Chapter 1: Acidified, Fermented, and Salted Fish and Fishery Products

• Potential Food Safety Hazard
• Clostridium botulinum
• Pathogens other than C. botulinum
• Control Measures
• C. botulinum control during processing and storage
• C. botulinum control in the finished product
• Control of pathogens other than C. botulinum
• FDA Guidelines
• State Guidelines
• Process Establishment
• Critical Aspects of Processes
• Analytical Procedures
• Moisture analysis
• Drying oven procedure
• Microwave oven method
• pH analysis
• Colorimetric methods
• pH meter method
• Salt (NaCl) analysis
• Conductivity method
• Quantabâ method
• Determination of sodium chloride in foods and other samples by Quantab^TM chloride titrators (HC)
• Water activity
• Determining water activity using the Decagon AquaLab CX2 meter
• Measuring water activity using the Novasina a_w Center (HC)
• Determination of water activity using the Decagon Aqualab CX-2 (HC)
• Water phase salt calculation
• Other analytical procedures
• Commercial Test Products
• Moisture
• Salt
• Water activity
• Acidifying, Fermenting, and Salting Processes
• Acidifying (pickling) processes
• Fermenting processes
• Salting processes
• References

There are two major groups of C. botulinum, the proteolytic group (i.e. those that break down proteins) and the nonproteolytic group (i.e. those that do not break down proteins). The proteolytic group includes C. botulinum type A and some of types B and F. The nonproteolytic group includes C. botulinum type E and some of types B and F.

The vegetative cells of all types are easily killed by heat. C. botulinum is able to produce spores. In this state the pathogen is very resistant to heat. The spores of the proteolytic group are much more resistant to heat than are those of the nonproteolytic group. Table A-4  provides guidance about the conditions under which the spores of the most heat resistant form of nonproteolytic C. botulinum, type B, are killed. However, there are some indications that substances that may be naturally present in some products, such as lysozyme, may enable nonproteolytic C. botulinum to more easily recover after heat damage, resulting in the need for a considerably more aggressive process to ensure destruction.

Temperature abuse occurs when product is exposed to temperatures favorable for C. botulinum growth for sufficient time to result in toxin formation. Table A-1  provides guidance about the conditions under which C. botulinum and other pathogens are able to grow.

Packaging conditions that reduce the amount of oxygen present in the package (e.g. vacuum packaging) extend the shelf life of product by inhibiting the growth of aerobic spoilage bacteria. The safety concern with these products is the increased potential for the formation of C. botulinum toxin before spoilage makes the product unacceptable to consumers.

C. botulinum forms toxin more rapidly at higher temperatures than at lower temperatures. The minimum temperature for growth and toxin formation by C. botulinum type E and nonproteolytic types B and F is 38°F (3.3°C). For type A and proteolytic types B and F, the minimum temperature for growth is 50°F (10°C). As the shelf life of refrigerated foods is increased, more time is available for C. botulinum growth and toxin formation. As storage temperatures increase, the time required for toxin formation is significantly shortened. Processors should expect that at some point during storage, distribution, display or consumer handling of refrigerated foods, proper refrigeration temperatures will not be maintained (especially for the nonproteolytic group). Surveys of retail display cases indicate that temperatures of 45-50°F (7-10°C) are not uncommon. Surveys of home refrigerators indicate that temperatures can exceed 50°F (10°C).

C. botulinum can enter the process on raw materials. The spores of C. botulinum are very common in nature. They have been found in the gills and viscera of finfish, crabs, and shellfish. C. botulinum type E is the most common form found in freshwater and marine environments. Types A and B are generally found on land, but may also be occasionally found in water. It should be assumed that C. botulinum will be present in any raw fishery product, particularly in the viscera (FDA, 2001a).

Pathogens can enter the process on raw materials. They can also be introduced into foods during processing from the air, unclean hands, insanitary utensils and equipment, unsafe water, and sewage, and through cross contamination between raw and cooked product (FDA, 2001b).

• Managing the amount of time that food is exposed to temperatures that are favorable for C. botulinum growth and toxin formation during finished product storage.

Note: FDA guidance emphasizes preventive measures for the control of C. botulinum in products that are contained in reduced oxygen packaging. This is because such an environment extends the shelf life of the product in a way that favors C. botulinum growth and toxin formation over aerobic spoilage. It is also possible for C. botulinum to grow and produce toxin in unpackaged or aerobically packaged product. This is because of the development within the product of microenvironments that support its growth. However, toxin formation under these circumstances requires the type of severe temperature abuse that is not reasonably likely to occur in most food processing environments. Nonetheless, the Good Manufacturing Practice Regulations, 21 CFR 110, require refrigeration of foods that support the growth of pathogenic microorganisms. 

• Evisceration of fish before processing. Because spores are known to be present in the viscera of fish, any product that will be preserved by salting, drying, pickling, or fermentation must be eviscerated prior to processing (see Compliance Policy Guide sec. 540.650). Without evisceration, toxin formation is possible during the process even with strict control of temperature. Evisceration must be thorough and performed to minimize contamination of the fish flesh. If even a portion of the viscera or its contents is left behind, the risk of toxin formation by C. botulinum remains. Small fish, less than 5 inches in length (e.g. anchovies and herring sprats), that are processed in a manner that prevents toxin formation, and that reach a water phase salt content of 10 percent in refrigerated products, or a water activity of below 0.85 (Note: this value is based on the minimum water activity for growth of S. aureus) or a pH of 4.6 or less, in shelf-stable products are exempt from the evisceration requirement (FDA, 2001a).

For products that do not require refrigeration (i.e. shelf-stable products):

• Heating the finished product in its final container sufficiently by retorting to destroy the spores of C. botulinum types A, B, E, and F (e.g. canned fish) (covered by the low acid canned foods regulations, 21 CFR 113). Note: these controls are not required to be included in your HACCP plan;

• Controlling the level of acidity (pH) in the finished product sufficient to prevent the growth of C. botulinum types A, B, E, and F (4.6 or below) (e.g. shelf-stable acidified products) (covered by the acidified foods regulations, 21 CFR 114). Note: these controls are not required to be included in your HACCP plan;

• Controlling the amount of moisture that is available in the product (water activity) sufficient to prevent the growth of C. botulinum types A,B,E, and F and other pathogens that may be present in the product (i.e. 0.85 or below) (e.g. shelf-stable dried products);

• Controlling the amount of salt in the product sufficient to prevent the growth of C. botulinum types A, B, E, and F and other pathogens that may be present in the product (i.e. 20% salt or more) (e.g. shelf-stable salted products).

