Selection

1 12% brine

2 Daily stirring with wooden paddle

3 In wooden or plastic containers

4 During approximately 6 hours, until reaching 1-2% salt

5 Optional: manual or mechanical

6 In plastic bags or glass or plastic jars

7 2% brine

8 Brine must cover nopalitos completely (to avoid air reaching the pads)

9 In cardboard boxes

10 Quarantine

1 12% brine

2 Daily stirring with wooden paddle

3 In wooden or plastic containers

4 During approximately 6 hours, until reaching 1-2% salt

5 Optional: manual or mechanical

6 In plastic bags or glass or plastic jars

7 2% brine

8 Brine must cover nopalitos completely (to avoid air reaching the pads)

9 In cardboard boxes

10 Quarantine

Figure 13.3. Flow diagram for processing nopalitos in brine. Adapted from Corrales-García (1998).

as unpainted iron); (4) maintain the brine at a minimum NaCl concentration of 10% that is verified constantly with a special salt meter, and stir daily to help ensure uniform salinity; (5) completely cover the nopalitos with brine (weigh them down with a plastic or wooden screen); and (6) because light and extraneous material (e.g., dust, dirt, litter, water, insects) are detrimental, cover the tanks.

Pickled

Pickled nopalitos consist of scalded nopalitos preserved in vinegar (maximum 2% of acetic acid) with spices and vegetable seasonings (García 1993). More than 25 companies in Mexico currently pickle nopalitos, and many have their own preparation processes (Fig. 13.2). The conditioned nopalitos (Fig. 13.1) are cut or diced (manually or mechanically; Fig. 13.4). Pickling is done with vinegar (1.92.0% acetic acid), spices, aromatic herbs, and olive oil. The vinegar is heated to boiling, and then the spices are added, either directly or in a cloth bag. The mixture is boiled for 5 minutes to allow the vinegar to absorb the aromas. Separately, onion slices, garlic cloves, laurel leaves, and carrot discs are lightly fried in vegetable oil. Then the nopalitos, vinegar, and sautéed vegetables are mixed. This mixture is canned, or put into plastic bags or jars. The bags are sealed, and the cans and jars are evacuated and covered; they are then sterilized in an autoclave or in a water-bath.

1 Manually or mechanically

3 Onion slices, garlic, laurel leaves, and carrot discs

4 Quarantine

1 Manually or mechanically

3 Onion slices, garlic, laurel leaves, and carrot discs

4 Quarantine

Figure 13.4. Flow diagram of production process for pickled nopalitos. Adapted from Corrales-García (1998).

Finally, they are left to air dry before labeling. Bags, cans, or jars are packed in cardboard boxes, stored for the quarantine period, and then shipped to the market.

Sauces, Marmalades, Jams, Candies, and Juices

Nopalito sauces are prepared using milled nopalitos, with addition of various chilis, tomato, onions, vinegar, and spices (in different proportions), and, often, a preservative. More than 15 brands of nopalito sauce occur, some with white wine or lemon concentrate. The sauces can have whole pieces of nopalito or be totally milled, depending on the market preference. In Mexico, nopalito sauces are generally prepared daily using fresh ingredients, rather than as canned sauces for the market. In addition to sauces, recently in Mexico nopalitos are incorporated into sausages using soybean flour, and nopalitos are prepared with tuna fish, beans, jalapeno chilis, and mushrooms. These products are prepared by large, established companies, following principles of modern food technology.

Another product from nopalitos is marmalade. This product is prepared using milled nopalitos cooked with various concentrations of sugar, pectin, and preservatives. The conditioned (scalded) nopalitos (Fig. 13.1) are chopped (manually or mechanically) and cooked for a second time. Tirado (1986) made a jam with cladodes, adding orange juice, peel, and sugar in the ratio of 1:1.5:0.8:0.8. The jam had no microbial growth after 40 days of storage. This product is similar to other jams in the Mexican market (e.g., fig and orange) with respect to aroma, color, taste, texture, and appearance.

