Spices are the plant products or a mixture thereof free from extraneous matter, cultivated, and processed for their aroma, pungency, flavor and fragrance, natural color, and medicinal qualities or otherwise desirable properties. They consist of rhizomes, bulbs, barks, flower buds, stigmata, fruits, seeds, and leaves of plant origin. Spices are food adjuncts, which have been in use for thousands of years, to impart flavor and aroma or piquancy to foods. They are used to prepare culinary dishes and have little or no nutritive value, but they stimulate the appetite, add zest for food, enhance the taste, and delight the gourmet. As there is a need to reduce the fat, salt, and sugar used in food preparation for health reasons, it becomes critical to pay attention to alternative ways to enhance the natural flavors of foods. Value can also be added to meals by enhancing and improving presentation and by using appropriate garnishes. The primary function of a spice in food is to improve its sensory appeal to the consumer. Food presentation is the arrangement of food on a plate, tray, or steam line in a simple appetizing way. This is generally accomplished by imparting its own characteristic color, flavor, aroma, and mouth feel to the food.
Perception of flavor is comprised of the sensory combination and integration of odors, tastes, oral irritations, thermal sensations, and mouth feels that arise from a particular food. When the flavors are perceived as a food is taken, their sensation immediately invokes feelings about the degree of pleasure of the immediate moment, at the same time strongly influencing intentions about consumption of that type at a later date. In this fashion, flavor plays a prominent role in the delivery of nutrition even though the majority of flavor compounds provide few or no calories in food. A spiced diet is likely to make life not only spicier but also healthier. Spices have also been recognized to possess medicinal properties and their use in traditional systems of medicine has been on record for a long time. With the advancement in the technology of spices and in the knowledge of the chemistry and pharmacology of their active principles, their health benefit effects were investigated more thoroughly in recent decades. Many health benefit attributes of these common food adjuncts have been recognized in the past few decades by pioneering experimental research involving both animal studies and human trials.
The rhizome of turmeric has been used as a medicine, spice, and coloring agent for more than 2 millennia. It is principally known for its yellow-orange coloring power, having a musky flavor and aroma, which necessitates classifying it as a spice. Although the use of natural colors in food is an ancient practice, it is currently gaining increasing importance because consumers are wary of food industries using synthetic colors, whereas use of natural colors is seen as an ecologically sustainable and nonhazardous process. In ancient Indian literature, turmeric is referred to as “Haridra” which is being used for coloring, flavoring, and digestive properties. The rhizome (underground stem, often referred as root) of turmeric has been used in Asian cookery, medicine, cosmetics, and fabric dying for more than 2000 years. Marco Polo wrote about turmeric in his memoirs, fostering its popularity in Europe during medieval times as a colorant and medicine. Turmeric is extensively used in India, the Middle East, and the Far East in food preparations. Besides, turmeric is traditionally used as the women’s cosmetics for its characteristic fragrance and color, due to its “cosmeceutical” and “antiaging” benefits. Use of turmeric is also very auspicious in the form of whole plant, rhizome, as well as powder in religious functions. Turmeric is often used as an inexpensive alternative to saffron. The primary product of C. longa, true turmeric, is the cured, dried rhizome. Cured and dried turmeric of commerce are available in the form of bulbs and fingers. The external appearance of rhizomes is bright yellow to dull yellow with a polished or rough surface.
Major Chemical Constituents
Turmeric contains gum, starch, minerals, cellulose, volatile oil, and a yellow colorant. The chemical composition of turmeric is given in Table Chemical Composition (%) of Turmeric and the nutritional composition in Table Nutritional Composition of Turmeric per 100 g. The essential oil is a pale yellow to orange-yellow volatile oil (6%) composed of a number of monoterpenes and sesquiterpenes, including zingiberene, curcumene, α- and β-turmerone among others. The coloring principles (about 5%) are curcuminoids, 50 to 60% of which are a mixture of curcumin, monodesmethoxycurcumin, and bisdesmethoxycurcumin.
TABLE Chemical Composition (%) of Turmeric
|Source||Moisture||Starch||Protein||Fiber||Ash||Fixed Oil||Volatile Oil||Alcohol Extractives|
TABLE Nutritional Composition of Turmeric per 100 g
|Composition||USDA Handbook 8–2a (Ground)||ASTAb|
|Food energy (kcal)||354||390|
|Ascorbic acid (mg)||25.85||50|
|Vitamin A activity (RE)||Trace||NDc|
a Composition of foods, spices and herbs, USDA Agricultural Handbook 8-2, January, 1977.
b The nutritional composition of spices. ASTA Research Committee.
c ND = not detected.