For products that require refrigeration:

• Heating the finished product in its final container sufficiently by pasteurization to destroy the spores of C. botulinum type E and nonproteolytic types B and F; and then controlling the growth of the surviving C. botulinum type A and proteolytic types B and F in the finished product with refrigerated storage (e.g. pasteurized crabmeat, some pasteurized surimi-based products);

• Heating the product sufficiently to destroy the spores of C. botulinum type E and nonproteolytic types B and F; and then minimizing the risk of recontamination by hot filling the product into the final container in a continuous filling system; and then controlling the growth of the surviving C. botulinum type A and proteolytic types B and F and other pathogens that may be present in the finished product with refrigerated storage;

• Controlling the amount of moisture that is available in the product (water activity) sufficient to inhibit the growth of C. botulinum type E and nonproteolytic types B and F by drying; and then controlling the growth of C. botulinum type A, and proteolytic types B and F, and other pathogens that may be present in the finished product through refrigerated storage;

• Controlling the level of acidity (pH), salt, moisture (water activity), or some combination of these barriers, in the finished product sufficiently to prevent the growth of C. botulinum type E and nonproteolytic types B and F by formulation (i.e. pH 5 or below; salt 5% or more; or water activity below 0.97); and then controlling the growth of C. botulinum type A and proteolytic types B and F and other pathogens that may be present in the finished product with refrigerated storage (e.g. refrigerated acidified ["pickled"] products);

• Controlling the amount of salt and preservatives, such as sodium nitrite, in the finished product, in combination with other barriers, such as smoke, heat damage and competitive bacteria, sufficient to prevent the growth of C. botulinum type E and nonproteolytic types B and F; and then controlling the growth of C. botulinum type A and proteolytic types B and F and other pathogens that may be present in the finished product with refrigerated storage (e.g. salted, smoked, or smoke-flavored fish);

• Controlling the amount of salt in the finished product, in combination with heat damage from pasteurization in the finished product container, sufficient to prevent the growth of C. botulinum type E and nonproteolytic types B and F; and then controlling the growth of C. botulinum type A and proteolytic types B and F and other pathogens that may be present in the finished product with refrigerated storage (e.g. some pasteurized surimi-based products) (FDA, 2001a).

• Managing the amount of time that food is exposed to temperatures that are favorable for pathogen growth and toxin production;
• Killing pathogens by cooking, pasteurizing, or retorting;
• Controlling the amount of moisture that is available for pathogen growth, water activity, in the product by drying;
• Controlling the amount of moisture that is available for pathogen growth, water activity, in the product by formulation;
• Controlling the amount of salt or preservatives, such as sodium nitrite, in the product;
• Controlling the level of acidity, pH, in the product.

Note: The use of irradiation for fish or fishery products has not been approved by FDA. Irradiated fish and fishery products may not be distributed in the U.S. (FDA, 2001b).

• Heated in the final container to destroy the spores of C. botulinum types A, B, E, and F,
• Acidified to pH 4.6 or below,
• Dried to a water activity of 0.85 or below, or
• Salted to contain 20% salt or more.

Refrigerated products must be:

• Dried sufficient to inhibit the growth of C. botulinum type E and nonproteolytic types B and F by drying; and then stored at or below 40°F (4.4°C) to control the growth of C. botulinum type A, and proteolytic types B and F, and other pathogens that may be present in the finished product;
• Acidified, salted, or dried to control the level of acidity (pH), salt, moisture (water activity), or some combination of these barriers, in the finished product sufficiently to prevent the growth of C. botulinum type E and nonproteolytic types B and F by formulation (i.e., pH 5 or below; salt 5% or more; or water activity below 0.97); and then stored at or below 40°F (4.4°C) to control the growth of C. botulinum type A and proteolytic types B and F and other pathogens that may be present in the finished product; 
• Stored and distributed at 40ºF (4.4°C) or below (FDA, 2001a).

New York Requirements For Shelf Stable Processing and Packaging of Caviar (Corby, 1999)

1. Minimum of 9% water phase salt
2. Pasteurization
3. Company must utilize a scheduled process developed by a qualified individual having extensive knowledge of thermal processing requirements of low-acid foods. This scheduled process must have FDA approval.

New York Requirements For Refrigerated Caviar (Corby, 1999)

1. 38°F storage minimum for products less than 5% water phase salt
2. 50°F storage minimum for products 5% or greater water phase salt

New York Guidelines for Processed fish (includes pickled, fermented and salted fish and fishery products) (Corby, 1999)

All processed fish shall be produced pursuant to a scheduled process established by a competent processing authority. A copy of said scheduled process shall be available for examination in each fish processing establishment. Each scheduled process shall identify the name and address of the competent processing authority by whom it was established. The scheduled process shall include processing methods, procedures and controls for each product, as well as packaging and labeling requirements. Whenever a deviation in a scheduled process occurs, as disclosed by records, processor check or otherwise, the processor shall destroy all product affected by said deviation or hold it for a determination as to whether it is adulterated within the meaning of Section 200 of the Agriculture and Markets Law.

• Brine/acid strength;
• Brine/acid to fish ratio;
• Brining/pickling time;
• Brine/acid temperature;
• Thickness, texture, fat content, quality, and species of fish;
• Water phase salt, pH, and/or water activity of the finished product;
• Accuracy of thermometers, recorder thermometer charts, high temperature alarms, maximum indicating thermometers, and/or digital data loggers;
• Accuracy of other monitoring and timing instruments (FDA, 1998a).

