Process Engineering for Bioflavour Production with Metabolically Active

Process Engineering for Bioflavour Production with Metabolically Active

<p><strong>Process engineering for bioflavour production with metabolically active yeasts - a mini-review </strong></p><p>Magnus Carlquist, Brian Gibson, Yonca Karagul Yuceer, Adamantini <br>Paraskevopoulou, Mari Sandell, Angel I. Angelov, Velitchka Gotcheva, Angel <br>D. Angelov, Marlene Etschmann, Gustavo de Billerbeck, et al. </p><p><strong>To cite this version: </strong></p><p>Magnus Carlquist, Brian Gibson, Yonca Karagul Yuceer, Adamantini Paraskevopoulou, Mari Sandell, et al.. Process engineering for bioflavour production with metabolically active yeasts - a mini-review. Yeast, Wiley, 2015, 32 (1), pp.123 - 143. ꢀ10.1002/yea.3058ꢀ. ꢀhal-01269072ꢀ </p><p><strong>HAL Id: hal-01269072 </strong><a href="/goto?url=https://hal.archives-ouvertes.fr/hal-01269072" target="_blank"><strong>https://hal.archives-ouvertes.fr/hal-01269072 </strong></a></p><p>Submitted on 28 May 2020 </p><ul style="display: flex;"><li style="flex:1"><strong>HAL </strong>is a multi-disciplinary open access </li><li style="flex:1">L’archive ouverte pluridisciplinaire <strong>HAL</strong>, est </li></ul><p>archive for the deposit and dissemination of sci-&nbsp;destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub-&nbsp;scientifiques de niveau recherche, publiés ou non, lished or not.&nbsp;The documents may come from&nbsp;émanant des établissements d’enseignement et de teaching and research institutions in France or&nbsp;recherche français ou étrangers, des laboratoires abroad, or from public or private research centers.&nbsp;publics ou privés. </p><p>Yeast </p><p>Yeast 2015; 32: 123–143. Published online 16 December 2014 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/yea.3058 </p><p>Special Issue Article </p><p>Process engineering for bioflavour production with metabolically active yeasts – a mini-review </p><p>Magnus Carlquist<sup style="top: -0.4063em;">1</sup>, Brian Gibson<sup style="top: -0.4063em;">2</sup>, Yonca Karagul Yuceer<sup style="top: -0.4063em;">3</sup>, Adamantini Paraskevopoulou<sup style="top: -0.4063em;">4</sup>, Mari Sandell<sup style="top: -0.4063em;">5</sup>, Angel I. Angelov<sup style="top: -0.4063em;">6</sup>, Velitchka Gotcheva<sup style="top: -0.4063em;">6</sup>, Angel D. Angelov<sup style="top: -0.4063em;">6</sup>, Marlene Etschmann<sup style="top: -0.4063em;">7</sup>, Gustavo M. de Billerbeck<sup style="top: -0.4063em;">8,9,10,11 </sup>and Gunnar Lidén<sup style="top: -0.4063em;">12 </sup><br>*</p><p><sup style="top: -0.3213em;">1</sup>Division of Applied Microbiology, Department of Chemistry, Lund University, Sweden <sup style="top: -0.326em;">2</sup>VTT Technical Research Centre of Finland, Espoo, Finland <sup style="top: -0.326em;">3</sup>Department of Food Engineering, Faculty of Engineering – Architecture, Canakkale Onsekiz Mart University, Terzioglu Campus, Canakkale, Turkey <sup style="top: -0.3213em;">4</sup>Laboratory of Food Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, Greece <sup style="top: -0.326em;">5</sup>University of Turku, Functional Foods Forum, Turku, Finland <sup style="top: -0.3213em;">6</sup>Department of Biotechnology, University of Food Technologies, Plovdiv, Bulgaria <sup style="top: -0.326em;">7</sup>DECHEMA Research Institute, Frankfurt am Main, Germany <sup style="top: -0.326em;">8</sup>Université de Toulouse, INSA, UPS, INP, LISBP, Toulouse, France <sup style="top: -0.3213em;">9</sup>INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, Toulouse, France <sup style="top: -0.326em;">10</sup>CNRS, UMR5504, Toulouse, France <sup style="top: -0.326em;">11</sup>INP-ENSAT, Castanet-Tolosan, France <sup style="top: -0.3213em;">12</sup>Department of Chemical Engineering, Lund University, Sweden </p><p>*Correspondence to: </p><p>Abstract </p><p>G. Lidén, Department of Chemical Engineering, Lund University, PO Box 124, SE-22100 Lund, Sweden. </p><p>Flavours are biologically active molecules of large commercial interest in the food, cosmetics, detergent