Essential oils and the diarylheptanoid curcumin, which are the major secondary metabolites of turmeric, have been shown to be largely responsible for the pharmacological activities of turmeric powder, extracts, and oleoresins. Turmeric is widely consumed for a variety of uses, including as a dietary spice, a dietary pigment, and an Indian folk medicine for the treatment of various illnesses. It is used in the textile and pharmaceutical industries as a natural dye. Turmeric in its varied form is extensively used in Ayurveda, Unani, and Siddha medicine as home remedy for various diseases. Recent research worldwide is mainly focused on the medicinal and pharmacological aspects of its constituents specifically with reference to curcumin.
There are three principal types of turmeric products, namely, essential oil, oleoresin, and curcumin. Essential oil of turmeric is obtained by the steam distillation of turmeric powder and contains all the volatile flavor components of the spice and none of the color. There is only a small commercial demand for this product. Turmeric oleoresin is the commonly produced extract that contains the flavor compounds and color in the same relative proportion as that present in the spice. It is obtained by solvent extraction of the ground turmeric, a process identical to that used in the production of other spice oleoresins. They ensure storage stability in the final product and are free from contamination. Custom-made blends are also offered to suit the specific requirement of the buyer. Spice oleoresins are mainly used in processed meat, fish and vegetables, soups, sauces, chutneys and dressings, cheeses and other dairy products, baked foods, confectionery, and snacks and beverages. India enjoys the distinction of being the single largest supplier of spice oleoresins to the world. Oleoresins are used at very low concentrations because they are highly concentrated. They have greater heat stability than essential oils. Turmeric oleoresin, from its use pattern, chiefly functions as a food color, and secondarily in some of the products to impart a characteristic mild spicy flavor. Cleanliness of rhizomes and high content of color of the curcuminoids determine the selection of preferred varieties such as Alleppey finger turmeric and Madras turmeric, as these types are known for their high curcumin contents. Turmeric oleoresin usually contains 25 to 55% curcumin. Curcumin is the pure coloring principle and contains very little of the flavor components of turmeric. It is produced by crystallization from oleoresin and has a purity level of about 95%, which is the standard commercially available. The new European specifications for curcumin states that the dye content must be not less than 90% when measured spectrophotometrically at 426 nm in ethanol.
It is important to note that the distinction between these three products lies in the ratio of color to flavor. A spice oleoresin contains the total sapid odorous and related characterizing principles normally associated with the spice. Thus, the ratio of flavor components to curcumin in ground spice and oleoresin is the same. A color however, results when an attempt is made to reduce the flavor of the product and increase the relative concentration of color such that the ratio of flavor to color is altered in favor of the color. Thus in the case of turmeric, the ratio of curcumin to volatile oil is of the order 50:50, usually lying within the range of 40:60 to 60:40.
Turmeric is valued for its characteristic color and flavor. The principal component of color is curcumin, and generally, it is present in the range of 0.3 to 7% depending on the variety. Among the 100 turmeric cultivars evaluated at Indian Institute of Spices Research, Calicut, Kerala, India, PCT 14 was found best with respect to curcumin (7.9%), essential oil (7%), and oleoresin (15%). Analysis of essential oils and curcumin from turmeric accessions from the plains of northern India indicated that the oil content of rhizomes varied between 0.16 and 1.94% on a fresh weight basis. The accessions were classified into two categories: (1) those in whose essential oil, the sum of major terpenes (β-pinene, p-cymene, α-curcumene, β-curcumene, arturmerone, α-turmerone, and β-turmerone) was in the range 58 to 79%, and (2) those in whose oil the sum was 10 to 22%. The rhizomes of all the accessions were also evaluated for their curcumin content, which was found to vary from 0.61 to 1.45% on a dry weight basis. Analysis of rhizomes and leaves of turmeric variety Roma grown under the agroclimatic conditions of the North Indian plains at Lucknow, on hydrodistillation, gave 2.2% of oils, which were analyzed by GC and GC–MS. The rhizome oil contained 84 constituents, comprising 100% of the oil, of which the major ones were 1,8-cineole (11.2%), -turmerone (11.1%), -caryophyllene (9.8%), arturmerone (7.3%), and -sesquiphellandrene (7.1%). The leaf oil contained 83 components, comprising 97.4% of the total oil, of which the main constituents were terpipolene (26.4%), 1,8-cineole (9.5%), -phellandrene (8%), and terpinen-4-ol (7.4%), whereas 20 compounds were identified in fresh turmeric leaves collected at flowering stage of the crop, accounting for 72% of the contents. The oil of turmeric consisted mainly of monoterpenoids, monoterpene hydrocarbons (57%), oxygenated monoterpenes (10%), sesquiterpene hydrocarbons (3.3%), and oxygenated sesquiterpenes (2.1%). The major constituents of the oil were p-cymene (25.4%) and 1,8-cineole (18%), followed by cis-sabinol (7.4%) and β-pinene (6.3%).
