combination of parameters resulted in temperature, 28 °C; inoculation level, 7.6 log cfu/mL; and time, 33 days. Under these conditions, the fermented product was predicted to have 63.6 g/L galactose, 4.0% v/v ethanol, and 0 g/L residual glucose. The optimal parameters were used to run 18 L fermentations followed by distillation and freeze-drying. As a result, four product streams were obtained and characterized for relevant physicochemical and nutritional attributes. Our results show that the partial fermentation of MP by B. claussenii can be the first step to develop lactose-free, low-in-glucose, galactose-rich bioproducts, which improve the value of this residue and broaden its applications in the food supply chain.
... However, use of concentrated whey permeate (9.8% lactose) yields high ethanol content (average of 5.45% v/v). Use of concentrated permeate also increases production efficiency, albeit insignificantly so with 89.4% efficiency using concentrated compared to 87.4% for non-concentrated permeate (Koushki et al. 2012;Risner et al. 2018). However, the production of concentrated whey permeate necessitates additional processing, subsequently increasing production time and costs, thus decreasing overall efficiency, likely negating the marginally improved production efficiency. ...
... Development of whey-based novel products may provide businesses with an economic edge, whilst also providing a craft product that may be sold at a premium price. Contrarily, distillation of fermented whey has been shown to reduce CO 2 emissions by 8.4 kg per functional unit and requires 0.44 kg less water to be added to the production process compared to malted barley equivalents (Risner et al. 2018). Nevertheless, production of alcohol from waste whey is an effective means of valorisation, with the utilisation of readily available microorganism cultures and cheese whey an inexpensive methodology suitable for developing countries and small organisations (Koushki et al. 2012). ...
Article
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Whey has several environmental risks if disposed of as waste in watercourses. However, there are numerous valorisation techniques to convert it into valuable and highly nutritious products. Techniques such as membrane filtration may be utilised, but these are not applicable to all categories of whey. Novel methodologies that are agile enough to deal with whey variability can produce val-orised products. This review assesses the capability of whey processing techniques, applications and methodologies, discussing pertinent research that can innovate product development further. It focuses on environmental impacts of whey as a waste and ways of minimising it.
... The first is produced from cheeses coagulated whit rennet (Chymosin protease) while the second is obtained from cheeses made by acid precipitation, adjusting pH to 4.6 by the action of lactobacillus, adding organic acids (lactic acid) or mineral acids such as hydrochloric or sulfuric [18,23]. This by-product is considered like a source of compounds of high nutritive valued, chemically contain 93-94% of water [22], that retain approximately the 55% of solids present in whole milk, including whey protein, most of it lactose, minerals like calcium and phosphorus, [12] vitamins soluble in water [3] such as C and vitamins from B complex like thiamine, riboflavin, pantothenic acid, pyridoxine, cobalamin, [4,19] also contain lactic and citric acid, compounds non-protein nitrogens such as urea or uric acid, [14] but this components are modified depending on the type of whey, as a consequence of the manufacturing process. In general acid whey has a low pH, low concentration of protein and lactose, but contains a higher amount of calcium, phosphorus and lactic acid compared to sweet whey. ...
... The application of whey can be divided in four basic ways: applying directly in some products, separation and application of whey components, use in biotechnological processing and partial processing whit after use. [25] Therefore, as a consequence of its components, it is use directly in bakery, meat, confectionery, dairy products, flavoured, carbonated, probiotic and alcoholic beverages, increasing the nutritional value or acting as an emulsifier, gelling or foaming agent [9,12,19,22] in addition, the components of whey promote the multiplication of desirable microflora in the intestine tract. [20] As for it fractionation, from whey can be obtained lactose, whey proteins, free amino acids, vitamins and minerals useful to supplement or enrich other food products. ...
Article
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El lactosuero es un subproducto de la industria láctea, el cual posee un alto valor nutritivo por la presencia de proteínas, lactosa, vitaminas y minerales que tienen funciones biológicas de interés. El lactosuero puede ser utilizado directamente como ingrediente en diversos productos o puede ser fraccionado en sus diferentes componentes, para utilizarlos con diversos objetivos, dando así un valor agregado a este subproducto, sin embargo la falta de información acerca de su aprovechamiento ha generado que productores terminen por desecharlo perdiendo con ello valiosos componentes nutritivos. Por lo cual la presente investigación ofrece una breve revisión de los usos y propiedades del lactosuero.
... yeast varieties to distil lactose) and promote the benefits of upcycled products to environmental outcomes of whey-based alternatives. A study of whey distillation showed it would emit 8.4 kg less CO2e greenhouse gases and use 0.44 kg less water per bottle of finished product than conventional malt barley spirits (Risner et al., 2018). These environmental benefits would appeal to environmentally-conscious consumers, as well as those motivated by food waste reduction (Aschemann-Witzel et al., 2023a;Nguyen et al., 2023a,b). ...
... While CE principles aim to simultaneously achieve economic and environmental outcomes, trade-offs can occur. This is true in the context of whey, which can have considerable bene ts or costs depending on the technology option [43] and scale of production [44]. Therefore, it is not always clear to rms which option is optimal given the broad range of factors that need to be accounted for. ...
Preprint
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Halving food loss and waste by 2030 is a major global challenge. The Food Waste Hierarchy underpins strategies to achieve this, but understanding the relative importance of motivators to incentivise change is limited. This study utilises the pertinent case study of the by-product of cheese-making, 'whey', to explore this in Australia. Through semi-structured interviews with 42 nationally-representative firms, motivators were quantified using a novel 100-point allocation instrument. Profit maximisation, environmental protection, and government regulation emerge as key motivators, but there is significant heterogeneity. Motivators generally do not differ markedly across hierarchy-levels, except for government regulations, which both incentivise and disincentivise change. Findings indicate a potential failure of markets, governments and social licenses to lead to efficient resource allocation while limiting negative externalities. Pathways to challenge the status quo and transform the food system are discussed, which will likely require simultaneous forces to move enough firms up the hierarchy by 2030.
