Luffa | |
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Egyptian luffa with nearly mature fruit | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Order: | Cucurbitales |
Family: | Cucurbitaceae |
Subfamily: | Cucurbitoideae |
Tribe: | Sicyoeae |
Genus: | Luffa Mill. [1] |
Species [2] | |
| |
Synonyms [2] | |
Luffa is a genus of tropical and subtropical vines in the pumpkin, squash and gourd family (Cucurbitaceae).
In everyday non-technical usage, the luffa, also spelled loofah [3] or less frequently loofa, [4] usually refers to the fruits of the species Luffa aegyptiaca and Luffa acutangula . 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, China, Nepal, Bhutan, Bangladesh and Vietnam. [5] When the fruit fully ripens, it becomes too fibrous for eating. The fully developed fruit is the source of the loofah scrubbing sponge.
The name luffa was taken by European botanists in the 17th century from the Arabic name لوفlūf. [1]
In North America it is sometimes known as "Chinese okra", [6] and in Spanish as estropajo. [7]
The fruit section of L. aegyptiaca may be allowed to mature and used as a bath or kitchen sponge after being processed to remove everything except the network of xylem 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. [8]
Luffa is a popular food item. There are various ways to prepare it including in soups or stir frys.
In Hindi-speaking North India states, it is called torai (तोरई), and cooked as vegetable. In eastern-UP it is also called nenua while in central/Western India, specially in Madhya Pradesh, it is called gilki (गिल्की). Torai is reserved for ridge gourd and is less popular than gilki in central western India.
In Punjabi-speaking Punjab, sponge gourd is called tori (ਤੋਰੀ), while ridged gourd is called ram tori (ਰਾਮ ਤੋਰੀ) and the fruit and flowers are mostly used in dishes.
In Bhojpuri speaking regions, it is called ghiura (घिउरा). Apart from the fruit of the vegetable, flowers are also used as a vegetable as chokha, tarua, pakoda, etc.
In Nepal and Nepali language speaking Indian states, sponge /smooth gourd is called ghiraula (घिरौंला), while the ridged variety is called pate ghiraula (पाटे घिरौंला). Both are popular vegetables usually cooked with tomatoes, potatoes and served with rice.
In Gujarat, ridge gourd and sponge gourd are known as turya (તુરીયા) and galka (ગલકા) in Gujarati respectively. Ridge gourd is called ghissori or ghissora (ઘિસ્સોરી/ઘિસ્સોરા) in Kutchi. They are simple yet popular vegetables, 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-speaking Bangladesh and the Indian state of West Bengal, ridge gourd is called jhinge (ঝিঙ্গে), while sponge gourd is known as dhundhul (ধুঁধুল), both being popular vegetables. They are eaten, fried or cooked with shrimp, fish, or meat.
In the Odia language of Odisha, ridge gourd (luffa acutangula) is known as janhi (ଜହ୍ନି), while sponge gourd (luffa aegyptiaca) is called tarada(ତରଡ଼ା), both accompanying many vegetarian and non-vegetarian dishes, most notably in dishes like "khira santula", where it is boiled with minuscule spices and simmered in milk. Another popular version involves mashing it in groundnut oil, herbs, peanuts and topping it with the peeled skin pieces.
In Assamese speaking areas of Assam, it is called bhula (ভোল, luffa aegyptiaca) and is cooked with sour fish curry along with taro . A related species is called jika (জিকা, Luffa acutangula), which is used as a vegetable in a curry, chutney and stir fry . [9]
In Tamil language of Tamil Nadu, 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 , [10] poriyal , and thogayal . [11] Even the skin is used to make chutney.
In Karnataka's Kannada speaking areas, sponge gourd is better known as tuppa dahirekayi (ಟುಪ್ಪಾದ ಹೀರೆಕಾಯಿ), literally translating to "buttersquash" in English, while ridge gourd is known as hirekayi (ಹೀರೆಕಾಯಿ) in standard Kannada. Naturally growing in this region, it's 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, ridge gourd is known as Peere(ಪೀರೆ) and is used to prepare chutney and ajethna. [12]
In both Telangana and Andhra Pradesh Telugu dialects, ridge gourd is generally called beerakaya (బీరకాయ), while sponge gourd is called nethi beerakaya (సేతి బీరకాయ). It is used in making Dal, Fry, Roti Pacchadi, and wet curry.
In Malayalam language of Kerala, ridge gourd is commonly called peechinga (പീച്ചിങ്ങ) and poththanga in the Palakkad dialect, while sponge gourd is called Eeṇilla peechinga (ഏണില്ല പീച്ചിങ്ങ). It is also used as a vegetable, cooked with dal or stir fried. The fully matured fruit is used as a natural scrub in rural Kerala. In some places such as Wayanad, it grows as a creeper on fences.
