ENZYMES - CLASSIFICATION IN THE NOMENCLATURA COMUM DO
MERCOSUL (NCM)

The enzymes must be
classified the heading 3507 of the NCM. This heading has the following
structure:

3507
Enzymes; prepared enzymes not elsewhere specified or included

3507.10.00 - Rennet and concentrates thereof

3507.90 - Others

3507.90.1 Amylases and concentrates

3507.90.11 Alpha-amylase (Aspergillus oryzae)

3507.90.19 Others

3507.90.2 Proteases and concentrates

3507.90.21 Fibrinucleases

3507.90.22 Bromelains

3507.90.23 Streptokinase

3507.90.24 Streptodornase

3507.90.25 Mixture of streptokinase and streptodornase

3507.90.26 Papain

3507.90.29 Others

3507.90.3 Others enzymes and concentrates

3507.90.31 Lisozyme and  hydrochloride

3507.90.32 L-Asparaginase

3507.90.39 Others

3507.90.4 Prepared enzymes

3507.90.41 Based on cellulases

3507.90.42 Based on transglutaminase

36507.90.49 Others

Enzymes are organic
substances produced by living cells; they have the property of causing and
regulating specific chemical reactions inside or outside living cells, without
themselves undergoing any change in their chemical structure.

Enzymes may be referred to
as follows :

(I)   According to their chemical constitution,
e.g. :

(a)  Enzymes in which
the molecule consists solely of a protein (e.g., pepsin, trypsin, urease).

(b)  Enzymes in which
the molecule consists of a protein combined with a non-protein compound of low
molecular weight, acting as a cofactor. The cofactor may be either a metal
ion (e.g., copper in ascorbate oxidase, zinc in human placental alkaline
phosphatase) or a complex organic molecule called a coenzyme (e.g., thiamine
diphosphate in pyruvate decarboxylase, pyridoxal phosphate in
glutamine-oxo-acid aminotransferase).  Sometimes both are required.

(II)  According to :

(a)  their chemical activity as
oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases; or

(b)  their biological activity as amylases,
lipases, proteases, etc.

This heading (3507)
includes :

(A)  “Pure” (isolated) enzymes.

These are generally in crystalline
form, and are mainly intended for use in medicine or in scientific research.
They are not as important in international trade as enzymatic concentrates and
prepared enzymes.

(B)  Enzymatic concentrates.

These concentrates are
generally obtained from either aqueous or solvent extracts of animal organs, of
plants, of micro-organisms or of culture-broths (the latter derived from
bacteria, moulds, etc.).  These products, which may contain several
enzymes in various proportions, can be standardised or stabilised.

It should be noted that
certain standardising or stabilising agents may already exist in the
concentrates in variable quantities, deriving either from the fermentation
liquor or from the clarifying or precipitating processes.

The concentrates can be
obtained, for example, in powder form by precipitation or freeze-drying or in
granular form by using granulating agents or inert supports or carriers.

(C)  Prepared enzymes not elsewhere specified or
included.

Prepared enzymes are
obtained by further dilution of the concentrates mentioned in Part (B)
above or by intermixing isolated enzymes or enzymatic concentrates.
Preparations with substances added, which render them suitable for specific
purposes, are also included in this heading, provided they are not
covered by a more specific heading in the Nomenclature.

This group includes, inter
alia :

(i) Enzymatic preparations for tenderising
meat, such as those consisting of a proteolytic enzyme (e.g., papain) with
added dextrose or other foodstuffs.

(ii) Enzymatic
preparations for clarifying beer, wine or fruit juice (e.g., pectic enzymes
containing added gelatin, bentonite, etc.).

(iii) Enzymatic
preparations for desizing textiles such as those with a basis of bacterial
?-amylases or proteases.

The following are the most
important among the enzymes found in trade :

(1) Rennet (lab-ferment, chymosin, rennin).

Rennet is obtained either
from the fresh or dried fourth stomach of calves or by the cultivation of
certain micro-organisms.  It is a proteolytic enzyme which curdles milk by
coagulating its casein. It is available in liquid, powder or tablet form. It
may contain salts (e.g., sodium chloride, calcium chloride, sodium sulphate),
remaining from the manufacturing process or added for standardisation, and preserving
agents (e.g., glycerol).

Rennet is mainly used in
the cheese industry.

(2) Pancreatic enzymes.