... En este contexto, la tabla 5 presenta un resumen de los resultados de máxima producción de etanol de diversos grupos de investigación, Gantumur et al. (2022) reportan un valor máximo de 56.4 g/L de etanol utilizando S. cerevisiae, mientras que Risner, Shayevitz, Haapala, Meunier-Goddik, andHughes (2018) y Guneser, Karagul-Yuceer, Wilkowska, andKregiel (2016), utilizaron K. marxianus, este último obtuvo una producción máxima de 46 g/L de etanol, excepto que en esta investigación utilizaron como fuente de carbono otro residuo agroindustrial, que contenía pulpa de tomates, pimientos y uvas procesadas. ...
Article
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El lactosuero es un residuo de la industria láctea, generado principalmente en la producción de queso. Este residuo representa entre el 80 y 90% del volumen de leche utilizada para la producción de queso, el cual se caracteriza por su alto contenido orgánico, con la capacidad de contaminar ríos, lagos, suelos, entre otros, cuando es desechado sin tratamiento previo, lo cual lo convierte de interés ambiental. Sin embargo, el principal problema de la mayoría de las industrias queseras, es no contar con sistemas adecuados para su gestión, en gran medida por su costoso tratamiento. Ante la situación planteada, la alta carga orgánica del lactosuero tiene potencial de ser valorizada como una fuente de carbono renovable, principalmente por su contenido de lactosa. Este disacárido puede ser tratado con Kluyveromyces marxianus, levadura con capacidad de degradar lactosa y utilizarla en la producción de diferentes productos. El presente documento, es una revisión de los bio-productos generados a partir de lactosuero utilizando la levadura Kluyveromyces marxianus, con el objetivo de proporcionar información comparativa de resultados de pre-tratamientos realizados al lactosuero, rendimiento de productos y reducción de contenido orgánico.
... They found that substituting water with whey or permeate in the production of Baladi bread significantly affected dough mixing qualities (Farinograph) and a slight increase in the water absorption ratio for dough preparation. According to Risner et al. (2018), it is possible to build whey spirits and white whiskey by fermentation and distillation of CW. They concluded fermented whey after distillation reduced the emission of CO2e with the rate of 8.4 kg/functional unit, and it took 0.44 kg less water for its production process compared to the same product development in the presence of malted barley as a substitute. ...
Article
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This review article explores recent advancements in converting cheese whey (CW) into high‐value‐added products, focusing on producing biofuels, bioelectricity and different whey‐based food items, as well as other potential uses. Additionally, new integrated reutilising strategies are proposed to utilise CW to develop innovative products with various applications, mainly focusing on sustainable alternatives at the industrial level. CW could be utilised with the help of different processes, for example separation of main protein components from cheese whey, like separation and purification of α‐lactalbumin, production of polysaccharides (lactose and lactulose), volatile fatty acids (VFAs), other organic acids and bioethanol. Besides these products, CW could also be utilised in the fermentation process, in the production of alcoholic drinks (whey sprite and white whisky), in the production of whey protein concentrate and as poultry feed. Biotechnological approaches for whey utilisation are the most recent alternatives. They can produce important products for the industries, such as whey‐based products, bioplastics, biofuels, bioelectricity, organic acids, bioactive compounds and whey‐based food items.
... Severe environmental issues may derive from incorrect disposal of the whey, and even legal practices such as treatments aimed at removing the organic load or animal feeding may cause technical and health problems, respectively (Pires et al., 2021). Cheese whey may be converted into value-added powders used for human or animal nutrition, but the involved processes require largescale operations and demand economic costs and energy consumption (Risner et al., 2018). However, the high organic load of cheese whey lends itself to biochemical transformations aimed at the recovery of biomaterials and energy, and, more importantly, cheese whey contains compounds characterized by high added value and great industrial interest. ...
Article
As a sustainable strategy to valorize the main effluent of the cheese industry and potent environmental pollutant, whey, several biopolymer-whey vesicles loaded with gingerol were tailored for counteracting intestinal oxidative stress and boosting wound healing. An eco-friendly method was used to combine whey with four different water-dispersible biopolymers (xanthan gum, tragacanth, Arabic gum and sodium alginate), phospholipid and a natural antioxidant (gingerol). The results of cryogenic transmission microscopy and dynamic light scattering indicated that the vesicles were mostly unilamellar and small in size (∼100 nm) with low polydispersity index, high negative zeta potential and ability to entrap a high amount of gingerol (up to 94%). The vesicles could maintain their structures in acidic and neutral media and Turbiscan® technology confirmed their stability during the storage. Vesicles prepared with whey and tragacanth exhibited the highest capability to protect intestinal cells from damages induced by hydrogen peroxide. When Arabic and tragacanth gums were added to the whey vesicles, the closure rate of the scratched area was fast and no trace of the wound was observed after 72 h of treatment. These promising findings could open a new horizon in the application of whey in nanomedicine for the treatment of intestinal damages.
... Although most of the nutritious proteins from whey are recovered, the lactose portion is mostly unused, and its disposal represents a severe environmental concern. The fermentation process reduces the biochemical oxygen demand by approximately 75% (Risner et al., 2018). Therefore, there is still scope for further work in terms of optimization value-added products, as well as the development of more economical and cost-effective strategies. ...
