Short communication Influence of sunflower oil based nanoemulsion (AUSN-4) on the shelf life and quality of Indo-Pacific king mackerel (Scomberomorus guttatus) steaks stored at 20  C Manoharan Melvin Joe a, b, * , Puneet Singh Chauhan b , K. Bradeeba a , Charlotte Shagol b , Palanivel Karpagavinaya Sivakumaar a , Tongmin Sa b, * a Department of Agricultural Microbiology, Annamalai University, Annamalainagar-608002, India b Department of Agricultural Chemistry, Chungbuk National University, Cheongju, Chungbuk 361-763, Republic of Korea article info Article history: Received 14 May 2011 Received in revised form 18 August 2011 Accepted 20 August 2011 Keywords: Nanoemulsion Scomberomorus guttatus Antimicrobial Preservative Shelf life abstract The influence of nanoemulsion (AUSN-4) on the microbiological, proximal, chemical, and sensory qualities of Indo-Pacific king mackerel (Scomberomorus guttatus) steaks stored at 20  C was studied for a time period of 72 h. AUSN-4 treatment showed initial reduction (P > 0.05) in the heterotrophic, H 2 S and lactic acid bacterial populations in 12 h, followed by a gradual increase in their respective populations. Irrespective of treatments, reduction in total carbohydrate, protein, and fat contents were observed in all samples with an increase in storage time (h), with AUSN-4 treated steaks having the lowest reduction. AUSN-4 treatment significantly (P < 0.05) decreased the values of chemical indicators of spoilage throughout the storage period. Organoleptic evaluation revealed that AUSN-4 treated steaks showed an extension of shelf life of 48 h, when compared with control and antibiotic treated samples, respectively. Based on the results obtained in our present study we conclude that sunflower oil based nanoemulsion preservative technique is able to extend the shelf life and maintain the quality of S. guttatus steaks during storage. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Fish are usually harvested in remote locations (Ward, 1994) and unlike other muscle food they have shorter shelf life and they deteriorate rapidly (Olafsdóttir et al., 1997). This shorter shelf life represents a substantial practical problem in the distribution of these products to the consumers (Gunsen, Ozcan, & Aydin, 2010). Although temperature control during all stages of the produc- tion and in the distribution chain is emphasized as one among the guidelines in good manufacturing practices, temperature fluctua- tions during these stages become unavoidable (Olafsdottir, Lauzon, Martinsdottir, & Kristbergsson, 2006). This may be due to unfore- seeable events such as improper icing of the raw material, trans- portation delay and exposure to high ambient tropical temperatures leading to quicken the process of deterioration (Ola, Babajide, Oladipo & Etanuoma, 2004; Olafsdottir et al., 2006). The average ambient temperature for storage during marketing of fish at local retailers in our region is 20  C contrary to the situation in western countries where fish is held at temperatures below 5  C. In local retailers, fish are generally not iced and if iced, insufficient enough to chill the fish, a common condition that prevail among the under developed and developing countries including India. Fish spoils eight times faster at 20  C than if stored between 1  C and þ4  C (Department of Fisheries government of Western Australia, 2005) since fish spoilage bacteria are most active at this temperature (FAO Corporate Document Repository, 2011) and this temperature favors the growth of most of spoilage bacteria belonging to mesophillic gram negative fermentative motile rods and psychotropic non fermentative gram negative motile rods (Gram, Trolle, and Huss, 1987). Moreover, this temperature retards the growth of histamine decomposing bacteria that may favor histamine accumulation (Sato, Fujii, Masuda, & Okuzumi, 1994 T. Sato, T. Fujii, T. Masuda and M. Okuzumi, Changes in numbers of histamine e metabolic bacteria and histamine content during storage of common mackerel, Fisheries Science 60 (1994) (3), pp. 299e302. Sato et al., 1994; Guizani, Al-Busaidy, Al-Belushi, Moth- ershaw, & Rahman, 2005). * Corresponding authors. Department of Agricultural Chemistry, Chungbuk National University, Cheongju, Chungbuk 361-763, Republic of Korea. Tel.: þ82 43263447. E-mail addresses: micromelvin@gmail.com, mel_vin@sify.com (M. M. Joe), tomsa@chungbuk.ac.kr (T. Sa). Contents lists available at SciVerse ScienceDirect Food Control journal homepage: www.elsevier.com/locate/foodcont 0956-7135/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodcont.2011.08.032 Food Control 23 (2012) 564e570