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Silk consists of two types of proteins, silk fibroin and sericin. Sericin contributes about 20-30 per cent of total cocoon weight. It is characterized by its high content of serine and 18 amino acids, including essential amino acids. There are different methods of isolation of sericin from silk thread. Solubility, molecular weight, and gelling properties of sericin depend on the method of isolation. It has wide applications in pharmaceuticals and cosmetics such as, wound healing, bioadhesive moisturizing, antiwrinkle and antiaging.
Journal of Scientific & Industrial Research
Vol. 63, April 2004, pp 323-329
Silk sericin and its applications: A review
M N Padamwar and A P Pawar*
Department of Pharmaceutics, Bharati Vidyapeeth Deemed University, Poona College of Pharmacy, Erandwane,
Pune 411 038
Silk consists of two types of proteins, silk fibroin and sericin. Sericin contributes about 20-30 per cent of total cocoon
weight. It is characterized by its high content of serine and 18 amino acids, including essential amino acids. There are
different methods of isolation of sericin from silk thread. Solubility, molecular weight, and gelling properties of sericin
depend on the method of isolation. It has wide applications in pharmaceuticals and cosmetics such as, wound healing,
bioadhesive moisturizing, antiwrinkle and antiaging.
Keywords: Silk, Silk proteins, Sericin, Isolation
IPC: Int. Cl.7: D 01 B 7/00, D 01 C 3/02, A 61 P
Sericulture in India
Silk has been a scientific curiosity for centuries
and a new insight about these polymers are surfacing
with improved analytical methods and the tools of
molecular biology. Silk includes a broad range of
primarily protein-based high molecular weight
polymers often associated with insects, silkworm, and
orb weaving spiders1. Sericulture, in India, is
essentially a cottage industry. The post rearing
operations are fairly cost-effective and silkworm
rearing is still only considered as a side activity to the
main farm activity. India is the second largest
producer of silk in the world and has the distinction
of producing all the four varieties of silk. Presently,
India produces nearly 16,700 mt silk/y and reeled silk
prices are in the range of Rs 900-1300/kg, the pierced
cocoons and wastesilk generated at the rearing are
sold at Rs 80-100/kg. This waste contributes nearly
30 per cent of total cocoon production2,3. Wastesilk
can be classified as waste from the cocoon, rearing
waste, and thread waste. Silk wastes can be used as
coarse yarn and spun silk, which can be incorporated
in natural rubber to achieve the physicochemical
properties4. It is also possible to utilize the silk waste
by extracting fibroin and sericin from silk polymer,
which helps to make sericulture a viable agro
Structure of Silk
Silk is a continuous strand of two-filaments
cemented together forming the cocoon of silkworm,
Bombyx mori. Silk filament is a double strand of
fibroin, which is held together by a gummy substance
called silk sericin or silk gum. Silk fibroin is the
protein that forms the filament of silkworm and gives
its unique physical and chemical properties4,5. Silk
adapts various secondary structures, including α-
helix, β-sheet, and crossed β-sheet6.
Fibroin is a glycoprotein composed of two
equimolar protein subunits of 370 and 25 kDa
covalently linked by disulphide bonds. Fibroin
filament is made of both crystalline and amorphous
domains. The amorphous domains are characterized
by the presence of amino acids with bulkier side
chains, whereas the crystalline domains are
characterized by high percentage of alanine, glycine,
and serine (12, 30, 44 per cent, respectively), which
contains short side chains to permit the close packing
densities for overlying sheets7. The β-sheet form (silk
II or β-silk) and crystalline form (silk I) have been
reported for silk fibroin, having relative molecular
masses of 350 – 415K (refs 3,8).
Anti-parallel β-sheet structure forming microfibrils
is responsible for the crystalline nature of the silk
fibre. The microfibrils are organized into fibril
bundles, with several bundles leading finally to a
single silk thread7.
*Ph. No: 91-20-5437237
Fax No: 91-20-5439383
Sericin is a second type of silk protein, which
contains 18 amino acids including essential amino
acids and is characterized by the presence of 32 per
cent of serine. The total amount of hydroxy amino
acids in sericin is 45.8 per cent. There are 42.3 per
cent of polar amino acid and 12.2 per cent of
nonpolar amino acid residues. Sericin contributes
about 20-30 per cent of total cocoon weight. Their
main role is to envelop the fibroin. In presence of
sericin the fibres are hard and tough and become soft
and lustrous after its removal. Sericin occurs mainly
in an amorphous random coil and to a lesser extent, in
a β-sheet organized structure. The randomly coiled
structure easily changes to β-sheet structure, as a
consequence of repeated moisture absorption and
mechanical stretching7,9.
