School of Chemical Engineering Current Research Studies on Tetragenococcus halophilus and Zygosaccharomyces rouxii interac.ons in soy sauce fermenta.on and formula.on in water-­‐oil-­‐water double emulsions Our research group Putu Virgina Partha Devanthi1, Hani El Kadri1, Abirajitha Manoharan1, Helen Onyeaka1, Kostas Gkatzionis1 School of Chemical Engineering, University of Birmingham, UK Chemical Engineering at Birmingham developed from the Department of Oil Engineering which was founded in the early 1900s. In the late 1940s, the Department changed its name to its current Btle. Recently, Chemical Engineering has formed the Research Centre for FormulaBon Engineering, concerning with products rather than processes. Research acBvity in the Centre for FormulaBon Engineering is divided into four research themes : (i) food, health, and nutriBon, (ii) energy and chemical industries, (iii) specialty products, (iv) bio-­‐engineering Our research group engages in areas of applied microbiology focusing on (i) applicaBons of microorganisms in food formulaBons and (ii) interacBon of microorganisms with nanomaterials. Soy sauce producBon consists of two fermentaBon stages. The first (koji) is facilitated by Aspergillus oryzae followed by the second stage (moromi) driven by the secondary microflora. Tetragenococcus halophilus and Zygosaccharomyces rouxii have been reported as key microorganisms for the development of taste characterisBcs of soy sauce. T. halophilus propagates during moromi fermentaBon and produces lacBc acid and aceBc acid, reducing the pH to <5, at which Z. rouxii is able to grow and alcoholic fermentaBon begins (1). These species could be uBlised as starter cultures subject to controlling their acBvity for avoiding antagonism. Double emulsions have been employed in probioBc bacteria encapsulaBon (2). The formulaBon of T. halophilus and Z. rouxii in a water-­‐oil-­‐water (W/O/W) double emulsion could be used for controlled release of species minimising antagonism and enhancing viability. This study aims to develop a soy sauce model system for (i) invesBgaBng the interacBon between T. halophilus and Z. rouxii and its effect on flavour formaBon (ii) tesBng the applicaBon of double emulsions during soy sauce fermentaBon. Z. rouxii in the water phase Preliminary result water oil oil Roasted, ground Soaked, cooked •  Mixed (1:1) and inoculated with Aspergillus oryzae spores •  Incubated for 3d at 30°C water T. halophilus in the conBnuous phase FormulaBon of soy sauce starter culture in double emulsion system. Z. rouxii release will be controlled by pH trigger Koji •  Koji is mixed with 18% (w/v) brine soluBon •  Incubated for 2 weeks at 30°C •  Microbial viability, pH, reducing sugar, amino nitrogen, total acids, and flavour (a) (b) (c) (d) (e) formaBon are monitored Moromi pH-­‐controlled release will be tested in moromi model system (a) control, (b) inoculated with T. halophilus, (c) inoculated with Z. rouxii, (d) inoculated with both T. halophilus and Z. rouxii at the beginning, (e) inoculated with T. halophilus followed by Z. rouxii inoculaBon a^er pH drop to <5 “With the support of the Erasmus+ programme of the European Union, Project No: 2014-­‐1-­‐MT01-­‐KA200-­‐000327” Soybean koji has been successfully made through solid-­‐state fermentaBon using Aspergillus oryzae spores. Furthermore, the nature of Tetragenococcus halophilus and Zygosaccharomyces rouxii growth has also been studied before their uBlisaBon in the moromi fermentaBon step. Our finding showed the ability of those microorganisms to grow under several salt concentraBons, although poor growth was shown in 18% NaCl medium. T. halophilus started growing exponenBally in MRS broth with 7% NaCl a^er went through 24 h of lag phase and reach maximum number of 8.28 log CFU/mL. Z. rouxii propagated more rapidly in YM broth with 5% NaCl a^er undergoing lag phase period for 4 h and reached maximum level of 7.50 log CFU/mL . In this period, linear relaBonship between cell number of T. halophilus and Z. rouxii and the opBcal density is also obtained.