and pharmaceutical industries. The production of flavours can take place by either extraction from plant materials, chemical synthesis, biological conversion of precursor molecules or de novo biosynthesis. The latter alternatives are gaining importance through the rapidly growing fields of systems biology and metabolic engineering, giving efficient production hosts for the so-called ’bioflavours’, which are natural flavour and/or fragrance compounds obtained with cell factories or enzymatic systems. Yeasts are potential production hosts for bioflavours. In this mini-review, we give an overview of bioflavour production in yeasts from the process-engineering perspective. Two specific examples, production of 2-phenylethanol and vanillin, are used to illustrate the process challenges and strategies used. Copyright © 2014 John Wiley &amp; Sons, Ltd. </p><p>E-mail: [email protected] </p><p>Received: 30 June 2014 Accepted: 1 September 2014 </p><p>Purpose and scope of this review </p><p>tongue distinguishing salt, sweet, bitter, sour and umami, and smell, which is detected by sometimes amazingly sensitive receptors in the olfactory system in the nose. The chemical diversity in flavour composition is quite large, but in order to generate a smell, the compound must be sufficiently volatile that it can reach the sensory system in the upper part of the nose (Buck and Axel, 1991; Lundström et al., 2011). Chemical synthesis and extraction <br>Flavours and fragrances are products of widespread use in food, detergents, cosmetics and pharmaceuticals. The world market was estimated to be close to $24 billion in 2013 <a href="/goto?url=http://www.leffingwell.com" target="_blank">(www.lef</a><a href="/goto?url=http://www.leffingwell.com" target="_blank">fi</a><a href="/goto?url=http://www.leffingwell.com" target="_blank">ngwell. </a><a href="/goto?url=http://www.leffingwell.com" target="_blank">com), </a>so the economic importance of these compounds is quite significant. <br>The concept of flavour is complex and involves most of our senses (Barham et al., 2010). How-&nbsp;from plant cells are the most common procedures </p><ul style="display: flex;"><li style="flex:1">ever, the central components most often discussed </li><li style="flex:1">for producing flavour compounds. Extraction- </li></ul><p>are taste, which is sensed by receptors on the dependent production has disadvantages, such as </p><p>Copyright © 2014 John Wiley &amp; Sons, Ltd. </p><p></p><ul style="display: flex;"><li style="flex:1">124 </li><li style="flex:1">M. Carlquist et al. </li></ul><p></p><p>flavour and fragrance compounds via biochemical pathways. Alternatively, bioconversion of a precursor in a single-step (or a few steps) enzymecatalysed process may also occur. Flavour and fragrance compounds that can be formed by yeasts include ketones, aldehydes, alcohols, carboxylic acids, esters, lactones and terpenoids (Figure 1). seasonal variation, risk of plant diseases, stability of the compound and trade restrictions. Chemical synthesis, on the other hand, will give compounds that, according to EU regulation (EC 1334/2008), will be termed ’flavouring substances’. The term ’nature-identical’, which was used in EC Directive 88/388 as a distinction from ’artificial’, no longer applies. Since consumers typically favour ’natural’ compounds, the price levels are substantially higher for these (Schrader, 2007). The European COST Action Bioflavour (Yeast Flavour Production – New Biocatalysts and Novel Molecular Mechanisms) was initiated to promote the development of biotechnological and eco-efficient production of natural flavour compounds. This mini-review aims to provide a background to bioflavour production in yeasts from an applied perspective, including flavour analysis and sensory evaluation aspects. Production of two specific flavour compounds, 2-phenylethanol (2-PE) and vanillin, will be used to exemplify process challenges and possible solutions from a processengineering perspective. </p><p>Flavours as an integrated part of a fermented product </p><p>The biological functions of