Asparagus - Green Versus White - Not Just a Different Color 

by Julia Lopez de Sagredo 

The asparagus traditionally consumed in Spain, and especially in Andalusia, was the wild green variety which is characteristic of the Mediterranean region. The Spaniards call it "triguero" because it used to grow amidst the wheat, or trigo. Consumption of asparagus was apparently introduced into the Iberian Peninsula by the Arabs although it was already eaten to some extent under the Roman Empire. But cultivation of green asparagus only began in the early twentieth century in the Genil Valley in the province of Granada using seeds from the wild variety. This is considered the only European variety of green asparagus because the rest of Europe cultivation and research has focused on white asparagus, essentially the Holland White, which was obtained in Holland in the seventeenth century, and its progeny. In the United States- especially in California- work began at the start of the twentieth century on green hybrids obtained from European genotypes of white asparagus, not from the wild green.

The native varieties were the only ones grown in Spain until the 1980s when commercial interest in green asparagus started to develop. But foreign markets were demanding bigger sizes than the Spanish variety could grow so American green hybrids were introduced which were also more productive and easier to pick. The overall growing area spread but the number of hectares devoted to the native asparagus dropped sharply. The hybrids adapted perfectly to the growing conditions, with the UC-157 being the most successful. Although this variety still predominates, the Grande and Atlas hybrids are now strong competitors being slightly more productive, earlier, larger, and more uniform.

The area of production and the producers of green asparagus are generally different to those of white asparagus. The latter requires little more than light soil, whereas green asparagus is especially demanding regarding climate and this factor limits its growing possibilities. The ideal is the continental Mediterranean climate with cold winter to hold back growth and, in spring, cold nights in contrast with mild daytime temperatures to allow for growth during the day only, so that the plants cannot go to seed and the harvesting period is longer. Sharp differences between the daytime and nighttime temperatures during harvesting encourage intense coloring of the spear and purplish tones. Summers should be dry and warm and autumns dry until October when vegetative growth stops, to prevent tips forming in September as this would affect quantity and quality in the next season.

Granada is ideal as a growing area. "The production that started in Seville and Cordoba where the white varieties are grown is now moving to Granada to escape from the April heat which opens up the tips of the spears, putting an end to the harvest and making the crop unprofitable. In Granada harvesting takes place from the end of February until June or even July," Explains Luis Marin, the manager of Asociafruit (Asociación Nacional de Productores- Exportadores de Hortícolas- the Spanish National Association of Producers and Exporters of Vegetables). Extremadura and some areas of Malaga, Cadiz, Murcia, and Toledo, amongst others, are other suitable growing areas. The forthcoming harvest is expected to be good. But, with the exception of 1997 which reached 17 million kg, the previous three harvests and that of 1998 were all affected by the weather- mainly too much or too little rain, and frost during harvesting. Granada alone produced almost 10 million kg.

The main difference in the field between white and green asparagus is that the latter needs light to gain its color whereas the former needs to be kept out of light to keep it white. Therefore green asparagus should not be piled up with soil as white asparagus is. This not only saves on labor but makes harvesting easier as the spears are perfectly visible. They are cut every day during the harvesting period (February/March to June/July) when they reach 27 cms (10 1/2 in). The same day they are sized, sorted, and prepared for the market. All these tasks are carried out by hand as there is no suitable machinery for green asparagus. They are handled while dry but at night are stood in water until they recover there weight. Then they are pre-cooled, loaded into refrigerator trucks, and transported at 2-3C (35-37F) to reach their final destinations at the latest the day after cutting. The spears are generally sold in crates of 4 and 12 kg, tied in 500 g bundles, "although there are some markets such as Switzerland which prefer 1kg bundles, and the English market prefers 250g," explains Jose A. Guarnido, the manager of Hortícolas de Huétor Tájar S.A., the top Spanish exporter of green asparagus which sold almost one million kg in 1998. The most popular sizes are from 16 to 22 mm (.6 to .85 in), although they also export spears measuring 12 to 16mm (.4 to .6 in) or over 22 mm (.85 in).

Exports of green asparagus started slowly, with a few cases being sent in the trucks of white asparagus to test acceptance. Today it is normal for a company to send two, three, or even four trucks a week to its customer destinations. Consumption of white asparagus still has tremendous potential for growth. The current limits are set by production. The poor harvests of the last few years have kept exports low although, in the best harvest of 1997, five million kg were sold outside Spain.

"Green and white asparagus have different markets," says Jose Blasco, president of the asparagus sector of Asociafruit and an exporter. "Germany and France are the top two customers for white asparagus followed by Switzerland, Italy, and Belgium. For green asparagus, France is the leader, followed by Italy, then Germany which is a growth market, and England."

Eighty-five percent of all the Spanish asparagus- both green and white- sold to foreign markets is sold by the members of Asociafruit, an association of the most important exporters in the 11 sectors it represents. According to Jose Alvarez Calderon, the national coordinator of exports of green asparagus for Soivre (the body which carries out control, inspection, and standardization for exports), "the advantage of Asociafruit from the point of view of quality control is that the partners are both producers and exporters so that if the market makes any sort of requirement, this is rapidly reflected in production. Any problem arising is immediately corrected at the source." The asparagus sector has signed an agreement with the Soivre laboratories for regular analyses in the field and in the stores. If the quality level falls short of market requirements and the standards set by the association, the export operation is called off. "There are very few sectors in Europe with such a high level of voluntary self control," states Jose Alvarez Calderon.

The main distribution channels are the large retail outlets in all the markets. The prices have been kept very stable and are never higher than those for white asparagus.

Delicious, Healthy, and Versatile

Neither green nor white asparagus can be said to be superior to the other. Their organoleptic characteristics and culinary uses are different, but green asparagus does have greater nutritional value. The white surpasses the green only in total sugar content, so has more calories. Both types of asparagus have a high content of the anti-oxidizing vitamin A and C and of group B vitamins including folic acid. The high levels of potassium and calcium phosphate make asparagus particularly good for bone structure. The anthocyans, which are responsible for the purplish coloring of the green asparagus, protect the cardiovascular system. They increase in quantity as the colors become more intense, as does rutin which is known to provide protection against radiation and to assist in blood clotting. It is also a precursor of B complex vitamins. Saponins are responsible for the diuretic effects of asparagus and have a high fiber content. With respect to organoleptic characteristics, green asparagus has a more intense aroma than the white and its flavor is stronger and slightly sweet. Whereas white asparagus always needs to be peeled before cooking, the green does not. It has a fleshy texture and is firmer than the white after peeling.

Each type of asparagus has a different culinary use. The advantage of green asparagus is that it can be grilled rather than boiled, keeping in the flavor and aroma as well as conserving the vitamins and minerals, and this makes it more versatile. In general, asparagus can be eaten either hot or cold- with meat of fish, or in salads. It goes well with other vegetables or can be served alone or as the main ingredient of more sophisticated dishes.

Julia Lopez de Sagredo is an agronomist. She works in the Spanish commercial office in Dusseldorf, Germany, for seven years dealing with the promotion of Spanish processed agricultural food products. She now lives in Malaga and, amongst other activities, writes on agricultural products and foreign trade.

 

Information Source:  Spain Gourmetour 
Provided by the Commercial Office of Spain - 405 Lexington Avenue NYC
Sponsored by ICEX (Institutio Español de Comercio Exterior)