Estimating Energy Consumption in Surimi Processing

Documented power consumption rates for individual food processing operations are applied to surimi processing, freezing, and cold storage. Electrical power consumption is predicted to be 314 and 272 kWh/t (285 and 247 kWh/ton) for representative surimi plants in Oregon and Alaska, respectively, during summer operation. The influencing factors for each operation are identified. INTRODUCTION S urimi is a minced, washed protein product to which cryoprotectants (typically an 8% sugar/sorbitol mixture) have been added to control degradation in long-term frozen storage. It is this storage stability that is one of the important surimi properties, enabling subsequent processing to occur at a uniform rate. A second important property is that surimi forms a firm gel when thawed, mixed with about 3% salt, and heated. Gelling during various extrusion processes can produce the shape and texture of fish muscle. The addition of colors and flavors leads to the production of such seafood analogs as shrimp, crab and scallops. The U.S. consumption of surimi-based products has grown dramatically in the last few years. Many U.S. companies are now producing the analog products that were once imported from Japan, where they were produced largely of surimi made from Alaskan pollock. Within the last 10 years, a few demonstration projects have been initiated to produce frozen surimi in the United States. The largest in scale was managed by the Alaskan Fisheries Development Foundation and housed in the Alaska Pacific Seafoods plant in Kodiak (AFDF, 1984; 1987). This project demonstrated the ability to produce good quality surimi in a shore-based plant and supported the adaptation of technological change to what were traditional Japanese machines and processes. There are currently four shore-based Alaskan surimi plants plus a number of processing operations aboard U.S. factory ships. More recently, attention has been focused on other geographic areas and fish species which would support U.S. surimi production. For example, Pacific whiting (Merluccius productus) represents a West Coast resource having an annual sustainable yield on the order of 175 000 metric tons (193,000 tons). Beale and Jensen (1989) Article was submitted for publication in July 1989; reviewed and approved for publication by the Food and Process Engineering Inst, of ASAE in December 1989. Presented as ASAE Paper No. 88-6593. The author is E. Kolbe, Associate Professor, Agricultural Engineering Dept., Oregon State University, Corvallis. reported that shore-based production on the West Coast is feasible, although "infrastructure" needs relating to land, utilities, cold storage capacity, and waste handling are major considerations. Processors considering the production of surimi need reliable estimates of production costs. An important component of these costs is energy consumption. Therefore, energy consumption in surimi production was calculated, based on observation of an Alaskan demonstration project, on measurements at the Oregon State University Seafoods Laboratory, and on documented energy consumption for similar processes. APPROACH The term "surimi production" is meant to include the following operations: On-shore processing. This includes fishing vessel offloading, in-plant processing machinery, and washwater chilling; Freezing. Horizontal plate freezers are considered in the example calculations; Cold storage. This is commercial storage of surimi blocks prior to final analog production. Energy consumption was separately calculated for each of these three operations. Significant amounts of energy are also consumed in the following related operations which were not considered in the calculations. 1. Catching fish. Lorentzen (1981), considering both direct and primary energy costs, reported that catching used 66% of the energy required to produce frozen fillets from trawl-caught fish (the other operations being processing, 16%; transport, 12%; and distribution, 6%). Watanabe (1983) went further to show that "catching" could involve fully 70-90% of the total energy to produce the gelled analog products. 2. Refrigeration of product at sea. Documentation and summary of these direct energy costs were presented by Kolbe (1988,1989). 3. Plant overhead, to include lights, heating, ventilating, and air conditioning. 4. Effluent treatment. This also can be a very significant cost in terms of direct energy. Watanabe et al. (1982) and H. Watanabe (personal communication) gave figures for electrical energy required to operate pumps, blowers, and presses in an activated sludge waste treatment system for one Japanese surimi plant. Waste treatment was about 120 kWh/t (109 kWh/ton) about four times the electrical energy required for surimi processing at that plant. 322 © 1990 American Society of Agricultural Engineers 0883-8542 / 90 / 0603-0322 APPLIED ENGINEERING IN AGRICULTURE This report estimates direct electrical energy consumed at the plant (kWh/t) on the basis of metric tons of frozen surimi produced. The analysis does not consider primary energy which includes "fossil fuel equivalence" of electric power generation and energy costs to manufacture machinery, chemical ingredients, and packaging. (Fossil fuel equivalence relates to the overall efficiency of producing electric power from the combustion of fossil fuels. Singh, 1984, gives this efficiency as 32.5%; Watanabe, 1985, uses a value of 43%.) Specific energy consumption is influenced by the production capacity of the plant. Selection of a representative plant size resulted from reports and projections of AFDF (1987), Holmes and Riley (1987), Surimi Inc. (undated), Hilderbrand (1986), Talley (1986), Sonu (1986), and Anon. (1988a):