Badillo (1987) made a jam using cladodes, sugar, and citric acid, obtaining a product with good sensory quality and microbiological stability. Saenz et al. (1995a) made a marmalade from cladodes after treating with 2% Ca(OH)2 to lower the mucilage content (which causes texture and acceptability problems). Lemon juice and lemon peel were included; the first lowered the pH and the second, together with pectin, aided the gelling of the product (67°Brix, 0.97% acidity, and good acceptability). About six companies in Mexico and the United States presently manufacture marmalades. Mucilage obtained by milling and filtrating nopalitos can lead to better consistency in marmalades of other fruits (e.g., blueberry, raspberry, blackberry, strawberry, peach, apple, pear, pineapple, and plum), and therefore has potential to expand the world market for nopalito products.

Candies made with nopalitos are processed with sugar and often various other ingredients. The main confectionary products include crystallized nopalitos, nopalitos in syrup, nopalito candies covered with chocolate, marsh-mallows with nopalito mucilage (gomitas), candies of nuts cooked with honey and platyopuntia mucilage. Villareal (1996) studied the manufacture of crystallized cladodes, which are similar to crystallized melon peel. Sucrose or sugar-cane syrup can be used, and the candies are especially enjoyed by children. The cladodes are cut into pieces that are 1.8 x 4.0 cm, treated with Ca(OH)2 (to remove the mucilage), washed, osmotically dehydrated with a high concentration sucrose solution, and further dehydrated in a forced-draft oven at 6o°C. The final product has an intermediate moisture content and can be covered with sweet or bitter chocolate to be more attractive to consumers.

Rodriguez (1999) developed a nopal juice using young pads by scalding, milling, and filtering, then adding citric acid and aspartate. The juice was put in bottles, pasteurized, and vacuum sealed. The product has a pleasant sweet taste, brilliant green color, only 10 calories per bottle, and 10% nopal pulp. A mixed juice of nopal and guava is being marketed nationally and internationally by a Mexican company. Despined and diced nopalitos are milled in a blender with water, the thick juice is filtered to separate solids, the filtered juice is mixed with guava juice, and finally the mixture is pasteurized and bottled. The world market for fruit and vegetable juices has expanded, so nopal juices, mainly in mixtures with other fruits, offer great possibilities for development.

Mucilage

The complex polysaccharide mucilage is an important component of platyopuntias. Mucilage has great potential as part of dietary fiber and also imbibes large amounts of water, forming viscous or gelatinous colloids (Amin et al. 1970; McGarvie and Parolis i979a,b, 1981; Paulsen and Lund 1979; Trachtenberg and Mayer 1981; Saenz et al. 1992). Mucilage is composed of varying proportions of L-arabinose, D-galactose, L-rhamnose, D-xylose, and galac-turonic acid, the latter representing 18 to 25% of the residues, depending on whether the mucilage comes from fruit or cladodes (Saenz i995). The primary molecular structure is a linear chain containing galacturonic acid, rhamnose and galactose, to which xylose and arabinose residues are attached in peripheral positions.

Mucilage can be used as a thickening agent in foods and pharmaceutical products. Sáenz et al. (1992) showed that increasing the pH from 2.6 to 6.6 increased the viscosity of water dispersions of mucilage from 37 to 58 cen-tipoise (37-58 mPa s). Cárdenas and Goicoolea (1997) and Cárdenas et al. (1997) studied the rheological properties of mucilage of different concentrations (0.4 to 6%) with NaCl (0.1 M) and report that the non-Newtonian shearing behavior is similar to that of okra mucilage solutions. In particular, with increasing mucilage concentration a strong tendency occurs for aggregation. Nobel et al. (1992) report that the mucilage content of cacti varies with species and is influenced by irrigation and temperature. For instance, for four sympatric cacti from the Sonoran Desert, mucilage is absent from Ferocactus acanthodes, is 19% of the dry weight for Opuntia basilaris, 26% for O. acanthocarpa, and 35% for Echinocereus engelmannii; L-arabinose varied from 17 to 51% of the sugar monomers. For Opuntia ficus-indica mucilage in the cladodes increases 24% as the day/night air temperatures during growth are reduced from 3o/2o°C to io/o°C (Goldstein and Nobel 1991). For the widely occurring, cold-hardy Opuntia humifusa, mucilage in the stems approximately doubles when plants growing at day/night air temperatures of 25/15^ are transferred to 5/-5°C for 7 weeks (Loik and Nobel 1991).