1. Samples must be protected from water loss before weighing. After grinding or blending, material for analysis should be stored in filled containers with close fitting lids. Freeze samples for long term storage and after defrosting, mix thoroughly to re-distribute water, which may have drained to the bottom.
2. If an oven is unavailable when samples are received or for excessive numbers of samples, materials may be weighed into dishes and stored frozen until oven space becomes available. Prolonged drying time (over the weekend, etc.) may result in degradation and volatile loss.
3. Oven dried material readily absorbs moisture from the atmosphere. Samples should be cooled in a desiccator after removal from the oven and weighed immediately upon cooling.
4. Lipids absorb oxygen from the air and increase in weight on standing. High fat samples should be dried for the minimum time required.
5. Drying of high moisture or fat samples may be expedited by placing a disc of oven dried filter paper on the bottom of the drying dish before sample addition to spread and absorb the excess fluid and reduce splattering. Sometimes draping a pre-weighed filter paper disc over the sample will reduce loss by absorbing excess fluid and splattering fat.
6. Samples must be homogeneous and spread thinly (0.7 cm [1/4 inch] maximum) and evenly over the bottom of the drying dish.
7. If severe crusting is evident, drying time should be extended and in extreme cases the sample mixed with a small amount of weighed pre-dried sand.
8. When dealing with atypical or new products, the weight should be checked during the drying process to determine optimum drying time (to constant weight).

1. Drying dishes, disposable aluminum moisture pans.
2. Drying oven set at 103° ± 1°C (217.4° ± 1.8°F), maintain good ventilation.
3. Balance capable of weighing 0.001 g.

1. Place 3 pre-numbered empty moisture pans for each sample in drying oven at 103°C for 1 h. Cool in desiccator for 20 min.
2. Weigh each pan to the nearest 0.001 g.
3. Mix comminuted sample well. Add 2-10 g to pan and spread evenly over bottom. Weigh pan and contents.
4. Dry in oven overnight, cool in desiccator, and weigh again. Samples may be checked for constancy of weight by returning to oven for 1 h and reweighing.

1. Select a piece of fish that is most likely to have the lowest water phase salt (WPS). This will usually be the largest and thickest piece.
2. Cut a slice from the center of the piece big enough to blend evenly (1-1.5 pounds [0.5-0.7 kg]). Avoid bones.
3. Blend the sample until it is evenly ground into a fine particle size.
4. Dry 2 glass fiber sample pads (C.E.M. Corp., Matthews, NC) and 2 microwave-safe paper plates to constant weight in the microwave oven (about 1 min).
5. Zero the balance (use balance accurate to 0.1 g). Place 1 predried glass pad on the balance (use forceps). Place 1 paper plate containing the second glass pad on top of the first pad. Weigh and record weight.
6. Weigh and record weight of about 10 g (± 0.1 g) ground sample on the glass pad that is nested in the paper plate. Spread sample and cover with second pad and a second paper plate (inverted). Mark the top plate because it will not be weighed.
7. Remove sample, pads, and plates from balance then compress sample by pressing firmly on top plate (do not contaminate the sample with grease from fingers or other foreign matter).
8. Microwave for 30 s; lift top plate and pad using forceps, and blot moisture from the lower plate with paper towel.
9. Replace top plate and pads. Microwave for another 60 s. Record weight.
10. Invert the 2 pads on the lower plate, replace upper plate and microwave for an additional 30 s. Record weight. Repeat step 10 if necessary until no further weight loss is observed. Do not "overheat or burn" sample.
11. Record weight, compute weight loss (wtl), and calculate % moisture (%m) as weight loss divided by sample weight (wts):

This method may be used in lieu of the pH meter method if the pH is 4.0 or lower.

1. The pH meter must be allowed sufficient time for warm-up.
2. The electrode must be kept clean and free of occluded protein. A weak base or a mild detergent solution may be used to clean the electrode. Soaking in 8M urea for 2 h may also help. At no time should abrasion be used since this will lead to permanent damage.
3. The pH meter must be standardized carefully 1 pH unit on either side of the anticipated pH to ensure linearity in the pH range being measured. Commercially available pH standards are available for this purpose.
4. All standardization solutions and samples should be at room temperature (or at a common temperature) when being measured. The effect of temperature variation on pH of standards is noted on their label.
5. When drying the pH electrode, the lip should be patted with tissue rather than wiped to prevent build up of static electricity in the electrode.
6. Use good quality fresh pH standards. Some standards change pH with age or on extended exposure to air.
7. Electrode should be stored immersed in distilled water between readings.
8. When the electrode is removed from a solution the meter should be placed on "standby."
9. All electrodes age resulting in a slower speed of response. Reconditioning may help restore electrode response. Reconditioning by immersing electrode tip 15 s in 0.1 N HCl rinsing in tap water, immersing for 15 s in 0.1 N NaOH, rinsing and repeating each step several times. If this does not restore electrode, immerse in a 20% solution of NH₄F·HF (ammonium bifloride) for 2-3 min, rinse and check.
10. Some magnetic stirrers may influence readings. Check during standardization. It is not necessary to use a stirrer for routine pH checks of homogeneous sample.
11. Several samples should be used to compensate for biological variation among samples.
12. Sample pH must be determined immediately after maceration or blending of sample.
13. Samples should not be allowed to remain at room temperature for extended periods of time since bacterial activity will raise pH.
14. If using method B (without water addition) ensure good flesh/electrode contact.

Representative samples should be rendered homogeneous by comminuting in a food processor and then immediately analyzed. Several samples should be used.

1. pH meter equipped with combination pH electrode.
2. Blender or food processor.
3. Glassware: 25 ml and 50 ml beakers.
4. Thermometer.

The method involves blending a sample with water, measuring the electrical conductivity in milli-mho units of the solution by means of a conductivity meter and interpreting the results from standard curves.

Temperature control is critical for the measurements; all measured solutions must be at the same temperature as standards used for the preparation of the standard curve.

For samples of low salt content the proportion of water must be decreased. However, in the extreme, some errors may be encountered from the presence of natural salts since the procedure is not specific for sodium but rather takes into account all inorganic ionizable salts. For low concentrations, the silver nitrate titration procedure may be preferable.

Sample preparation

1. With a sharp knife cut sample into portions of approximately ½" x ½" (1.3 x 1.3 cm).
2. Comminute sample:
1. For lean fish (salt cod), place several portions into a dry blender jar and blend for 10 s intervals until material is shredded.
2. For fatty fish (herring, mackerel), comminute sample in a food processor until a homogeneous paste has been produced. If portions are very dry a blender may be used for comminution.
3. Pre-weigh portions of fish according to anticipated salt content, i.e., 10, 20, or 40 g portions for 18, 8, and 4% NaCl (wet weight) respectively.
4. Save some material for moisture determination.

