Development and application of a best practice supply chain model to 4 species of Australian seafood to define maximum microbial and quality shelflife

• Main Author: Milne, DC
• Format: Thesis
• Language: English
• Published: 2013
• Subjects: sea food quality; shelflife; packaging; temperature; Atlantic salmon; Salmo salar
• Online Access: https://eprints.utas.edu.au/17553/; https://eprints.utas.edu.au/17553/1/Whole-Milne-_thesis.pdf

Chilled seafood is considered to have a short quality shelflife when compared to other protein alternatives. Quality deterioration evidenced by high microbial counts, textural degradation and exudates loss affects palatability and subsequently consumer satisfaction and confidence. Australian produced chilled seafood competes directly for market share with other fresh protein products. Consumer demand, price, repeat purchasing and resultant business viability is based on customer satisfaction achieved at the point of consumption. Barriers to seafood consumption include concerns regarding product origin, freshness and difficulty in evaluating seafood quality. Chilled seafood goes through complex distribution channels before reaching the retail consumer, which can allow quality deterioration to occur. Consequently, one of the most challenging tasks for the seafood industry is controlling product quality and consistency throughout the supply chain. This research defined best practices for the handling, processing and storage of chilled seafood throughout the supply chain and applied these to 4 Australian species. Flathead (Platycephalus bassensis), Atlantic salmon (Salmo salar), southern calamari (Sepioteuthis australis) and abalone (Haliotis rubra) were packed in modified atmospheres comprising primarily CO2 and in air before storage at temperatures of 0°C and no more than 5°C (maximum regulatory limit). To date, few published studies specifically related to the species considered in this study or conducted in the Australian context could be located on spoilage rates and quality indicators over time. Consequently, no maximum quality benchmark exists that will enable assessment of supply chain performance. Microbial spoilage and temperature are cited as the most significant factors impacting on seafood shelflife. This study applied the principles of hurdle technology throughout the supply chain to disrupt microbial growth in order to extend the lag phase and minimise microbial effects on quality shelflife. The effectiveness of treatments was evaluated by microbial, chemical, textural and sensory parameters from harvest to spoilage. To facilitate comparison between storage temperatures the equivalent days on ice was calculated for each species. The quality shelflife of modified atmosphere packed (MAP) product stored at 0°C was determined as 21 days for flathead, 20 days for Atlantic salmon, 19-20 days for squid and 21 days for abalone. Corresponding microbial total plate counts (TPC) colony forming units per gram (CFU/g) were flathead 1.4 x 103 CFU/g, Atlantic salmon 2.9 x 104 CFU/g, squid 2.8 x 103 CFU/g, abalone 2 x 102 CFU/g. It was concluded that microbial spoilage was not the primary factor limiting quality shelflife for any of the species stored in MAP at 0°C. Instead, the primary factors that limited quality shelflife were identified as autolytic spoilage reducing texture, and nucleotide degradation adversely affecting flavour. The impact on shelflife of storage at temperatures of 0°C and 5°C or less was investigated. The time taken for microbial counts for the 4 species to reach 107 CFU/g when air stored at 5°C, or air stored at 0°C or MA packed at 5°C was respectively: Flathead 9 days: 18 days and 19 to 20 days. Atlantic salmon: 9 days; 16 days and 17 days. Southern calamari: 10 days, 17 and 20 days. Abalone: 10 days, 21 days and 25 days. Samples held in air at storage temperatures of 5°C or less (mean 4.7°C) had approximately 50% of the microbial shelflife of those stored at 0°C. Samples stored in MAP and held at 0°C had a shelflife increase of approximately 300% compared to air packed samples stored at 5°C. This investigation provides new information on spoilage rates, microbial and sensory shelflife and key quality indicators of Flathead, Southern Calamari and Abalone while providing new information on Atlantic salmon in an Australian context. The study also provides practical guidance to industry on best practice applied throughout the supply chain, including harvest, temperature control, cross contamination, processing and packaging. The outcome of this is the establishment of quality benchmarks for each of the species under optimum conditions of MA packed at 0°C. The work conducted on abalone provides industry with key technical information including texture, driploss, microbial and quality shelflife estimations to enable the development of a new chilled MAP packed abalone meat product for the Asian market.