Forms of Silk Sericin
Sericin can be classified into three fractions,
depending on their solubility as sericin A, sericin B,
and sericin C. Sericin A is the outermost layer and
insoluble in hot water. It contains about 17.2 per cent
of nitrogen and amino acids like, serine, threonine,
glycine, and aspartic acid. Sericin B is the middle
layer and on acid hydrolysis it yields amino acid of
sericin A, in addition to tryptophan. It contains 16.8
per cent of nitrogen. Sericin C is the innermost layer,
which is adjacent to fibroin and is insoluble in hot
water and can be removed from fibroin by treatment
with hot dilute acid or alkali. On acid hydrolysis it
yields proline in addition to amino acids of sericin B.
It also contains sulphur and 16.6 per cent of nitrogen
9,10. Sericin has been divided into various species
based on relative solubilities. Various fractions of
sericin are also designated by other researchers
depending on their dissolution behaviour as sericin A
and B, or sericin I, II, III, and IV, or S1, S2, S3, S4,
and S5, and as α, β, and γ modification6,7. The major
molecular conformation of easily soluble sericin is
random coil, whereas the β-sheet structure is more
difficult to dissolve. The repeated moisture
absorption makes molecular aggregation structure
denser and forms more crystalline structure, which is
having reduced solubility.
The γ-ray study shows the three layers in the
sericin structure. The outer layer contained some fibre
direction filaments, middle layer exhibits cross-fibre
direction filaments, and the inner layer shows
longitudinal filaments11. The structure of sericin also
depends on the casting temperature. Lower the
casting temperature more the sericin molecules
assume β-sheet structure rather than random coil12,13.
Properties of Silk Sericin
Gelling Property
Sericin contains random coil and β-sheet structure.
Random coil structure is soluble in hot water and as
the temperature lowers the random coil structure
converts to β-sheet structure, which results in gel
formation14, 15.
Sol-Gel Transition
Sericin has sol-gel property as it easily dissolves
into water at 50-60oC and again returns to gel on
Isoelectric pH
As there are more acidic than basic amino acid
residues the isoelectric point of sericin is about 4.0
(ref. 7).
Solubility of Sericin
Solubility of sericin in water decreases when the
sericin molecules are transformed from random coil
into the β sheet structure. The solubility of sericin
increases by addition of poly (Na acrylate) and
decreases by the addition of polyacrylamide,
formaldehyde, or resin finishing agents17-19.
Molecular Weight
Extracting sericin using 1 per cent sodium
deoxycholate solution followed by precipitation,
using equal volume of 10 per cent trichloroacetic
acid, shows molecular weight in the range of 17100 to
18460 (ref. 20).
Extraction of sericin by hot water shows molecular
weight of 24000 by gel electrophoresis, whereas
spray-drying method produced sericin of molecular
weight 5000-50,000, with enzyme action 300-10,000
and 50,000 when it is extracted with aqueous urea at
100ºC (ref. 21).
Isolation of Silk Sericin
Isolation with Aid of Heat
The removal of gum from crude silk is based
entirely upon its solubility in hot water. The number
of methods illustrated by researchers for removing
gum are as follows:
The removal of gum by dilute solution of
sodium carbonate.
Hot water extraction of raw silk, followed by
evaporation to obtain powder.
Boiling of the crude silk in water and renewing
the water until the extract no longer gives a
precipitate with gallic acid.
Three successive 1 h extractions of silk or
simply heating in water at 100ºC or autoclaving
at 118°C or autoclaving for 3 h under 2.5-3
atmosphere pressure.
Sericin with average molecular weight of 50,000
extracted with aqueous solution of urea at 100ºC
from cocoons21.
Using water at 50-60ºC for 25 d to avoid the
Silk fibres can be completely degummed in
boiling solutions of pH 11 containing 5-6 per
cent bentonite23.
