Figure 11.14 Transformation of gingerols.
tative estimation of pungent principles of ginger (Osisiogu, 1973; Kucera and Kucerova, 1974; Nambudiri et al. 1975; Govindarajan and Govindarajan, 1979). GC and combined GC MS (Masada et al., 1973, 1974; Harvey, 1981; Middleditch et al., 1989) are improvements; but gingerols are susceptible to breakdown under the high temperature used in GC (Connell and McLachlan, 1972; Smith, 1982; Baranowski, 1985). HPLC has been found to be a more efficient tool in tracking the ginger pungency components (Smith, 1982; Baranowski, 1985; Chen et al., 1986b; Wood, 1987; Zhang et al., 1994; ISO, 1995). The principal difficulty with gingerol determination has been the lack of a stable and easily purified analytical standard. Gingerols are labile oily liquids, which are difficult to purify. Since the capsaicinoids and gingerols and their analogues have closely related chemical structures, the possibility of selecting from among them one easily purified analytical standard for determination of both the groups of compounds by HPLC was investigated. It was found that caprylic acid vanillyl amide (CVA), one of the minor naturally occurring capsaicinoids, but an easily synthesized crystalline compound, was very suitable for this purpose (Wood, 1987; ISO, 1995).
The following conclusions have emerged from the investigations of Ananthakrishna and Govindarajan (1974):
• There is much difference in the pungency stimulated by the three homologues.
• The major component 6-gingerol has the highest potency.
• Contrary to the earlier assumptions, the formed 6-shogaol is twice as pungent as the parent 6-gingerol.
• The higher homologues of shogaols are only weakly pungent.
• Quality deterioration by breakdown of gingerols does not happen easily at the temperature and pH conditions of normal processing and storage conditions.
Zhang et al. (1994) also reports higher pungency for shogaols compared to the gin-gerols.
In addition to these major compounds, the presence of a number of minor components has also been reported in ginger oleoresin (Connell and McLachlan, 1972; Murata et al., 1972; Masada et al., 1973, 1974; Harvey, 1981; Smith, 1982; Chen et al., 1986a). Table 11.23 lists the pungent components identified in ginger oleoresin. A typical HPLC chromatogram of ginger oleoresin is given in Figure 11.15.
The oleoresin extracted from fresh ginger retains the fresh aroma and wholesome flavor that closely matches the parent spice. The oleoresin of fresh ginger is termed green ginger oleoresin. Green ginger oleoresin finds application in flavor formulations where the fresh note of the spice is the prime quality determinant.
Sometimes a straight extracted oleoresin may require modification to suit specific applications. It can be fortified with distilled essential oil to achieve a balance between pungency and aroma. The strength of the oleoresin can be adjusted to the required level by dilution with permitted diluents. Diluents also improve the flow properties of the product.
Table 11.23 Pungent components in ginger oleoresin
6-gingerol 8-gingerol 10-gingerol 12-gingerol 14-gingerol methyl-6-gingerol mehyl-8-gingerol methyl-10-gingerol methyl-12-gingerol 4-shogaol 6-shogaol 8-shogaol 10-shogaol 6-methylshogaol 8-methylshogaol 4-paradol 6-paradol zingerone 4-gingediol 6-gingediol 8-gingediol 10-gingediol 6-methylgingediol 4-gingediacetate 6-gingediacetate 6-methylgingediacetae 4-gingerdione 6-gingerdione 8-gingerdione dihydrogingerol hexahydrocurcumin desmethylhexahydrocurcumin
The oleoresin may be rendered water soluble using permitted emulsifiers or converted to powder form by dispersing on dry carriers such as flour, salt, dextrose, or rusk powder.
These plated products impart the strength of good-quality freshly ground spices and can be easily incorporated in food.
Microencapsulated extracts are microfine particles of oils and oleoresins coated with an envelope of an edible medium such as starch, maltodextrin, or natural gums so that the flavor is locked within the tiny capsule. The encapsulated product is usually prepared
by spray-drying technique. When incorporated in food, the outer coating dissolves off, thereby releasing the flavor. Encapsulated oleoresins can be designed to contain a predetermined level of the core material.
Ginger oil as well as oleoresin can be microencapsulated/spray dried to convert to powder form with an improved shelf life and application convenience. Microencapsula-tion serves the following purposes:
• Controls the release of the core material
• Locks the flavor to ensure against loss on storage
• Offers convenience in handling by converting liquids and semisolids into free-flowing powder
• Provides uniform dispersibility in the food matrix
Figure 11.16 gives the flow diagram for the microencapsulation/spray drying of spice oils and oleoresins.
