Introduction
Long ago in Japan, fruits were called "water sweets." They were popularly categorized as confections in Japanese culture. Such fruits included persimmons, nashi pears, peaches, ume, Chinese apples (Malus asiatica), grapes, and so on. Prior to the Meiji era (before 1868), persimmons and nashi were the main fruits that people enjoyed. From the Meiji era on, many types and varieties of fruit were introduced from abroad and started being cultivated in Japan in a form adapted to the Japanese climate.
Food culture and environment have played a significant part in the differences found in fruits between Japan and the West. In Europe, where Western culture originated, much of the water is hard water, which is difficult to drink, and few crops could provide a source of vitamins throughout the year, so fruits, which were rich in water content and vitamins, were considered essential food in people's lives. Fruits were also the main type of preserved foods, being used for jams, juices, wines, and more. In contrast, Japan has a lot of rain, good quality water, and the availability of an abundance of vegetables and edible wild plants year round, from which water content and vitamins can easily be obtained. For this reason fruits were always considered luxury items and gift items.
Such differences significantly affect fruit production today. Western countries have expansive monoculture plantations all over the world and concentrate on the mass production of limited varieties at low prices. Crop yields are high and the focus is on selecting and cultivating varieties that have a high resistance to disease and pests. Moreover, much of the crop is used for processing into juices, jams, wines, and so on, so there tends to be little concern for appearance. In contrast, Japan is a long, narrow country with much steep, rugged terrain. The amount of arable land per farming household is small and the high-mix, low-volume production comes with high costs. So, in order to raise the unit price and improve the economics of growing fruit, there is a focus on selecting and cultivating varieties that both look and taste good, which is important for table fruits. Also, because of the custom of giving fruits as gifts, they are presented and sold as regional specialty items at luxury fruit stores located in the most prestigious urban areas, and even handled as luxury goods overseas.
In this paper Japanese fruits will be introduced which that are grown in Japan like this and are attracting attention overseas, taking a look particularly at the differences in odor components between different varieties of grapes.
Production Situation and Trends in Recent Years
The volume of fruit production in Japan 2006, including fruit trees, watermelons, melons, and strawberries, totaled approximately 3.85 million tons. In order of higher production, the fruits were mandarins (mikan), apples, watermelons, nashi, persimmons, melons, grapes, strawberries, peaches, and ume. In terms of fruit production volume, the most commonly grown fruits in Japan is also produced widely in other parts of the world.
In the last several years, fruit tree production in Japan has been decreased, but the Japanese government has been promoting Japanese fruits exporting for their high quality and safety, they are set them apart from locally grown products. Exports of peaches, nashi, apples, and melons have been already increased, and there is hope that these efforts will put the brake on the drop in production volume.
Japanese nashi was previously introduced overseas as "sand pears," but recently there has been high production of varieties such as Kosui and Hosui, which have few seeds and soft flesh, with a lot of sweet juice, so they are gaining popularity as "water pears."
In apples, the variety with the largest production in Japan since 1981 is the Fuji apple, which has won worldwide attention for its quality. Fuji is a main cultivar also in the state of Washington - the main apple growing area in the United States, the second biggest apple production area in the world.
Strawberries are a fruit that go through rapid changes in variety. The main varieties at the Tokyo Central Wholesale Market in the year 2000 were Toyonoka, Tochiotome, and Nyoho, switching in 2006 to Tochiotome, Sagahonoka, and Amao. Recent concerns over food safety have focused attention on domestic varieties that can be harvested in the summer season to replace products that mainly comes from overseas to the summer strawberry market. But because of the great popularity of strawberries, Japan's main varieties are being commercially cultivated overseas without permission, a situation that is causing problems through its effects on the Japanese market, and ongoing trends are to be watched closely.
Grapes
Grapes are a fruit that has been cultivated since ancient times. Most varieties, except for Koshu, were introduced into Japan from overseas from the Meiji era on (starting in 1868). Grapes are generally classified into three types: European, American, and European-American hybrids. Most of the global production in grapes is of the European varieties, primarily for wine. Many of these varieties grow well in poor, aerated soil and in dry climates. Japanese has little available land that matches these production conditions. American varieties, in contrast, are used mainly for juice and eaten as table grapes, and they grow well in fertile soil and in high moisture conditions, which describe Japan's natural conditions well.