With regard to special applications, farmers in Chile and some other countries use cactus mucilage to clarify drinking water. As for other water-soluble polymers, mucilage flocculates sediment particles and precipitates them out of solution (B. Crabb, personal communication). Another traditional use by the farmers in Chile is to take advantage of the adhesive properties of mucilage to improve external paint; chopped cladodes are blended with lime (mostly Ca[OH]2) and applied to the external walls of houses. Cladode mucilage has also been used for a long time as a glue in combination with lime plaster in Mexico. Mucilage helps the lime to set more quickly and improves the water repellency. This plaster is traditionally used over both earthen (adobe) and brick walls and also as a breathing water-barrier in stucco. Gardiner et al. (1999) found that a cladode extract improves water infiltration in soils, similar to the effects of polyacrylamides. Cactus mucilage also has culinary uses, such as a fat replacer and a flavor binder (J. McCarthy, cited in Cárdenas et al. 1997).

Dietary Fiber from Cladodes

The market in developed countries is increasing for healthful foods with low calories, low cholesterol, low fat, and a high fiber content. Studies showing the relation among fiber consumption and control of cholesterol as well as the prevention or treatment of some illnesses, such as diabetes, obesity, gastrointestinal disorders associated with a lack of dietary fiber intake, and even colon cancer (Sloan 1994; Grijspaardt-Vink 1996; Hollingsworth 1996), have helped to promote this market. Dietary fiber is composed of several chemical components that are resistant to digestive enzymes, e.g., cellulose, hemicellulose, pectin, lignin, and gums (Spiller 1992; Periago et al. 1993). The fiber content of a food varies with the plant species and the stage of maturity, but seeds, berries, fruit skins, and the bran layers of cereal grains generally contain a large amount of fiber. Based on water solubility, soluble dietary fiber is contributed by mucilage, gums, pectin, and some hemicellu-loses, and insoluble dietary fiber by cellulose, lignin, and most hemicelluloses (Periago et al. 1993). Nopal cladodes (i.e., nopalitos) are a good source of dietary fiber.

Sepulveda et al. (1995) obtained a natural concentrate of nopal fiber ("nopal flour") using 2- to 3-year-old cladodes obtained from pruning. Saenz et al. (1997) and Saenz (1998) studied the dietary fiber content and some physical and chemical characteristics of this concentrate, as well as the effect of concentration (2.5, 5.0, and 7.0%), temperature, and pH on the viscosity. Viscosity of nopal flour suspensions is an important parameter when the nopal flour is mixed with other food ingredients; the pH also affects such suitability (Lecaros 1997). Nopal flour consists of 43% total dietary fiber, of which 28% is insoluble and 15% is soluble. Rosado and Diaz (1995) reported a dietary fiber content in dehydrated nopal of 50%, indicating that the type of Opuntia, the climatic conditions, irrigation, and/or the age of the cladodes can influence the dietary fiber. The water-holding capacity in the former case is 5.6 g per g dry mass, and in the latter case is 11.1 g g-1 dry mass for cladodes and 7.1 g g-1 for a nopal isolate. The water content indicates the physiological status of the fiber, as water absorption increases the bolus and produces a satiation effect. The water absorption ability depends mainly on particle size and can be modified by controlling the milling process: the smaller the size of the particles, the greater the water retention, as for wheat bran flour.