flavours in food are manifold. They may, for example, attract animals to improve seed dispersal and propagation, or warn that the food is spoilt. Flavour compounds play an important role in consumer preference and acceptance of food products, and consumers typically prefer natural over synthetic flavour compounds. Odour- and taste-stimulating components can be classified in the following groups (Reineccius, 1999): </p><p>• Volatiles and non-volatiles formed during normal plant metabolism and remaining in the plant after harvest, e.g. essential oils, fruits and vegetable flavours. </p><p>The flavour chemistry of yeasts </p><p>• Flavour compounds produced by enzymatic reactions. <br>• Flavours developed by microorganisms and fermentation (wines and dairy products). <br>• Flavour compounds resulting from processing <br>(heat treatment, cooking, etc.). <br>Yeasts are microbes with large synthetic capacity that are able to convert simple carbohydrates and nitrogen sources into many complex molecules, including many flavour compounds, via enzymecatalysed reactions. Control of yeast-derived flavour compounds as part of fermented beverages has been of interest to producers of beer, wine, sake and other fermented beverages, as long as these processes have existed. Tailoring of process conditions to develop specific organoleptic characteristics occurred over time through artisanal observation and trial-and-error approaches. Latterly, more accurate analytical methods and an improved understanding of the biochemical mechanisms that determine flavour production have enabled more rapid development of process conditions, via hypothesis-driven research, to achieve desired flavour characteristics for particular products. A flavour compound can thus be an integrated part of </p><p>fermented liquors or food, but it can also be a dedicated product in itself. Flavour and fragrance </p><p>Fermentation processes provide wide varieties of flavour compounds in, for example, cheese, yogurt, kefir, beers, wines, soy sauce, sausages, sauerkraut, kimchi and fermented fish products. Flavour may be generated by biochemical reactions of microbial metabolism or by the activities of residual enzymes after microorganisms have lysed (Reineccius, 1999). The use of metabolically active yeasts for integrated flavour production is exemplified below by the production of alcoholic beverages, e.g. beer and wine. </p><p>Beverages </p><p>compounds can be produced de novo, i.e. simple&nbsp;Yeast is historically linked to the production of sugars and nutrients can be metabolized into&nbsp;fermented beverages. One aspect is, of course, that </p><p></p><ul style="display: flex;"><li style="flex:1">Copyright © 2014 John Wiley &amp; Sons, Ltd. </li><li style="flex:1">Yeast 2015; 32: 123–143. </li></ul><p>DOI: 10.1002/yea </p><p></p><ul style="display: flex;"><li style="flex:1">Bioflavour production with yeasts – a mini-review </li><li style="flex:1">125 </li></ul><p></p><p>Figure 1.&nbsp;Flavour and fragrance compounds produced by yeast de novo from sugars, or via biotransformation of precursors (source: Wang et al., 2011b: 404–407) </p><p>the fermentations give rise to ethanol in the bever-&nbsp;ethanol and other fusel alcohols is determined not age – thereby preserving it. However, equally im-&nbsp;only by the substrate concentration but also by the portant for the enjoyment of the beverage are the&nbsp;various factors that influence uptake and assimilaflavour compounds produced during the fermenta-&nbsp;tion of the substrate. Utilization may, for example, tion. In fermented beverages, fusel alcohols formed&nbsp;be affected by the assimilable nitrogen matrix, the through the Ehrlich pathway, schematically shown&nbsp;physical conditions, such as temperature, that may in Figure 2 (see e.g. Hazelwood et al., 2008), are&nbsp;affect uptake and the affinity of transporters for central flavour compounds. While all of the amino&nbsp;the particular substrate. All of these factors may inacids necessary for the formation of fusel alcohols&nbsp;fluence flavour differentially and distinct differcan