The production process of frozen red snapper fillets involves several key steps: raw material pretreatment, freezing, thawing with antioxidants, scale removal, washing, slicing, trimming, descaling, secondary cleaning with antioxidants, freezing, fractionation, ice glazing, packaging, and final storage.
**1.3.2 Operational Details**
Raw material pretreatment includes bleeding, head removal, internal organ removal, and thorough cleaning. Bleeding is crucial to maintain the quality of frozen red snapper fillets. It requires removing all blood, residual muscle tissue, and clots without damaging the internal organs to preserve color and taste.
If raw materials are not processed immediately, they should be frozen. When thawing, the fish is taken from the freezer and partially thawed in an ice water bath containing 0.3% antioxidant (Vc-Ma) at 0°C. Ice is added to maintain temperature.
After thawing, scales are removed quickly, followed by a rinse under running water. The fish is then cut into three pieces: two fillets and one central bone. Care is taken to keep the fillets intact and store them on ice.
Trimming involves removing any imperfections and picking out parasites, which are commonly found on the skin. These can be visually identified and removed using a tool without causing excessive damage to the skin.
Thorn removal is essential for market value. Red snapper typically has about 15 spines per side, which are carefully extracted using specialized tools. A quality check is performed to ensure complete removal.
After trimming, the fillets are washed with ice water and then rinsed with 0.3% iso-Vc-Na solution. Fillets are arranged neatly on plates, and those with discoloration or defects are classified as second-grade products.
Single freezing is done at -32°C with a speed of 300–400 rpm. Afterward, the fish is transferred to a plate freezer until the core temperature reaches -15°C.
Grading, ice glazing, and packaging follow. Fillets are weighed and categorized based on size, then packed into plastic bags. Final storage involves quick loading and proper labeling.
**2 Results and Discussion**
The fading of red snapper during processing and storage is a major concern. This is due to oxidation of unsaturated fatty acids, leading to loss of color. Antioxidants like iso-Vc-Na help prevent this.
Seven groups were tested with varying concentrations (0%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%). After 2 hours of processing and 4 hours of freezing, only group 1 showed fading. After 45 days of storage, results showed that 0.3% iso-Vc-Na provided the best protection. At this concentration, no visible fading was observed, and the surface remained glossy.
To maintain the antioxidant effect throughout processing, several measures are necessary: monitoring process water quality, adding ice during thawing, controlling washing time, and reapplying iso-Vc-Na during ice glazing.
Microbial control is also critical. Red snapper has high moisture content, making it prone to spoilage. Bacterial counts must stay below 1.0×10âµ/g, and coliforms below 3 MPN/g. Listeria monocytogenes may be present, but direct disinfectants like sodium hypochlorite are avoided due to their oxidizing effects. Instead, strict hygiene practices, including regular disinfection of equipment, are enforced.
**3 Product Quality Standards**
Sensory criteria include bright red skin, shiny surface, and no dark spots over 3 cm. Microbiological standards require total bacteria <1.0×10âµ/g, coliforms <3 MPN/g, and no detection of Salmonella or cholera bacteria.
**4 Conclusion**
Using 0.3% iso-Vc-Na during processing ensures optimal color retention for frozen red snapper fillets. This method meets international quality standards and enhances market value.
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