''Luffa'' is a genus of tropical and subtropical
vine
A vine (Latin ''vīnea'' "grapevine", "vineyard", from ''vīnum'' "wine") is any plant with a growth habit of trailing or scandent (that is, climbing) stems, lianas or runners. The word ''vine'' can also refer to such stems or runners themselv ...
s in the cucumber family (
Cucurbitaceae
The Cucurbitaceae, also called cucurbits or the gourd family, are a plant family consisting of about 965 species in around 95 genera, of which the most important to humans are:
*''Cucurbita'' – squash, pumpkin, zucchini, some gourds
*''Lagena ...
).
In everyday non-technical usage, the luffa, also spelled loofah, usually refers to the fruits of the species ''
Luffa aegyptiaca
''Luffa aegyptiaca'', the sponge gourd, Egyptian cucumber or Vietnamese luffa, is an annual species of vine cultivated for its fruit, native to South and Southeast Asia.
Description
The three-lobed leaves are wide.
The fruit, approximately ...
'' and ''
Luffa acutangula
''Luffa acutangula'' is a cucurbitaceous vine that is commercially grown for its unripe fruits as a vegetable. Mature fruits are used as natural cleaning sponges. Its fruit slightly resembles a cucumber or zucchini with ridges. It ranges from cen ...
''. It is cultivated and eaten as a vegetable, but must be harvested at a young stage of development to be edible. The vegetable is popular in
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
,
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
,
Bangladesh
Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
and
Vietnam
Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...
. When the fruit is fully ripened, it is very fibrous. The fully developed fruit is the source of the loofah
scrubbing sponge which is used in bathrooms and kitchens.
Names
The name ''luffa'' was taken by European botanists in the 17th century from the Egyptian-Arabic name ''lūf''.
[The plant name "luffa" was introduced to Western botany nomenclature by the botanist ]Johann Vesling
Johann Vesling (Latin: Veslingius) (1598 – 30 August 1649) was a German anatomist and botanist from Minden, Westphalia. He published a major illustrated work on human anatomy ''Syntagma Anatomicum'' (1641).
Life and work
Vesling was born in ...
(died 1649), who visited Egypt
Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Mediter ...
in the late–1620s and described the plant under cultivation with artificial irrigation in Egypt. In 1706 the botanist Joseph Pitton de Tournefort
Joseph Pitton de Tournefort (5 June 165628 December 1708) was a French botanist, notable as the first to make a clear definition of the concept of genus for plants. Botanist Charles Plumier was his pupil and accompanied him on his voyages.
Lif ...
introduced the formal botany genus name "Luffa". Tournefort referred to Veslingius's earlier description and reiterated that "Luffa Arabum" is a plant from Egypt in the cucumber family. In establishing the genus ''Luffa'', Tournefort identified just one member species and called it "Luffa Arabum". His 1706 article includes detailed drawings of this species (which is now called ''Luffa aegyptiaca''). The species is native to tropical Asia but has been under cultivation in Egypt since late medieval times. The botanist Peter Forsskål
Peter Forsskål, sometimes spelled Pehr Forsskål, Peter Forskaol, Petrus Forskål or Pehr Forsskåhl (11 January 1732 – 11 July 1763) was a Swedish-speaking Finnish explorer, orientalist, naturalist, and an apostle of Carl Linnaeus.
Earl ...
visited Egypt in the early–1760s and noted that it was called ''lūf'' in Arabic. In the 18th century the botanist Linnaeus
Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
adopted the name ''luffa'' for this species but assigned it to the genus ''Momordica
''Momordica'' is a genus of about 60 species of annual or perennial climbers herbaceous or rarely small shrubs belonging to the family Cucurbitaceae, natives of tropical and subtropical Africa and Asia and Australia. Most species produce floral ...
'', and did not use a separate genus ''Luffa''. More refs on ''Luffa'' in 18th century botanical nomenclature
"A commentary on Loureiro's "Flora Cochinchinensis" "
by E.D. Merrill, year 1935, in ''Transactions of American Philosophical Society'' volume 24 part 2, pp 377-378
''Luffa'' @ ATILF
an
"''Suite de l'Etablissement de Quelques Nouveaux Genres de Plantes''"
by J.P. de Tournefort (1706) in ''Mémoires de l'Academe Royale des Sciences année 1706''.