Apparatus

1. Conductivity meter equipped with conductivity cell. For example, Radiometer CDM2 meter with CDC-114 flow cell (Radiometer Analytical Group, Westlake, OH) is appropriate.
2. Blender, Waring or equivalent.
3. Water bath, constant temperature, maintained at 20 or 25 ± 0.5ºC.
4. Glass wool or filter paper, Whatman #4.
5. Glassware: 100 ml measuring cylinders, funnels (glass or plastic), test tubes (18 x 150 mm), 100 ml beaker, 100 ml volumetric flasks.

Reagents

1. Sodium chloride: dry 30 g ACS grade NaCl at 110ºC overnight in 100 ml beaker and store in desiccator.
2. Sodium chloride standards: To 100 ml volumetric flasks add 0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6 and 1.8 g portions (accurately weighed) of NaCl with 80 ml distilled water. Swirl to dissolve and make up to volume. Standards represent 0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, and 1.8% w/v solutions.

Procedure

1. Calibration of meter.
1. Add standard solutions to clean test tubes and equilibrate in constant temperature bath - allow at least 15 min.
2. With attached bulb rinse cell with distilled water. Cell should be stored filled with distilled water or soaked for at least 30 min before use.
3. With function switch on "calibrate" and range at 5 milli-mho, set pointer to red calibration mark on meter.
4. Partially fill cell with standard solution of lowest salt concentration and dispel into waste container.
5. Fill and empty (back into test tube) cell several times with standard solution to ensure temperature equilibration of cell. Allow cell to rest in test tube (in bath).
6. Record reading from meter.
7. Proceed (without rinsing) to solution of next higher concentration, discarding first aliquot drawn. If meter goes off scale switch to 15 milli-mho range.
2. Salt in sample
1. Determine moisture of samples.
2. Blend preweighed samples of fish with 200 ml distilled water for 1-2 min until homogeneity is achieved.
3. Filter a portion of the blend through glass wool or Whatman #4 filter paper into a glass test tube to remove particles.
4. Place test tube in water bath at set temperature and allow at least 15 min for equilibration.
5. Rinse cell with distilled water at temperature of water bath; cell should always be stored partially filled with distilled water.
6. On conductivity meter set output to 5 milli-mho and function switch to "calibrate." With calibration knob adjust meter so that needle rests on red calibration mark. Set switch to "measure."
7. With rubber bulb attached to cell partially fill cell chamber with filtered sample solution to rinse. Dispel into waste beaker.
8. Refill chamber with new solution ensuring that coil in cell is immersed in solution. Leave cell in the test tube (in water bath) and fill and empty cell several times to ensure constancy of and homogeneity of solution. Record reading from meter. If reading is off scale set meter to 15 milli-mho. Dispel solution.

Calculations

1. Standard Curve.

On graph paper plot meter reading vs. g NaCl/100 ml.
2. Salt Concentration in Samples

From the meter reading obtained for each solution determine from the calibration graph a final NaCl concentration. Salt in sample may be calculated as: Where: C = concentration of NaCl in sample expressed as % on a wet weight base
M = moisture as % by weight
R = %NaCl reading determined from graph
V = volume (ml) distilled water added
W = weight (grams) of sample used.

Quantabâ method (Hilderbrand, 1991; ETS, 1998)

Contents

1. Select a piece of fish that is most likely to have the lowest salt content. This will usually be the largest and thickest piece.
2. Cut a slice from the center of the piece big enough to blend evenly (1-1.5 pounds [0.5-0.7 kg]). Avoid bones.
3. Blend the sample until it is evenly ground into a fine particle size.
4. Place exactly 10 g of sample in a 250 ml beaker.
5. Add 90 ml (or 90 g) of boiling distilled water. Use boiling tap water only if a test with a Quantab® (Hach Company, Loveland, CO) shows the tap water to be salt free.
6. Stir for 30 s, wait 1 min (or longer if particles are large), and stir another 30 s to insure all salt is extracted from sample.
7. Place lower end of salt titrator into sample solution. Do not allow solution to reach yellow completion string at top of titrator.
8. Wait for solution to saturate titrator and turn yellow string dark blue. Note where the tip of the yellow/white peak on reacted titrator falls on the numbered scale in Quantab® units.
9. Determine salt concentration from calibration table on Quantab® container. Multiply by dilution factor of 10.
10. Note: Filtration of the sample solution may be needed to prevent obstruction of the titrator.

Determination of sodium chloride in foods and other samples by QuantabTM chloride titrators (HC MFLP-45)

Contents

Water Activity

Contents

Determining water activity using the Decagon AquaLab CX2 meter (Decagon, 1997)

Contents

1. Place AquaLab (Decagon Devices, Inc., Pullman, WA) on a level surface and in a location where the temperature remains fairly stable.
2. Plug in AquaLab and turn on power switch. The display will show all zeros in about 15 s. The instrument requires a warm up time depending on the ambient temperature.
3. Verify the calibration against a known salt standard before and after each sample run. For batch processing, calibration should be verified more frequently.
4. Make sure sample to be measured is homogeneous. Spread the sample material in the bottom of the disposable sample cup, covering the bottom of the cup if possible.
5. Place a sample in the sample drawer. Close the drawer and turn the knob from "Open/Load" to "Read." When the reading is complete, the instrument will beep continuously and the decimal points will blink.
6. The display will show a final a_w and temperature of the sample in degrees Celsius. The drawer can be opened at this time and the reading will be retained until the next sample is started. Most readings take less than 5 min.

Measuring water activity using the Novasina aw Center (HC MFLP-63)

Contents

Determination of water activity using the Decagon Aqualab CX-2 and Series 3 (HC MFLP-66)

Contents

Water phase salt calculation

Contents

Calculate water phase salt (WPS) as % salt (%S) divided by % salt + % moisture (%M) multiplied by 100 (Hilderbrand, 1992).

Other analytical procedures

Contents

• pH of acidified foods (AOAC, 1995a).
• Potentiometric method for the determination of pH (21CFR114.90(a)).
• Titratable acidity (21CFR114.90(c)).
• Salt (chlorine as sodium chloride) in seafood: Potentiometric method(AOAC, 1995c).
• Salt (chlorine as sodium chloride) in seafood: Volumetric method(AOAC, 1995b).

Commercial Test Products Disclaimer Clause

Contents

Moisture

Contents

Commercial test products for moisture.