Nopal flour is being tested for various foods, such as vegetable soup and a gelled dessert (Albornoz 1998; Vallejos z999). The percentage of added flour is limited: greater than 20% affects the texture of the product. Saenz et al. (1995b) and Fontanot (1999) tested different replacement proportions of wheat flour by nopal flour in biscuits; more than 15% replacement affects the texture and sensory characteristics of the biscuits but increases the dietary fiber content. Recently, a dehydrated pelletlike product made from dehydrated cladodes has appeared in the Mexican market. This product, which is a blend of wheat fiber, nopal fiber, salt, and the sweetener aspartame, is similar to a common breakfast cereal and is recommended to help control obesity.

Use of Cladodes in Medicine

According to popular medicine, mainly in Mexico, many diseases can be fought and cured with the cladodes, fruit, or other parts of cacti, such as the flowers (Hegwood 1990; Pimienta Barrios 1990; Barbera 1991; Mulas 1993). Nevertheless, only a few applications have a strong scientific basis, such as their effect on diabetes mellitus, blood glucose levels, hyperlipidemy (excess of lipids in the blood), and obesity (Gulías and Robles 1989).

Frati-Munari et al. (1990) studied the hypoglycemic effect of cladodes of Opuntia ficus-indica, concluding that glycemia decreased in all patients tested following ingestion and reached statistically significant lower levels after 3 hours; Ibañez-Camacho et al. (1983) confirmed this hypoglycemic action. Ramírez and Aguilar (1995) in a metaanalysis conclude that Opuntia has a strong glucose reduction effect. Trejo et al. (1995) evaluated the hypoglycemic activity of a purified extract from platyopuntias on STZ-in-duced diabetic rats; although the mechanism of action is unknown, the magnitude of the glucose control by the small amount of Opuntia extract required (1 mg per kg body weight per day) precludes a predominant role for dietary fiber. Hernández et al. (1997, 1998) used Wistar rats to compare the effect on weight loss of the consumption of nopal fiber and other vegetable fibers, such as cellulose and corn peel fiber. The nopal fiber produces more feces than the other fibers, although all rats lost weight during the study.

Frati-Munari et al. (1992) evaluated the role of commercial capsules (Fig. 13.5) containing dried and ground cladodes in the management of diabetes mellitus. Thirty capsules, each containing 335 mg of dried cladodes, were given to diabetic subjects, and serum glucose was measured throughout 3 hours; the control was performed with 30 placebo capsules. The dried cladodes did not show a hypo-glycemic effect and did not influence the glucose tolerance test. In diabetic patients, serum glucose, cholesterol, and triglycerides levels did not change with ingestion of Opuntia cladodes. In healthy individuals, glycemia did not change with cladode ingestion, whereas cholesterol and triacylglyc-erides decreased. Fernández et al. (1990) found effects of platyopuntia cladodes on low-density lipoproteins, suggesting that an extract may decrease cholesterol levelg

Figure 13.6. Various brands and preparations of Opuntia cladode extracts used cosmetically in Mexico, as collected by CIESTAAM (see Fig. 13.2.).

More than 30 brands of powders, capsules, and tablets made of dried platyopuntia cladodes are produced in Mexico as nutritious complements (Fig. 13.5). Powder is prepared from cladodes (1.5-2.5 years old) that are washed (chlorinated water), despined, cut, and then dehydrated (at 35-40°C), preferably with forced air. They are then milled and screened, until a fine powder is obtained. This powder is sold in bulk or encapsulated, or it is added with an agglutinant and then compressed to obtain tablets (Frati-Munari et al. 1992; Sepulveda et al. 1995). Such products are marketed by promoting their alleged medicinal effects, and consumers consume them as medications. Indeed, cladode-derived products are sold for the control of diabetes, cholesterol, gastric and intestinal afflictions, and obesity. This utilization is due to three main factors: (1) the existence of customs, traditions, and pre-Hispanic knowledge of medicine and the traditional herbalists of Mesoamerica (cla-dodes can cure renal illnesses and erysipelas, induce childbirth, alleviate pain, and heal wounds); (2) various medical studies indicating that the consumption (ingestion) of raw, boiled, roasted, or stewed cladodes decreases glucose and cholesterol in blood in healthy and certain diabetic people, but not in insulin-dependent animals or humans (Ibanez-