In
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
it is sometimes known as "Chinese
okra
Okra or Okro (, ), ''Abelmoschus esculentus'', known in many English-speaking countries as ladies' fingers or ochro, is a flowering plant in the mallow family. It has edible green seed pods. The geographical origin of okra is disputed, with su ...
", and in Spanish as ''estropajo''.
Uses
Fibers
The fruit section of ''L. aegyptiaca'' may be allowed to mature and used as a bath or kitchen
sponge
Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through t ...
after being processed to remove everything except the network of
xylem
Xylem is one of the two types of transport tissue in vascular plants, the other being phloem. The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients. The word ''xylem'' is derived from ...
fibers. If the loofah is allowed to fully ripen and then dried on the vine, the flesh disappears, leaving only the fibrous skeleton and seeds, which can be easily shaken out. Marketed as ''luffa'' or ''loofah'', the sponge is used as a body scrub in the shower.
In Paraguay, panels are made out of luffa combined with other vegetable matter and recycled plastic. These can be used to create furniture and construct houses.
Food
Indian subcontinent
In
Hindi
Hindi (Devanāgarī: or , ), or more precisely Modern Standard Hindi (Devanagari: ), is an Indo-Aryan language spoken chiefly in the Hindi Belt region encompassing parts of northern, central, eastern, and western India. Hindi has been de ...
-speaking
North India
North India is a loosely defined region consisting of the northern part of India. The dominant geographical features of North India are the Indo-Gangetic Plain and the Himalayas, which demarcate the region from the Tibetan Plateau and Central ...
n states, it is called ''torai'' (), and cooked as vegetable. In eastern-UP it is also called ''nenua''. But in central/Western India, specially in Madhya Pradesh, it is called ''gilki'' (). ''Torai'' is reserved for ridge gourd and is less popular than ''gilki'' in central western India.
In
Bhojpuri
Bhojpuri (;[Bhojpuri entry, Oxford Dictionaries](_blank)
, Oxford U ...
speaking regions it is called ''ghiura''. Apart from fruit of the vegetable, flowers are also used as vegetable as ''chokha'', ''tarua'', ''pakoda'', etc.
In
Nepal
Nepal (; ne, नेपाल ), formerly the Federal Democratic Republic of Nepal ( ne,
सङ्घीय लोकतान्त्रिक गणतन्त्र नेपाल ), is a landlocked country in South Asia. It is mai ...
and
Nepali language
Nepali (; , ) is an Indo-Aryan language native to the Himalayas region of South Asia. It is the official, and most widely spoken, language of Nepal, where it also serves as a '' lingua franca''. Nepali has official status in the Indian st ...
speaking Indian states, it is called ''ghiraula'' (घिरौंला). It is popular vegetable usually cooked with tomato and potatoes and served with rice.
In
Gujarat
Gujarat (, ) is a state along the western coast of India. Its coastline of about is the longest in the country, most of which lies on the Kathiawar peninsula. Gujarat is the fifth-largest Indian state by area, covering some ; and the ninth ...
it is known as ''turia'' or ''turya'' (તુરીયા) as well as or ''ghissora'' in the
Kutchi language
Kutchi (; કચ્છી, , ڪڇّی) or Kachhi is an Indo-Aryan language spoken in the Kutch region of India and Sindh region of Pakistan. The name of the language is also transliterated as Katchi, Kutchhi, Kachchi, Kachchhi, Kachhi or Cutch ...
. It is a simple but very popular vegetable usually made with a plentiful tomato gravy and garnished with green chillies and fresh coriander. When cooked roti is shredded by hand and mixed into it, it is colloquially known as "rotli shaak ma bhuseli". Alternatively this dish is also eaten mixed with plain cooked rice.
In
Bengali
Bengali or Bengalee, or Bengalese may refer to:
*something of, from, or related to Bengal, a large region in South Asia
* Bengalis, an ethnic and linguistic group of the region
* Bengali language, the language they speak
** Bengali alphabet, the w ...
-speaking
Bangladesh
Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
and the Indian state of
West Bengal
West Bengal (, Bengali: ''Poshchim Bongo'', , abbr. WB) is a state in the eastern portion of India. It is situated along the Bay of Bengal, along with a population of over 91 million inhabitants within an area of . West Bengal is the fourt ...