Test Kit	Analytical Technique	Approx. Total Test Time	Supplier
HR73 and HG53 Halogen moisture analyzers	Drying lamp		Mettler Toledo, Inc. 1900 Polaris Parkway Columbus, OH 43240-2020 Phone: 888-216-8585 E-mail: info@mico.mt.com Web: http://www.mico.mt.com
M2 Microwave moisture analyzer	Microwave		Denver Instrument Company 6542 Fig St  Arvada, CO 80004 Phone: 800-321-1135 Fax: 303-423-4831 E-mail: dic@denverinstrument.com Web: http://www.denverinstrument.com

Salt

Contents

Commercial test products for salt.

Test Kit	Analytical Technique	Approx. Total Test Time	Supplier
CDM210 Conductivity Meter	Conductivity		Radiometer Analytical Group A division of Struers Inc. 810 Sharon Drive  Westlake, Ohio 44145-1598 Mr. Nick Mizencko  Phone: 440/ 871-5975  Phone: 1 800/998-8110 Fax: 440/899-1139  E-mail: analytical@clevelandoh.com Web: http://www.radiometer.tm.fr/index.html
Quantab® chloride titrators		20-45 min	Hach Company P.O. Box 389 Loveland, CO 80539 Phone: 1-800-227-4224 or 970-669-3050 Web: http://www.hach.com/
Ultra S® Salt Measurement System	Ion selective electrode	5-15 min	Lazar Research Laboratories, Inc. 731 N. Labrea Ave. Los Angeles, CA 90038 Phone: 213/931-1433 Fax: 213/931-1434 E-mail: service@lazarlab.com Web: http://www.lazarlab.com

Water Activity

Contents

Commercial test products for water activity.

Test Kit	Analytical Technique	Approx. Total Test Time	Supplier
AquaLab CX2 water activity meter	Cooled mirror condensation dewpoint sensor	3-4 min	Decagon Devices, Inc. 950 NE Nelson Court Pullman, WA 99163 USA  Phone: 509-332-2756  Fax: 509-332-5158 E-mail: sales@decagon.com Web: http://www.decagon.com
A2101 Water Activity Meter	Relative humidity sensor	4-6 min	Rotronic Instrument Corp. 160 E. Main Street Huntington, NY 11743 Phone: 516/427-3898 Fax: 516/427-3902 Web: http://www.rotronic-usa.com

Acidifying, Fermenting, and Salting Processes

Contents

Examples of seafood processes are provided for information only. The National Seafood HACCP Alliance does not endorse or recommend specific seafood processes. Some of the referenced processes are of historical interest and may not reflect current best management practices. Processes should not be followed as written without validation.

Acidifying "pickling" processes

Contents

Bismarck herring

Use herring of uniform size. Wash the fish in a special washing machine consisting of a large revolving drum equipped with a spray of water. Clean, behead, and bone the washed and scaled fish. Rinse with water and brush the inside to remove the black lining of the belly cavity. Place fish in salt brine for 2-3 h and then into a vinegar pickle (from 5-6% acetic acid) containing a moderate amount of salt. After 2 d in the pickle, pack the fish tightly in boxes with slices of onion, and some pepper and mustard seed. A vinegar sauce (from 2.2-2.4% acetic acid) containing some sugar is added and the box is closed and wrapped for marketing. Ship immediately or store in cool dry rooms (Long et al., 1982).

Cut spiced herring I

Ingredients

10 pounds (4.5 kg) salt herring, 2 quarts (946 ml) 6% acidity vinegar, 2 quarts (1.89 L) water, 2½ ounces (70.9 g) sugar, 4 ounces (113.4 g) sliced onion, 2 ounces (56.7 g) mustard seed, 1 ounce (28.3 g) bay leaves, 1 ounce (28.3 g) whole allspice, 1 ounce (28.3 g) whole black peppers, 1 ounce (28.3 g) whole white peppers, 1 ounce (28.3 g) whole red chili peppers, ½ ounce (14.2 g) whole cloves.

Procedure

Cut herring across the body in pieces 1-2 inches (2.5-5.1 cm) long. Pack pieces in wooden tubs holding 10-20 pounds (4.5-9.1 kg), or in kegs holding 100 pounds (45.4 kg). Mix together the dry spices. Place a few spices, 1-2 bay leaves, and several slices of onion in the bottom of the tub or keg, then a layer of cut herring, over which are laid onion slices and a sprinkling of spices. Repeat until tub or keg is filled. Dissolve sugar in the water and mix with vinegar. Cover cut herring with sugar-vinegar mixture. Store at 4.4ºC (40ºF) for 10 d to cure. At the end of this time, if the fish are to be repacked, fill cut pieces into 8, 16, or 32 ounce (237, 474, or 947 ml) glass containers. Use the curing vinegar to fill containers but strain it before reuse. Some packers prefer to use fresh vinegar diluted to 3% acidity. Place a few spices, 1-2 bay leaves, and a little chopped onion in each jar. Vacuum seal the containers, wipe containers clean and label (Long et al., 1982).

Cut spiced herring II

The shelf life of this product depends upon the care in manufacture and temperature of storage. If held at 4.4ºC (40ºF), the product should remain in good condition for at least 6 months. Exposure to light causes deterioration more rapidly even if held under refrigeration, as in a refrigerated showcase (Long et al, 1982).

Escabeche

Cut fish into small serving portions. Wash thoroughly, drain, and place in 90° salimeter brine for ½ h. Wipe the fish dry. Heat a minced clove of garlic, 6 bay leaves, and a few red peppers in olive oil until they are light brown, and then cool. Cook onions in the oil until they are yellow. Add black peppers, cumin seed, marjoram, and vinegar. Cook slowly for 15-30 min and cool. Pack cold fish into sterilized jars with the rest of the bay leaves and red peppers. Fill the jars with sauce and close immediately. Store in a cool place for at least 24 h before use (Jarvis, 1987).

Fish pickled in wine

Thyme may be substituted for rosemary, and the spice combination may be otherwise altered to suit the individual preference (Long et al., 1982).

Gabelbissen

Use fresh fat herring. Cure round herring 30-40 h in 90º salimeter brine. In some instances, however, this preliminary brine cure is omitted and the fresh fish are packed directly into barrels. Scatter a special curing mixture on the bottom of the barrel between the fish and over each layer. Pack the herring with bellies straight up and tails overlapping. Pack layers of fish in rather loosely. Head up the barrels and put them in cold storage at about 4.4ºC (40ºF), for several months to cure and ripen.