Camacho and Roman 1979; Ibañez et al. 1983; Fernández et al. 1990; Meckes and Roman-Ramos 1986; Frati-Munari et al. 1989; Trejo et al. 1991); and (3) a modern trend toward "natural" product consumption.

The production of cladode products as over-the-counter medicinal products is growing fast. Frequently, these products have scientifically unfounded claims as to their healing properties. Currently, 21 companies in Mexico produce capsules, 15 produce tablets, and five produce powders (Fig. 13.5). Some of these companies export their products to the United States as nutritious complements. The hypoglycemic effects that many of these products purport to have is unproved (Frati-Munari et al. 1992). At least 30 capsules may need to be consumed per day, which is not comfortable for the patients.

Cosmetics (Fig. 13.6) incorporating cladodes are used for hygienic purposes to beautify the skin and the hair, in accordance with the herbalists of Mesoamerica and popular as well as traditional knowledge. In Mexico more than 20 companies manufacture more than 40 different cosmetic products with platyopuntias, adding portions of juice of the cladodes in their formulations. These products, being of "natural" origin, are increasingly accepted in

Mexico and the United States. However, the cosmetics industry does not require large quantities of cladodes, because they are only a small ingredient in the formulations of these products. The principal cosmetic products (Fig. 13.6) are: (1) shampoos, conditioners, and gels for the hair; (2) soaps; (3) creams as well as facial masks to reconstitute, moisten, clean, or strengthen the skin; and (4) astringent or absorbent lotions (to reduce epidermal fat).

Cochineal

Two types of cochineal, the dye-producing cactus parasite, are recognized. They are classified according to the quality and concentration of their pigments, as well as their biological and morphological characteristics: (1) fine cochineal (Dactylopius coccus Costa), and (2) wild cottony cochineal, comprising a group of eight species. Though a noxious pest in nopal fruit orchards, wild cochineal is beneficial as a biological control of weedy nopal infestations throughout the world. Both D. coccus and cottony cochineal are easily propagated in various microclimates of North and South America. Although Mexico's central, southern, and southeastern highlands harbor a great diversity of both Opuntia and Dactylopius and the Meso-american region has the oldest records of systematic exploitation of cochineal, Mexico is presently not a major commercial producer of cochineal. The Andean region of South America, noteworthy for having the oldest evidence of cochineal use, currently accounts for 95% of world production. Use of the dye has spread to all nations except several Middle Eastern and Asian countries. Cochineal depends on platyopuntias for its propagation and survival, making its role as host one of the most important uses of Opuntia. Therefore, until technological development obviates the need of a host in the cultivation of cochineal, platyopuntias will be a determining factor in the production of the dye insect.

Pre-Colonial and Colonial History

Archaeological evidence for the use of cochineal exists in prehistoric textiles recovered from the Nazca (Classic) and Chimu (Postclassic) cultures of Peru. Saltzman (1992) reports incipient use of Dactylopius around the time of Christ and increased utilization in woolen textiles from the late Classic period (7th century). By the 10th century, cochineal was in common use. The first historical reports of cochineal from Peru date from 1533 (Donkin 1977). Evidence of pre-Hispanic cochineal use in Mexico is surprisingly scarce; only a few fragments of pre-Conquest cochineal-dyed fabrics have been found (Donkin 1977). Nevertheless, cochineal was a tribute item in Aztec and