, it is known as ''dhudhul'' () and a popular vegetable. It is eaten fried or cooked with shrimp, fish, or meat.
In
Assam
Assam (; ) is a state in northeastern India, south of the eastern Himalayas along the Brahmaputra and Barak River valleys. Assam covers an area of . The state is bordered by Bhutan and Arunachal Pradesh to the north; Nagaland and Manipur ...
, it is called ''bhul'' (ভুল) and is cooked with sour fish curry along with ''
taro
Taro () (''Colocasia esculenta)'' is a root vegetable. It is the most widely cultivated species of several plants in the family Araceae that are used as vegetables for their corms, leaves, and petioles. Taro corms are a food staple in Africa ...
''.
In
Tamil Nadu
Tamil Nadu (; , TN) is a States and union territories of India, state in southern India. It is the List of states and union territories of India by area, tenth largest Indian state by area and the List of states and union territories of India ...
, ''Luffa acutangula'' (ridged gourd) is called ''peerkangai'' (பீர்க்கங்காய்) and ''Luffa aegyptiaca'' / ''Luffa cylindrica'' (sponge gourd) is called ''nurai peerkankai'' (நுரை பீர்க்கங்காய்) and are used as vegetables to make ''peerkangai
kootu
Kootu (Tamil:கூட்டு) is a lentil and vegetable stew in South Indian, particularly Tamil and Kerala cuisines. The etymology for kootu derives from the Tamil word "kootu" which means "add" or "mixture/medley" i.e. vegetable added wit ...
'', ''
poriyal
''Poṟiyal'' ( ta, பொரியல்) is a Tamil word for any fried, or sometimes sautéed, vegetable dish. It is called ''palya'' in Kannada, ''vepudu'' in Telugu, and ''mezhukupuratti'' in Malayalam. It is usually made by shallow frying ...
'', and ''
thogayal
A chutney is a Spread (food), spread in the cuisines of the Indian subcontinent. Chutneys are made in a wide variety of forms, such as a tomato relish, a ground peanut Garnish (food), garnish, yogurt or curd, cucumber, spicy coconut, spicy o ...
''. Even the skin is used to make chutney.
In
Karnataka
Karnataka (; ISO: , , also known as Karunāḍu) is a state in the southwestern region of India. It was formed on 1 November 1956, with the passage of the States Reorganisation Act. Originally known as Mysore State , it was renamed ''Karnat ...
's
Malenadu
Malnad (; Malēnādu) is a region in the state of Karnataka in India. Malenadu covers the western and eastern slopes of the Western Ghats or Sahyadri mountain range, and is roughly 100 kilometers in width.
Malnadis a region of Karnataka ...
(
Western Ghats) it is known as ''tuppadahirekayi'', which literally translates as "buttersquash", also known as Hirekayi in
Kannada
Kannada (; ಕನ್ನಡ, ), originally romanised Canarese, is a Dravidian language spoken predominantly by the people of Karnataka in southwestern India, with minorities in all neighbouring states. It has around 47 million native s ...
. It grows naturally in this region and is consumed when it is still tender and green. It is used as a vegetable in curries, but also as a snack, ''bhajji'', dipped in chickpea batter and deep fried. In
Tulu language
Tulu () in Kannada script, ml, തുളു ഭാഷെ in Malayalam script. ''bhāṣe'', , ''bhāśe'', and ''bāśe'' are alternative spellings for the Tulu word ''bāse'' in the Kannada script. The correct spelling for the word ...
it is known as Peere and is used to prepare chutney and ajethna.
In
Telangana
Telangana (; , ) is a States and union territories of India, state in India situated on the south-central stretch of the Indian subcontinent, Indian peninsula on the high Deccan Plateau. It is the List of states and union territories of India b ...
, it is called ''beerakaya''. It is used in making Dal, Fry, Roti Pacchadi, and wet curry.
In
Andhra Pradesh
Andhra Pradesh (, abbr. AP) is a state in the south-eastern coastal region of India. It is the seventh-largest state by area covering an area of and tenth-most populous state with 49,386,799 inhabitants. It is bordered by Telangana to the ...
