Development of spoilage bacterial community and volatile compounds in chilled beef under vacuum or high oxygen atmospheres Elina Jääskeläinen a, ⁎, Jenni Hultman a , Jevgeni Parshintsev b , Marja-Liisa Riekkola b , Johanna Björkroth a a Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland b Laboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki, Helsinki, Finland abstract article info Article history: Received 11 September 2015 Received in revised form 22 January 2016 Accepted 31 January 2016 Available online 2 February 2016 Chemical compounds studied in this article: Acetoin (PubChem CID: 179) Acetic acid (PubChem CID: 176) Butanoic acid (PubChem CID: 264) Diacetyl (PubChem CID: 650) Ethanol (PubChem CID: 702) Hexanal (PubChem CID: 6184) Hexanoic acid (PubChem CID: 8892) Nonanal (PubChem CID: 31289) 1-octen-3-ol (PubChem CID: 18827) 2-octen-1-ol (PubChem CID: 29060) Research into microbial community development and metabolism is essential to understand meat spoilage. Re- cent years have seen the emergence of powerful molecular techniques that are being used alongside convention- al microbiology approaches. This enables more accurate studies on meat spoilage. The aim of this study was to investigate the influence of packaging (under vacuum and in high oxygen atmosphere) on the development of microbial communities and metabolic activities at 6 °C by using culture-dependent (cultivation, ribotyping) and culture-independent (amplicon sequencing) methods. At the beginning of shelf life, the microbial community mostly consisted of Carnobacterium and Lactobacillus. After two weeks of storage, Lactococcus and Lactobacillus were the dominant genera under vacuum and Leuconostoc in high oxygen meat packages. This indicates that ox- ygen favoured the genus Leuconostoc comprising only heterofermentative species and hence potential producers of undesirable compounds. Also the number of volatile compounds, such as diacetyl, 1-octen-3-ol and hexanoic acids, was higher in high oxygen packages than under vacuum packages. The beef in high oxygen atmosphere packaging was detected as spoiled in sensory evaluation over 10 days earlier than beef under vacuum packaging. Leuconostoc gelidum, Lactococcus piscium, Lactobacillus sakei and Lactobacillus algidus were the most common spe- cies of bacteria. The results obtained from identification of the isolates using ribotyping and amplicon sequencing correlated, except for L. algidus, which was detected in both types of packaging by amplicon sequencing, but only in vacuum packaged samples using the culture-based technique. This indicates that L. algidus grew, but was not cultivable in high oxygen beef using the Nordic Committee on Food Analysis standard method. © 2016 Elsevier B.V. All rights reserved. Keywords: Lactic acid bacteria Packaged beef Spoilage 16S rRNA amplicon sequencing Volatile compounds 1. Introduction Spoilage of raw meat is a combination of biological and chemical activities. The microbial communities occurring frequently in fresh meat belong to the genera of Acinetobacter, Pseudomonas, Brochothrix, Flavobacterium, Psychrobacter, Moraxella, Staphylococcus, Micrococcus, lactic acid bacteria (LAB) and the family of Enterobacteriaceae (Dainty et al., 1983; Doulgeraki et al., 2012; Enfors et al., 1979; Erichsen and Molin, 1981). A set of organisms interacting to spoil the products is called specific spoilage organisms (SSO) (Gram et al., 2002). These SSO form only a minor part of the initial microbial community (Huis in't Veld, 1996), but during storage certain extrinsic and intrinsic factors favour their growth and develop into a major fraction of the microbiota. Temperature and packaging atmosphere are the most important extrin- sic factors which determine the development of microbial communities. Combining refrigeration with modified-atmosphere packaging (MAP) or vacuum packaging (VP) favours the growth of Pseudomonas spp., Enterobacteriaceae, Brochothrix thermosphacta, and LAB (Ercolini et al., 2011). In low storage temperature, such as -1.5 °C, the Clostridium spp. has been described as a major SSO in VP beef (Hernandez-Macedo et al., 2012; Silva et al., 2012). An understanding of microbial community development is a key factor for meat quality, but the microbial ecology alone might not ex- plain meat spoilage in general (Doulgeraki et al., 2012). Spoilage usually occurs when SSO grow to unacceptable levels and the spoilage potential of SSO depends on their ability to produce metabolites, such as alde- hydes, ketones, esters, alcohols, organic acids, amines, and sulphur com- pounds, which determine the sensory spoilage characteristics of meat. International Journal of Food Microbiology 223 (2016) 25–32 Abbreviations: GC, Gas chromatography; HS-SPME, Headspace solid phase microextraction; LAB, Lactic acid bacteria; MAP, Modified atmosphere-packaging/ packaged; MS, mass spectrometry; OTU, Operational taxonomic units; SSO, Specific spoil- age organism; VP, Vacuum packaging/packaged; VOC, Volatile Organic Compounds. ⁎ Corresponding author at: Agnes Sjöbergin katu 2, (P.O. Box 66), FI-00014, Helsinki University, Finland. E-mail address: Elina.L.Jaaskelainen@helsinki.fi (E. Jääskeläinen). http://dx.doi.org/10.1016/j.ijfoodmicro.2016.01.022 0168-1605/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect International Journal of Food Microbiology journal homepage: www.elsevier.com/locate/ijfoodmicro