Contents lists available at ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres Volatile compounds associated with growth of Asaia bogorensis and Asaia lannensis-unusual spoilage bacteria of functional beverages Hubert Antolak a, ⁎ , Henryk Jeleń b , Anna Otlewska a , Dorota Kręgiel a a Institute of Fermentation Technology and Microbiology, Faculty of Biotechnology and Food Science, Lodz University of Technology, 171/173 Wolczanska, 90-924 Lodz, Poland b Faculty of Food Science and Nutrition, Poznan University of Life Sciences, Wojska Polskiego 31, 60-642 Poznan, Poland ARTICLE INFO Keywords: Asaia spp. Asaia lannensis Asaia bogorensis Acetic acid bacteria Volatile compounds Food contamination Bacterial spoilage Functional beverages ABSTRACT Acetic acid bacteria of the genus Asaia are recognized as common bacterial spoilage in the beverage industry. Their growth in contaminated soft drinks can be visible in the form of flocs, turbidity and flavor changes. Volatile profiles associated with the growth and metabolic activities of Asaia lannensis and As. bogorensis strains were evaluated using comprehensive gas chromatography-time of flight mass spectrometry (GC × GC-ToF MS). Based on obtained results, 33 main compounds were identified. The greatest variety of volatile metabolites was noted for As. lannensis strain W4. 2-Phenylethanol, 3-pentanone, 2-nonanol, 2-hydroxy-3-pentanone, and 2-nitro-1- butanol were detected as dominant volatile compounds. Additionally, As. lannensis strains formed 2-propenoic acid ethyl ester. As. bogorensis ISD1 was distinguished by the higher concentration of 2-hydroxy-3-pentanone and 3-methyl-1-butene but the lowest concentration of 2-phenylethanol. Based on these results, it was found that volatile profiles of Asaia spp. are unique among acetic acid bacteria. Moreover, obtained profiles depended not only on bacterial species and strains but also on the composition of culture media. 1. Introduction Globalization and industrialization of food-supply chains, as well as changes in eating habits and consumer behavior, influenced public in- terest in food quality and safety (Oms-Oliu, Odriozola-Serrano, & Martín-Belloso, 2013). Food contamination, either from the micro- biological or chemical origin, is the highest concern for consumers (Nerín, Aznar, & Carrizo, 2016). Therefore, continuous research on the analysis of the composition of chemical compounds derived from food, as well as on metabolites resulting from food contamination is con- ducted (Castro-Puyana & Herrero, 2013). In general, metabolomics is an emerging field that use multiple analytical platforms for different applications. Metabolomics is an important tool which may provide in- depth insights into human diseases and nutrition, drug discovery, plant physiology and others. In food science, it can be used as a tool for quality, processing and safety of raw materials, and final products as- sessment (Cevallos-Cevallos, Reyes-De-Corcuera, Etxeberria, Danyluk, & Rodrick, 2009; Hu & Xu, 2013). The key steps in metabolic profiling are separation and detection of metabolites. Main separation techniques are liquid chromatography in high-performance (HPLC) or ultra-per- formance (UPLC), gas chromatography (GC), and capillary electro- phoresis (CE). Detection techniques coupled to these separation techniques are mass spectrometry (MS), nuclear magnetic resonance (NMR), as well as near infrared spectroscopy (NIR) (Cevallos-Cevallos et al., 2009). In the field of food metabolomics, most separation ana- lyses have been achieved by gas chromatography, capillary electro- phoresis, and liquid chromatography. Generally, gas chromatography coupled to mass spectrometry (GC–MS) is one of the most widespread routine metabolomics methods applied to the large scale screening of biological material (Koek, Jellema, van der Greef, Tas, & Hankemeier, 2011). Although, due to a high number of metabolites belonging to different chemical classes, food samples are quite complicated to ana- lyze. Therefore, comprehensive two-dimensional gas chromatography (GC × GC), combined with MS is widely used in the analysis of these type of samples (Strączyński & Ligor, 2018). Gas chromatography has been used in the analysis of profiles characteristic to certain micro- organisms (Güneşer, Karagül-Yüceer, Wilkowska, & Kregiel, 2016; Wilkowska, Kregiel, Guneser, & Karagul Yuceer, 2014). It has been documented that GC is extremely useful in the analysis of food products contaminated by microorganisms (Ellis et al., 2012), such as molds existing in post-harvest fruits (Pan, Zhang, Zhu, Mao, & Tu, 2014), bacteria present in cooked shrimps (Jaffrès et al., 2011), cold-smoked salmon (Jørgensen, Dalgaard, & Huss, 2000), Listeria monocytogenes in milk (Beale, Morrison, & Palombo, 2014) or Salmonella Typhimurium in https://doi.org/10.1016/j.foodres.2019.03.054 Received 14 November 2018; Received in revised form 24 March 2019; Accepted 25 March 2019 ⁎ Corresponding author. E-mail address: hubert.antolak@p.lodz.pl (H. Antolak). Food Research International 121 (2019) 379–386 Available online 26 March 2019 0963-9969/ © 2019 Published by Elsevier Ltd. T