, it is called ''nethi beerakaya'' or ''beerakaya''. And in
Assam
Assam (; ) is a state in northeastern India, south of the eastern Himalayas along the Brahmaputra and Barak River valleys. Assam covers an area of . The state is bordered by Bhutan and Arunachal Pradesh to the north; Nagaland and Manipur ...
it is called ''jika'' (জিকা,
Luffa acutangula
''Luffa acutangula'' is a cucurbitaceous vine that is commercially grown for its unripe fruits as a vegetable. Mature fruits are used as natural cleaning sponges. Its fruit slightly resembles a cucumber or zucchini with ridges. It ranges from cen ...
) and ''bhula'' (ভোল,
Luffa aegyptiaca
''Luffa aegyptiaca'', the sponge gourd, Egyptian cucumber or Vietnamese luffa, is an annual species of vine cultivated for its fruit, native to South and Southeast Asia.
Description
The three-lobed leaves are wide.
The fruit, approximately ...
). It is used as a vegetable in a curry, chutney and stir fry.
In
Kerala
Kerala ( ; ) is a state on the Malabar Coast of India. It was formed on 1 November 1956, following the passage of the States Reorganisation Act, by combining Malayalam-speaking regions of the erstwhile regions of Cochin, Malabar, South ...
, it is called ''peechinga''; in the Palakkad area it is particularly called ''poththanga'' and used in while bathing. It is also used as a vegetable, cooked with dal or stir fried. Fully matured fruit is used as a natural scrub in rural Kerala. In some places such as
Wayanad
Wayanad () is a district in the north-east of Indian state Kerala with administrative headquarters at the municipality of Kalpetta. It is the only plateau in Kerala. The Wayanad Plateau forms a continuation of the Mysore Plateau, the southern ...
, it grows as a creeper on fences.
In
Maharashtra
Maharashtra (; , abbr. MH or Maha) is a states and union territories of India, state in the western India, western peninsular region of India occupying a substantial portion of the Deccan Plateau. Maharashtra is the List of states and union te ...
, India, (ridge gourd luffa) and ''ghosavala'' (smooth luffa) are common vegetables prepared with either crushed dried peanuts or with beans.
In
Manipur
Manipur () ( mni, Kangleipak) is a state in Northeast India, with the city of Imphal as its capital. It is bounded by the Indian states of Nagaland to the north, Mizoram to the south and Assam to the west. It also borders two regions of Myanm ...
,
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
, is cooked with other ingredients like potato, dried fish, fermented fish and served. It is also steamed and consumed or crushed () with other ingredients and served with steamed rice (''chaak''). Fried ones () are also favorites for many. ''Sebot'' is also eaten as a green vegetable
Other Asian cuisines
In
Vietnamese cuisine
Vietnamese cuisine encompasses the foods and beverages of Vietnam. Meals feature a combination of five fundamental tastes ( vi, ngũ vị, links=no, label=none): sweet, salty, bitter, sour, and spicy. The distinctive nature of each dish reflec ...
, the
gourd
Gourds include the fruits of some flowering plant species in the family Cucurbitaceae, particularly ''Cucurbita'' and ''Lagenaria''. The term refers to a number of species and subspecies, many with hard shells, and some without. One of the earli ...
is called "'" and is a common ingredient in soups and stir-fried dishes.
In China and Taiwan (where it is called , or in English, "silk melon"), Indonesia (where it is called ''oyong''), and the
Philippines
The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no),
* bik, Republika kan Filipinas
* ceb, Republika sa Pilipinas
* cbk, República de Filipinas
* hil, Republ ...
(where it is called ''patola'' in
Tagalog and ''kabatiti'' in
Ilokano), in
Timor-Leste
East Timor (), also known as Timor-Leste (), officially the Democratic Republic of Timor-Leste, is an island country in Southeast Asia. It comprises the eastern half of the island of Timor, the exclave of Oecusse on the island's north-weste ...
it is also called "patola" or "batola" in
Tetum
, nativename=Tetun
, states= Indonesia East Timor
, speakers=, mostly in Indonesia
, date=2010–2011
, ref=e18
, speakers2=50,000 L2-speakers in Indonesia and East Timor
, familycolor=Austronesian
, fam2=Malayo-Polynesian
, fam3= Central–East ...
and in Manipur, India, (where it is called ) the luffa is eaten as a green vegetable in various dishes.