Inca empires, in the form of richly colored woolen and cotton mantles (Donkin 1977) and in dye taxed by the Aztec governors. Two basic forms were used: (1) dried cochineal, and (2) cakes or tablets (panes, pastillas), known as nochezt-laxcalli in Nahuatl, produced by the Indians from the dried, milled insect, leaves of the tezhoatl tree, and alum (Dahlgren 1963; Donkin 1977). In contrast to wool, cotton is difficult to dye with cochineal alone. To make the color bind and become permanent, a mordant is required, and alum was used for this in both Mexico and South America. De Sahagun (1829) reported that alum (tlaxocotl) was well known in Mexico; other additives were also used as reinforcing agents with cochineal or to vary the shades of red (Donkin 1977).

Cochineal was also used as a paint for articles ranging from houses (Zoque Indians in Chiapas) to the famous Mixtec codices. It was employed by Indian women as a cosmetic, and possibly had pharmaceutical and culinary uses (Dahlgren 1963; Brana 1964; Donkin 1977). Cochineal and silk production flourished in New Spain during the 16th century, although competition occurred between the two insect cultures, particularly in the Mixteca Alta region of Oaxaca. Main producing areas continued to be Oaxaca and Puebla, and at the urging of governor Gomez de Cervantes, Tlaxcala became an important producer. Before 1600, proposals for a royal monopoly of cochineal production in New Spain were circulating. Production in Tlaxcala and Puebla, however, dropped in the mid-i7th century. After 1650, Oaxaca was described as the main supplier, and, by the end of the 18th century, Oaxaca was the only significant producer of fine cochineal (Donkin 1977).

Decline and Resurgence

In the 1860s, the introduction of aniline dyes, stronger and faster binding than cochineal, apparently sounded the death knell for the insect dye. France, in i860, and soon thereafter, the United States, authorized the use of synthetic colorants in foods. In the early i880s, mineral colorants, including lead-based pigments, began to be used in foods and cosmetics. However, toward the end of the i9th century, medical problems arising from dye use began to be detected. For this reason, in the late 1890s and early 1900s, several European countries, including Italy, Germany, France, and Belgium, as well as Australia and the United States, promulgated regulations for the control and use of certain colorants in food. During 1950 to 1980, various synthetic colorants were decertified. As a result of these prohibitions, interest in natural colorants was renewed. The natural red dyes belonging to three pigment groups (carminic acid, anthocyanin, and betalains) were allowed

Figure 13.7. Structure of carminic acid.

OH O

Figure 13.7. Structure of carminic acid.

to bypass the certification process by the United States Federal Drug Administration Agency (von Elbe 1977).

In 1974 possible toxicological effects of cochineal carmine were reported. In response, the Joint FAO/WHO Expert Committee on Food Additives demanded testing of the colorant for toxicity, and urged lower levels in food products. In 1976, the use of carmine was only permitted in alcoholic beverages and only for a limited time, thus precipitating a price drop for cochineal and carmine. At the request of Peru, the principal producer country, and of the FAO/WHO, the British Industrial Biological Research Association (BIBRA) undertook a series of investigations to determine effects of carmine in food and cosmetics. Several studies were undertaken in 1980 through 1982, including tests of teratogenicity and embryotoxicity as well as effects on multigenerational reproduction in rats (Ford et al. 1987; Grant and Gaunt 1987; Grant et al. 1987). On the basis of these results, in 1982 the FAO/WHO renewed authorization of carmine and its derivatives. Certain imprecision in the BIBRA studies, as well as cases of reactions to carmine in persons with allergies, have led to more recent studies with contradictory results: adverse effects were reported by Quirce et al. (1994), whereas innocuous-ness was indicated by Kawasaki et al. (1994) and many others. The pros and cons of carmine use have had a significant impact on the prices of this pigment in the world market.

