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Introduction Nuts and Seeds

 

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Generally speaking, the term "nuts" refers to edible fruits and seeds that are surrounded by a firm, dry shell. In the fruit trade the name hard-shelled dry fruit also applies.

The botanical definition of nuts varies from normal usage. Thus only the so-called single-seeded indehiscent fruits count as nuts; i.e., a single seed is enclosed by a dry pericarp. The pericarp does not open as the fruit ripens and can be ligneous (woody), coriaceous (leathery), or membranous. Many fruits that we know as nuts do not belong to the "true nuts" at all in the botanical sense, but rather to the most varied plant families.


Availability

Nuts with shells can be bought mainly in the autumn and winter months. Shelled nuts, on the other hand, are on offer throughout the year, usually packaged in bags, and are processed industrially into many products.


Contents

In contrast to other types of fruit, nuts and seeds have a negligible water content. Most nuts and seeds are very rich in fat and contain large amounts of protein and carbohydrates. For this reason they are considerably higher in energy than other fruits; sometimes they are even called "calorie bombs".

Recent studies, above all in the USA, have shown, however, that regular (but moderate) consumption of nuts ("a handful per day") reduces the risk of cardiovascular disease. Particularly the favorable composition of fatty acids plays an important role in this regard: This is characterized by a large proportion of mono- and polyunsaturated fatty acids.

At the same time, nuts and seeds are rich in fibre and contain large amounts of vitamins of the B group and vitamin E. They also contain many minerals such as potassium, calcium and magnesium, as well as iron. For these reasons, nuts, when eaten in appropriate amounts, are a very valuable part of the diet.


Harmful Substances

Nuts appear in the headlines at times because of an increased aflatoxin content. Aflatoxins are degradation products of moulds which are regarded as being carcinogenic. They develop above all when nuts are stored in a damp environment.

One should naturally take care that no foods become mouldy, but with nuts this is especially important. Unfortunately, one cannot see whether nuts contain aflatoxins just by looking at them.

If harvested nuts are correctly dried and stored, the formation of aflatoxins can be prevented to a great extent. Imported fruits must adhere to threshold values for this substance; every batch of particularly endangered types is individually tested.


Quality Criteria, Optimal Storage Conditions

Nuts and seeds should always be stored cool and dry. With good storage, most kinds can be kept for several months in their shells.

Shelled, chopped nuts keep only a short time, as they turn rancid at room temperature. Shelled nuts keep best when they are cooled. They can also be frozen. The best-by date on packaged goods, as with other foods, is relevant only for the unopened package.

Form of Consumption, Use, Further Processing, Practical Tips for Preparation Nuts are popular as a between-meals snack and are contained in many sweets and baked goods. They have very varied uses in the kitchen and impart a special flavour to numerous dishes.

Most nuts and seeds are also used to produce oil. This is used as edible or cooking oil, processed as margarine, or employed in the cosmetic industry.


Additional Information

The best-known nuts are described in detail on the following pages. In addition there are other nuts or nutlike fruits that are of no great importance in Germany. Several of these are presented briefly here:

• Babassu nuts are the fruits of the Brazilian babassu palm. They weigh between 100 and 250 grams, are similar to coconuts, and contain up to 70% fat. They are used mainly to extract oil.
• Coquitos are the sperm nuclei of the honey palm. The fruits the size of cherries are also known as mini-coconuts, which describes them well.
• Ginkgo nuts are the seeds of the ginkgo tree, which has been around for 250 million years and is one of the oldest species of tree. Ginkgo nuts are the kernel of the Syrian-plum-like stone fruit and are also known as ginkgo plums, ginnan or white nuts. In China and Japan they are offered marinated or roasted as a delicacy.
• Kemiri are seeds of the candlenut tree; they contain oil and are the size of hazelnuts. This East-Indian nut tastes slightly bitter and spicy and is also known as candlenut or bankul nut. Kemiri are used for their oil and as a spice.
• Kola nuts, also called cola nuts, guru nuts or goro nuts, are the seeds of the kola tree. On the tree grow lemon-shaped fruits, the size of a pigeon egg; the red pulp is sold fresh or as dried fruit. Each fruit contains four or five bitter-tasting seeds, the kola nuts. They contain caffeine and theobromine, i.e., substances that have a stimulating effect on human beings. Kola nuts are added to some refreshing drinks (Coca Cola), sweets and chocolate, and they have always been chewed by the West African natives as a stimulant and as a remedy to allay hunger.
• The water nut is the dark-brown, starchy stone fruit of an aquatic plant that is found in the Mediterranean area and in southeastern Europe. In areas with a favourable climate it grows sporadically in Germany as well. The water nut is approximately 4 cm and resembles the marron, or edible chestnut.
• The water chestnut, also called Chinese chestnut, is related to the water nut and is one of the most important ingredients in Chinese cuisine. It can be eaten raw or cooked and is similar in taste to the edible chestnut. In our area water chestnuts are available only preserved in tins.