A recipe for smoking squid from Kreuzer (1984) was adapted to suit giant clam. It was tried out in 4 experiments (Nos. 1, 3, 5 and 7).
After butchering the clams as described above, the different parts were immersed in a boiling brine consisting of 70 g salt per litre of water (six litres of brine were used in most cases). Boiling time was counted from the moment the mixture was brought back to the boil after immersion of the meat. After 10 minutes, the liquid was drained and the meat allowed to cool completely in a colander. Weight of the different parts was then recorded.
When gonads are being boiled, it is important the mixture is barely simmering, as otherwise, the roe will spill and be lost as happened in experiment 1. Mantle and adductor muscle can withstand heavier boiling.
A dry seasoning marinade was prepared according to Kreuzer (1984) but later modified in the following way:
were thoroughly mixed together for every kilogram of cooked product. This mixture was then worked with the cooked meat and layered in a plastic tub, covered with a loose fitting plate and put under pressure with heavy weights. This was left to stand overnight in an air-conditioned room (approximately from 5.00 PM till 8.00 AM). Before smoking, the marinated meat was allowed to drip for 5 minutes, the excess crystals were shaken off and the weight recorded.
A similar small drum smoker as used in experiments in Kiribati (Trachet, 1989) was constructed at the MMDC workshop. Details on the construction are given in Appendix 2.
The meat was hung or skewered on steel rods and pre-dried in this smoker over a small fire with the smoker lifted on stones (5–10 cm off the ground) for greater air intake and with the top open. It took 45 minutes to 1 hour to get a dripfree dried product. As a rule for temperature control (in absence of a thermometer) it was taken that the metal rods should never feel hot to the touch.
The product was further smoked for 4 to 5 hours with all air intake reduced and with the smoker covered with a plywood sheet, the fire being subdued with sawdust, and not allowed to burst into flame. At the end of the smoking time, the temperature was allowed to rise. The product was then allowed to cool in an air-conditioned room, and the weight recorded. The product was further stored in the kitchen refrigerator.
A more detailed account of the whole process is given in Appendix 1.
The product was given to staff and visitors of the MMDC, comprising Palauans, Americans and Japanese, to taste.
The end product had a matt, dark amber to woody colour, the texture being chewy but not unpleasantly so. The taste being only slightly salty, with a light sweetness and a clear clam taste.
The smoked mantle took up the shape of a ring. This product being considered more tasty, if more chewy than the adductor muscle.
The coloured part of the processed mantle ended up a very dark green, almost black, with a certain vegetable taste to it. Some tasters in the panel objected to this part of the meat, but it was considered important to leave it in order to give the product a typical “giant clam” appearance, and to avoid further weight loss.
The surface of the cut appeared translucent white.
The adductor muscle, although more appealing in aspect, had a blander taste and a more outspoken “grain” in the structure. The colour of the cut is of a more opaque white.
After trials, the panel found the smoked guts to be a less valuable product, although the taste is good. These were therefore not utilised in later experiments.
Product yields at the different processing stages are given in table 2.
The limited weight loss after marinating in experiment 3 is due to the inability to apply pressure on the mixture (no cover of suitable size was found for the marinating bucket).
| Table 2: Japanese style smoking: yields at different processing stages. (total yield is smoked adductor + mantle weights as compared to raw adductor + mantle weights. Each other percentage is as compared to the previous processing step) | |||||||||||||
| Exp. | FRESH | COOKED | MARINATED | SMOKED | TOTALYIELD | ||||||||
| M | A | G | M | A | G | M | A | G | M | A | G | ||
| 1 | 1410g | 490g | 673g | 465g | 304g | - | 421g | 285g | - | 322g | 227g | - | |
| 32% | 62% | - | 90% | 93% | - | 76.5% | 79.6% | - | 28.9% | ||||
| 3 | 1801g | 612g | 420g | 563g | 389g | 171g | 549g | 386g | 165g | 411g | 302g | 127g | |
| 31% | 63.5% | 40.7% | 97% | 99% | 96.5% | 75% | 78.2% | 77% | 29.5% | ||||
| 5 | 6920g | 2240g | 3090g | 1683g | 1192g | - | 1536g | 1094g | - | 1324g | 981g | ||
| 24.3% | 53.2% | - | 91% | 92% | - | 86.2% | 89.7% | - | 25.2% | ||||
| 7 | 2865g | 902g | 1415g | 752g | 473g | - | 679g | 441g | - | 531g | 364g | - | |
| 26.2% | 52.4% | - | 90.3 | 92.2% | - | 78.2% | 82.2% | 23.8% | |||||
| Legend: Exp. = experiment number;M = mantle;A = adductor muscle;G = guts. | |||||||||||||
The lower yields after cooking in the two latter experiments (5 and 7) are due to overestimation of the fresh weight. The larger size of the sample did not allow an equal efficient dripping before fresh weights were recorded.