Article
This research aimed to advance the understanding of acceptable sensory qualities of potable whey-based spirit from nonsupplemented, mid-supplemented, and high-supplemented whey samples by analyzing major volatile compounds during different stages of distillation (head, heart, and tail). The results demonstrated that commercial Saccharomyces cerevisiae strain in lactase-hydrolyzed whey showed rapid and complete sugar hydrolysis and efficient ethanol production in 24, 30, and 36 h on average, producing up to 29.5, 42.1, and 56.4 g/L of ethanol, respectively. The variations in titratable acidity, specific gravity, pH value, residual protein, sugar content, and alcohol yield were investigated during the fermentation. The total amount of volatile compound concentrations significantly decreased from the head (2,087-2,549 mg/L) to the tail whey spirits (890-1,407 mg/L). In the whey spirit, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-1-propanol, 1-propanol, acetaldehyde, and ethyl acetate were the most prevalent ruling compounds, accounting for the largest proportion of total volatile compounds. The volatile compounds detected were far below the acceptable legal limit. The results suggest that high sensory qualities of potable whey-based spirits can be produced by fermentation of lactose-supplemented whey with S. cerevisiae cells.
... The first type is produced from cheeses obtained by coagulation with rennet, while the second is obtained from cheeses made by acid precipitation adjusting pH to 4.6 (Broyard and Gaucheron, 2015) through the action of lactobacillus, adding organic acids (lactic acid) or hydrochloric acid or sulfuric acid (Nguyen et al., 2016;Ryan and Walsh, 2016;Risnar et al., 2019). Whey is the main component obtained by the cheese industry, its chemical composition comprises 93-94% of water (Risner et al., 2018) that contains approximately 55% of the solids present in whole milk. These include whey proteins, lactose, minerals such as calcium and phosphorus (Martins et al., 2018), water soluble vitamins for example vitamin C, thiamine, riboflavin, pantothenic acid, pyridoxine and cobalamin (Chandrapala et al., 2015;Corrochano et al., 2018), organic acids such as lactic acid and citric acid, as well as non-protein nitrogenous compounds such as urea and uric acid (Monami et al., 2016). ...
Article
The hydration process is critical in soccer players. The hydrating capacity, energy recovery, and electrolyte excretion in urine were determined by the use of a whey beverage as a hydration medium for high-performance athletes compared to the effects of purified water and a sport beverage. The study was carried out through an approved research protocol, which contemplates the determination of hydrating capacity by monitoring body weight during a period of exercise and a subsequent hydration period. Energy recovery was determined by monitoring blood glucose levels and electrolyte excretion was performed by quantifying the concentration of sodium (Na+ ), potassium (K+ ), calcium (Ca2+) and magnesium (Mg2+) in urine samples provided by the participants during the research protocol. It was concluded that the whey beverage has an appropriate capacity for hydration and energy recovery, while with regard to minerals it was observed that it effectively regulates the excretion of Na+ , Ca2+ and Mg2+ .
... The concept of producing whey-based spirits has been recently shifted to small craft distilleries which used pot distillation instead of extractive method. Based on life cycle analysis, production of distilled whey-based spirit resulted more sustainable than the conventional method for unaged spirit production from malted barley in terms of carbon dioxideequivalent (CO 2 ) emissions and water usage ( Risner et al. 2018). Volatilome of distillates changed depending upon CW, with sweet whey distillates enriched in alcohols, acids, esters, and ketones, whereas acid whey distillates in aldehydes, terpenes, and terpenoids ( Risner et al. 2019). ...
Article
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Cheese whey (CW), the liquid resulting from the precipitation and removal of milk casein during cheese-making, and the second cheese whey (SCW) derived from the production of cottage and ricotta cheeses are the main byproducts of dairy industry. The major constituent of CW and SCW is lactose, contributing to the high BOD and COD content. Because of this, CW and SCW are high-polluting agents and their disposal is still a problem for the dairy sector. CW and SCW, however, also consist of lipids, proteins, and minerals, making them useful for production of various compounds. In this paper, microbial processes useful to promote the bioremediation of CW and SCW are discussed, and an overview on the main whey-derived products is provided. Special focus was paid to the production of health-promoting whey drinks, vinegar, and biopolymers, which may be exploited as value-added products in different segments of food and pharmaceutical industries.
... This by-product corresponds to 85-95% of the total milk volume and retains 55% of milk nutrients (Geiger et al. 2016). Dairy industries, especially small-and medium-sized producers of artisanal cheeses, commonly discard large volumes of whey landspreading, causing environmental contamination (Risner et al. 2018). Whey as an effluent is a potential pollutant due to its high biochemical oxygen demand, and its adequate disposal requires expensive treatment (Pescuma et al. 2015). ...
Article
Reconstituted goat whey was fermented with the starter Streptococcus thermophilus TA‐40 in co‐culture with four probiotic adjuncts (independent treatments): Lactobacillus casei BGP93 (T1), Lactobacillus paracasei BGP1 (T2), Lb. paracasei LPC37 (T3) and Lactobacillus rhamnosus LR32 (T4). Lactobacillus populations were higher than 7 log cfu/mL after fermentation and storage. Proteolysis increased significantly (P < 0.05) during fermentation in all trials. Relative amount of low‐molecular‐weight protein fractions (<6.5 kDa) increased in goat whey trials with T1, T3 and T4 during fermentation and storage. The goat whey powder was considered a potential substrate for starter and probiotic cultures, which raised the opportunities to upgrade this by‐product into a functional food.
... Although hardly economically competitive with the currently established fermentation processes using sugarcane, cornstarch or lignocellulosic biomass as substrates [1], whey fermentation has received wide attention nowadays as a way to obtain high value products [8,12,13,15,16,[32][33][34][35], because it allows combining in a valuable production strategy several advantages, among which are (a) the treatment of a polluting byproduct, (b) the production of bioethanol and (c) the production of yeast biomass with high β-gal activity. ...