Turmeric as a Colorant
Turmeric is one among the three natural spice colorants, i.e., paprika, saffron, and turmeric. The principal functional property of turmeric is being a food colorant. The characteristic deep yellow color is due to the group of pigments, curcuminoids; the important ones being curcumin, demethoxy-curcumin and bis-demethoxy-curcumin. All the three compounds exhibit fluorescence under ultraviolet light, and this feature can be used for detecting turmeric in presence of other yellow colors. These three compounds can be separated by TLC along with their geometrical isomers, which are also expected to form in traces. The estimation of curcuminoids is easily achieved by extraction with alcohol and absorption spectra measured at 429, 424, and 419 nm for curcumin, demethoxy-curcumin, and bis-demethoxy-curcumin, respectively. Curcumin with boric acid gives a characteristic color, the formation of rubro-curcumin and rosocyanin. Curcumin is used as a colorant for improving the color of broiler meat and overall performance. Chatterjee et al. have reported that gamma irradiation does not affect the composition or stability of natural pigments present in turmeric.
Turmeric as Spice
Food is one of the most intimate and important components of our environment. Flavor is considered an important attribute determining the acceptance of food by the consumer. Whether we accept or reject food depends mainly on its flavor, which plays a very important role in the palatability of food and is one of the key parameters determining the overall quality of a food product. Turmeric as a spice not only imparts color to food but also enriches the flavor. The pleasant flavor of turmeric is due to the volatile oil fraction. The oil content ranges from 0.3 to 7.2% (is orange-yellow), and contains mainly turmerone, alpha-turmerone, and zingiberene. Prolonged distillation of turmeric can convert minor amounts of alcohols into ketones, i.e., the formation of turmerones. Hence, a standard heating process has to be established for the fixing of color and formation of aroma, since curing and drying are followed in the processing of turmeric.
The use of spices varies greatly according to the region and culture of the people. Hirasa and Takemasa developed a patterning theory on the use of spices. According to this theory, the sustainability of a spice depends on the interaction of the spice with other materials that occurs in the mouth, which results in the “synthesis” of a new taste and flavor perception. A preference for a specific spice is determined by individual judgement. Hirasa and Takemasa developed a frequency patterning analysis, in which the frequency of each of 40 spices is analyzed so that a pattern of spice use for each nation, each cooking ingredient, and each cooking technique can be evolved. Govindarajan has depicted the preparation of various turmeric products. The study by the above workers led to the following conclusions:
• Turmeric is more suitable for Indian, Southeast Asian, and British cuisines, the suitability decreasing in that order.
• Turmeric is suitable for preparation of (increasing order): Beans and seeds, vegetables, meat, seafood, milk, egg, grains, and fruits.
• Turmeric is more suitable for: (1) fried, (2) steamed, and (3) food dressed with sauce. Less suitable for boiled, baked, deep fried, and pickled foods.
However, the above patterning analysis study probably did not include the South Indian vegetarian and nonvegetarian dishes. In South India, turmeric is added to about every dish, and it is an essential ingredient in all curry masala mixes. Turmeric is common with baked or fried items especially in the case of deep fried banana chips. In this case, banana slices are steeped in turmeric water for about 1/2 to 1 h, which imparts a more attractive yellow color to the chips.
Turmeric is used primarily to impart color to the food in most regional cookings. In Eastern cooking, turmeric, red chillies or paprika, and saffron (rarely) are the coloring spices. This is also the case with Western, Indian, and Southeast Asian cooking. In U.S., Germany, and other West European regions, paprika is the only coloring spice used. In U.K., turmeric is commonly used, whereas in Italian dishes mostly saffron is used. It is also interesting to note that in Chinese and Japanese dishes coloring spices are not used, or when used Perilla is the preferred herb that gives a red color to the dish. Turmeric (and also paprika/chillies) is useful in meat, seafood, milk products, egg, grains and seeds, and vegetable dishes, but it is not used for imparting color to beverages. Turmeric is useful in all forms of cooking, with heat or without heat, but it is not used with fresh food such as fresh salads. Spices also perform a deodorizing function in food. In many food preparations spices are used for masking or deodorizing unpleasant odors or flavors. Turmeric has very low deodorizing property; its deodorizing rate is only 5% (Table Deodorizing Rate of Turmeric in Comparison with Other Common Spices).