From the yields during smoking, it can be seen that substantial differences occur. In the future therefore, the weight change of the product during smoking should be the prime indicator for establishing the smoking time (colour being the second one), this is the only way to obtain a consistent product under artisanal conditions as described here.
Samples were kept in a domestic refrigerator in open containers (to prevent problems with condensation) and were still organoleptically acceptable after a week. Under refrigerated conditions (+5°C), further drying of the product occurred and taste became more bland.
A small sample was taken back to Fiji (packed in sealed Freezer bags) and after a 36 hour delay in cooling re-stored in a domestic refrigerator where they were kept another week. During the transport, formation of condensation droplets could not be avoided. At the end of the period, clam smells had become stronger, and it can be considered the product was near the end of its shelf life.
A sample of both adductor muscle and mantle meat were brought to the Institute of Natural Resources of the University of the South Pacific in Suva on the first of December 1989 for analysis of moisture and salt content (Mr. William Dixon). The analyses where done on the 21st December.
Salt content was analysed through titration of the extract against Silver Nitrate (FAO 1982, appendix 4) and expressed as weight percents NaCl for sample weight. Moisture percentage (against wet weight) was measured after 48 hours drying at 105 °C. The results can be seen in Table 3.
| Table 3: Moisture and salt content of Japanese style smoked product. | ||
| Moisture % | Salt (Nacl) content (%) | |
| Adductor Muscle: | 41.0 | 4.4 |
| Mantle Meat: | 35.9 | 7.1 |
It was established for smoked finfish products that the salt concentration in the water of the finished product should be minimum 3 % in order to inhibit the growth of most of the food poisoning organisms present, particularly Clostridium botulinum (Bannerman, Undated). If this rule can be applied to smoked giant clam, these conditions are here fulfilled, indicating the product could be vacuum packed without major health risks.
The results in Table 3 indicate anyway that the product has only a limited shelf-life, as the measured water and salt levels will not inhibit the growth of moulds. Refrigeration and/or vacuum packing will therefore be necessary to give the product a better keeping quality.
It must be pointed out that the moisture content in the analysis is probably underestimated with regards to the fresh finished product due to the further drying in the domestic refrigerator.
Although the pieces could be sold without further processing, the product can best be presented to the consumer in 2mm thick slices. The slices can be made longer by cutting at an angle to the axis of the meat.
There are many types of Japanese dried and smoked products on the market in Koror. Most are thin slices and typically they come in 30g vacuum packed pouches with a price tag between US$2.- and US$3.- per packet.
As the production in this early stage should be sold at a stand at MMDC, for the benefit of Japanese tourists visiting the centre, a small kitchen type vacuum packer might be purchased. On the other hand it was found that the sliced product packed in a small clam shell and covered with plastic foil (Klingwrap) was very attractive. A half clam shell (2 year old) was found to contain 16 grams of the sliced product. It is sure that this way of packing would be less time consuming than vacuum-packing and the cosmetic value would be enhanced.
Although requested in the terms of reference for this study, no marketing trials were undertaken. This was omitted upon request from the clam farm manager, who considered it too soon to raise hopes for such a product in the local marketplace.
As no estimates exist on the production costs for 6 year old giant clam and as there is no sufficient stock to sustain even a small production unit continuously at this stage, it would have been impossible to give the potential client an idea of price or available quantity, which is the type of information they do require before considering buying a product like this.
