VII.3. Liquid fish products
Fish sauces are basically water-extracted solutions of fully
fermented fish and are used in a similar manner to soya bean sauce. Indeed, the
manufacture and final composition of many fish sauces is similar to that of soya
sauce, it being basically a mixture of protein breakdown products (i.e.
peptides, amino acids, amines, etc.) in combination with high salt
concentrations. Fish sauces may be of limited nutritional value (van Veen, 1965)
as their high salt content precludes bulk consumption. However, in some regions,
consumption is surprisingly high and in Viet Nam the sauce nuoc-mam can
provide up to 20% of the daily protein intake. Fish sacues are rich in
hydrolysed proteins and minerals (e.g. sodium chloride and calcium salts) and
can be an important source of calcium in the diet.
VII.3.1. Nuoc-mam (Viet Nam)
Nuoc-mam is by far the most important fish sauce in South
East Asia, many thousands of tonnes being produced each year, principally in the
coastal regions of Viet Nam, Thailand and Cambodia. Nuoc-mam of good
quality is a fairly stable, clear dark brown or amber liquid with a distinctive
odour and flavour. The lower quality nuoc-mam may, however, have an
unpleasant odour and a reduced storage life. Quite often, additional ingredients
are added in order to darken the liquid and improve the flavour of the product.
These include such materials as caramel, roasted rice, molasses and roasted or
boiled corn. Due to its widespread distribution and consumption, legislation has
been introduced in some countries in order to guarantee set quality standards.
The fish species used in the production of nuoc-mam are
usually of the genera Stolephorus, Engraulis, Dorosoma and
Decapterus and clupeoids. Nuoc-mam can also be prepared from
shrimp. The processing method is similar to that of bagoong except that
the fermentation is generally protracted and the product is the exudate rather
than the solid fraction. The actual process varies according to scale. In the
small scale operations, whole fish are kneaded lightly by hand, mixed with salt
in earthenware pots and buried in the ground for a few months. The
nuoc-mam is the clear liquid which settles on top and is carefully
decanted off. In the large scale operations the fish (whole and unwashed) are
piled, with salt spread between layers, in timber vats. 4 parts of salt to 6
parts fish should be used for this purpose. After three days, the blood pickle
(nuoc-boi) is allowed to flow out slowly over a 3-day period into another
recipient. The fish are then trampled by foot until a flat surface is obtained.
The latter is covered with coconut leaves over which are set two semi-circular
bamboo trays, the whole system being wedged down tightly. The nuoc-boi is
then poured back over the fish until a 10 cm liquid layer is formed on the top
of the trays. It is then left to mature for four months to a year depending on
the species of fish. After maturation, the pickle which is run off is the top
quality nuoc-mam. The trays and leaves are removed, and fresh salt is
added to the top layer of the fish residue. Fresh brine is also added to obtain
a lower quality of nuoc-mam.
The yield varies from 2 to 6 parts of nuoc-mam from 1
part of fish, the residual mass being used as fertiliser. Nuoc-mam is
normally packed in bottles but may also be stored in earthenware pots.
VII.3.2. Other fish sauces
A number of other fish sauces are also produced in South-East
Asia in large quantities. Patis (Philippines) is produced from the
bagoong process and is similar to nuoc-mam. Nam-pla is made in
Thailand, the preferred fish species being Stolephorus spp. Production of
the latter is similar to that of nuoc-mam although less salt is used
(i.e. 1 part salt to 4 parts fish). The process may take from 6 to 36 months to
complete depending on the quality required. In Malaysia, a sauce known as
budu is made from small anchovies. Production involves mixing 1 part of
salt and 5 parts of fish in eartheware pots together with tamarind and palm
sugar. A dark, sweet-smelling sauce results after 6 months of fermentation. The
product has a storage life of 2 years or
more.