be found in brewery worts and grape musts, iso-&nbsp;ences are observed, depending on the strain or leucine, leucine, phenylalanine and valine may be&nbsp;species involved. </p><ul style="display: flex;"><li style="flex:1">considered to be the most important, due to the fact </li><li style="flex:1">When nitrogen supplementation is considered as </li></ul><p>that their Ehrlich pathway-derived products are of-&nbsp;an option for control of the concentration of yeast ten found at concentrations close to flavour thresh-&nbsp;volatiles, the impact of the nitrogen matrix must olds, and small changes may therefore have a&nbsp;be taken into account. Hernàndez-Orte et al. significant impact on flavour perception (Christoph&nbsp;(2005) noted that an increase in available nitrogen, </p><ul style="display: flex;"><li style="flex:1">and Bauer-Christoph, 2007; Meilgaard, 1975). </li><li style="flex:1">regardless of whether this was due to higher amino </li></ul><p>An intimate relationship exists between amino&nbsp;acid or ammonium concentrations, resulted in lower acid availability and yeast higher alcohol produc-&nbsp;levels of phenylethanol (as well as methionol and tion during fermentation (Schulthess and Ettlinger,&nbsp;isoamylalcohol). The results suggest that a higher 1978; Äyräpää, 1971). Yeast production of phenyl&nbsp;level of assimilable nitrogen may reduce the uptake </p><p>Figure 2.&nbsp;Ehrlich pathway overview. The R group is different, depending on which amino acid is converted (source: Adler et al., 2011: 285–292) </p><p></p><ul style="display: flex;"><li style="flex:1">Copyright © 2014 John Wiley &amp; Sons, Ltd. </li><li style="flex:1">Yeast 2015; 32: 123–143. </li></ul><p>DOI: 10.1002/yea </p><p></p><ul style="display: flex;"><li style="flex:1">126 </li><li style="flex:1">M. Carlquist et al. </li></ul><p></p><p>of certain individual amino acids, presumably due&nbsp;(Piddocke et al., 2011), with potential for into competition for transmembrane transport. A sim-&nbsp;creased synthesis of higher alcohols during ferilar phenomenon is known to affect the levels of the&nbsp;mentation. Different protein-solubilizing enzymes vicinal diketone diacetyl during brewery fermenta-&nbsp;operate maximally under different conditions tion. The precursor of diacetyl is produced by yeasts&nbsp;(Swanston et al., 2014). Where multiple enzymes as a by-product of valine metabolism, and any&nbsp;act in concert, such as in the case of brewery increase in amino acid concentration will reduce&nbsp;malting or mashing, the amino acid profile will uptake of valine and have a direct influence on the&nbsp;be influenced by process conditions, such as diacetyl concentration of beer (and a corres-&nbsp;mashing temperature or pH. Igyor et al. (2001), ponding influence on process efficiency) (Krogerus&nbsp;for example, found that changing the malting and </p><ul style="display: flex;"><li style="flex:1">and Gibson, 2013). </li><li style="flex:1">mashing temperature significantly influenced wort </li></ul><p>While specific amino acids may be added to fer-&nbsp;nitrogen availability and resulted in beers with almentation media to tailor the final aroma and fla- tered&nbsp;concentrations of important volatile comvour profile of the medium, in practice this may&nbsp;pounds, including ethyl acetate, isobutanol and not be feasible, due to the expense of purified isoamyl&nbsp;alcohol (Igyor et al., 2001), thus providing amino acids. Other approaches that alter the amino&nbsp;further evidence that proteins in brewing may be acid profile may be equally effective without a ma-&nbsp;manipulated for the generation of free amino nitrojor effect on process cost. Process changes such as&nbsp;gen fractions with specific amino acid profiles and extended must maceration times can be used to&nbsp;potentially different functional properties. This raise the concentration and alter the relative pro-&nbsp;feature may be exploited to alter the amino acid portions of amino acids available to yeasts during&nbsp;profile and hence the flavour of the beer. </p><ul style="display: flex;"><li