Effects of Vacuum and Modified Atmosphere Packaging on Microbial Flora and Shelf-life of Pacific White Shrimp (Litopenaeus vannamei) during Controlled Freezing-point Storage at −0.8°C

Abstract

Effects of vacuum and modified atmosphere packaging (MAP) on microbial flora, pH, total volatile basic nitrogen (TVB-N), trimethylamine (TMA-N), the exudates and sensory attributes in IntroductionPacific white shrimp (Litopenaeus vannamei) is one of the most important seafood traded worldwide, and also one of the most representative aquatic products for its positive culinary quality and high nutritional values (Oosterveer, 2006;Qian et al., 2013). Since fresh shrimps have a short shelf life, which causes substantial practical problems for its transportation and distribution, and they are very sensitive to microbial spoilage and can be contaminated by bacteria naturally present in the marine environment, such as lactic acid bacteria, Vibrio spp., Enterobacteriaceae, Aeromonas spp. and Jeyasekaran et al., 2006;Wang et al., 2010;Behnam et al., 2013;Binsi et al., 2013;Carrascosa et al., 2013), or in the digestive tract, which is not always removed directly after catch. Besides, flesh of shrimp after death is still active and biochemically alive, the organic decomposition or the change of shrimp composition may be triggered by various factors, Wang et al. 1142 i.e. enzymes and microbiological activities, the need to develop methods for maintaining good postmortem quality of shrimps on their way to the market increases (Wang and Zeng, 2009;Cui et al., 2013). The effectiveness of MAP to curtail bacterial growth and improve shelf-life stability of shrimp has also been evaluated in some studies (Bak et al., 1999;Thepnuan et al., 2008;Wang et al., 2010).More recently, an additional storage technique based on the Japanese concept of 'Hyo-on' has attracted considerable interest.'Hyo-on', also called controlled freezing-point storage, employs a temperature range, in which foods remain in a non-frozen temperature-zone between the freezing point of water and that of an individual material (Yamane, 1982;Fukuma et al., 1998).Storing food at controlled freezing-point temperatures can be advantageous in terms of maintaining food freshness and suppressing harmful microorganisms as compared to other storage temperature (Yamane, 1996;Wang and Zeng, 2009). In addition to these advantages, there is an additional effect that may keep food quality (Bohnert and Jensen, 1996;Guo et al., 2008). However, to our knowledge, limited research has been conducted to assess the impact of MAP on the microbiological, physicochemical and sensory attributes of shrimps stored under chilled or refrigerated temperature. In particular, it is completely unknown how MAP with mixed CO 2 , O 2 and N 2 gases would affect the quality attributes of raw shrimp during controlled freezing-point storage. The purpose of this study was to investigate the effects of air, vacuum and MAP on microbial flora and shelf-life of Pacific white shrimp (Litopenaeus vannamei) during controlled freezing-point storage at _ 0.8℃. The air packaging was used as control for comparison. For AP, the pouches were sealed using an impulse heat-sealing machine (Model SF-200, P&S Co., Ltd...

Optimal Modified Atmosphere for Packaging and its Effects on Quality and Shelf-life of Pacific White Shrimp (<i>Litopenaeus vannamei</i>) under Controlled Freezing-point Storage at −0.8°C

“…However, considering the effects of different gas mixtures on responses at sampling, the Lu, 2009;Wang et al, 2010Wang et al, , 2014, was used as the control.…”

“…Wang's descriptive methods (Erickson et al, 2007;Wang et al, 2010Wang et al, , 2014 (Table 1). Briefly, raw shrimp was presented to a panel of trained panelists for sensory evaluation.…”

“…The pH was measured using a pH meter (PHS-3C, Shanghai, China) (Wang et al, 2010(Wang et al, , 2014.…”

“…'Hyo-on', also called controlled freezing-point storage, employs a temperature range, in which foods remain in a non-frozen temperature-zone between the freezing point of water and that of an individual material (Yamane, 1982;Fukuma et al, 1998). Storing food at controlled freezingpoint temperatures can be advantageous in terms of maintaining food freshness and suppressing harmful microorganisms as compared to other storage temperature (Yamane, 1996;Wang et al, 2010Wang et al, , 2014. In particular, controlled freezing-point storage, combined with the optimized gas mixtures, will be a considerably better method to maintain the freshness and extend the shelf-life of…”

“…Introduction increasingly popular preservation techniques, which have brought major changes in storage, distribution, and marketing of raw shrimps to meet consumer demands (Chinivasagam et al, 1996;Lakshmanan et al, 2002;Lalitha and Surendran, 2006;Thepnuan et al, 2008;Lu, 2009;Wang et al, 2014). However, MAP solutions often hampered by high gas volume to product volume ratio (g/p) and gas concentration (i.e.…”