Article
Cheese whey is a dairy industry by-product responsible for serious environmental problems. Its fermentation would allow reducing its environmental impact and producing, at the same time, high-value products, hence ensuring cleaner production. Batch fermentations of cheese whey permeate, either as such or 1.5-fold or twice-concentrated, by Kluyveromyces lactis CBS2359 were performed in flasks with or without agitation to select the best conditions to produce simultaneously ethanol and biomass with high β-galactosidase activity. In shake cultures, the highest ethanol concentration (15.0 g.L⁻¹), yield on consumed lactose (0.47 g.g⁻¹) and productivity (0.31 g.L-1.h⁻¹), were obtained on cheese whey permeate as such, corresponding to 87.4% fermentation efficiency, but β-galactosidase activity was disappointing (449.3-680.0 U.g⁻¹). In static cultures on twice-concentrated whey permeate, despite a decrease in fermentation efficiency and yield, ethanol production increased by 48% and β-galactosidase activity by no less than 209-367%. Therefore, cheese whey should be considered an alternative feedstock rather than an undesirable dairy industry by-product.
... Food manufacturers use now whey as a functional ingredient in food and pharmaceutical applications, and as nutrient in dietetic and health foods [9]. Additionally, milk whey has been applied for producing microbial oil [10], butanol [11], lactobionic acid [12], whey spirits and white whiskey [13] and biogas production [14]. These developments have been implemented successfully in many countries to manage properly these residues together with food and feed use. ...
Article
Energy conversion strategies based on lignocellulosic and industrial waste streams is considered a challenge in many countries producing huge quantities of biomass. The production of biogas as an energy vector has been gaining attention in the industry sector due to the energy policies for wastes managements or the feasibility of using the biogas for electricity and steam generation. An interesting feedstock alternative for the biogas production is milk whey, one of the main residues of the dairy industry. Additionally the potato stem generated in the harvest stage can be an attractive raw material for biogas production. Co-digestion is the combination of biodegradable raw materials to improve the balance of nutrients in anaerobic digestion. In this context, the characteristics of milk whey and potato stem are not enough to consider it as a good single substrate. However, the synergetic use of these two residues can represent an improvement in biogas production. The biogas production was calculated in Aspen Plus software using stoichiometric and kinetic models based on the experimental characterization of both materials. Through seven different scenarios: potato stem digestion, milk whey digestion and five co-digestion relations of both materials. Heat and electricity generation using biogas was analyzed. Then the generation of heat and electricity was simulated, where the economic profit was evaluated in terms of the production cost, capital cost, revenues and net present value. In terms of biogas production, the scenarios that involved high organic load were the best. For the economic assessment the raw material cost had the most influence over the total processing cost (80% approximately). However, even if energy is produced it is necessary to include the valorization of the digestate as biofertilizer in order that the different scenarios present economic viability.
... Traditional brewer's yeast, Saccharomyces cerevisiae, cannot use lactose (Oleary et al., 1977b). Some non-Saccharomyces yeast strains, such as Kluyveromyces marxianus (Kosikowski and Wzorek, 1977;Mawson, 1994;Risner et al., 2018), have been used to convert lactose to ethanol, but they are not used in beer brewing and are considered spoilage organisms in wines, potentially producing undesirable off-notes. Another option is the addition of lactases to break down the lactose in glucose and galactose, that can then be used by S. cerevisiae (Oleary et al., 1977a,b;Mawson, 1994). ...
Article
Acid whey, a by-product of strained yogurt production, represents a disposal challenge for the dairy industry. Utilization schemes are currently limited; however, acid whey contains valuable components that could be used to create value-added products. One potential scheme would be the fermentation of acid whey into an alcoholic beverage. Sour beers are gaining popularity and acid whey, which is sour to begin with, could provide a new product opportunity. However, the main sugar of acid whey, lactose, cannot be fermented by the traditional brewer's yeast, Saccharomyces cerevisiae. It has been reported that barley contains enzymes capable of hydrolyzing lactose to glucose and galactose, which are fermentable by S. cerevisiae. We investigated whether a barley-based mash resulted in detectable hydrolysis of lactose into sugars fermentable by S. cerevisiae. We demonstrated the ability to hydrolyze lactose in acid whey using a barley-based mash, resulting in the average release of 3.70 g/L of glucose. Additionally, the subsequent liquid was fermented by S. cerevisiae to an average ethanol concentration of 3.23% alcohol by volume. This work demonstrates the ability to hydrolyze the lactose in acid whey using barley and the opportunity to use acid whey as a fermentable sugar source in beer production.
... One avenue includes the conversion of the lactose within whey to ethanol. The fermentation process reduces the biochemical oxygen demand by approximately 75% (Siso, 1996) and it has been illustrated on an artisanal creamery level to be environmentally advantageous (Risner et al., 2018). ...
Article
Lactose within whey can be fermented and distilled to produce a potable distilled spirit. The aim of this study was to determine if acid and sweet whey types can be fermented and distilled using similar processes and to investigate differences in volatile aroma compounds for the 2 distillates. Fermentation and distillation of the 2 whey types progressed in a similar manner, using Kluyveromyces marxianus for the initial fermentation and a glass still fitted with a Vigreux column for the subsequent distillation. Ethanol content of the wash (fermented whey) varied considerably following each fermentation and ranged from 1.2 and 2.0% (wt/wt) with no clear trend between acid and sweet whey samples. Volatile aroma compounds were extracted using headspace solid-phase microextraction and identified via gas chromatography-mass spectrometry. Acid and sweet whey distillates contained unique volatile aromatic compounds, and significant differences in compound peak areas were observed. These differences may have an effect upon the organoleptic qualities of spirits produced from whey; therefore, whey source may be an important factor when fermenting and distilling whey.