In
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
it is called ''hechima'' () and is cultivated all over the country during summer. It is commonly used as a green vegetable in traditional dishes of the
Ryukyu Islands
The , also known as the or the , are a chain of Japanese islands that stretch southwest from Kyushu to Taiwan: the Ōsumi, Tokara, Amami, Okinawa, and Sakishima Islands (further divided into the Miyako and Yaeyama Islands), with Yonaguni ...
(where it is called ''naabeeraa''). In other regions it is also grown for uses
other than food.
In Nepal it is called ''ghiraula'' and consumed as a vegetable at a young age. When it becomes ripe and dried, it is used as a body scrubbing material during bathing.
Western cuisines
Luffa is also known as "Chinese
okra
Okra or Okro (, ), ''Abelmoschus esculentus'', known in many English-speaking countries as ladies' fingers or ochro, is a flowering plant in the mallow family. It has edible green seed pods. The geographical origin of okra is disputed, with su ...
" in
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
and the
U.S.
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
Other uses
In Japan, in regions other than the Ryukyu Islands and Kyushu, it is predominantly grown for use as a sponge or for applying soap, shampoo, and lotion. As with
bitter melon
''Momordica charantia'' (commonly called bitter melon; Goya; bitter apple; bitter gourd; bitter squash; balsam-pear; with many more names listed below) is a tropical and subtropical vine of the family Cucurbitaceae, widely grown in Asia, Afri ...
, many people grow it outside building windows as a natural sunscreen in summer.
Role in food chain
Luffa species are used as food plants by the
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
The ...
e of some
Lepidoptera
Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...
species, including ''
Hypercompe albicornis
''Hypercompe albicornis'' is a moth of the family Erebidae first described by Augustus Radcliffe Grote in 1865. It is found on Cuba.
Larvae have been recorded feeding on ''Helianthus'', ''Luffa
''Luffa'' is a genus of tropical and subtropi ...
''.
Mechanical properties
The luffa sponge is a
biological cellular material. These materials often exhibit exceptional
mechanical properties
A materials property is an intensive property of a material, i.e., a physical property that does not depend on the amount of the material. These quantitative properties may be used as a metric by which the benefits of one material versus another ca ...
at low
densities
Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek language, Greek letter Rho (letter), rho), although the Latin letter ''D'' ca ...
. While their mechanical performance tends to fall behind manmade materials, such as
alloy
An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...
s,
ceramic
A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain ...
s,
plastic
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...
s, and
composites, as a
structural material
Structural engineering depends on the knowledge of materials and their properties, in order to understand how different materials resist and support loads.
Common structural materials are:
Iron
Wrought iron
Wrought iron is the simplest form ...
, they have long term
sustainability
Specific definitions of sustainability are difficult to agree on and have varied in the literature and over time. The concept of sustainability can be used to guide decisions at the global, national, and individual levels (e.g. sustainable livi ...
for the natural environment. When compressed longitudinally, a luffa sponge is able to absorb comparable energy per unit mass as
aluminum foam. Luffa sponges are composed of a complex network of
fiber
Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporate ...
bundles connected to form a 3-dimensional, highly-
porous
Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure ...
network.
The hierarchical structure of luffa sponges results in mechanical properties that vary with the component of sponge tested. Specifically, the mechanical properties of fiber bundles differ from those of blocks from the bulk of the sponge, which differ from those of the
cross sections of the entire sponge.
Fiber-bundles
Uniaxial tensile tests of fiber bundles isolated from the inner surface provide insight this basic
strut
A strut is a structural component commonly found in engineering, aeronautics, architecture and anatomy. Struts generally work by resisting longitudinal compression, but they may also serve in tension.
Human anatomy
Part of the functionality o ...
element of the luffa sponges. These fibers bundles vary in
diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for ...
from 0.3 to 0.5 mm.
Each fiber bundle has a low density core region not occupied by fibers.
The
stress-strain response of the fiber bundles is nearly
linear elastic all the way until
fracture
Fracture is the separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displa ...
, suggesting the absence of
work hardening
In materials science, work hardening, also known as strain hardening, is the strengthening of a metal or polymer by plastic deformation. Work hardening may be desirable, undesirable, or inconsequential, depending on the context.
