Table of content A-Z
Synonyms: French bean, string bean
botanical name: Phaseolus vulgaris and other species
Introduction
Beans in general are often called legumes, but this is not entirely correct, as only the seeds, ripened in the pod and dried, are sold as legumes in the narrower sense.
Green beans belong to the fruit vegetables. These are fresh seeds, not dried, with or without their pods.
The beans are harvested while still unripe, cooked and eaten as a vegetable. In this form not only the seeds but also the pods are edible.
Origin, areas of cultivation
The bean originated in the tropical and subtropical forests of Central and South America. It was brought to Europe in the 16th century. Here and in East Asia it is cultivated most extensively. Not all varieties of bean grow in the European climate, however.
Among the main suppliers to Germany are some European countries, such as Italy, Spain, Turkey, and the Netherlands, but also the USA, Canada and Romania. Kenya exports beans all year round.
Availability
Fresh beans grown outdoors are available from May to October; beans are harvested in hothouses from March to December. Domestic produce is sold from July until September.
Mainly Kenya exports beans all year round, so that a limited supply is also available in the interim period. In addition, tinned and frozen beans are sold at all times.
Appearance, taste, characteristics
Four varieties of the green bean Phaseolus vulgaris are cultivated. There is great diversity; more than 100 varieties differ in shape, colour, taste, nutrient content and use.
There are several ways to categorize beans in groups.
1) Botanists differentiate the following groups according to their growth form:
a) Dwarf beans / bush beans (Phaseolus vulgaris ssp. vulgaris var. nanus)
As the name implies, dwarf beans grow in the form of a bush and without support. The principal customer is the food industry, but they are also grown for the greengrocery.
b) Pole bean / climbing bean / string bean (Phaseolus vulgaris ssp. vulgaris var. vulgaris)
In contrast to dwarf beans, pole beans need a pole as support or - in the greenhouse - strings to tie them up. They are also called climbing beans and they require more work than dwarf beans but have a higher yield. The pods are green or yellow, depending on the variety. Less frequently, blue pods can be found. They are cultivated chiefly for the greengrocery. They are often used as cut beans for stews.
2) Beans can also be differentiated according to the cross-section of their pods, into the following groups:
a) Sword beans, with flat pods (Attention: In India, Malaysia and Southeast Asia another species of plant, Canavalia gladiata, is grown, which is also known as a sword bean. Its white seeds are edible, but difficult to digest, and can be toxic if they are undercooked.
b) Flageolet beans, with flat, oval pods
c) Pearl beans, thin skinned, with round or oval-round pods that show the outlines of the small, round seeds inside them. These must be differentiated from the pearl beans that are usually sold in the dried form and from the term 'pearl beans' used for coffee beans that grow separately and assume a round shape.
Most bean varieties have oval or round pod cross-sections and cannot be definitely assigned to one of the above-mentioned groups.
In each group, no matter whether classified botanically or according to shape, there are numerous varieties. Here are brief descriptions of some of the familiar ones:
* Snap bean. This is easy to break or snap even when it is fully ripe. Its pods are round or oval and thick and fleshy.
* Broad bean (Vicia faba ssp. faba var. major), also known as fava bean. It is actually not a bean but a vetch. Please read about it under Broad bean.
* Fire bean or scarlet runner bean (Phaseolus coccineus). Some varieties of this magnificent-looking bean have scarlet-red flowers, which gives them their name. The ripe seeds are black and sometimes have red spots. Fire beans are also popular as decorative twining plants to cover walls and fences.
* Haricots verts (Phaseolus vulgaris ssp. vulgaris). These are green dwarf beans with very thin pods, with or without tiny seeds, stemming chiefly from France or the Netherlands. They should be dark green or waxy yellow with no strings.
* Katjang bean (Vigna unguiculata ssp. cylindrica). The katjang bean is a subspecies of the cowpea. It is grown in Africa and South Asia. The pod is 7-13 cm long and contains brown to purple-black seeds the size of peas. Another pulse, the pigeon pea (Cajanus cajan) is frequently called katjang bean, but it is a different botanical species. More information can be found under Pigeon pea .
* Princess and Delicate beans (Phaseolus vulgaris ssp. vulgaris var. nanus). These are also a type of dwarf bean. They are picked when very young and tender and have short green pods. Princess beans are short and thin; delicate beans are medium long.