Traditional methods of preserving ginger by immersion in brine or syrups consisting of a mixture of dissolved sugars have been practiced for centuries (Brown, 1969a). The quality requirements of ginger for making preserved ginger are different from those for dried ginger. The ginger for the preserve should not be very hot or fibrous and hence should be harvested at an earlier stage than that for drying and further processing.
Ginger in Syrup: In commercial sugar syruping, the peeled rhizomes are normally held in a preserving solution prior to treatment to prevent possible mold formation (Ingleton, 1966). The preserving solution is usually brine at a concentration range of 14 to 17 percent. The preserving solution is drained out on a loose mesh sieve. The salt must be washed off the rhizomes before the sugar treatment. Sometimes the rhizomes are also given a boiling treatment prior to syruping to soften it (Brown, 1969a). The ginger is then diced into pieces of required size and shape and immersed in sugar syrup. Alternatively, the sugar syrup may be circulated through the ginger pieces held in vats. The syrup concentration is gradually increased to minimize shrinkage. Process conditions are so selected to ensure optimum sugar absorption (Brown, 1969a, 1969b, 1969c). The invert sugar:sucrose ratio requires close control to prevent crystallizing of the syrup. It has been found that the optimum reducing sugar concentration is 25 to 33 percent of the total sugars. The optimum pH for syruping has been reported to be 4.3 for the desirable flavor. The ginger, after attaining the desirable level of absorption, is packed in its own syrup in small glass jars. The addition of honey up to 15 percent of the weight of the syrup produced a distinctive flavor in ginger in syrup.
Ginger in Brine: Tender rhizomes are also preserved in brine. This is used for making sauces and pickles and can also form the raw material for syruping after the salt has been removed by boiling in water (Sills, 1959).
Crystallized Ginger: Another version of preserved ginger is the crystallized or candied ginger produced by taking the ginger-in-syrup process a stage further. For producing crystallized ginger, the ginger is further dipped in syrups of progressively increasing concentration (Ingleton, 1966; Brown, 1969b). Optimum process conditions are followed for satisfactory sugar absorption, weight gain, desirable color, and desirable texture. The ginger is then removed from the syrup, rolled in castor sugar in a rotating drum, and dried in air-draft dehydrators (Leverington, 1969; Brown, 1969b). The product is cooled and packed in sealed polythene bags. In crystallized ginger, the pieces are small but of regular size and uniformity of cut. Different additives may also be incorporated to give a noticeable improvement in crispness of texture as well as to modify the flavor (Natarajan et al., 1970). Solutions of gelatin of varying strengths and temperatures, as well as hot pectin solutions, were found to be suitable adhesives to hold the sugar crystals onto the ginger (Leverington, 1969).
These candies are perfect to settle the stomach and soothe the throat, especially in travel. They may be popped into the mouth and chewed to enjoy the sweet heat. They also help to relieve the heaviness after a full meal. Candied ginger can be chopped and used as toppings on ice cream or added in cookies or cakes.
Ginger Puree and Ginger Paste: Ginger puree consists of fresh ginger that has been peeled, washed, sanitized, cooked briefly, and ground. The puree may be stored frozen or permitted preservatives may be added to keep the quality. Ginger paste, on the other hand, is salted and seasoned. Commercial packs contain salt, oil, acetic acid/vinegar, permitted preservatives, and occasionally other spices.
Smooth and instant ginger in these forms adds convenience to cooking. Ginger puree and paste are used in stir fries, soups, sauces, cakes, breads, puddings, chutneys, creams, fillings, and marinades.
Uses of Ginger and Ginger Products
Ginger is perhaps the most widely used spice, both for flavoring as well as medicinal purposes.
Culinary: Fresh ginger is an essential ingredient in the preparation of oriental dishes, both sweet and savory, from entrees to desserts. It finds application in almost all meat, poultry, seafood, and vegetable preparations. Ginger contributes a freshness to foods that other spices do not (Farrell, 1985). A tenderizing effect has been observed when meat is cooked with slices of fresh ginger (Lawrence, 1984). Tender rhizomes are used in pickling. Ginger is extensively used in the preparation of different types of condiments and to flavor breads, cakes, biscuits, cookies, candy, jelly, toffees, and beverages.
Ginger Bread: Ginger bread is prepared by incorporating finely grated fresh ginger, cold pressed ginger juice, or ginger powder in the dough. Occasionally, this is supplemented with other spices such as garlic, cinnamon, and clove.
Ginger Biscuits, Cookies, and Cakes: These traditional family favorites are unique in their warm spicy flavor. Typical dosage is one teaspoon of ginger powder for four cups of flour. Sometimes small quantities of cinnamon and nutmeg are also added.