The most important enzymes
produced by the pancreas are trypsin
and chymotrypsin (which break
down proteins), ?-amylase (which
breaks down starches) and lipase
(which breaks down fatty substances).  They are mainly used in medicine
and pharmacy for treating digestive disturbances.

Enzymatic concentrates of
the pancreas are normally obtained from fresh or dried pancreas.  They may
contain highly absorbent salts (added to take up part of the water of
crystallisation) and certain protective colloids (to facilitate storage or
transport). They are used in the manufacture of preparations for desizing,
washing, hair-removal or tanning.

The enzymatic preparations
of the pancreas classified in this heading include those used for de-sizing
textiles.

(3) Pepsin. 

Pepsin is obtained from the
stomach mucosa of hogs or cattle. For the purposes of stabilisation, it is
sometimes preserved in a saturated solution of magnesium sulphate or is mixed
with sucrose or lactose (powdered pepsin).

Pepsin is used mainly for
medicinal purposes, combined with hydrochloric acid or betaine hydrochloride,
or as pepsin wine.

(4) Malt enzymes.

This group covers only malt amylases.

(5)   Papain, bromelains, ficin.

The term papain is used to describe both the
dried latex of the papaya tree (Carica papaya) and the two fractions
obtained from this product, viz., papain
(in the more limited sense of this term) and chymopapain.

Papain is used, for
example, for the manufacture of chillproof beer, in the preparation of meat
tenderisers (see paragraph (C) (i) above) and in medicine.

Bromelains are
obtained from pineapple plants.

Ficin is
obtained from the latex of certain varieties of fig trees.

(6) Amylases and proteases obtained from micro-organisms.

Certain micro-organisms,
when grown in appropriate culture media, secrete a considerable quantity of
amylases and proteases.

After removal of the cells
and other impurities, the solutions are either concentrated by low temperature
vacuum evaporation or the enzymes are precipitated by the addition of inorganic
salts (e.g., sodium sulphate) or organic, water-miscible solvents (e.g.,
acetone).

Examples of microbial
amylases and proteases are :

(a) Bacterial alpha-amylases.

Bacterial alpha-amylases
(obtained, for example, by use of Bacillus subtilis) are
starch-liquefying enzymes, used for the production of adhesives and of
starch-based paper coatings, in bakeries and other food industries and for
desizing textiles.

 (b) Fungal
amylases.

Fungal amylases are
essentially ?-amylases derived from mould cultures, mainly of the genus Rhizopus
or the genus Aspergillus.

Although their liquefying
power is marked, it is much less than that of bacterial amylases.

Fungal amylases have many
uses in the food industry.

It should be noted that
fungal amylases sometimes contain proteases, glucose oxidase and invertase.

(c) Amyloglucosidases.

These enzymes, obtained,
for example, from moulds of the genus Rhizopus or the genus Aspergillus
are strong saccharifying agents but have no liquefying properties. They are
used to obtain a high yield of dextrose from starchy materials.

Their main applications are
in the production of glucose syrups and dextrose, and as saccharifying agents
for grain alcohol fermentation mashes.

(d) Proteases.

Bacterial proteases
(obtained by use of, for example, Bacillus subtilis) are proteolytic enzymes used to
prepare textile desizing agents, as ingredients in certain washing preparations
and in beer-making.  Proteases produced from moulds are used for medicinal
and pharmaceutical purposes.

(7) Beta-Amylases.

These enzymes are obtained
from vegetable materials, such as malted barley, wheat and soya beans. 
They produce maltose from starch and dextrins.

 (8) Pectic
enzymes.

These enzymes are
manufactured by cultivating various mould types, mainly of the genus Rhizopus
or the genus Aspergillus.  They are used in the manufacture (in
order to facilitate the pressing operation and increase the juice recovery) and
processing of fruit and vegetable juices.

(9) Invertase (Beta-fructofuranosidase).

Invertase is usually
derived from low fermentation brewer’s yeast. This enzyme splits sucrose
into glucose and fructose.  It is used in the manufacture of golden syrup,
chocolate and marzipan.

(10) Glucose isomerase.

This enzyme is manufactured
by culture of certain micro-organisms, mainly of the genus Streptomyces
or the genus Bacillus.  It is used for the partial conversion of
glucose to fructose in the production of syrups with a high degree of
sweetness.

Cesar Olivier Dalston, www.dalston.com.br.

Sources: NCM and Explanatory Notes (SH).