Importance and Uses

The main coloring element of cochineal is carminic acid (Fig. 13.7); secondary elements include kermesic and flavokermesic acid (Wouters 1990) and minor pigments (Sugimoto et al. 1998). Carminic acid is used today in the industrial production of cosmetics, food, and medicines, as well as in textile and other dyeing, although azo synthetic dyes have, to a great extent, replaced the natural dyes in the latter two categories. Tutem et al. (1996) have also reported possible therapeutic uses. Moreover, cochineal, in powdered form, is utilized in food products and especially in the dyeing of textiles in countries such as Iran and Iraq and, in Mexico, among the Zapotec Indians (Ross 1986). Color and hue in textiles depend upon the mineral salts or reagents with which the powder is mixed (Avila and Remond 1986).

As an aqueous or alcohol extract, cochineal is an important colorant in food and beverages; as carmine, it is of importance in cosmetology, medicine, and food products. Carmine is marketed in a number of commercial presentations, including carminic acid at 90% (used as a colorant in processed food products and soft drinks) and lakes (pur plish red pigments) composed of carminic acid at concentrations of 40 to 65% combined with a variety of inorganic carriers, of which aluminum and calcium are the most common. Carmine 50 is the most sought-after commercially, e.g., as an additive to acidic beverages.

Carminic Acid

The physical and chemical properties of carminic acid were studied by Lieberman and his associates in 1909 and by Dimroth and colleagues from 1909 to 1920. The molecular structure of carmine was first proposed by Miyagawa and Justin-Mueller in 1920s, with further evidence provided by Fieser and Fieser in 1944 and by Hay and Haynes in 1956 and 1958 (Ali and Haynes 1959). Carminic acid is a hydroxyanthraquinone linked to a glycosyl group (Fig. 13.7). Lac dye and kermesic acid (Old-World insect-derived red dyes) have the same basic chemical structure but without the glycosyl linkage. Glycosyls apparently enhance the intensity of the anthraquinone group in the visible part of the spectrum. The chemical formula of carminic acid is 7P-D-glucopyranosyl-9,i0-dihydro-3,5,6,8-tetrahydroxy-i-methyl-9,10- dioxo-2 anthracene carboxylic acid (Fiecchi et al. 1981). The colorant is listed in the Chemical Index as Natural red 75470. Carmine is an aluminum chelate of this molecule at a rate of 1:2 aluminum: carminic acid. The great resistance of carminic acid to hydrolysis is due to the glucosyl group. According to Hay and Haynes (i956, 1958; cited in Ali and Haynes 1959), the glucosyl can be D-arabinose, which lends it a pink color, or glucose, which provides a yellow color. There are many commercial products on the market, so chemical and physical properties are asssigned by the firms. Carminic acid precipitates from alkaline solutions as prism-shaped crystals, obliquely truncated and red; they turn reddish-orange in the presence of light. The Merck Index describes their characteristics as:

(i) no distinct melting point; (2) darken at i2o°C; and (3) deep red color in water and yellow to violet in acid solutions.

For the fabrication of carmine and its derivatives, Avila and Remond (1986) review 12 of the many extraction and purification techniques commonly employed. All techniques follow the principles established by De la Rue, Lieberman, Dimroth, and others. In particular, the processing steps are: (1) separation of fats; (2) extraction of the coloring agent by steeping in a solvent; (3) salt precipitation, which also varies according to the technique employed; and (4) separation, washing, concentration, and drying of the final product. ITINTEC (1990) published a detailed methodology to obtain a carmine extract with a carminic acid content of 62 to 64%: (1) cleaning of insect using a screen; (2) separation of fats with hexane; (3) milling; (4) water extraction (ioo°C for 10 minutes) adding sodium carbonate until the pH is 9.0; (5) screening and filtering; (6) precipitation (aluminum and calcium salts, ioo°C for 15 minutes); (7) pH modification (4.85.4); (8) decanting for 2 hours; (9) centrifuging or press filtering; (io) washing with deionized water; (11) drying (4o°C) to achieve a water content of 7 to io%; and (i2) packaging in polyethylene bags. Acetone can be used for the separation of fats, an ethanol-water solution for their extraction, and a concentration operation done before filtration (Pérez i992). To obtain essentially pure carminic acid (99.5%), the main operation is crystalization, beginning with a supersaturated solution.