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β‐Galactosidases are crucial enzymes that hydrolyse oligosaccharides and polysaccharides with terminal β‐1,4‐glycosidic bonds. Though the traditional application of β‐Galactosidases has been to catalyse the breakdown of lactose in dairy products, its application extends beyond the production of lactose‐free products since variants capable of facilitating lactose condensation and exhibiting galactosyl transferase activity are extensively utilised for the synthesis of prebiotic galacto‐oligosaccharides. This review analyses β‐Galactosidase in multiple aspects, including sources, classification, characterisation, immobilisation, genetic engineering and applications in terms of whey treatment, biofuel production, production of lactose‐free dietary product, synthesis of galacto‐oligosaccharides and the early detection of cellular senescence and tumours.
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Scotta is an underutilized whey by-product of ricotta making. In this study, we investigated the utilization of scotta in beer production. To understand the quality of regional scotta, samples from eight Sicilian ricotta makers were analyzed for pH, total protein, fat, lactose, titratable acidity, % salt, total plate count, lactic acid bacteria counts, and minerals. Overall, the samples had low amounts of residual protein and fat. The average lactose content was 4.81 g/100 mL ± 0.52 g, with a pH of 6.12 ± 0.17 and a salt content of 1.05% ± 0.24. The majority of lactic acid bacteria counts were below the limit of detection. The total plate counts were more variable, ranging between 102 to 103 CFU/mL, suggesting occasional post-processing contamination during handling. Scotta was then used to replace some of the water and sugar in the production of two beer styles: (i) a Gose, a salty and acidified German beer style, and (ii) a sweet milk stout. A trained panel used for sensory analysis found that these prototypes fit within the sensory profiles of commercial beers of these styles. This work highlights opportunities to upcycle dairy by-products into novel fermented beverages that would be appealing to consumers.
Article
Whey, a major by-product of cheese production, is primarily composed of whey protein (WP). To mitigate environmental pollution, it is crucial to identify effective approaches for fully utilizing the functional components of whey or WP to produce high-value-added products. This review aims to illustrate the active substances with immunomodulatory, metabolic syndrome-regulating, antioxidant, antibacterial, and anti-inflammatory activities produced by whey or WP through fermentation processes, and summarizes the application and the effects of whey or WP on nutritional properties and health promotion in fermented foods. All these findings indicate that whey or WP can serve as a preservative, a source of high-protein dietary, and a source of physiologically active substance in the production of fermented foods. Therefore, expanding the use of whey or WP in fermented foods is of great importance for converting whey into value-added products, as well as reducing whey waste and potential contamination.
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Under specific conditions, the fermentation of whey permeate (WP) by Brettanomyces claussenii can create bioproducts with high galactose concentrations and potential functionalities. The aims of this research are to optimize the fermentation of WP by B. claussenii using response surface methodology to maximize the production of ethanol and galactose, and to characterize various products obtained with this approach. For this purpose, five fermentation factors were studied to determine their impacts on ethanol and galactose: temperature (20 - 40°C), substrate concentration (5 - 15%TS), lactase enzyme/substrate ratio (0 - 40 IU/ g lactose), inoculation level (6 - 8 log cfu/mL), and time (6 - 30 days). Linear models, containing quadratic and interaction effects, were built for the optimization of both responses. Optimal levels were predicted for the maximum obtainment of ethanol and galactose simultaneously, which utilized the following parameters: 15%TS, 37 IU / g lactose, 28°C, 7.5 log cfu/mL, and 30 days, which together were predicted to produce 4.0%v/v ethanol and 51 g/L galactose in the final product. These parameters were then applied to 18-L fermentations, and the resulting fermentates were processed via distillation and freeze-drying. As a result, four product streams were obtained: a fermented product with 3.4%v/v ethanol and 56 g/L galactose; a 45%v/v ethanol distillate; a galactose-rich drink base (63 g/L); and a galactose-rich powder (55%w/w). These results demonstrate that it is possible to maximize the production of ethanol and galactose from the fermentation of WP and to design manufacturing processes based on these optimization models, to develop novel, potentially functional bioproducts from this stream.
Article
There are limited naturally derived protein biomaterials for the available medical implants. High cost, low yield, and batch-to-batch inconsistency, as well as intrinsically differing bioactivity in some of the proteins, make them less beneficial as common implant materials compared to their synthetic counterparts. Here, we present a milk-derived whey protein isolate (WPI) as a new kind of natural protein-based biomaterial for medical implants. The WPI was methacrylated at 100 g bench scale, >95% conversion, and 90% yield to generate a photo-cross-linkable material. WPI-MA was further processed into injectable hydrogels, monodispersed microspheres, and patterned scaffolds with photo-cross-linking-based advanced processing methods including microfluidics and 3D printing. In vivo evaluation of the WPI-MA hydrogels showed promising biocompatibility and degradability. Intramyocardial implantation of injectable WPI-MA hydrogels in a model of myocardial infarction attenuated the pathological changes in the left ventricle. Our results indicate a possible therapeutic value of WPI-based biomaterials and give rise to a potential collaboration between the dairy industry and the production of medical therapeutics.
