category: food/groceries: fruits

fruit, de.: Obst, Früchte, fr.: fruit, it.: frutta, es.: fruta

The term fruit is mostly associated with sweet fruits and excludes vegetables. Its biological definition is quite different though. The common and the biological definition of fruit have a different background and are explained in the following.

Common definition

Speaking about the fruit of a plant most people mean the part that is of use to humans. For example the root part in carots and turnips the axis of the plant in kohlrabi and the grain in cereals. The leafs of some cabbage varieties or shallots are also named fruit. With apples the pericarp surrounding the seeds is called fruit.

Botanical definition

The botanical meaning of "fruit" is always the pericarp that surrounds the seed. Fruits are therefore organs formed from the ovary of the plant – botanically called the gynoecium, which is part of the flower. They surround the seed until it is ripe and help in its dissemination.

From a botanical view fruits develop from pollinated flowers. Therefore eggplants, avocados, cucumbers, pumpkins, peppers and zucchini are not vegetables, but also fruits. Rhubarb on the other hand is a vegetable.

Definition of foodlexikon

Within foodlexicon fruits are edible, mostly juice and fleshy fruits and seeds of domesticated species. Especially the fruits of fruit trees belong to this category.

Etymology

The term fruit has its origin in the Middle English and is derived from the Latin word fructus, which means enjoyment of produce or harvest. It is also related to fruges, which means fruits of the earth.

Classification of fruits

• berries and softfruits
• pome fruits
• nuts
• drupes
• tropical fruits
• citrus fruits

Fruits that are not cultivated but grow in nature are called wild fruits.

Classification of fruits as a domesticated plant

• seed fruits – the actual seed is eaten (i.e. seeds, nuts)
• pericarp fruits – the fleshy pericarp surrounding the seed is eaten (i.e. drupes, pome fruits)

Nutrients of fruits

Fresh fruits contain many vitamins, dietary fibres, fruit acids, fruit sugar, minerals and sometimes tanning agents and amphetamines. They belong to the most valuable foods. Depending on the type, storage and surrounding conditions the amount of nutrients fluctuates enormously. The amount of the minerals potassium, calcium, magnesium and iron is also high in many fruits. Fruits with a deep yellow or orange pulp contain much carotene and folic acid. The amount of vitamin C is especially high in citrus fruits, strawberries, blackcurrants, kiwifruits and papayas. Dietary fibres have an average of 3,7 % in fruits. With the exeption of avocados fruits do not contain much fat and proteins. The water content on the other hand is usually above 80 %. All put together fruits and vegetables contain the highest amount of essential nutrients of all food groups, especially compared to their energetic value.

Commercial standards for fruits

Where fruits are sold they have to comply with international standards of trade. Those constitute objective measures for the evaluation. Fruits with considerable flaws cannot be sold as fresh fruit. Fresh fruits are divided into different classifications by the use of minimum requirements. This guarantees a range of products that is uniform and easy to understand and compare. The customer is able to buy products of different quality and price groups and has a possibility to file complaints if the products do not comply with those standards of trade.

Fruits produced within the European Union fall under the EU marketing standards. Imports of fresh fruit and vegetables into EU countries are checked for compliance with EU marketing standards. These standards apply at all marketing stages and include criteria such as size, quality, packaging, labelling and presentation.

Marketing standards of fruits

No matter which marketing standard is used (EU marketing standard, grading of specific countries, UN/ECE standard or Codex Alimentarius), the underlying scheme is always the same.

Which marketing standard applies?

The marketing standard is specified for the botanical name of each fruit variety.

Grading

Most important part of each marketing standard is the grading of fruits into different quality groups. They are made up from minimum requirements and attributes of their class.

Minimum requirements

Minimum requirements are valid for all classes of fruits. Some fruits have specific requirements in addition to the minimum requirements.

Attributes of high-quality fruits

Fruits should be...

• whole. No part should be missing.
• healthy. No defects or rotting should be visible.
• clean and free from visible foreign matter.
• fresh looking.
• free from pests.
• free from damage caused by pests.
• free of abnormal moisture on the outside.
• free of any foreign smell and/or taste.
• carefully harvested, packed and transported.
• sufficiently developed.
• sufficiently ripe.
• The fruit should be of a development and condition that tolerates handling and transport without spoiling and arrive at its destination in acceptable condition.

Class criteria

Fruits are divided into up to three classes, depending on their defects.

• "Extra" Class: Fruits of superior quality, free of dirt and foreign matter and without any defects, including in colour. In shape, size and colouring they must be characteristic of the variety and the stalk must be intact.
• Class I: Fruits must be of good quality. Slight defects in skin, stalk and shape are allowed and they can be a little smaller. The flesh must be perfectly sound.
• Class II: Fruits must be marketable and satisfy all minimum requirements. Defects in shape and colouring are allowed. Size of the fruits is regulated. Slight defects in skin and flesh are allowed but cannot exceed specific provisions.