In Marathi-speaking Maharashtra, its called dodka (दोडका, ridge gourd luffa) and ghosaļ (घोसाळ ,smooth/sponge luffa) which are common vegetables, prepared with either crushed dried peanuts or with beans.
In Meitei language of Manipur, ridge gourd is called sebot (ꯁꯦꯕꯣꯠ) and sponge gourd is called sebot hekpa (ꯁꯦꯕꯣꯠ ꯍꯦꯀꯞ), which is cooked with other ingredients like potato, dried fish, fermented fish and served. They are also steamed before consuming or crushed (ironba) with other ingredients and served with steamed rice (chaak). Fried ones (kaanghou) are also favorites for many. Sebot is also eaten as a green vegetable.
In Sri Lanka, it's called වැටකොළු (Waeṭakola, the Luffa acutangula variety) in Sinhalese and is a common ingredient in curries, even in dried forms.
In Vietnamese cuisine, the gourd is called "mướp hương" and is a common ingredient in soups and stir-fried dishes.
In China and Taiwan (where it is called simplified Chinese :丝瓜; traditional Chinese :絲瓜; pinyin :sīguā, or in English, "silk melon"), Indonesia (where it is called oyong), and the Philippines (where it is called patola in Tagalog and kabatiti in Ilokano), in Timor-Leste it is also called "patola" or "batola" in Tetum and in Manipur, India, (where it is called sebot) the luffa is eaten as a green vegetable in various dishes.[ which? ]
In Japan it is called hechima (へちま) and is cultivated all over the country during summer. It is commonly used as a green vegetable in traditional dishes of the Ryukyu Islands (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.
Luffa is also known as "Chinese okra" in Canada and the U.S.
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, many people grow it outside building windows as a natural sunscreen in summer.[ citation needed ]
Luffa species are used as food plants by the larvae of some Lepidoptera species, including Hypercompe albicornis and Zeugodacus tau . [13]
The luffa sponge is a biological cellular material. These materials often exhibit exceptional mechanical properties at low densities. While their mechanical performance tends to fall behind manmade materials, such as alloys, ceramics, plastics, and composites, as a structural material, they have long term sustainability for the natural environment. When compressed longitudinally, a luffa sponge is able to absorb comparable energy per unit mass as aluminum foam. [14] Luffa sponges are composed of a complex network of fiber bundles connected to form a 3-dimensional, highly-porous network. [15]
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. [15]
Uniaxial tensile tests of fiber bundles isolated from the inner surface provide insight this basic strut element of the luffa sponges. These fiber bundles vary in diameter from 0.3 to 0.5 mm. [15] Each fiber bundle has a low density core region not occupied by fibers. [16] The stress-strain response of the fiber bundles is nearly linear elastic all the way until fracture, suggesting the absence of work hardening. The slope of the linear region of the stress-strain curve, or Young’s modulus, is 236* MPa. The highest stress achieved before fracture, or ultimate tensile strength, 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 of 2.07– 4.05 MPa⋅m3/kg, and their overall properties are improved when a high ratio of their cross sectional area is occupied by fibers, they are evenly distributed, and there is strong adhesion between fibers. [15] [16]
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 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 significantly impact the longitudinal properties of the luffa sponge column followed by the circumferential properties. There is no noticeable contribution to the radial properties. Additionally, the core region exhibits lower yield stress and energy absorption (as determined by the area under the stress-strain curve) compared to the hoop region due to its greater porosity. [15]
Overall, the stress-strain curves of block samples exhibit three stages of mechanical behavior common to porous materials. Namely, the samples follow linear elasticity 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. [15] The three stages can be described by the equations:
In the above equations, is the Young's modulus and the yield strength of the sponge material. These are chosen to best fit experimental data. The strain at the elastic limit, where the plateau region begins, is denoted as , while the strain at the onset of the densification region is . [17]
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. [17]
The mechanical properties of Luffa sponges change under different strain rates. Specifically, energy adsorption, compressive stress, and plateau stress (which is in the case of foam materials corresponds to the yield stress) are enhanced by increasing the strain rate. [15] [18] 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). [18]
A composite material is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or physical properties and are merged to create a material with properties unlike the individual elements. Within the finished structure, the individual elements remain separate and distinct, distinguishing composites from mixtures and solid solutions. Composite materials with more than one distinct layer are called composite laminates.
Young's modulus is a mechanical property of solid materials that measures the tensile or compressive stiffness when the force is applied lengthwise. It is the modulus of elasticity for tension or axial compression. Young's modulus is defined as the ratio of the stress applied to the object and the resulting axial strain in the linear elastic region of the material.
In engineering, deformation may be elastic or plastic. If the deformation is negligible, the object is said to be rigid.
In engineering and materials science, a stress–strain curve for a material gives the relationship between stress and strain. It is obtained by gradually applying load to a test coupon and measuring the deformation, from which the stress and strain can be determined. These curves reveal many of the properties of a material, such as the Young's modulus, the yield strength and the ultimate tensile strength.