Article
The use of the lactose present in the whey can be fermented to produce a compound of interest: lactic acid, bringing positive changes to artisanal creameries. The goal of this study was to provide basic information on the production of lactic acid from whey using a wild strain of the yeast Kluyveromycesmarxianus by evaluating the effect of the initial concentration of substrate, inoculum, and oxygen while investigating the Rheological properties of the fermentation broths. The factors were evaluated through the implementation of a completely randomized 23 factorial design. The rheological properties of the broths were determined in steady state using an Anton PaarMCR 301 rheometer. The results obtained allowed concluding that the factors that most influence the production of lactic acid is the initial concentration of substrate, inoculum and the interaction between the factors inoculum and oxygen. The fermentation broths presented a non-Newtonian behavior with dilatant characteristics, fitting the Herschel-Bulkley rheological model adequately to the experimental data (R2 =0.98). The apparent viscosity of the fermentation broths increased slightly due to the growth of the yeast, associating the parameters of yield stress and rheological behavior index to the increase of the biomass, expressed by an exponential and linear model respectively. While the parameter coefficient of consistency showed an antagonistic behavior, i. e. decreased with the increase of biomass.
Article
Consumer interest in functional beverages has been increasing recently and has led to expansion in the market. Fermented beverages containing acetic acid such as kombucha are often produced using alternative microorganisms such as lactic and acetic acid bacteria as well as non-Saccharomyces yeasts. These organisms are used to produce health-promoting compounds which make these products popular with consumers. One such alternative yeast, Brettanomyces claussenii, has been gaining recognition for its biotechnological potential. Its capabilities include fermentation of non-traditional substrates and production of valuable by-products. Specifically, this species has the ability to utilize lactose and aerobically produce acetic acid. Harnessing the potential of this yeast leads to opportunities to upcycle lactose-containing dairy by-products to acetic acid fermented beverages.
Article
Whey, a byproduct cheese production, is often treated as an industrial dairy waste. A large volume of this product is disposed of annually due to inadequate bioconversion approaches. With its high pollutant load, disposal without pretreatment has raised a lot of environmental concerns alerting the need to seek optimal methods for adequately extracting and utilizing its organic content. In recent years, several techniques for whey valorization have emerged which may serve as interventionary measures against its environmental effects after disposal. In this review, we discuss five major approaches, by which whey can be converted into eco-friendly products, to significantly cut whey wastage. The approaches to whey valorization are therefore examined under the following perspectives; whey as a raw material for the production of bioethanol and prebiotic oligosaccharides via β-galactosidase and microbe catalyzed reactions, for the production of refined lactose as an excipient for pharmaceutical purposes, the clinical significance of whey hydrolysates and its antifungal property in food processing.
Article
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Cheese whey utilization is of major concern nowadays. Its high organic matter content, in combination with the high volumes produced and limited treatment options make cheese whey a serious environmental problem. However, the potential production of biogas (methane), hydrogen or other marketable products with a simultaneous high COD reduction through appropriate treatment proves that cheese whey must be considered as an energy resource rather than a pollutant. The presence of biodegradable components in the cheese whey coupled with the advantages of anaerobic digestion processes over other treatment methods makes anaerobic digestion an attractive and suitable treatment option. This paper intends to review the most representative applications of anaerobic treatment of cheese whey currently being exploited and under research. Moreover, an effort has been made to categorize the common characteristics of the various research efforts and find a comparative basis, as far as their results are concerned. In addition, a number of dairy industries already using such anaerobic digestion systems are presented. Nomenclature AD = Anaerobic Digestion. BOD = Biological (Biochemical) Oxygen Demand. BOD 5 = Five day Biological (Biochemical) Oxygen Demand. COD = Chemical Oxygen Demand.
Article
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Cheese whey, is a byproduct of cheese or dairy industry, as raw material for ethanol production, because it contains 4.8% of lactose. This study used Fed-batch process during fermentation. The advantage of this process is to prevent the reduction in substrate for fermentation. The aim of this study is examine the optimum temperature operating conditions on ethanol production through fed-batch fermentation using Kluyveromycess marxianus with variations of temperature 300C, 350C, 400C respectively. Results showed that the highest biomass and the ethanol concentration was achieved at temperature 300C, with μ (0.186/h), Yp/s (0.21 g/g), and Yx/s (0.32 g/g).
Article
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The purpose of this study was to optimize the production of ethanol from cheese whey permeate using Kluyveromyces marxianus UFV-3. We used the response surface methodology (RSM) with a central composite rotational design (CCRD) to evaluate the effects of pH (4.5–6.5), temperature (30–45 °C), lactose concentration (50–250 g l−1), and cell biomass concentration (A600 2–4). We performed 29 fermentations under hypoxia in cheese whey permeate and seven fermentations for the validation of the equation obtained via RSM. Temperature was the most significant factor in optimizing ethanol production, followed by pH, cell biomass concentration and lactose concentration. The conditions for producing ethanol at yields above 90% were as follows: temperature between 33.3 and 38.5 °C, pH between 4.7 and 5.7, cell biomass concentration between A600 2.4 and 3.3, and lactose concentration between 50 and 108 g l−1. The equation generated from the optimization process was validated and exhibited excellent bias and accuracy values for the future use of this model in scaling up the fermentation process.