At the end of about 3 months, remove the herring from storage, drain well, head, bone, and skin. Cut the fillets into sections and pack in glass containers, or pack whole fillets in oval or oblong flat cans. If desired, lay a bay leaf and a thin slice of lemon in each can. Fill the containers with the original curing brine diluted ½ with distilled vinegar or pack in wine sauce, dill sauce, or curry sauce. Seal the containers and hold under refrigeration until sold (Long et al., 1982).

Gaffelbiter

Cut fat, mild-cure salt herring into fillets and skin. Freshen in running water 2-3 h depending upon size of the herring, whether mild or heavy cure, and local market preference. Cut fillets into 1 inch (2.5 cm) sections; pack into tubs or crocks and mix in the chopped onions and spices; cover with distilled vinegar. Store in a cool place (about 4.4ºC [40ºF]) and allow to cure for 48 h. Then repack herring pieces in sterilized containers. Fill containers with either fresh vinegar or the vinegar used for curing, but strain before using. Seal containers and pack for market distribution (Long et al, 1982).

German delicatessen anchovies

The following preservation and spicing mixtures are given for 1-liter tins:

Table 1-5. Ingredients for German delicatessen anchovies.
 

Weigh out salt, sugar, and sodium nitrate and thoroughly mix together. Then weigh out the remaining spice ingredients and mix thoroughly with the salt-sugar mixture.

Spread some of the spice mixture on the bottom of the 1-L tins and between each layer of fish. Place the first layer of fish in rows with backs down; the second layer in rows obliquely to the rows below with backs of the fish down. Repeat until there are 4 layers in the tin. Place 1 bay leaf on the bottom of the tin, 1 between each layer, and 1 on top. The lid is then put on and, for local use, made airtight with paraffin. Store the tins in a cool place, preferably under refrigeration (Long et al., 1982).

Herring in sour cream sauce

Use the mild-cured herring (Holland style). Fillet and save the milts. Soak fillets in cold water for 2 h. Rub the milts through a fine sieve. Drain fillets of surplus moisture. Boil together the vinegar, wine, and mixed spices for 3-5 min; cool and remove spices. Blend together the sour cream, sweet cream, milts, and cooled vinegar. Pack fillets in a large container with sliced onions, cover with the cream-vinegar sauce, and marinate in a cool place for 1 week. Pack fish and onion slices in glass jars with the sauce (Long et al., 1982).

Herring in wine sauce

Put all the ingredients into a large jar with cover. Place jar in a large enough cooking pot to which water can be added to the depth of the ingredients in the jar. Bring water to a boil and boil for 2 h. Then allow jar to stand overnight. When sauce is ready to be used, strain to remove the spices.

If vinegar-salt cure herring are used, cut the fillets in pieces of suitable size, rinse in freshwater, drain, and pack in sterilized jars with a few fresh spices and a slice of lemon. Fill jars with wine sauce. Seal.

If ordinary salt herring are used, fillet and freshen in water. Drain the fillets; pack in a stoneware crock; cover with 1 quart (946 ml) distilled vinegar (3% acidity) and let stand for 48 h. Remove the fillets from the vinegar and cut into pieces of suitable size; pack into sterilized jars and fill with wine sauce (Long et al., 1982).

Matjeshering

Wash the herring and scale. Remove the gills and pull the intestines out through the gill opening so that the throat or belly walls are not cut open. Soak the cleaned fish in a 7% white wine vinegar solution for 12-18 h (they must be removed from this solution before the skin becomes soft and flabby). Wipe fish dry. Roll in a curing mixture of: 2.2 pounds (1 kg) salt, 1.1 pound (0.5 kg) brown sugar, and 4 ounces (113 g) sodium nitrate.

Pack herring in a small keg in straight layers with backs up. Scatter some of the curing mixture between the fish as they are packed and sprinkle some over each layer. Allow to stand 24-48 h. Then repack fish, using the original brine that has collected. If not enough brine has formed, make up additional brine to cover herring by boiling together 1 part salt-sugar mixture (as above) to 4 parts water. Cool and filter before using. Close kegs and store at 4.4ºC (40ºF) for at least 1 month before using (Long et al., 1982).

Mustard or Kaiser-Friedrich herring

Pickled and spiced mackerel fillets

Clean fish and wash thoroughly, and cut into fillets, removing the backbone. Divide the fillets into 2 inch (5.1 cm) lengths and dredge with fine salt. Pick up pieces with as much salt as will cling to the flesh and pack in a crock or tub. Let the fish stand for 1-2 h, then rinse in freshwater. Cook the vinegar, water and other ingredients slowly and gently for 10 min after reaching boiling point. Add the fish and cook slowly for 10 min longer, counting from the time at which the solution again begins to boil after the fish has been put in. Remove the fish and allow the pieces to drain, then pack them in sterilized jars, adding some chopped onion, a bay leaf, a few spices, and a slice of lemon to each jar. Strain the spice vinegar sauce and bring to a boil. Fill the containers with hot sauce and seal immediately. Store in a cool, dry place (Long et al., 1982).

Pickled eels

Pickled haddock fillets

The fish are covered with a solution of 2 parts vinegar and 1 part water, adding a small piece of alum about the size of a walnut. Boil slowly until the fish may be pierced easily with a fork. After cooling, the product is packed in glass containers, adding a few fresh spices, a bay leaf, and a slice of lemon around the side of the jar for decoration. A few slices of onion may also be packed with the fish. Strain the vinegar sauce, heat it, and pour over the fish until the top is well covered. Seal the containers immediately. For maximum preservation, store under refrigeration (Long et al., 1982).

Pickled herring for rollmops, cut spiced, or Bismarck herring

For final manufacture, repack herring in kegs and fill with a solution of distilled vinegar diluted with water to a 3% acidity and containing sufficient salt to test 35º salimeter. Dressed herring may be cut into fillets or the backbone may be removed leaving the fish otherwise whole before repacking. Store repacked kegs in cold storage at 1.1ºC (34ºF).

Begin the final process by soaking the herring in a tank of cold water 8-10 h. Remove the herring and drain. Place the fish in a solution of vinegar, salt and water for 72 h. Make up the solution in the following proportions: 1 gallon (3.79 L) of 6% white distilled vinegar to 1 gallon (3.79 L) of water, and 1 pound (454 g) of salt. Be certain the fish are well covered with the solution. Then make them up into cut spiced herring, rollmops, or Bismarck herring (Long et al., 1982).

