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Delicious Fruit - Peach

ritau
07月16日
Peaches were cultivated in China as far back as 8,000 years ago, with domestication at least 4,000 years ago. Some sources claim that peaches originated in China, whilst others claim that it originated in Iran.

Hundreds of peach and nectarine cultivars are known. These are classified into two categories — the freestones and the clingstones, depending on whether the flesh sticks to the stone or not. Freestones are those whose flesh separates readily from the pit. Clingstones are those whose flesh clings tightly to the pit. Some cultivars are partially freestone and clingstone, so are called semifree. Freestone types are preferred for eating fresh, while clingstone types are for canning. The fruit flesh may be creamy white to deep yellow, to dark red; the hue and shade of the color depends on the cultivar.

Peaches with white flesh typically are very sweet with little acidity, while yellow-fleshed peaches typically have an acidic tang coupled with a sweet floral taste (sometimes described as the classic peach taste, which mellows as the peach ripens and softens), red fleshed varieties are typically flavourful and tangy but with a tart skin, though this also varies greatly. Yellow peaches have a sturdier flesh that is not as easily bruised.Both colors often have some red on their skin. Low-acid white-fleshed peaches are the most popular kinds in China, Japan, and neighbouring Asian countries, while Europeans and North Americans have historically favoured the acidic, yellow-fleshed cultivars.

Peach breeding has favored cultivars with more firmness, more red color, and shorter fuzz on the fruit surface. These characteristics ease shipping and improve supermarket sales due to eye appeal. However, this selection process has not necessarily led to increased flavor. Peaches have a short shelf life, so commercial growers typically plant a mix of different cultivars to have fruit to ship all season long.



lthough its botanical name Prunus persica refers to Persia (present Iran) from where it came to Europe, genetic studies suggest peaches originated in China, where they have been cultivated since the neolithic period. Until recently, it was believed that the cultivation started c. 2000 BC.More recent evidence indicates that domestication occurred as early as 6000 BC in Zhejiang Province of China. The oldest archaeological peach stones are from the Kuahuqiao site. Archaeologists point to the Yangtze River Valley as the place where the early selection for favorable peach varieties probably took place. Peaches were mentioned in Chinese writings and literature beginning from the early 1st millennium BC.

A domesticated peach appeared very early in Japan, in 4700–4400 BC, during the Jōmon period. It was already similar to modern cultivated forms, where the peach stones are significantly larger and more compressed than earlier stones. This domesticated type of peach was brought into Japan from China. Nevertheless, in China itself, this variety is currently attested only at a later date of c. 3300 to 2300 BC.

In India, the peach first appeared by c. 1700 BC, during the Harappan period.

It is also found elsewhere in Western Asia in ancient times. Peach cultivation reached Greece by 300 BC. It is often claimed that Alexander the Great introduced the fruit into Europe after he conquered the Persians, although there is no historical evidence for this belief. Peaches were, however, well known to the Romans in the 1st century AD; the oldest known artistic representations of the fruit are in two fragments of wall paintings, dated to the 1st century AD, in Herculaneum, preserved due to the Vesuvius eruption of 79 AD and now held in the National Archaeological Museum in Naples. Archaeological finds show that peaches were cultivated widely in Roman north-western Continental Europe, but production collapsed around the sixth century; some revival of production followed with the Carolingian Renaissance of the ninth century.

The peach was brought to the Americas by Spanish explorers in the 16th century, and eventually made it to England and France in the 17th century, where it was a prized and expensive treat. The horticulturist George Minifie supposedly brought the first peaches from England to its North American colonies in the early 17th century, planting them at his Estate of Buckland in Virginia. Although Thomas Jefferson had peach trees at Monticello, American farmers did not begin commercial production until the 19th century in Maryland, Delaware, Georgia, South Carolina, and finally in Virginia.

In April 2010, an international consortium, the International Peach Genome Initiative (IPGI), that include researchers from the United States, Italy, Chile, Spain, and France announced they had sequenced the peach tree genome (doubled haploid Lovell). Recently, IPGI published the peach genome sequence and related analyses. The peach genome sequence is composed of 227 million nucleotides arranged in eight pseudomolecules representing the eight peach chromosomes (2n = 16). In addition, a total of 27,852 protein-coding genes and 28,689 protein-coding transcripts were predicted.

Particular emphasis in this study is reserved for the analysis of the genetic diversity in peach germplasm and how it was shaped by human activities such as domestication and breeding. Major historical bottlenecks were individuated, one related to the putative original domestication that is supposed to have taken place in China about 4,000–5,000 years ago, the second is related to the western germplasm and is due to the early dissemination of the peach in Europe from China and the more recent breeding activities in the United States and Europe. These bottlenecks highlighted the substantial reduction of genetic diversity associated with domestication and breeding activities.

Raw peach flesh is 89% water, 10% carbohydrates, 1% protein, and contains negligible fat. A medium raw peach, weighing 100 g (3.5 oz), supplies 39 calories, and contains small amounts of essential nutrients, but none is a significant proportion of the Daily Value (DV, right table). A raw nectarine has similar low content of nutrients. The glycemic load of an average peach (120 grams) is 5, similar to other low-sugar fruits.
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