## 1 Introduction  
Beef is one of the protein-rich foods that is prone to pathogenic bacteria contamination because it contains high levels of water and nutrient content, so that beef is also considered as a cause of foodborne disease [1]. After slaughtering process, this contamination could occur during handling and storage processes, and it is mainly caused by _Salmonella_ sp., _Escherichia coli_ O157:H7, _Campylobacter jejunie_, _Listeria monocytogenes_, _Clostridium perfingens_, _Bacillus cereus_, _C. botulinum, _Yesinia enterocolitia_, and _Staphylococcus aureus_[2]. To preserve beef products, many industries often use chemicals or physical treatments [3]. Chemicals such as nitrates are frequently used, but they can easily be converted to nitrite compounds which can produce nitrosamines as a carcinogen [4]. Furthermore, when ingested, nitrite compounds can trigger methemoglobin production which is the cause of methemoglobinmia. In addition, physical treatments such as freezing can be an alternative way to inhibit microbial growth, but this method also has negative effects on physical and sensory beef quality. During frozen storage, meat's capacity to retain water will be reduced, which will change the structure of muscles and the beef's suppleness. Moreover, myoglobin in beef is quickly oxidized, so the color of the beef will be diminished [5]. Defrosting is also considered to affect beef quality under improper conditions by triggering higher levels of microbial contamination [6]. Biopreservation is an approach to extend the shelf life of foods by exploiting biological systems, such as lytic bacteriophages, lactic acid bacteria and their metabolites, and bacteriocins, that have antagonistic activities to inhibit or destroy undesired microorganisms in foods. Biopreservation has been developed as a promising antimicrobial technology in improving safety of foods with extended shelf life. Lactic acid bacteria (LAB) are potentially utilized in biopreservation because they are recognized as safe microorganisms and naturally act as probiotics that produce a range of metabolites with antimicrobial activities [7]. Postbiotics or cell-free supernatants (CFS) are liquids with inactivated microbial cells containing bacterial metabolites, such as antimicrobial peptides (bacterioin), organic acids, and hydrogen peroxide. As antimicrobial agents, these metabolites are also known as bioactive compounds which are able to inhibit spoilage by suppressing the growth of foodborne pathogens [8; 9]. In addition, LAB with their metabolites also contribute to improve the flavor, color, and texture of foods by attenuating chemical reactions, such as lipid oxidation [1; 10]. With these advantages, in this study LAB are applied as a biopreservation technique to preserve beef products. Mostly, LAB can be found in a variety of fermented foods, such as fermented milk products (yogurt, kefir, cheese) and fermented vegetable products (sauerkrauts, kimchi). Dadih is a typical fermented food from West Sumatra, Indonesia, that is originally made from buffalo milk [11]. Previous investigation showed that dadih produced the greatest numbers of LAB colonies compare to those on various types of Indonesian traditional fermented foods [12]. Dadih produced the greatest number of colonies (20 colonies), followed by tempolyak (18 colonies), tamarind (six colonies), and sticky rice tape (two colonies). Several studies demonstrated that LAB isolated from dadih inhibited the growth of pathogenic bacteria such as Salmonella sp., _Escherichia coli_ O157:H7, and _Staphylococcus aureus_[11]. In addition, LAB also produced antibiotics that suppressed the growth of _Listeria monocytogenes_[13]. Bacteriocins are prominent antibiotics which have been known as antimicrobial agents in food preservation. Bacteriocins are frequently used with surfactants, such as acids or organic salts, to improve their effectiveness in high-protein foods, such as beef [1; 3; 14].