TABLE Deodorizing Rate of Turmeric in Comparison with Other Common Spicesa
|Spice||Deodorizing Rate (%)|
a Deodorizing rate-percent of methyl mercaptan (500 mg) captured by methanol extract of each spice.
Preservative Action and Health Benefits
Curcuminoids from turmeric are reported to possess antioxidative, antibacterial properties. Besides, they also exert anti-inflammatory and anticarcinogenic properties. Turmerene and curlone present in turmeric oil are the major compounds responsible for the antibacterial activity. Negi et al. studied the antibacterial activity using a by-product of curcumin manufacture. Curcumin, which is the main yellow pigment of turmeric, exhibits antioxidant activity and the chloroform extract had higher antioxidative activity than the other solvent systems. However, the curcumi-noid-derived compounds, which are colorless, also exert antioxidant activity. The antioxidative activity of turmeric as such in comparison to other spices is given in Table Antioxidative Activity of Turmeric in Comparison with Other Common Spices Against Lard. Chatterjee et al. have reported that γ-irradiation at a dose of 10 kGy does not affect the antioxidative activity of turmeric extract. The antioxidant principle of turmeric as reported by Hirasa and Takemasa includes curcumin, 4-hydroxy cinnmoyl (feruloyl)methane, and bis(4-hydroxy cinnamoyl) methame. The 50% inhibhitory concentration values of these and related compounds are given in Table 50% Inhibitory Concentration (IC50) of Antioxidative Compounds of Turmeric and Related Compounds on Air Oxidation of linoleic Acid. IC50 values of these compounds were lower than that of α-tocopherol meaning that they are more effective antioxidants. Besides food systems, curcumin has been studied for its antioxidant activity in rats as well as under in vitro system. Noguchi et al. reported that curcumin reacted with stable radicals such as galvinoxyl and N,N-diphenyl-l-picryl hydrazyl, suggesting that it can serve as a hydrogen donor and is a strong antioxidant as compared to eugenol. Song et al. reported free radical scavenging and hepato-protective activity of turmeric rhizomes in in vitro system, and the activity was much better than that of ascorbic acid. The mechanism of antioxidative activity of curcumin has been reported by Masuda et al.. He found that curcumin formed dimers as radical termination products especially at 2´-position of curcumin molecule and oxidative coupling reaction at 3´-position. Watanabe and Fukai have reported that curcumin suppresses the oxidative stress by scavenging various free radicals andits antioxidative activity seems to be derived from its suppressive effects. Asai and Miyazawa showed that phenolic yellowish pigments of turmeric display antioxidative activity in rats while Okada et al. in his study on induced oxidative renal damage in male mice showed that curcumin is an effective protectant against oxidative stress. Curcumin, having antioxidative property, may act as anticancer agent, but also inhibits the regulatory enzymes and exhibits anticarcinogenic action.
TABLE Antioxidative Activity of Turmeric in Comparison with Other Common Spices Against Lard
|Spice||Ground Spice POV (meq/kg)||Petroleum Ether Soluble Fractions POV (meq/kg)||Petroleum Ether InsolubleFraction POV (meq/kg)|
TABLE 50% Inhibitory Concentration (IC50) of Antioxidative Compounds of Turmeric and Related Compounds on Air Oxidation of linoleic Acid
|Sample||50% Inhibitory Concentration|
|TBAV (%)||POV (%)|
|Methanol ex.||1.22 x 10-2||1.21 x 10-2|
|Curcumin||1.83 x 10-2||1.15 x 10-2|
|4-Hydroxycinnamoyl (feruloyl) methane||1.88 x 10-2||2.79 x 10-2|
|bis(4-Hydroxycinnamoyl) methane||2.80 x 10-2||3.17 x 10-2|
|Caffeic acid||5.63 x 10-3||5.30 x 10-3|
|Ferulic acid||8.95 x 10-3||5.41 x 10-3|
|Protocatechuic acid||1.85 x 10-2||1.54 x 10-2|
|Vanillic acid||2.01 x 10-2||1.83 x 10-2|
|BHA||3.37 x 10-3||3.75 x 10-3|
|BHT||1.92 x 10-3||2.24 x 10-3|
|dl-α-Tocopherol||1.95 x 10–1||2.4 x 10–1|
Turmeric as a spice has properties of sensory, physiological, functional, and preservative action. It is widely used in the preparation of foods as a colorant, flavorant, and for its preservative action. Turmeric powder is used in the preparations of curries, dhals, salad-based raitas, fish, meat products, etc. Curry powder formulations have turmeric as an ingredient and the details are given in Table Typical Curry Powder Formulation Containing Turmeric, and Table Curry Blends and Masala Mixes Having Turmeric as a Component. Curry powder is a very general term used for spice mixtures made for specific dishes — vegetable curry, fish curry, chicken curry, mutton curry, etc. Especially, in the southern states of India, a number of curry powders are in vogue specific for sambhar, rasam, dry vegetables, dry powders for mixing with rice, and so on. Curcumin is insoluble in water, and hence when used in confectionary, agricultural products, and processed marine products, a solution in alcohol or propylene glycol is employed. However, it is relatively stable to heat but not to light. In acidic and neutral medium, it imparts an appealing yellow color to food, but in alkaline medium, the color changes to a dark reddish brown. Presence of certain metal compounds such as iron and boron can also influence the color. These factors are important when curcumin is used as a food color.