This strengt ...
. The
slope
In mathematics, the slope or gradient of a line is a number that describes both the ''direction'' and the ''steepness'' of the line. Slope is often denoted by the letter ''m''; there is no clear answer to the question why the letter ''m'' is use ...
of the
linear
Linearity is the property of a mathematical relationship (''function'') that can be graphically represented as a straight line. Linearity is closely related to '' proportionality''. Examples in physics include rectilinear motion, the linear r ...
region of the stress-strain curve, or
Young’s modulus
Young's modulus E, the Young modulus, or the modulus of elasticity in tension or compression (i.e., negative tension), is a mechanical property that measures the tensile or compressive stiffness of a solid material when the force is applied len ...
, is 236* MPa. The highest stress achieved before fracture, or
ultimate tensile strength
Ultimate tensile strength (UTS), often shortened to tensile strength (TS), ultimate strength, or F_\text within equations, is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials t ...
, is 103 MPa. The strain at which failure occurs, or failure strain, is small at only 5%. The mechanical properties of fiber bundles decrease dramatically when the size of the hollow region inside the bundle increases. Despite their low tensile strength, the fiber bundles have a high
specific modulus
Specific modulus is a materials property consisting of the elastic modulus per mass density of a material. It is also known as the stiffness to weight ratio or specific stiffness. High specific modulus materials find wide application in aerospace a ...
of 2.07– 4.05 MPa⋅m
3/kg, and their overall properties are improved when a high ratio of their cross sectional area is occupied by fibers, the fibers are evenly distributed, and there is strong adhesion between fibers.
Bulk-sponge
Block samples (height: 12.69 ± 2.35mm, width: 11.30 ± 2.88mm, length: 13.10 ± 2.64mm) cut from the core region and hoop region of the luffa sponge exhibit different mechanical behaviors under compression depending on both the orientation they are loaded in as well as the location in the sponge they are sampled from. The hoop region consists of the section of sponge located around the outside between the inner and outer surfaces, while the core region is from the sponge center. Samples from both the hoop and core regions exhibited
yielding when compressed in the longitudinal direction due to the
buckling
In structural engineering, buckling is the sudden change in shape (deformation) of a structural component under load, such as the bowing of a column under compression or the wrinkling of a plate under shear. If a structure is subjected to a gr ...
of fibers. With the highly aligned fibers from the inner surface removed from the hoop region block samples, this yield behavior disappears. In general, the inner surface fibers most significant impact the longitudinal properties of the luffa sponge column followed by the
circumferential properties. There is no noticeable contribution to the
radial
Radial is a geometric term of location which may refer to:
Mathematics and Direction
* Vector (geometric), a line
* Radius, adjective form of
* Radial distance, a directional coordinate in a polar coordinate system
* Radial set
* A bearing f ...
properties. Additionally, the core region exhibits lower
yield stress
In materials science and engineering, the yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning of plastic behavior. Below the yield point, a material will deform elastically and wi ...
and energy absorption (as determined by the area under the stress-strain curve) compared to the hoop region due to its greater
porosity
Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure ...
.
Overall, the stress-strain curves of block samples exhibit three stages of mechanical behavior common to porous materials. Namely, the samples follow
linear elasticity
Linear elasticity is a mathematical model of how solid objects deform and become internally stressed due to prescribed loading conditions. It is a simplification of the more general nonlinear theory of elasticity and a branch of continuum mech ...
for strains less than 10%, followed by a plateau for strains from 10% to 60%, and finally a stress increase associated with densification at strains greater than 60%. Segment samples created from cross sections of the entire luffa sponge (diameter: 92.51 ± 6.15mm, height: 19.76 ± 4.95mm) when tested in compression exhibit this same characteristic behavior.
The three stages can be described by the equations:
# Linear elasticity region:
for
# Plateau region:
for
# Densification region:
for
In the above equations,
and
are the
Young's modulus
Young's modulus E, the Young modulus, or the modulus of elasticity in tension or compression (i.e., negative tension), is a mechanical property that measures the tensile or compressive stiffness of a solid material when the force is applied leng ...
and the
yield strength
In materials science and engineering, the yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning of plastic behavior. Below the yield point, a material will deform elastically and wi ...
of the sponge material. These are chosen to best fit
experimental data
Experimental data in science and engineering is data produced by a measurement, test method, experimental design or quasi-experimental design. In clinical research any data produced are the result of a clinical trial. Experimental data may be qua ...