* Runner bean / Turkish bean (Phaseolus coccineus). This green garden bean is edible but plays only a negligible role on the market because of its rough pod. It tastes earthy and distinctly like a bean. It is similar in size to the broad bean. Its seeds are also green.
* Fat bean. This has a long, fleshy pod and a sweet taste.
* Wax or Butter bean (Phaseolus vulgaris). This is a dwarf or pole bean with a yellow pod. It is tender, firm, and frequently used as a salad bean.
* Sugar bean. This green bean has a wrinkled, fleshy pod that shrinks a bit when the bean is fully ripe, so that the seeds are outlined.
* Sugar snap bean. This combines the features of the snap bean and the sugar bean.
Ingredients
Green beans contain secondary plant substances, above all phytoestrogens, saponines and protease inhibitors. 100 g contain:
|
Green beans, fresh |
Green beans, cooked |
Green beans, tinned |
Wax beans, cooked |
Princess beans, dried1 |
Energy (kcal) |
33 |
25 |
22 |
32 |
401 |
Water (g) |
90 |
89 |
89 |
89 |
11 |
Protein (g) |
4 |
2 |
2 |
2 |
33 |
Fat (g) |
<1 |
<1 |
<1 |
<1 |
16 |
Carbohydrates (g) |
1 |
3 |
3 |
6 |
31 |
Fiber (g) |
3 |
3 |
3 |
3 |
|
Vitamin A (RE) (µg) |
53 |
55 |
45 |
9 |
|
Vitamin E (mg) |
0.1 |
0.1 |
0.1 |
0.5 |
|
Vitamin B1 (mg) |
0.8 |
0.1 |
0.0 |
0.1 |
|
Vitamin B2 (mg) |
0.1 |
0.1 |
0.1 |
0.1 |
|
Niacin (mg) |
0.5 |
1 |
1 |
1 |
|
Vitamin B6 (mg) |
0.3 |
0.2 |
0.1 |
0.1 |
|
Folic acid (µg) |
|
24 |
9 |
19 |
|
Vitamin C (mg) |
19 |
12 |
5 |
13 |
|
Potassium (mg) |
243 |
202 |
140 |
202 |
1020 |
Sodium (mg) |
2 |
2 |
2172 |
6 |
50 |
Calcium (mg) |
56 |
62 |
55 |
50 |
530 |
Magnesium (mg) |
26 |
25 |
19 |
27 |
170 |
Phosphorous (mg) |
38 |
37 |
33 |
43 |
480 |
Iron (mg) |
0.8 |
0.8 |
0.6 |
1 |
15 |
1 The nutrient density is greater with dried fruits. They contain more energy, vitamins and minerals per 100 g than the same amount of fresh produce because the water, which has practically no nutrients and contributes greatly to the weight of fresh fruits, is gone.
2 Salt is usually added to conserved foods, and our cooking salt contains sodium.
Harmful substances
It is general knowledge that beans should not be eaten raw, the reason being that they contain the toxic protein phasine, which is destroyed only by cooking. The nitrate content of green beans is low at less than 50 mg/100 g fresh weight.
Quality criteria, optimal storage conditions
Green beans dry out quickly, making them strawy. Withered beans are tough and hard even after being cooked. When they are purchased, fresh beans should be crisp and have no spots. Beans do not tolerate temperatures below 4°C; the cold causes damage and red-brown spots.
Since fresh beans do not keep very long, they should be stored for a maximum of 2 days in the refrigerator.
Form of consumption, use, processing, practical tips for preparation
There is little waste with most varieties of green beans. Only the tips and the stem ends of the pods need to be cut off prior to cooking. However, there are varieties that have tough strings when they are harvested later. These strings should be removed, as they detract greatly from the enjoyment of the beans.
As already mentioned, beans should not be eaten raw. They can be steamed, stewed or cooked. If they are rinsed with cold water after being cooked al dente they will retain their green colour.
There are numerous ways to use cooked beans; salads, vegetable dishes, soups and stews are just a few examples.
In the supermarket deep-frozen and tinned beans can be found.
Seasoning tip
Parsley, savory, lovage, basil, garlic, oregano, lemon juice and thyme all taste good with beans.
Miscellaneous
The rather exotic asparagus bean (Vigna unguiculata) is an especially long, thin green bean. The pod can be up to 1 m long. These beans are normally sold with a length of 40-50 cm. Botanically speaking, they do not belong to the green beans. Because of their shape they are also called snake beans, yard-long beans and garter beans, and they belong to the exotic vegetables.
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