Clerodendron tvichotomum Thunb., whose Japanese name is kusagi, meaning bad-smelling tree, belongs to the Verbenaceae and grows wild in fields and mountains in Japan and China. It has a stalk of more than 3 m in height and a wide egg-shaped leaf. It blossoms in August, has many white flowers with five red sepals, and the fruits assume a sky-blue pigment when they ripen in October. Formerly, the blue pigment of the fruit was used to color clothes in sky-blue and its extract was used as a herbal medicine. Clerodendrine A, B and clerodenronine A, B are contained in the leaf, and clerodron and clerodon triterpenoids are contained in the root. These substances are effective in the treatment of hypertension, rheumatism, diarrhea, etc.
Current Condition of Food Colors
The Food Sanitation Act (Law No. 233) was established and issued in Japan on 24 December 1947 and enforced on 1 January 1948. The Food Sanitation Act Enforcement Regulations (ordinance No. 23 of the Ministry of Health and Welfare, 1948) were established and issued on July 13 in the following year. Simultaneously, specifications and standards of foods, additives, apparatus, containers, and packages were delineated (Notification No. 54, 1948), specifying for the first time 62 kinds of food additives. With the development of food processing techniques, change in food styles, change in the taste of consumers, modification of the food distribution mechanism, etc., requirements for kinds, styles, tastes, etc. of foods were greatly changed. Thus, a remarkable diversification of processed foods resulted. As the processed foods develop, the necessity for food additives has increased, resulting in the additional specification of products. Now, 348 items are specified as food additives. Of these, 12 products are chemically synthetic food colors.
As a result of the cancellation of the specification of some products as food additives and the consumer’s trend to choose safer food additives, use of natural additives has increased, and these came to be the main source in the field of color in particular. The List of the Minister of Health and Welfare (the list of food additives other than chemically synthetic products) issued in accordance with the requirement for full labeling of food additives used contains 87 items of natural food colors (Table List of natural food colors).
Table List of natural food colors. ()
|Annatto color||Bixa orellana|
|Carotenoid||Gardenia yellow||Gardenia jasminoides Ellis.|
|Paprika color||Capsicum annuum|
|Carrot carotene||Daucus carota L.|
|Grape skin color||Vitis vinifera L.|
|Grape juice color||Vitis vinifera L.|
|Purple corn color||Zea mays L.|
|Anthocyanin||Red cabbage color||Brassica oleracea L.|
|Flavonoid||Berry color||Sambucus caerulea|
|Vaccinium corymbosum L.|
|Perilla color||Perilla frutescens|
|Chalcone||Carthamus yellow||Carthamus tinctorius L.|
|Carthamus red||Carthamus tinctorius L.|
|Flavone||Kaoliang color||Sorghum nervo|
|Cacao color||Theobroma cacao L.|
|Cochineal extract||Coccus cacti L.|
|Quinone||Anthraquinone||Lac color||Laccifer lacca|
|Madder color||Rubia tinctorum L.|
|Betacyanine||Beet red||Beta vulgaris L.|
|Diketone||Curcumin||Curcuma longa L.|
|Azafirone||Monascus color||Monascus anka|
|Spirulina color||Spirulina platensis|
|Others||Gardenia blue||Gardenia jasminoides Ellis.|
|Gardenia red||Gardenia jasminoides Ellis.|
As to edible, chemically synthetic food colors for foods, as many as 24 items of chemically synthetic colors were specified at the peak time, and inspection (product inspection by the Minister of Health and Welfare) of 380 tons of chemically synthetic colors was carried out in 1973. It, was however, drastically reduced to 225 tons in 1985 and has been stable ever since. In 1990, 239 tons were subjected to inspection.
On the other hand, labeling of natural food colors for processing foods was not required before the enforcement of full labeling for additives used. Reflecting the consumers’ consciousness that they are natural products and thus generally considered safer, the demand for these products has expanded. About 3500 tons (except for caramel 1988) are probably produced, as follows.
Natural food colors are first extracted using water, alcohol, and other solvents from natural raw materials and then subjected to processes such as purification, concentration, spray drying, etc. Since these food colors are indeed natural, harvest time and area are restricted. Furthermore, the harvest is affected by the weather. In the worst case, none can be obtained. The color contents, color tone, etc. are also greatly affected by weather conditions such as temperature. In addition, almost all the raw materials are imported from overseas countries. Thus, it is very difficult to keep the quality of natural colors constant. The production of effective substances using cell cultures (callus) of a number of plants has been studied. Many studies on food color production using this technique were reported. It is possible to facilitate the efficient and constant production of natural colors whose raw materials are difficult to preserve, so that they are independent of the effects of natural conditions.
We studied the color production in cell cultures of Clerodendron trichotomum Thunb.. Reported here is a possibility of the production of colors by means of a culture, proving the possibility of constant industrial production of colors by in vitro cultures and the usefulness as colors for foods. Commercial production of food colors by biotechnologies is, however, considered difficult at the current stage. Basic cost reduction or proof of the safety seems necessary now.
It is believed that biotechnologies are safe techniques, including the cell blending technique and tissue culture technique used here. There is, however, insufficient experience in their application. Since these techniques have not been used frequently for production of food additives so far, it is necessary to further ensure safety in their use from the point of view of the prevention of infiltration of harmful impurities, etc. For natural colors obtained by the production method described here, no report has been submitted on results of detailed examinations on the identification of the effective components (color components) in comparison with those contained in natural colors produced using natural materials, or the possibility of infiltration by harmful impurities (plant hormones, etc.). However, no scientific reasons have arisen to indicate that biotechnologies are harmful in the production of food colors.
The efficient production of food colors through the use of biotechnologies is certainly a hopeful method.
Selections from the book: “Medicinal and Aromatic Plants IX” (1996).