style="flex:1">wine fermentation (Guttart et al., 1997), a result </li><li style="flex:1">While substrate availability has an important </li></ul><p>which may explain the improved aroma quality&nbsp;influence on concentrations of higher alcohols in of wines produced after extended maceration&nbsp;fermented beverages, ultimately it is the uptake (Defranoux and Joseph, 1992). The amino acid&nbsp;and assimilation of these substrates that deterprofile of brewery worts can be influenced through&nbsp;mines higher alcohol concentration. This fact has selective hydrolysis of the available barley pro-&nbsp;been exploited to manipulate the levels of teins. Wort contains, in particular, high levels of&nbsp;2-phenylethanol and other yeast-derived com the glutelin and prolamin protein classes (Steiner&nbsp;pound during fermentation. Evolutionary engiet al., 2011). The different protein types are known&nbsp;neering of yeasts has been used to alter phenylalto contain different concentrations of individual&nbsp;anine metabolism and hence product level. amino acids with, for example, hordein, a prolamin&nbsp;Fukuda and colleagues have successfully applied protein, characterized by high levels of proline and&nbsp;this method to increase the production of glutamic acid and relatively low levels of lysine&nbsp;2-phenylethanol and 2-phenylethylacetate by (Steiner et al., 2011). Different proteases and pep-&nbsp;yeast during sake production (Akita et al., tidases are known to differentially hydrolyse bar-&nbsp;1990; Fukuda et al., 1990a, 1990b). Yeasts ley proteins, with cysteine proteases particularly&nbsp;resistant to toxic analogues of phenylalanine, such effective against the hordein proteins (Jones and&nbsp;as o-fluoro-D,L-phenylalanine or p-fluoro-D,L- Budde, 2005). A commercial enzyme preparation&nbsp;phenylalanine, showed changes in the action of has been shown to be particularly effective at liber-&nbsp;phenylalanine-dependent DAHP synthase, the ating proline and glutamic acid from spent barley&nbsp;first step in production of aromatic amino acids. grain, suggesting that the enzyme was specifically Concentrations&nbsp;of 2-phenylethanol produced targeting the hordein proteins present (Treimo&nbsp;could be increased by as much as 40-fold in et al., 2008). In this case, if the amino acids,&nbsp;adapted mutants. A similar process has been glutamic acid and proline were made available, it&nbsp;applied to brewing yeast strains for increasing would be expected that the former, being a pre-&nbsp;2-phenylethanol concentrations in lager beer ferred source of nitrogen, would promote yeast&nbsp;(Lee et al., 1995). </p><ul style="display: flex;"><li style="flex:1">growth but possibly reduce the catabolism of other </li><li style="flex:1">In addition to exploiting the potential genetic </li></ul><p>amino acids via the Ehrlich pathway. By contrast,&nbsp;diversity of Saccharomyces yeast strains, one another commercial protease was found to&nbsp;may also consider the feasibility of utilizing specifically liberate branched-chain amino acids&nbsp;non-Saccharomyces yeasts for manipulation of </p><p></p><ul style="display: flex;"><li style="flex:1">Copyright © 2014 John Wiley &amp; Sons, Ltd. </li><li style="flex:1">Yeast 2015; 32: 123–143. </li></ul><p>DOI: 10.1002/yea </p><p></p><ul style="display: flex;"><li style="flex:1">Bioflavour production with yeasts – a mini-review </li><li style="flex:1">127 </li></ul><p></p><p>the concentration of 2-phenylethanol and other&nbsp;production. Substrates from the agro-industry ofimportant yeast-derived volatiles. Such an&nbsp;ten have low costs, and the closeness to the food approach may be more acceptable in the wine&nbsp;industry in general leads to more easily obtained industry, where traditional spontaneous fermenta-&nbsp;consumer acceptance as compared to synthetic tions would be influenced to some extent by the&nbsp;flavours of petrochemical origin. A number of local non-Saccharomyces microflora. Many&nbsp;studies that focus on characterizing product yeasts, such as Kluyveromyces spp., produce high&nbsp;spectra from