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Purpose A life cycle assessment was conducted to determine a baseline for environmental impacts of cheddar and mozzarella cheese consumption. Product loss/waste, as well as consumer transport and storage, is included. The study scope was from cradle-to-grave with particular emphasis on unit operations under the control of typical cheese-processing plants. Methods SimaPro© 7.3 (PRé Consultants, The Netherlands, 2013) was used as the primary modeling software. The ecoinvent life cycle inventory database was used for background unit processes (Frischknecht and Rebitzer, J Cleaner Prod 13(13–14):1337–1343, 2005), modified to incorporate US electricity (EarthShift 2012). Operational data was collected from 17 cheese-manufacturing plants representing 24 % of mozzarella production and 38 % of cheddar production in the USA. Incoming raw milk, cream, or dry milk solids were allocated to coproducts by mass of milk solids. Plant-level engineering assessments of allocation fractions were adopted for major inputs such as electricity, natural gas, and chemicals. Revenue-based allocation was applied for the remaining in-plant processes. Results and discussion Greenhouse gas (GHG) emissions are of significant interest. For cheddar, as sold at retail (63.2 % milk solids), the carbon footprint using the IPCC 2007 factors is 8.60 kg CO2e/kg cheese consumed with a 95 % confidence interval (CI) of 5.86–12.2 kg CO2e/kg. For mozzarella, as sold at retail (51.4 % milk solids), the carbon footprint is 7.28 kg CO2e/kg mozzarella consumed, with a 95 % CI of 5.13–9.89 kg CO2e/kg. Normalization of the results based on the IMPACT 2002+ life cycle impact assessment (LCIA) framework suggests that nutrient emissions from both the farm and manufacturing facility wastewater treatment represent the most significant relative impacts across multiple environmental midpoint indicators. Raw milk is the major contributor to most impact categories; thus, efforts to reduce milk/cheese loss across the supply chain are important. Conclusions On-farm mitigation efforts around enteric methane, manure management, phosphorus and nitrogen runoff, and pesticides used on crops and livestock can also significantly reduce impacts. Water-related impacts such as depletion and eutrophication can be considered resource management issues—specifically of water quantity and nutrients. Thus, all opportunities for water conservation should be evaluated, and cheese manufacturers, while not having direct control over crop irrigation, the largest water consumption activity, can investigate the water use efficiency of the milk they procure. The regionalized normalization, based on annual US per capita cheese consumption, showed that eutrophication represents the largest relative impact driven by phosphorus runoff from agricultural fields and emissions associated with whey-processing wastewater. Therefore, incorporating best practices around phosphorous and nitrogen management could yield improvements.
Article
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The objective of the present laboratory scale experiment was to compare ethanol production by Kluyveromyces marxianus strain ATCC8554 and Candida kefyr ATCC 14245 from unconcentrated and concentrated cheese whey permeate. The results indicated that ethanol production was greater when using concentrated whey permeate (9.8% lactose) compared to unconcentrated whey permeate (4.9% lactose) by both the yeasts, especially in presence of growth supplements. The rate and extent of ethanol formation increased noticeably and partly linearly for both the yeasts with sharp and partly linear decrease in both lactose and Chemical Oxygen Demand (COD), especially after the first 10 h of fermentation; total time of fermentation was 60 h. The optimum pH and temperature conditions for ethanol production were 4.8 and 30º C respectively. Klu. marxianus strain had greater ethanol producing ability from cheese permeate whey than Can. kefyr.
Article
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Background Kluyveromyces marxianus combines the ease of genetic manipulation and fermentation with the ability to efficiently secrete high molecular weight proteins, performing eukaryotic post-translational modifications. It is able to grow efficiently in a wide range of temperatures. The secretion performances were analyzed in the host K. marxianus L3 in the range between 5°C and 40°C by means of 3 different reporter proteins, since temperature appears a key parameter for production and secretion of recombinant proteins. Results The recombinant strains were able to grow up to 40°C and, along the tested temperature interval (5-40°C), the specific growth rates (μ) were generally lower as compared to those of the untransformed strain. Biomass yields were slightly affected by temperature, with the highest values reached at 15°C and 30°C. The secretion of the endogenous β-fructofuranosidase, used as an internal control, was efficient in the range of the tested temperature, as evaluated by assaying the enzyme activity in the culture supernatants. The endogenous β-fructofuranosidase production was temperature dependent, with the highest yield at 30°C. The heterologous proteins HSA, GAA and Sod1p were all successfully produced and secreted between 5°C and 40°C, albeit each one presented a different optimal production temperature (15, 40, 5-30°C for HSA, GAA and Sod1p, respectively). Conclusions K. marxianus L3 has been identified as a promising and flexible cell factory. In a sole host, the optimization of growth temperatures for the efficient secretion of each individual protein can be carried out over a wide range of temperatures.
Article
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Cheese-whey utilization has been the subject of much research. BOD reductions of higher than 75%, with the concomitant production of biogas, ethanol, single cell protein or another marketable product, have been achieved and about half the whey produced nowadays is not a pollutant but a resource. However, annual world cheese-whey production is increasing and new bioproductions are being sought through biotechnology in order to get full use of the whey produced. In this paper the most representative applications of cheese whey being exploited and under research are briefly discussed.
Article
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Water and wastewater management constitutes a practical problem for the food and beverage industry including the brewing industry. In spite of significant improvement over the last 20 years, water consumption and disposal remain critical from an environmental and economic standpoint. This paper gives an overview of the world beer market in order to highlight the heterogeneity in capacity of global beer production. From a synthesis of existing literature, water consumption is analysed and the most common treatments and the associated costs are reported. Finally, biological and technical alternatives including membrane operation processes and economic reality are described.
Article
Long recognized as the bestselling textbook for teaching food engineering to food science students, this 5e transitions with today's students from traditional textbook learning to integrated presentation of the key concepts of food engineering. Using carefully selected examples, Singh and Heldman demonstrate the relationship of engineering to the chemistry, microbiology, nutrition and processing of foods in a uniquely practical blend. This approach facilitates comprehensive learning that has proven valuable beyond the classroom as a lifetime professional reference. © 2014, 2009, 2001, 1993, 1984 Elsevier Inc. All rights reserved.