. The strain at the
elastic limit
In materials science and engineering, the yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning of plastic behavior. Below the yield point, a material will deform elastically and wi ...
, where the plateau region begins, is denoted as
, while the strain at the onset of the densification region is
.
Here
is the density of the bulk sponge
is the density of its constituent, the fiber bundle. The constant D defines the strain at the onset of densification as well as the stress relationship in the densification region. It is determined by fitting experimental data.
Dynamic loading
The mechanical properties of Luffa sponges change under different
strain rate
In materials science, strain rate is the change in strain ( deformation) of a material with respect to time.
The strain rate at some point within the material measures the rate at which the distances of adjacent parcels of the material change ...
s. Specifically, energy adsorption,
compressive stress
In long, slender structural elements — such as columns or truss bars — an increase of compressive force ''F'' leads to structural failure due to buckling at lower stress than the compressive strength.
Compressive stress has stress units (fo ...
, and plateau stress (which is in the case of foam materials corresponds to the
yield stress
In materials science and engineering, the yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning of plastic behavior. Below the yield point, a material will deform elastically and wi ...
) are enhanced by increasing the strain rate.
One explanation for this is that the luffa fibers undergo more axial deformation when dynamically loaded (high strain rates) than when
quasi-statically loaded (low strain rates).
Gallery
File:Leiden University Library - Seikei Zusetsu vol. 26, page 023 - 苦瓜 - Momordica charantia L. - 糸瓜 - Luffa cylindrica (L.), 1804.jpg , Luffa, illustration from the Japanese agricultural encyclopedia Seikei Zusetsu (1804)
File:Luffa cylindrica1.jpg , Habitus of the vine
File:Luffa plant.jpg , Luffa in a coconut tree
File:Ridge Gourd Southern India.jpg, Commonly known as Ridge Gourd from Southern India
File:Glands in probract that attract ants.jpg, Extrafloral nectar glands in Luffa acutangula
''Luffa acutangula'' is a cucurbitaceous vine that is commercially grown for its unripe fruits as a vegetable. Mature fruits are used as natural cleaning sponges. Its fruit slightly resembles a cucumber or zucchini with ridges. It ranges from cen ...
and Oecophylla smaragdina
''Oecophylla smaragdina'' ( common names include Asian weaver ant, weaver ant, green ant, green tree ant, semut rangrang, semut kerangga, and orange gaster) is a species of arboreal ant found in tropical Asia and Australia. These ants form colon ...
ants
File:பீர்க்கு இலை, சென்னை,ஜூன் 2020.jpg, Luffa leaf
File:Natural loofah luffa sponges on an organic farm in Israel.jpg , A bag of dried mature luffa fruits.
File:Luffa aegyptiaca MHNT.BOT.2011.3.94.jpg , ''Luffa aegyptiaca'', fruit and seeds - MHNT
File:Luffa operculata MHNT.BOT.2011.3.93.jpg , ''Luffa operculata'', fruit - MHNT
File:Luffa sponge.png , A luffa sponge whose coarse texture helps with skin polishing
File:Spongegourd.jpg , ''Luffa aegyptiaca
''Luffa aegyptiaca'', the sponge gourd, Egyptian cucumber or Vietnamese luffa, is an annual species of vine cultivated for its fruit, native to South and Southeast Asia.
Description
The three-lobed leaves are wide.
The fruit, approximately ...
'' sponge section magnified 100 times
File:Luffa acutangula seeds.jpg , ''Luffa acutangula'' seeds. Each division of the ruler is 1 mm. Seeds of ''Luffa aegyptica'' look very similar.
File:Pollens of Luffa.jpg, Pollen grains of Luffa
File:Lufa flowers.jpg, Luffa flowers
File:Sponges made of sponge gourd.jpg, Sponges made of sponge gourd
References
External links
Multilingual taxonomic informationfrom the University of Melbourne
{{Taxonbar, from=Q232909
Cucurbitaceae genera
Cucurbitoideae
Fruit vegetables
Taxa named by Philip Miller