The extraction of dye from the insect is generally made without any other aid but pure water (J. A. Bustamante, personal communication). The water should be near boiling, and the dye is extracted from dried insects using two or three extractions (7o:i H2Ü:cochineal). The resulting fluid is filtered, usually through a press filter, to obtain a solid-free extract (the pH is often reduced to 4.5 with hydrochloric acid). The carminic dye solution can either be spray-dried or laked with aluminum-calcium salts in the presence of citric acid at a high temperature, and then allowed to cool and precipitate in the form of insoluble, bright-red carmine lake particles. The lake is then dried in a low-temperature oven and later milled to the customer's particular requirement.

Biology of Cochineal

Despite some controversy, cochineal apparently belongs to order Homoptera, suborder Stenorryncha, and superfam-ily Coccoidae, which includes all mealy bugs and scale insects (Gullan and Kosztarab i997). The family Dactyl-opiidae belongs to the Neococcoidea group of the Coc-

coidae (Miller and Kosztarab 1979). Named by Ferris (1955), it comprises the genera Apezcoccus, Cryptococcus, Dactylopius, Eriococcus, Gymnococcus, Kermes, Oncerotyga, Trachiococcus, and Xerococcus. De Lotto (1974) has identified nine species in the genus Dactylopius: Dactylopius autrinus (De Lotto), D. ceylonicus (Green), D. coccus (Costa), D. confertus (De Lotto), D. confusus (Cockerell), D. opuntieae (Cockerell), D. salmianus (De Lotto), D. to-mentosus (Lamarck), and D. zimmermani (De Lotto). Dactylopius ceylonicus, D. coccus, D. confusus, D. opuntieae, and D. tomentosus are abundant in the southwestern United States, Mexico, and northern South America (Miller 1976; Macgregor L. and Sampedro R. 1984).

Origin and Diversity

The center of origin and dispersal of the various species of cochineal have not been unambiguously determined. However, the place or places of origin undoubtedly are intimately related to the development and diffusion of the genera Opuntia and Nopalea. The cacti apparently originated in the neotropical regions of the Americas (southern Mexico and northern South America), and then spread both northward and southward (Gibson and Nobel 1986; Nobel 1998). Maximum diversity is found from southern Mexico to the southwestern United States. Although many platyopuntias are important for fruit and forage, Opuntia ficus-indica (L.) Miller is the species of greatest economic importance and is the most useful host for cochineal (Borrego and Burgos 1986). Although the range of nopal species and varieties that serve as host to the cochineal insect is ample—75, according to Portillo (i995)—those that function as natural hosts to D. coccus are few: notably, O. ficus-indica var. Castilla, O. pilifera Weber, O. sarca Griff, O. tomentosa Salm-Dyck, and Nopalea cochenillifera (L.) Salm-Dyck (Pina 1977, 1981). A number of species and varieties can, however, be artificially adapted as hosts, including several varieties of O. amyclaea Webber, O. atropes Rose, O. jaliscana Bravo, O. megacantha Salm-Dyck, and O. streptacantha Lemaire. In South America, D. coccus is reared on both spiny and spineless varieties of O. ficus-indica (Flores 1995; Tekelemburg 1995).

The greatest diversity of natural enemies of the nopal cactus is found in Mexico, among which are the different species of Dactylopius. Unfortunately, however, detailed studies of the full potential and diversity of the cochineal insect in Mexico do not exist, compared with the meticulous investigations of the parasite by Ferris (1955) and Gilreath and Smith (i988) for North America and South America and by De Lotto (i974) for South Africa. Furthermore, the wide diversity of predators and parasitoids that

Life stage durations for Dactylopius coccus

Male

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