Processing Spice Crops, Part 5 Pepper, Onion, Annatto, Turmeric

Chemical Composition, Processing and Uses of Individual Spices


Pepper contains a volatile oil, fixed oil, resin, alkaloids, proteins, cellulose, pentosans, starch, mineral elements, etc. It contains l to 3% of volatile oil which is colorless or yellowish liquid, not pungent, but with aromatic flavor of pepper. The pungent principle of pepper are contained in its oleoresin, and consists of piperine, charvicine and peperidine.

When the berries begin to turn red, the spikes are pick from the vines, then beaten lightly with sticks or rubbed by hand to separate the berries from the stalks, which are removed by winnowing. The berries are then prepared for the market. In Asia, the practice is to steep the berries in boiling water for about ten minutes, then are spread in mats to dry in the sun. Drying is carried out as rapidly as possible to prevent mold growth and with good sun, drying is complete in 3 to 4 days. The hot water treatment makes the skin turn black in an hour. The end product is dried black pepper.

White pepper is prepared by keeping ripe berries in moist heaps for 2 or 3 days, or by soaking the berries contained in gunny sacks, in running water for 7 to 8 days to soften the outer pericarp, or outer coating as is usually called. The process of removing the outer part of the pericarp begins with the trampling of the berries under foot, after which they are placed in rattan baskets, then rubbed and washed by hand to remove the pulpy covering and stalks. The berries are then spread out on mats in the sun for a day or two to dry. The resultant berry is light yellowish gray in color and consists of the seed coated with the inner part of the pericarp.

White pepper can also be prepared by mechanical abrasion of dried black peppercorns. This process permits the manufacture of various grades depending upon the length of time of attrition. Part of the peericarp of the black peppercorn or all of it can be removed. The resultant product is known as “decorticated white pepper”. This pepper is preferred by food manufacturers in the production of such preparations as mayonnaise and salad dressings where black specks are undesirable.

In Brazil, black pepper is prepared by drying the berries in the sun (in case of small producers) or in driers (large producers). To obtain white pepper, the berries are soaked in water for 8 days to loosen the outer coat (small producers) or the outer coat is removed by mechanical means and washing in water (large producers). The berries are then dried in the sun or in driers.

Both black and white pepper berries are imported whole by spice merchants who mill them to the requirements of the food processing industry and the retail food trade.

Both black and white pepper enjoy almost universal use. They are available whole, cracked, coarsely ground or finely ground. Both have many culinary uses including the seasoning and flavoring of soups, meats, poultry, game, fish eggs, vegetables, salad dressings, mayonnaise and other foods.


Onion contains a volatile oil, fixed oil, protein, cellulose, sugars, mineral elements, etc. The volatile oil of onion is very small and little is known about its chemistry.

The spice consists of:

  1. onion powder which is the ground product of dehydrated onion bulbs, and is a creamy white powder with an aroma and taste similar to that of the fresh onion.
  2. onion salt, which is the ground dehydrated onion mixed with free running table salt and sometimes with a small quantity of edible starch to prevent caking. Flaked and minced dehydrated onion have been added to the spice shelf.

The above products maybe employed in place of onion in the culinary art. Onion powder is employed commercially in the processing of fancy meats and sausages.

Onion spice products are effective, labor-saving, and convenient for both kitchen and outdoor cooking. They readily absorb moisture and their containers should be tightly capped when not in use.


The ripe seed contains by weight some l0% inner seed, 22% peel or test and 68% mark or outer covering. The mark contains 4 to 5.5% pigment, 40-45% cellulose, 3.5-5.2% sugars and 0.25- .85% essential oils. The only useful known material obtainable from Bixa orellana is the pigment in the mark which is the annatto of commerce.

Annato or Bixin is widely used by the natives as a dye. It is used as an artificial coloring for food stuffs like butter, margarine, cheese, chocolate and the like.

The coloring pigment is best extracted by leaching with alkali followed by subsequent washings with water, the combined extracts are then precipitated with a mineral acid, then washed again with water until acid-free, drying at 60oC followed by pulverizing of the extract.


Turmeric contains a volatile oil, fixed oil, resin, a coloring matter, protein, cellulose, pentosans, starch, mineral elements, etc.

On distillation, turmeric yields from about l.3 to 5.5% of volatile oil, orange yellow in color, slightly fluorescent and aromatic. It is reported that the main fraction of the volatile oil consists of turmerone, a ketone. The coloring matter is curcumin.

Methods of curing the rhizome varies somewhat in the different countries of production. It is the practice to split the stout tuberous portions (mother sets) lengthwise in four pieces. The prepared rhizomes are then placed in an earthen or metal vessel and just enough water added to cover the rhizomee. The remaining space is packed with dry tumeric laves and the mouth of the vessel is covered with jute material and sealed with mud plaster. The vessel is placed over a slow fire for about three hours and then allowed to cool. Following the boiling process the rhizomes are removed from the vessel and spread in the sun to dry for 5 to 7 days.

The process of preparing the spice is completed by rubbing the rhizomes by hand in a serrated earthen vessel or by rotating them for about l0 minutes in a cylindrical metal container fitted with handles at either end and mounted horizontally. The product is then ready for market. It takes 5 lbs. of fresh rhizomes to produce l lb. of cured turmeric.

The quality, appearance, and color of whole turmeric varies according to its source. Ground turmeric of good quality is orange-yellow in color and has a characteristic pepper-like odor and slightly aromatic somewhat bitter taste.

Turmeric is available whole or ground. It is used to flavor meat and egg dishes and to add flavor to pickles, relishes and prepared mustard. It is an indispensable constituent of curry powder.

For more information contact:

Dept. of Science and Technology
Rm. 303 DOST Bldg., DOST Complex,
Gen. Santos Ave., Bicutan, Taguig City 1631
Telephone Nos: (632) 837-20-71 to 82



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