Product Quality & Value Adding 4.1
Optimising at-sea post-harvest handling procedures for the Australian sardine (Sardinops sagax).
| ID Number | Project Number | Manager | Start Date | End Date | Total Project Funds ($) |
| R&D-5506 | 2002/236 | Carragher, John | 01-Jul-2002 | 31-Jan-2005 | 261,534 |
Outcomes Achieved to Date
The research documented in this report has contributed to the development of the value-adding component of the South Australian sardine (Sardinops sagax) fishery by providing information on the key factors affecting sardine quality from harvest through to the factory. The research showed that although there were differences in the rate at which sardine quality deteriorated between different times of year, different fishing boats, different on-board holding tanks, and the start and end of each net haul, the main effect was the detrimental consequence of not chilling the fish as quickly as possible after capture. Emphasis was placed on the ability to chill fish rapidly to maximize sardine quality via an appropriate low fish load, hold water:volume ratio, more effective circulation of chilling water and/or the opportunities for new flo-ice technologies. This information, together with an audit of vessel hygiene and operating practices, has been used by industry to improve processes and practices to maintain sardine quality such that several more vessels and value-adding ventures are now operating in Port Lincoln than when the project started. Indications are that these ventures are supplying value-added sardines to the substantial domestic commercial and recreational fishing bait markets and thereby replacing some imported baitfish. The option of being able to value-add to a percentage of the sardine catch is of economic and social benefit to the fishers and factory owners in Port Lincoln.
Non-Technical Summary
The sardine (Sardinops sagax) fishery based in Port Lincoln, South Australia expanded to ~26,000 tonnes in 2006. Most of the catch is used as feed for the established tuna farming operations that are co-located at Port Lincoln. The tuna aquaculture industry is willing and able to absorb the total output from the sardine fishery but at a low price per kg. Some of the sardine fishers have sought to increase their earnings by supplying value-added sardine products – recreational and commercial fishing bait, and/or sardines for human consumption. The main issue these fishers face in striving to supply these markets is deterioration in the physical integrity of the sardines. This deterioration shortens the window during which fish are suitable for value adding, this is further compounded by the limited capacity of the on-land freezing infrastructure to process a significant proportion of the catch. The aims of this project were to (a) understand the pre-harvest, harvest and post-harvest factors that are responsible for the rapid rate of deterioration in the physical integrity of sardines, (b) identify the domestic market status and opportunities for value-added sardines, and (c) undertake a cost-benefit analysis of implementing the recommended changes that would improve sardine quality.
An audit of harvest practices on several boats interested in undertaking value adding revealed a number of shortcomings that were likely to contribute to deterioration in product quality. The main issues were related to holding tank hygiene and the effective circulation of refrigerated water in fish filled holds. This information was used by some of the boats to make modifications to holding tank cooling functionality and improvements to holding tank hygiene practices.
A desktop and survey approach was used to identify the nature of the current domestic markets for frozen bait sardines and fresh, frozen and processed sardines for human consumption. Following this status report there was an assessment of where Port Lincoln sardine products could capture some of this market. The short-medium term opportunities were assessed as being in the bait markets and the fresh fish markets in Sydney and Melbourne. The marketing advantages of Port Lincoln sardines as bait would include the ‘clean and green’ perception of the fishery, as well as the perception that this is a ‘natural food’ for the main target species. These advantages, however, will not overcome an inferior quality product or a significant price premium. For the human-consumption market the price premium is guaranteed for fresh product providing the quality is high; however, any further processing to butterfly fillets and/or canned product would require substantial investment in processing technology, and the financial returns may not be justified in the short-medium term.
An investigation was carried out on the biological and ecological factors affecting rates of deterioration in sardine quality in the immediate post-harvest period (i.e. net to processing factory) using a quality index (QI) and physico chemical measurements. One of the major issues to be addressed in the study was post mortem belly burst, thought to result from visceral autolysis accentuated by consumption of particular prey species (i.e. copepods). However, although a degree of visceral post-mortem autolysis was detected, very few fish were found with burst bellies therefore it is suggested that this issue is not a major constraint on the progress of value-adding in the fishery. There was only one significant instance of burst stomachs/bellies within the field sample. There may be a relationship between spawning fish and susceptibility to stomach/belly burst as this was also the only time ripe gonads were observed during the fieldwork. Postmortem autolysis was more commonly recorded and is likely to have been caused by digestive enzyme activity, significantly contributing to the observed increase in sardine QI with time.
The QI method proved useful in sardine quality assessment, with inclusion of ten of the seventeen parameters suggested in the literature. Four of these (i.e. gill colour, eye clarity, body appearance and body stiffness) accounted for 76% of the overall QI. It was evident that the QI would provide a framework for standardisation of the quality of fish going to market, a necessity in the process of value adding. The setting of the QI acceptability threshold would involve market acceptability trials including taste testing, microbiological studies to determine safe levels of bacteria on/in the product, and work to determine safe rancidity levels and should be included as a essential element of any further value adding work on this species.
Methods are suggested for maintaining sardine quality through the onboard storage process to allow entry of the product into premium markets. These include more rapid water temperature reduction using more efficient, dedicated, on-board value-adding tanks, and reduction in the quantity of fish loaded into tanks to maintain water circulation and facilitate cooling. The practice of topping up nearly-full, cold tanks with the later shots containing relatively warm fish should be limited as this practice causes a temperature spike and probably accelerates deterioration of fish already in the tank. Fish should also be iced between unloading at the jetty and arrival at the processing factory, and jetty-to factory transport bins chilled using an efficient cooling medium such as flow ice.
A cost-benefit analysis was undertaken of various options including investment in small scale (processing 50 to 100 tpa) and large scale (processing 200 to 400 t.p.a) equipment for improved post-harvest handling and processing of sardines. The analysis was conducted from an individual licence holder (single boat) perspective using a model based on financial data provided by all active licence holders.
The results of the analysis showed that investment in post harvest handling equipment can generate positive returns to the fishery. However, the outcomes are sensitive to the premiums available for human consumption sardines, the quantity processed (which will be determined by the volume that the licence holder can market) and the initial cost of the equipment and its installation. For small scale equipment, for example, the prices (landed beach price equivalent) at which the investment would yield a breakeven return ranged from $1.46/kg for 50 tpa throughput down to $1.15/kg for 100 tpa throughput. For large scale investment, the breakeven prices ranged from $1.26/kg for 200 tpa throughput down to $1.06/kg for 400 tpa throughput.
While the analysis demonstrates the potential returns that can be generated by investment in post harvest handing of sardines, it also highlights the critical role that marketing will play in securing those returns. Successful marketing of the product will be essential to achieve both the price and the volume necessary to generate positive returns to licence holder investment.