Article
Purpose India’s biofuel programme relies on ethanol production from sugarcane molasses. However, there is limited insight on environmental impacts across the Indian ethanol production chain. This study closes this gap by assessing the environmental impacts of ethanol production from sugarcane molasses in Uttar Pradesh, India. A comparative analysis with south-central Brazilian sugarcane ethanol is also presented to compare the performance of sugarcane molasses-based ethanol with sugarcane juice-based ethanol. Methods The production process is assessed by a cradle-to-gate life cycle assessment. The multifunctionality problem is solved by applying two variants of system expansion and economic allocation. Environmental impacts are assessed with Impact 2002+ and results are presented at the midpoint level for greenhouse gas emissions, non-renewable energy use, freshwater eutrophication and water use. Furthermore, results include impacts on human health and ecosystem quality at the damage level. Sensitivity analysis is also performed on key contributing parameters such as pesticides, stillage treatment and irrigation water use. Results and discussion It is found that, compared to Brazilian ethanol, Indian ethanol causes lower or comparable greenhouse gas emissions (0.09–0.64 kgCO2eq/kgethanolIN, 0.46–0.63 kgCO2eq/kgethanolBR), non-renewable energy use (−0.3–6.3 MJ/kgethanolIN, 1–4 MJ/kgethanolBR), human health impacts (3.6 · 10−6 DALY/kgethanolIN, 4 · 10−6 DALY/kgethanolBR) and ecosystem impairment (2.5 PDF · m2 · year/kgethanolIN, 3.3 PDF · m2 · year/kgethanolBR). One reason is that Indian ethanol is exclusively produced from molasses, a co-product of sugar production, resulting in allocation of the environmental burden. Additionally, Indian sugar mills and distilleries produce surplus electricity for which they receive credits for displacing grid electricity of relatively high CO2 emission intensity. When economic allocation is applied, the greenhouse gas emissions for Indian and Brazilian ethanol are comparable. Non-renewable energy use is higher for Indian ethanol, primarily due to energy requirements for irrigation. For water use and related impacts, Indian ethanol scores worse due groundwater irrigation, despite the dampening effect of allocation. The variation on greenhouse gas emissions and non-renewable energy use of Indian mills is much larger for high and low performance than the respective systems in Brazil. Conclusions Important measures can be taken across the production chain to improve the environmental performance of Indian ethanol production (e.g. avoiding the use of specific pesticides, avoiding the disposal of untreated stillage, transition to water efficient crops). However, to meet the targets of the Indian ethanol blending programme, displacement effects are likely to occur in countries which export ethanol. To assess such effects, a consequential study needs to be prepared.
Article
An alcoholic beverage (35.4% v/v ethanol) was produced by distillation of the fermented broth obtained by continuous whey fermentation with a lactose-fermenting yeast Kluyveromyces marxianus. Forty volatile compounds were identified in this drink by gas chromatography. Higher alcohols were the most abundant group of volatile compounds present, with isoamyl, isobutyl, 1-propanol, and isopentyl alcohols being found in highest quantities (887, 542, 266, and 176 mg/l, respectively). Ethyl acetate had the highest concentration (138 mg/l) among the esters. Besides higher alcohols and esters, other components, including aldehydes, acids and terpenes were also identified in the whey spirit. Considering that the quality of an alcoholic beverage can be evaluated by the relation between isoamyl alcohol/2-methyl-1-propanol and 2-methyl-1-propanol/1-propanol, which have to be higher than unity, it was concluded that a novel spirit of acceptable organoleptic characteristics can be produced by cheese whey continuous fermentation with K. marxianus.
Article
Solid paper-mill residues amounting to thousands of tonnes per annum are usually disposed of in landfill sites. However, by the addition of spent yeast from the brewing industry, the carbon to nitrogen ratio of these paper sludges can be adjusted to make them into a feed which can satisfy the requirements of earthworm growth. Using one such feed comprising a 66 : 1 mixture, by mass, of wet paper waste and dry yeast extract, the lob worm (Lumbricus terrestris) can be grown from the hatchling stage (50 mg) to maturity (3–4 g) within 90 days, with an acceptably low level of mortality. These large, soil-dwelling earthworms have potential value as agents in soil amelioration projects if they can be reared intensively, therefore their utilisation may be encouraged by using the type of superior feed described.
Article
Wine production generates huge amounts of waste. Before the 1990s, the most economical option for waste removal was the payment of a disposal fee usually being of around 3000 Euros. However, in recent years the disposal fee and fines for unauthorized discharges have increased considerably, often reaching 30,000-40,000 Euros, and a prison sentence is sometimes also imposed. Some environmental friendly technologies have been proposed for the valorization of winery waste products. Fermentation of grape marc, trimming vine shoot or vinification lees has been reported to produce lactic acid, biosurfactants, xylitol, ethanol and other compounds. Furthermore, grape marc and seeds are rich in phenolic compounds, which have antioxidants properties, and vinasse contains tartaric acid that can be extracted and commercialized. Companies must therefore invest in new technologies to decrease the impact of agro-industrial residues on the environment and to establish new processes that will provide additional sources of income.
Article
Cheese whey, the main dairy by-product, is increasingly recognized as a source of many bioactive valuable compounds. Nevertheless, the most abundant component in whey is lactose (ca. 5% w/v), which represents a significant environmental problem. Due to the large lactose surplus generated, its conversion to bio-ethanol has long been considered as a possible solution for whey bioremediation. In this review, fermentation of lactose to ethanol is discussed, focusing on wild lactose-fermenting yeasts, particularly Kluyveromyces marxianus, and recombinant Saccharomyces cerevisiae strains. The early efforts in the screening and characterization of the fermentation properties of wild lactose-consuming yeasts are reviewed. Furthermore, emphasis is given on the latter advances in engineering S. cerevisiae strains for efficient whey-to-ethanol bioprocesses. Examples of industrial implementation are briefly discussed, illustrating the viability of whey-to-ethanol systems. Current developments on strain engineering together with the growing market for biofuels will likely boost the industrial interest in such processes.
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