Ginger Drinks: Ginger drinks provide a cool, refreshing beverage as well as health benefits to the consumer. The most popular ginger drinks are the ginger ale and the ginger beer, which are carbonated ginger-flavored soft drinks. Even though the two terms are used interchangeably, sometimes the term "ginger beer" is associated with the spicier ginger ales. Ginger ale can be conveniently prepared at home. Even though a vast number of recipes are available, the essential steps for a typical preparation may be summarized as follows:
To 50 g grated or crushed ginger, add 5 L of boiling water. Add 500 g sugar and stir to dissolve. Leave to cool. When the contents cool to lukewarm, strain and add 15 g yeast. Flavoring agents like lime or lemon juice, vanilla essence, or other spices may also be added at this stage to suit the taste. Cover the container opening with a clean cloth and leave in a warm place overnight. Remove any scum from the top of the mixture, strain, and transfer the clear liquid into sterilized bottles. Seal the bottles with screw-caps and leave for 2 days at room temperature. Leaving the bottles at room temperature too long will cause overcarbonation and the drink will taste too yeasty. Refrigerate to finish the aging process. Add sparkling water or club soda and serve. The quantities of ingredients may be altered to suit the taste. Drinking ginger ale or ginger beer has all the benefits of consuming ginger.
Ginger Wine: Ginger wine is a popular beverage that is very warming in the winter weather. It is brewed by the fermentation of grapes or raisins with sugar, ginger, and yeast. Fifty grams of ginger would be required for 1 L of wine. The wine is usually stored 3 to 4 months for aging. It may be served as is or blended with alcoholic drinks.
Ginger Tea: Ginger tea is a standard remedy for sore throat, colds, and flu. This is an infusion prepared by steeping grated fresh ginger in boiling water for 5 to 10 minutes. The liquid is strained and mixed with honey or sugar to taste. Some lemon juice also may be added. This soothing tea may be taken hot in winter and iced in summer. This tea is also good to take after a meal to aid digestion. Powdered dry ginger can also replace the fresh ginger for making ginger tea.
Ginger Syrup: Ginger syrup can make perfectly spiced sweet ginger drinks. To make ginger syrup, boil 50 g of finely chopped ginger in sugar syrup containing one cup of sugar in two cups of water. Simmer and cook for 1 hour. Strain the liquid and add vanilla or lemon essence to taste. Cover and refrigerate. This syrup will keep for several days. The concentrated syrup may be extended with carbonated or plain water. The syrup could also be drizzled over ice cream.
The syrup from candied/crystallized ginger processing can also be used in the same way.
Ginger Coffee: Ginger coffee is a blend of roasted coffee powder and ginger powder. A hot beverage is prepared by boiling the powder in water. Milk and sugar are optional. Ginger coffee is a cordial beneficial in the cold weather and is a remedy for colds, cough, and flu.
Ginger is also the major ingredient in "masala" tea, a spicy tea popular in some parts of India.
Ginger oil and oleoresin can replace raw ginger in all flavoring and medicinal applications. These concentrates, which can be standardized to the required level of aroma and taste, overcome all the disadvantages associated with the raw spice, especially with respect to flavor consistency and shelf life. They are extensively used in the processed food industry for formulating seasonings for meat, poultry, seafood, and vegetable preparations. They
Table 11.24 Approximate dosages of ginger oil and oleoresin for typical applications Ginger Oil
Nonalcoholic beverages Ice cream, ices etc Candy
Baked goods Condiments Meats
17 ppm 20 ppm 14 ppm 47 ppm 13 ppm 12 ppm
Nonalcoholic beverages Ice cream, ices etc Candy
79 ppm 36-65 ppm 27 ppm 52 ppm 10-1000 ppm 30-250 ppm also find application in flavoring baked goods, confectionery, beverages, cordials, liqueurs, spicy table sauces, and in pharmaceutical preparations for cough syrups and creams for the relief of joint pains. Ginger oil finds a limited use in perfumery, where it imparts an individual note to compositions of the Oriental type. It is also recognized as a masking agent for mouth odor in dentifrices and oral hygiene products. Toothpaste flavored with ginger oil has a unique refreshing taste.
Approximate dosages of ginger oil and oleoresin for typical applications are given in Table 11.24 (Fenaroli, 1975). The figures are only indicative and vary with regional preferences. Exact dosage levels may be determined through application trials.
A relatively new area of application of essential oils is aroma therapy. Ginger oil finds extensive application in aroma therapy, in the treatment of rheumatism, arthritis, nausea, hangovers, travel and seasickness, colds and flu, congestion, coughs, sinusitis, sore throat, diarrhea, colic, chills, and fever.
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