Pickled mussels I

Pickled mussels II

Pickled octopus meat

Pickled oysters I

Remove oysters from liquor. Strain liquor and add sufficient salted water to make 3 pints (1.4 L). Simmer liquor over low heat. When it is near the boiling point, add a few oysters at a time and cook until fringe curls. Cool. Make a sauce of the cooking liquor, vinegar, wine, and spices. Simmer for 30-45 min then cool and strain. Pack oysters in glass jars with a bay leaf, slice of lemon, and a few fresh spices in each jar. Fill jars with strained sauce. Seal jars and cure for 10-14 d in a cool, dark place (Long et al., 1982).

Pickled oysters II

Blanch oysters in their own liquor until fringe curls. Remove and cool oysters. Bring the oyster liquor to a boil, then cool. Cook vinegar and spices over low heat for 5 min. Strain vinegar to remove spices. Combine oyster liquor and spiced vinegar and cool. Pack the oysters in glass jars with a bay leaf and thin slice of lemon in each jar. Fill containers with the cool sauce and seal immediately. Store under refrigeration (Long et al., 1982).

Pickled salmon I

Cut salmon into individual serving portions. Wash well in cold water, drain, and dredge in fine salt. Allow to stand for 30 min, drain off leakage, and slowly simmer salmon until done. Place the warm fish pieces in an earthenware crock. Cover with a vinegar-spice sauce made as follows: Sauté onions in olive oil slowly until they are yellow and soft. Add remainder of ingredients and simmer gently for 45 min. Cool sauce, then pour it over the fish making sure that all pieces are covered. Let fish stand in sauce for 48 h then repack in pint (0.5 L) jars with a slice of lemon, slice of onion, and 1 bay leaf inserted around sides of jar for decoration. Filter the spice sauce before pouring it over the fish; fill container with sauce, then seal. This product should be held under refrigeration at 4.4ºC (40ºF) (Long et al., 1982).

Pickled salmon II

Some mild-cure salmon is cut into 2 inch (5.1 cm) cubes, freshened in cold water, and packed in spiced vinegar sauce or in wine sauce (Long et al., 1982).

Pickled spiced shrimp

Pickled sturgeon, pike, pickerel, salmon, herring, trout, and other fish

Wash fish well and cut into small, 2-4 ounce (57-113 g), individual serving size portions. Dredge pieces in fine salt and store for 1-3 h. Rinse off salt, dry the pieces, and brush with cooking oil. Broil the pieces over a hot fire until both sides are light brown, brushing with cooking oil during the process. Cool fish and pack in glass containers with 1-2 slices of lemon, bay leaves, onion, and a scattering of rosemary, whole black peppers, and whole cloves between layers of fish. Fill jars with a marinade made of white wine, vinegar and water, and seal immediately. Store in a dry, cool place (Jarvis, 1987).

Rollmops

Cut each dill pickle lengthwise into 4 parts, then each of these across the center, making 8 pieces in all.

Roll the fillets around a piece of pickle and fasten with a fresh clove. A clove serves the purpose just as well as a toothpick and adds to the attractiveness of the pack.

Place 1 teaspoon (10 ml) of mixed used spices on the bottom of the jar, then pack the fish. With a medium sized herring, 3 rolls will pack nicely into a No. 306 jar (6 fluid ounces [178 ml] capacity) if placed on end. Decorate around the sides with a couple of chili peppers and a bay leaf. Add sufficient pickle to fill (from 25 to 30 ml) (this is about equivalent to 2 level tablespoonful). The net weight should be 5½ ounces (156 g) or over. Seal the jars immediately after packing. Vacuum sealing is preferable.

Store is a cool place. Cold storage at about 1.7ºC (35ºF) is advisable to ensure longest preservation.

Note: If vinegar-salt-cured herring are used, the preparation and preliminary vinegar-cure steps will be unnecessary. (It is believed that a better product will be obtained if the vinegar-salt-cure herring are used.) In this case, the spice-vinegar sauce should be diluted to 3% acidity and the rollmops should be cured in the spice sauce for 10 d. They should then be repacked in jars with a few spices and the jars filled with fresh 3% vinegar to which are added 2 tablespoons (59 ml) sugar and 1 tablespoon (30 ml) salt per quart (946 ml). Store at 1.1-4.4ºC (34º-40ºF) (Long et al., 1982).

Russian sardines

Pack fresh small herring (5-7 inches [12.7-17.8 cm]) in 90-100º salimeter brine as soon as possible after catching. Hold in the brine about 10 d until they are thoroughly salt-cured or struck through. After salting, remove heads, pulling out the viscera with the same stroke of the knife without tearing the belly open. Wash in clean water and place on wire trays for draining. Allow to drain for several h. Sort for size and pack each size separately in small kegs holding about 7 pounds (3.2 kg) of fish. For packing, mix all spices and flavorings together. Scatter a thin layer of these ingredients in the bottom of the keg and a layer of herring with backs up. Lightly press down layer, scatter another thin layer of spice ingredients over fish, and add a little vinegar. Repeat this process until keg is filled. Pour in as much vinegar as the keg will hold and head up the keg. The fish is ready for the market in from 4-5 d (summer) to 3-4 weeks (winter). Refrigerate at about 4.4ºC (40ºF) for a 1-year shelf life (Long et al., 1982).

Scandinavian anchovies

Cure 25-30 pounds (11.3-13.6 kg) of bristling for 12 h in brine made of 4½ pounds (2.0 kg) of Liverpool salt and 7 quarts (6.62 L) of water. Drain the fish on a wire screen. Make up a spice mixture with all spices well pulverized and the ingredients thoroughly blended: 2¼ pounds (1.0 kg) Luneberg salt, 3 ounces (85 g) black pepper, 3 ounces (85 g) allspice, 3 ounces (85 g) sugar, ½ ounce (14 g) cloves, ½ ounce (14 g) nutmeg, ½ ounce (14 g) cayenne.

Use half of the spice mixture and mix well with the sprats. Pack them in a large container and cure for 14 d. Repack in individual containers in layers, bellies up. Scatter some of the remaining spice mixture between each layer with pieces of chopped bay and cherry leaves. On the bottom and top of each container, lay 2 whole bay leaves. The brine formed in the original spice cure is filtered and used to fill the small containers after packing. During the first few d after the containers are closed, roll them about and invert them at least every other day.