Size

Depending on the fruit variety the classification according to size is specifically defined. Size is determined by cross diameter, circumference and weight.

Tolerances
When fruits are divided into those three classes according to size, specific tolerances cannot be undercut.

Packing

The package must have enough stability and must be durable according to its content so that the fruits are protected adequately. Usage of paper and adhesive labels are allowed if non-toxic ink and glue are used.

Labelling

Labelling must be applied to the package in legibly and indelibly letters and visible from the outside.

All labels must contain the following information:

• Packer and/or dispatcher with name and address
• Nature of produce and/or name of variety
• Country of origin
• Class
• Official control mark (optional)

In addition different products must have further information on their label (for example size or variety).

Storage of fruits

Modern methods of storage that are used during transport as well, allow customers to buy fresh fruit around the year and independent of harvesting time. Whether fruits can be stored depends on the harvesting time. Only physiologically ripe fruits should be harvested. This means that fruits are fully-grown and the storage of nutrients is completed. The perfect time differs between climacteric fruits (fruits that ripen off the plant) and non-climacteric fruits (ripening stops when harvested). Non-climacteric fruits are picked when fully ripe, ripe enough for eating or shortly before that time. Climacteric fruits are picked when they are ripe for harvesting, meaning the storage of nutrients is completed and they are fully-grown. During storage time those fruits ripen until they are ready for eating.

Airtight and insulated storage rooms automatically maintain the perfect atmosphere and climatic conditions for each fruit variety. Some fruit varieties can be stored up to nine months in such rooms.

Long storage times relieve the producer in times of oversupply and allow to sell products longer than the harvesting time would normally permit. A steady supply of fruits for the market can such be maintained.

How long fruits can be stored is determined by the storage temperature, relative air humidity and air composition.

Storage temperature

Fruits are not dead material after they have been harvested. They continue to have a metabolism that changes the condition of the fruit. Most important to slow down this metabolism and prevent rotting of the fruits is the temperature of the storage rooms. Microorganisms responsible for rotting and deterioration are also slowed down when the temperature is low. Moreover low temperature reduces the activity of enzymes that regulate the metabolism.

Each fruit variety has its own perfect storage temperature. Most varieties need a temperature of just above 0 °Celsius. Some varieties can also stand low minus degrees and the perfect storage temperature for tropical fruits is for most varieties between 10 and 15 °C.

Relative air humidity
Air humidity in storage rooms has just as much influence on the loss of moisture of the fruits, as temperature, condition of skin or peel and ripeness. Most fruit varieties need a relative air humidity of 90 %.

Air composition
Air is composed of 78 % nitrogen (N), 21 % oxygen (O₂), 0,03 % carbon dioxide (CO₂) and a small rest of other gases. CO₂ is of extreme importance for green plants, which need it for photosynthesis. With the help of chlorophyll plants form carbohydrates from CO₂, light and water.

For the storage of fruits the amount of CO₂ in the air is of great importance. Through metabolism of the stored products in closed storage rooms the levels of CO₂ and O₂ are changed. The amount of CO₂ increases through dissimilation of carbohydrates, fruit acids and free alcohol and the O₂-level decreases. While not enough O₂ can result in suffocation of the fruits and a fermented taste, too much CO₂ increases the fruit metabolism. The flesh breaks up and can become mushy.

Each fruit variety has different demands on the perfect CO₂ : O₂-proportion in the air composition of storage rooms.

To increase the storage time of specific fruits (for example citrus fruits) an wax emulsion is applied to the fruits. The fruit then cannot lose weight through evaporation and certain metabolism activities are reduced.

When talking about the storage of fruits the plant hormone ethylene should also be mentioned. It acts highly physiologically and stimulates ripening of fruits. With some fruits like bananas ethylene is used to accelerate ripening. Green bananas are stored in so-called ripening rooms with a slightly higher temperature and ethylene concentration.

Some vegetables age very fast if the ethylene concentration is high (for example cauliflower and cucumbers). Therefore ripe bananas, pears, apples, kiwifruits or avocados should not be stored close to vegetables.

Use of fruits

Fruits are very versatile in their usage. They are eaten raw on a daily basis. Fruits coming from the same region and picked when very ripe have the best taste and the highest content of nutrients.

Besides eating them raw fruits can be used for canning and bottling, extracting juice or to prepare purees, jams and other spreads. To prevent the loss of vitamins peeled or cut fruits should be eaten as soon as possible. The breakdown of vitamins can be slowed down if the cut fruit is sprinkled with lemon juice and stored in an airtight container in the refrigerator until consumption.

The surface of many fruits, especially citrus fruits, is treated with glazing agents or preservatives for better storage. To prevent drying out the surface of citrus fruits, apples, pears and melons can also be coated with a wax emulsion. Some of these substances are detrimental to health, the skin of treated citrus fruits should therefore not be consumed. In conventional agriculture pesticides are used. Fruits from organic farming are the healthy alternative, since it does not allow modern pesticides at all.

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