the bioprocessing of agro-industrial levels of 2-phenylethanol (Fabre et al., 1998) but&nbsp;biomaterial by various yeast species have been are not suitable for use in anaerobic fermentations&nbsp;reported previously. These flavour-mapping studies (Garavaglia et al., 2007). Mixed-culture wine&nbsp;have often been based on the use of gas chrofermentations involving Hanseniaspora guilliermondii&nbsp;matography (GC) analysis for the identification or Pichia anomala have been proposed by Rojas&nbsp;and quantification of volatile compounds in the et al. (2003) as being suitable for increasing the&nbsp;headspace during fermentation of the substrates in levels of certain volatiles in wine. In particular, H. litre-scale bioreactors. </p><ul style="display: flex;"><li style="flex:1">guilliermondii was shown to increase the levels of </li><li style="flex:1">Christen et al. (2000) characterized volatile com- </li></ul><p>2-phenylethyl acetate (although not 2-phenylethanol)&nbsp;pounds produced via Rhizopus-catalysed bioprocessing in wines. Concentrations of individual volatiles in&nbsp;of agro-industrial solid wastes, such as cassava wine may be controlled by careful selection of&nbsp;bagasse, apple pomace, soya bean, amaranth grain non-Saccharomyces yeasts in co-culture fermenta-&nbsp;and soybean oil. As can be expected, large differtions (Moreira et al., 2005, 2008, 2011; Viana et al., ences&nbsp;were found in the profiles of volatile com2009). The brewing industry is, however, more con-&nbsp;pounds, depending on the specific substrate. servative than the wine industry in terms of the yeast&nbsp;Acetaldehyde, ethanol, 1-propanol, ethyl acetate, employed and considerable effort is put into eliminat-&nbsp;ethyl propionate and 3-methyl butanol were some ing any possible source of wild yeast contamination.&nbsp;of the volatiles determined in the samples. The Lager beer is also characterized by a finely-balanced effect&nbsp;of the substrate type and use of precursors volatile composition which would be detrimentally af-&nbsp;on fruit flavour production in solid-state fermentafected by a disproportionate increase in any one vola-&nbsp;tion by Ceratocystis fimbriata was also demontile compound. Adaptive evolution or careful&nbsp;strated (Christen et al., 1997). Cassava bagasse has selection of brewing yeast strains may therefore be&nbsp;also been studied as a substrate for production of more acceptable than utilization of wild yeasts for fla- flavour compounds by Kluyveromyces marxianus </p><ul style="display: flex;"><li style="flex:1">vour control. </li><li style="flex:1">in an aerobic packed-bed column bioreactor </li></ul><p>Any flavour changes that can be made through sim-&nbsp;(Medeiros et al., 2001). The main volatiles deterple adjustments to process conditions are preferable to&nbsp;mined by headspace GC analysis were ethyl acetate, major changes in raw material use or production&nbsp;ethanol and acetaldehyde. </p><ul style="display: flex;"><li style="flex:1">yeast. Disproportionate uptake of phenylalanine has </li><li style="flex:1">Coffee pulp and husk are generated in large </li></ul><p>been observed at higher temperatures (Beltran et al., amounts&nbsp;in the food industry. Coffee husk was re2007) and this phenomenon may, to some extent,&nbsp;ported to be a good substrate for aroma production explain the higher concentrations of 2-phenylethanol&nbsp;by C. fimbriata (Medeiros et al., 2003); ethyl acein wine and beer fermented at higher temperatures&nbsp;tate, ethanol and acetaldehyde were identified as </p><ul style="display: flex;"><li style="flex:1">(Molina et al., 2007; Saerens et al., 2008). </li><li style="flex:1">the major volatiles. In a similar study on solid-state </li></ul><p>fermentation using coffee husk (Soares et al., 2000), acetaldehyde, ethanol, isopropanol, ethyl acetate, ethyl isobutyrate, isobutyl acetate, isoamyl acetate and ethyl-3-hexanoate were identified. <br>Orange and citric pulps are other agro-industrial substrates with high potential for yeast-based fla- </p>

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