TABLE Typical Curry Powder Formulation Containing Turmeric
|Ingredients||Typical Range (%)|
TABLE Curry Blends and Masala Mixes Having Turmeric as a Component
|Indian curry blends||Basic curry blend consists of coriander, cumin, red pepper, and turmeric. Special blends for fish, meat, etc. contain in addition to the above, ginger, cardamom, clove, cinnamon, mustard, fenugreek, curry leaf, mint, coriander leaf, and celery seed, depending upon the particular blend.|
|Pickling masala blends||Many different types of pickling blends are in vogue. The important ingredients are mango/or lime pieces, Chili pepper, ginger, garlic, mustard oil, mustard seed paste, turmeric, sesame seeds, mint and cilantro. Mango, lime and mixed fruit pickles are the most common ones|
|Burmese curry blend||Onion, garlic, ginger, turmeric, fish sauce, chillies and tamarind|
|Malaysian curry blend||Lemongrass, atar anise, ginger, galangal, pandan leaf, tamarind, mint, coriander, turmeric, shallot|
|Mediterranean spice blend||Cardamom, ginger, cassia cinnamon, black pepper, cumin, fenugreek, lovage, mace, cubeb, long pepper, allspice, nutmeg, rose petals, lavender blossoms, orange blossoms, grains of paradise, chillies, nigella, onion, thyme, rosemary, and turmeric|
Commercially, turmeric is used for:
• Manufacture of kumkum
• pH test paper because curcumin changes from yellow to brown red in alkali
• Fluorescence test for detection of turmeric
• Manufacture of curcumin and its use in ice creams, gelatins, lemonades, and liquor
• Manufacture of oleoresin and their use in processed foods
The marketed products, which are branded, processed foods are listed in Table List of Manufactured Products Containing Turmeric where turmeric is used as one of the ingredients.
TABLE List of Manufactured Products Containing Turmeric
Powder and paste for vegetarian foods
- Turmeric powder
- Sambhar powder
- Rasam powder
- Curry powder
- Curry paste
- Amchoor paste
- Channa gravy
- Mustard paste
Paste for nonvegetarian foods
- Mutton curry paste
- Butter chicken curry paste
- Fish curry paste
- Tandoori curry paste
Masalas — vegetarian
- Instant upma masala
- Kharabhath masala
- Subzi masala
- Paw bhaji masala
- Chhole masala
- Garam masala
- Vangibhath masala
- Green masala
Masalas — nonvegetarian
- Tandoori chicken masala
- Chicken masala
- Fish masala
- Meat masala
- Biryani mix
- Kitchen king masala
- Khabab masala
- Mixed pickle
- Mango pickle
- Garlic pickle
- Vadu mango pickle
- Green chillies pickle
- Lime pickle
- Mixed vegetable pickle
- Avakkai mango pickle
- Chillies pickle
- Bisibele bath
- Tomato rice
- Lemon rice
- Rajma masala
- Kadi pakora
- Mixed vegetable curry
- Pineapple sweet and sour curry
- Navaratna kurma
- Alu methi
- Channa masala
- Dal fry
- Awadhi alu mutter
- Punjabi kadhi pakora
- Yellow dal tadka
- Potato sagu
- Hyderabadi biryani bhath
Selections from the book: “ Turmeric. The Genus Curcuma”. Edited by P. N. Ravindran, K. Nirmal Babu, and K. Sivaraman. Series: “Medicinal and Aromatic Plants — Industrial Profiles”. 2007.