Dynamic mechanical analysis is a technique used to study and characterize materials. It is most useful for studying the viscoelastic behavior of polymers. A sinusoidal stress is applied and the strain in the material is measured, allowing one to determine the complex modulus. The temperature of the sample or the frequency of the stress are often varied, leading to variations in the complex modulus; this approach can be used to locate the glass transition temperature of the material, as well as to identify transitions corresponding to other molecular motions.
In mechanics, compressive strength is the capacity of a material or structure to withstand loads tending to reduce size (compression). It is opposed to tensile strength which withstands loads tending to elongate, resisting tension. In the study of strength of materials, compressive strength, tensile strength, and shear strength can be analyzed independently.
A Newtonian fluid is a fluid in which the viscous stresses arising from its flow are at every point linearly correlated to the local strain rate — the rate of change of its deformation over time. Stresses are proportional to the rate of change of the fluid's velocity vector.
In materials science and metallurgy, toughness is the ability of a material to absorb energy and plastically deform without fracturing. Toughness is the strength with which the material opposes rupture. One definition of material toughness is the amount of energy per unit volume that a material can absorb before rupturing. This measure of toughness is different from that used for fracture toughness, which describes the capacity of materials to resist fracture. Toughness requires a balance of strength and ductility.
In materials science and continuum mechanics, viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Viscous materials, like water, resist both shear flow and strain linearly with time when a stress is applied. Elastic materials strain when stretched and immediately return to their original state once the stress is removed.
A Kelvin–Voigt material, also called a Voigt material, is the most simple model viscoelastic material showing typical rubbery properties. It is purely elastic on long timescales, but shows additional resistance to fast deformation. The model was developed independently by the British physicist Lord Kelvin in 1865 and by the German physicist Woldemar Voigt in 1890.
In engineering and materials science, necking is a mode of tensile deformation where relatively large amounts of strain localize disproportionately in a small region of the material. The resulting prominent decrease in local cross-sectional area provides the basis for the name "neck". Because the local strains in the neck are large, necking is often closely associated with yielding, a form of plastic deformation associated with ductile materials, often metals or polymers. Once necking has begun, the neck becomes the exclusive location of yielding in the material, as the reduced area gives the neck the largest local stress.
Dynamic modulus is the ratio of stress to strain under vibratory conditions. It is a property of viscoelastic materials.
The J-integral represents a way to calculate the strain energy release rate, or work (energy) per unit fracture surface area, in a material. The theoretical concept of J-integral was developed in 1967 by G. P. Cherepanov and independently in 1968 by James R. Rice, who showed that an energetic contour path integral was independent of the path around a crack.
In materials science the flow stress, typically denoted as Yf, is defined as the instantaneous value of stress required to continue plastically deforming a material - to keep it flowing. It is most commonly, though not exclusively, used in reference to metals. On a stress-strain curve, the flow stress can be found anywhere within the plastic regime; more explicitly, a flow stress can be found for any value of strain between and including yield point and excluding fracture : .
The standard linear solid (SLS), also known as the Zener model after Clarence Zener, is a method of modeling the behavior of a viscoelastic material using a linear combination of springs and dashpots to represent elastic and viscous components, respectively. Often, the simpler Maxwell model and the Kelvin–Voigt model are used. These models often prove insufficient, however; the Maxwell model does not describe creep or recovery, and the Kelvin–Voigt model does not describe stress relaxation. SLS is the simplest model that predicts both phenomena.
Viscoplasticity is a theory in continuum mechanics that describes the rate-dependent inelastic behavior of solids. Rate-dependence in this context means that the deformation of the material depends on the rate at which loads are applied. The inelastic behavior that is the subject of viscoplasticity is plastic deformation which means that the material undergoes unrecoverable deformations when a load level is reached. Rate-dependent plasticity is important for transient plasticity calculations. The main difference between rate-independent plastic and viscoplastic material models is that the latter exhibit not only permanent deformations after the application of loads but continue to undergo a creep flow as a function of time under the influence of the applied load.
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.
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 is native to South Asia and has been naturalised in other regions. It is also grown as a houseplant in places with colder climates. English common names include angled luffa, Chinese okra, dish cloth gourd, ridged gourd, sponge gourd, vegetable gourd, strainer vine, ribbed loofah, silky gourd, silk gourd,
A fiber-reinforced composite (FRC) is a composite building material that consists of three components:
In geotechnical engineering, rock mass plasticity is the study of the response of rocks to loads beyond the elastic limit. Historically, conventional wisdom has it that rock is brittle and fails by fracture, while plasticity is identified with ductile materials such as metals. In field-scale rock masses, structural discontinuities exist in the rock indicating that failure has taken place. Since the rock has not fallen apart, contrary to expectation of brittle behavior, clearly elasticity theory is not the last word.