Japan's leading varieties include: the European-American hybrids Kyoho, Delaware, Pione, Muscat Bailey A, and Campbell Early; the European varieties Neo Muscat, Muscat of Alexandria, Koshu, and Kaiji; and the American variety Niagara. Koshu is an orientalis European variety that is said to have been cultivated in Japan for over 800 years. Kyoho, Pione, Muscat Bailey A, Neo Muscat and Kaiji are varieties that have been bred in Japan. Since 1994, the most commonly produced variety has been Kyoho (See Fig.1). The main growing regions include Yamanashi, Nagano, Yamagata, and Okayama.
Kyoho is a tetraploid variety, which is rare overseas. For this reason, it gathered much attention in abroad. The Geisenheim Research Institute of Germany, world famous for wine research, has requested Kyoho parent vines for breeding, and Taiwan has become the first country outside of Japan to succeed in introducing and growing the variety.
The Odor Components of Kyoho Grapes
There are much reports on the odor components of grapes, have been already clarified approximately 450 volatile components. Most of these have been either the European variety Vitis vinifera or the American variety Vitis labrusca. Here will be introduced results of research comparing the odor differences between Kyoho, the leading variety of Japanese grapes, and European and American varieties. Are used Kyoho grapes grown in Nagano Prefecture, the European variety Muscat of Alexandria grown in Okayama Prefecture, and the American variety Concord grown in Nagano Prefecture. After picking, the grapes were juiced and a method of steam distillation under reduced pressure and solvent extraction method were used to obtain the odor components concentrates, which were analyzed using various equipment.
In the sensory evaluation of the fruit prior to analysis, the Kyoho featured a fresh, rich sweetness, the Concord a sweet fruitiness and strong foxy odor, and the Muscat a floral flavor and fresh fruitiness. From the results of GC-MS and GC-FID analysis we were able to compare odor component proportions by functional group, and found large discrepancies, as shown in Fig. 2. This shows that the distinctive character of Kyoho grapes lies in its ethyl esters. Methyl anthranilate, found in high concentration in Concord grapes, was not detected in the Kyoho grapes, terpene alcohol was slightly found in Kyoho grape, however is found in high concentration in Muscat grapes. (See Fig. 3) In regard to nitrogenous compounds and sulfur-containing compounds, it has already been reported that European-American hybrids contain methyl anthranilate, methional, and ethyl 3-(methylthio)propanoate, while European varieties contain 4-mercapto-4-methyl-2-pentanone, for example. In Kyoho grapes over 30 compounds were detected, including ethyl methylthioacetate, ethyl 3-(methylthio)propionate, and ethyl 3-(methylthio)-trans-2-propenoate.
Odor-contributing components were detected using the AEDA method and among the many components detected, in Kyoho were found phenylethyl alcohol,
2,5-dimethyl-4-hydroxy-3(2H)-furanone, ethyl butyrate, ethyl crotonate,
and ethyl 3-(methylthio)-trans-2-propenoate were found;
in Muscat were found linalool, 2-methylbutyric acid, geraniol, δ-decalactone, rose-oxide, cis-3-hexenal, hotrienol, and 4-mercapto-4-methyl-2-pentanone; and in Concord were found ethyl 2-methylbutyrate, phenylethyl alcohol, and methyl anthranilate. In addition, to find several important chiral compounds among the odor components were used CHIRAROMA® analysis, the results of which are shown in Chart 1. The odor-contributing components confirmed through the processes above are the basis for the features confirmed through sensory evaluation.
Fig.3 Terpenes percentage of volatile compounds.
Conclusion: Regarding Flavor Development
Up to this point, grape flavor has meant a Concord type, which primarily contains methyl anthranilate, and a Muscat type, which contains linalool and geraniol. But from the knowledge above mentioned, could be possible to develop a Kyoho type flavor. As with Kyoho grapes, there are many other fruits that do not have natural raw matirials for compounding such as recovery flavors, nor any odor components that by themselves create an image, and it is important to analyze these to grasp their characteristics. Moreover, flavorist creativity will become necessary in order to have an impact on flavor and to create an aura that seems more genuine than the real thing. Through analytical data and flavorist ingenuity, the Kyoho-type flavor introduced here is also adaptable to various applications, the form of the final product or concept. Flavors created in this way have strong potential to assist in final products development, discovered as part of Takasago's continuing research and development efforts.
Shigeyuki Sasaki (2008)