| Applications of biotechnology to traditional fermented foods |
|V. Animal derivatives|
R. C. Mabesa, E. V. Carpio, and L. B. Mabesa
The single, probably most important, limitation in the manufacture of fish sauce is the length of time required for its production. It normally takes approximately 12 months from salting to maturity. This limits the turnover rate and overall profitability of a potentially lucrative enterprise. Considering the capital outlay and operating expense required to run a fish sauce business, it is imperative to develop a simple, economical, practicable accelerated process that yields acceptable fish sauce.
With this goal, research and development efforts were undertaken at the food pilot plant of the Institute of Food Science and Technology, University of the Philippines at Los Banos.
This investigation stemmed from the observation in commercial tanks that freshly drawn fish sauce lacks the desirable aroma of mature sauce; this aroma develops after overnight storage or longer. The appropriate color is there initially but typical flavor is lacking. It was also observed that flavor, aroma, and color development of palls in both concrete and wooden vats is more rapid and pronounced during the hot summer months. Constant agitation through pumping and frequent transfer of fish sauce from one container to another also hastened and enhanced development of flavor and aroma. It was hypothesized, therefore, that artificial agitation and/or aeration and heat may help with the development of desirable qualities in fish sauce. Thus, small-scale laboratory experiments were carried out initially. It was determined that timing is of primary importance in the application of heat and aeration. The typical fish sauce characteristics did not develop when freshly salted fish was aerated and heated immediately after mixing. Trials were carried out to determine the appropriate time for aeration and heating of the fish salt mixture. It was found that aging for about a month after salting was sufficient and that higher temperatures resulted in more rapid and greater improvement in quality. However, preliminary experiments indicate that the maximum temperature should not exceed 50°C or a cooked flavor results.
A concrete tank simulating the dimensions of a commercial tank was constructed to test the findings in the laboratory. Technical specifications are given below (see box). It was concluded that fish sauce comparable to traditionally manufactured sauce can be obtained in about 2 months or less using modified reaction conditions. These conditions are given under B and C. Sauce characteristics are given under D.
It is likely that production time may be further reduced if strongly halophilic, proteolytic, and thermophilic Bacillus and Pediococcus species used in the laboratory can be used in production.
Fish sauce with the desirable qualities of traditionally produced sauce was obtained in the pilot plant. The improved process resulted in an acceptable product in about 2 months instead of the 10 to 12 months required for the traditional process. Clearly, savings in time and an improved turnover rate can result if these results are applied commercially. This means greater income-generating capacity.
Some problems, such as loss of volume and contamination with molds and bacteria, were encountered during heating and aeration. The former was remedied by day-to-day monitoring of fish sauce levels and replenishment with plain tap water when necessary. The second problem was resolved by installing cotton filters at the intake end of the pumps and by adding sorbic acid to the sauce at 0.05 percent prior to bottling.
With pilot-level success, there is reason to believe that the process can be applied on a commercial scale. However, there are problems attendant to adaptation of the process. Additional expense will be incurred in equipment acquisition, installation, and operation. Heating and aeration alone will increase the price of palls by about P 50 per drum or about P 0.25 per liter.
1. Type - concrete, cube approximately 0.265 m x 0.265 m x 0.265m I.D.
2. Material - concrete 3:2:1 mixture of sand, gravel, and cement with Sahara water proofing added.
3. Heaters - two 1,000-watt rod-type heaters located close to the center of the tank.
4. Air pump - one aquarium-type air pump with discharge capacity of 5 liters/minute; pump discharge located 2.5 centimeters below heaters.
B. Operating Information
1. Preliminary incubation - 50 days at ambient temperature.
2. Air pump - operated 4 hours a day for 10 days.
3. Heaters - operated 4 hours a day for 10 days.
4. Temperature - 45° to 60°C for 10 days.
5. Power requirement - 7 amperes (pump and heater).
6. Voltage requirement - 220 volts.
C. Raw Material Information
1. Total weight of fish salt mixture - 320 kilograms.
2. Proportion - 1 salt:2 fish by weight (106.6 kilograms salt:213.3 kilograms fish).
3. Fish species - Decapter`'s macrosoma.
4. Source - Navotas Fishery Port.
D. Sauce Characteristics
1. Color - golden yellow-brown highly typical of fish sauce and clear.
2. Odor - slightly acidic and fishy, typical of fish sauce.
3. Flavor - typical fish sauce.
4. Total solids percent.
5. Protein - 14 percent.
6. pH - 6.0.
7. Salt - 24 percent.
8. Specific gravity - 1.21.
9. Yield - 137.5 kilograms.
These costs must be weighed against savings or advantages such as faster turnover rate, decreased overhead, salaries, and power.
Each manufacturer or potential user of a new technology such as this stands to gain substantially despite the additional costs. However, each interested user may find his or her situation unique. A careful study of all terms, factors, and conditions affecting a user should be undertaken before embarking on a new and innovative process such as this.
In light of these results and consequent problems, efforts are under way in the laboratory to reduce process costs, particularly with respect to reducing heating time, minimizing heat losses, increasing heating efficiency, and exploring alternative sources of energy for use in the process.