Tin containers are preferred to wooden kegs which are often leaky and the airtight seal of a tin container permits a longer period of preservation.

For 40 pounds (18.1 kg) of bristling prepare the following spice mixture well pulverized and thoroughly blended: 2¼ pounds (1 kg) Luneberg salt, 7 ounces (198 g) black pepper, 7 ounces (198 g) allspice, 7 ounces (198 g) sugar, 1-1/8 ounce (32 g) cloves, 1-1/8 (32 g) ounce nutmeg, 1-1/8 ounce (32 g) Spanish hops.

Place fresh bristling in strong salt brine from 12-24 h. Drain on a screen, and pack in layers in small kegs after being rolled in a spice-curing mixture. Scatter some of this mixture between the layers of fish. At the top, bottom, and in the middle of the keg, lay several bay leaves. Pack the kegs tightly and roll them about or invert them for 14 d. Repack the anchovies in tins in 14 d in summer or after 4-8 weeks in winter.

Wash brine-salted bristling in light brine testing 40º salimeter. Drain and pack loosely in new barrels with some of the following spice mixture scattered between each layer of fish. This quantity of spice mixture is for 1 barrel original weight: 2 pounds (0.9 kg) black peppers, 1 pound (0.5 kg) allspice, 1½ pounds (0.7 kg) sugar (best raw), 1 pound (0.5 kg) sodium nitrate, 1 pound (0.5 kg) bay leaves, 6 ounces (170 g) Spanish hops, 2 ounces (57 g) mace, 2 ounces (57 g) cloves, 2 ounces (57 g) cinnamon, 2 ounces (57 g) ginger.

Filter the brine used for washing and the original brine and pour into the barrels after filling. Place the barrels in cool storage for several months for the fish to ripen or acquire and aromatic flavor. Roll the barrels about daily or at the least, at intervals of 2-3 d. When the fish have completely absorbed the spice flavor, repack in small individual containers, small kegs holding about 7 pounds (3.2 kg), cans holding from 2-5 pounds(0.9-2.3), and glass jars. Filter the brine used in curing and fill into the containers when they have been packed with fish. In summer 0.5% benzoic acid may be added to the brine (Long et al., 1982).

"Scotch-cured" herring

Table 1-6. Sizes for Scotch-cured herring.
 

When sufficient "pipped" herring have been sorted "rouse" with salt by placing them in a large tub and covering them with fine salt; mix thoroughly by hand until the entire surface of each herring is evenly covered with salt. Pack either in tight 250 pound (113.4 kg) or 125 pound (56.7 kg) barrels. The standard Scotch barrel (250 pounds [113.4 kg]) is made of staves about ¾ inch (1.9 cm) thick; 30 inches (76.2 cm) high and has a head 17 inches (43.2 cm) in diameter; its capacity is 32 U.S. gallons (121.1 L). Carefully pack the fish in layers with backside down, taking care to keep the rows even so the layers are uniform. Pack the second layer at right angles to the first layer. Using Liverpool No. 2 fishery salt, half-ground Spanish salt, or half-ground double washed California salt, sprinkle enough salt over each layer to almost cover them. Fish containing milt or roe require more salt. But, do not use an excess of salt, as the completely cured fish should be free from undissolved salt.

Some herring salters allow the fish to make their own pickle; others add some saturated brine immediately after the fish are packed into barrels. Adding the brine is advisable during warm weather and when curing extra large herring for it enables the pickle to "strike the bone" immediately from the inside and outside as well.

On the first or second day after salting when the herring have settled somewhat, fill the barrel with herring of the same day's pack. Put the head on the barrel and place it on its side for 8-10 d. At the end of this time, up-end the barrel, head up, and remove the head. Bore a bunghole in the center of the side of the barrel and drain the pickle as far down as the bunghole. Pour the drained pickle over the top tiers of fish in the barrel 2-3 times, which will cause the herring to settle. Again fill the barrel with salted herring of the same day's pack. In repacking the barrel, sprinkle a very small quantity of salt over each additional layer except the last layer to which no salt is added. When the layers of salted fish reach the top of the staves, the head is "jumped" in. After tightening the hoops, place the barrel on its side and fill with saturated brine. Replace the bung (Long et al., 1982).

Ayu-sushi

Black fermented squid meat

Cured ayu in koji

Cured Atka mackerel or flat-fish

Cured fermented ayu in sake-lees

Cured fermented abalone in sake-lees

Cured herring in koji

Cured herring in rice bran

For dried herring meat, soak in freshwater for 2-3 d. Wash thoroughly and drain. Make a paste of rice bran and saturated salt solution and cure softened herring and rice bran paste in a barrel (Tanikawa et al., 1985).

Cured mackerel in koji

Cured mackerel roe in koji

Cured octopus or squid meat in koji

Cured puffer fish meat in rice bran

Cured puffer fish roe in rice bran

Cured salmon or cod meat in sake-lees

Cured salmon-"sushi"

Cured sardine in rice bran

Cured sea bream in koji

Cured squid meat

Fermented ayu milt

Fermented ayu roe

Fermented bonito meat

Fermented bonito stomach

Fermented bonito viscera

Fermented meat and viscera of ayu

Fermented mixture of ayu roe and milt

Fermented sea-cucumber viscera

Fermented viscera of ayu

Fermented "sushi"

Liquid fermented sand fish (Arctoscopus japonicus) sauce

Ordinary fermented squid meat

Mix together 100 parts of meat strips, 4-8 parts liver, and 20 parts salt in summer (15 parts salt in winter) in a barrel and store. Stir the mixture 2-3 times a day during the first week, then seal the barrel tightly and store (Tanikawa et al., 1985).

Pasty fermented sea urchin

Pulpy fermented sea urchin

Red fermented squid meat

Watery fermented sea urchin

White fermented squid meat

Alaska Scotch-cure herring

Anchovies, Spanish style

Hold tanks at 26.7-32.2ºC (80-90°F) for about 4 months. The anchovies are ready when the flesh is red from skin to backbone and has a strong, sharp flavor.

Remove anchovies from tank, drain, and pack in round tins holding 8, 14, or 28 pounds (3.6, 6.4, or 12.7 kg). Press fish to remove excess moisture and oil. Seal cans and store (Jarvis, 1987).

Appetitslid

Brine packed cod

Brine-salted mackerel

Brine-salted mullet