In a series of experiments, it is demonstrated that
most of the sericin is removed by autoclaving for one
and half hour under pressure of 600-700 mm Hg (14
lb), whereas increasing the time of treatment to 2 h
causes no greater loss in weight of fibres. It is also
observed that the extracting sericin at low pressure
(25 cm Hg, 5 lb) shows good results.
When sericin is extracted from cocoons of Bombyx
mori by heating on water bath and autoclaving at
different temperatures the satisfactory yield is
obtained by autoclaving at 105°C for 30 min with
good gelling property and yield. Further increase in
temperature increases the yield but looses its gelling
Extraction of Silk Sericin using Enzymes
Extraction is carried out by using enzyme
alkylase25 or with 2-2.5g/L alkaline protease at 60°C
for 90 min, at pH 10 (ref. 26).
Hydrolysis with trypsin at different concentrations,
temperatures and treatment times is employed for
extraction of sericin. For 1 per cent of trypsin
solution the hydrolysis is almost complete in 10 and
32 h at 37 and 20°C, respectively. The amount of
sericin obtained by 4 h treatment with 1 and 8 per
cent of trypsin solution is 26.4 and 28.7 per cent,
Precipitation of Silk Sericin from Aqueous Solution
Several methods22 proposed for precipitations of
sericin from its aqueous solution are as follows:
Precipitation of sericin with lead acetate from
aqueous solution, which is decomposed by
hydrogen sulphide and the protein is separated
by alcohol.
Evaporation of sericin solution and dissolution
of obtained residue in alkali followed by
precipitation by alcohol.
Precipitation of sericin from aqueous extract by
acetic acid and then treating the precipitate with
alcohol and ether.
According to Shelton and Johnson22 the method
of recovery by evaporation to dryness is least
satisfactory. Protein molecule on continuous
boiling of the aqueous solution in an open kettle
loses its capacity to form gel. A method in
which hot concentrated sericin solution is
poured directly from the autoclave into 7 to 8
vol of 95 per cent alcohol is found to be
satisfactory. The clear supernatant liquor is
separated from the precipitate and the
precipitate is washed with 95 per cent alcohol.
The obtained cake is dried slowly over calcium
chloride in a desiccator to get white and easily
pulverized powder.
Salting out of sericin solution by addition of
15 g solid ammonium sulphate to each 100 mL
of solution results in gelatinous precipitate,
which does not support bacterial growth.
Hamaoka et al.28 have extracted silk with
hexane to remove oils and fats and by heating in
water at 120°C for 30 min. After freeze thawing
the sericin deposited in thawing is washed with
hydrophilic organic solvent and the powdered
sericin is recovered.
Applications of Silk Sericin
Silk sericin due to its proteinous nature is
susceptible to the action of proteolytic enzymes
present in body and hence it is digestible. This
property makes it a biocompatible and biodegradable
material. Because of some additional properties like,
gelling ability, moisture retention capacity, and skin
adhesion. it has wide applications in medical,
pharmaceutical, and cosmetics.
Medical and Pharmaceutical Applications
Sericin is soluble in hot water and as the time
precedes it converts into gel. Jun et al.29 have found
that conversion of α-random coil to β-sheet structure
gives gel. One per cent aqueous sericin solution
produces gel at pH 6-7 at room temperature and
gelation speed increases as the concentration of
sericin increases30-32. The aqueous sericin solution
containing 1.5 and 2 per cent w/w of sericin obtained
by autoclaving at 105°C for 30 min does not show
good gelling. Sericin gel in the presence of glycerin,
propylene glycol, and tween-80 shows synerisis,
whereas sericin with pluronic and carbopol gives
stable gels. In the presence of pluronic sericin gel it
shows concentration dependance24. Kewon et al.33
have shown the effect of concentration of pluronic
and temperature on the gel property of sericin. The
gelling of sericin is accelerated with increase in
temperature and with increase in poloxamer
concentration, whereas the sol-gel transition of
sericin becomes irreversible. Blends of polyvinyl
alcohol and sericin are cross-linked to give hydrogels.
Hydrogels with good mechanical strength and water
resistance are produced by casting aqueous solution
containing sericin and dimethyl urea on a glass plate
and heating at 80 and 120°C for 1 and 3 h,
Sericin gives a very stable emulsion when shaken
with water immiscible liquid22,35. The sericin protein
is also used as horizontal alignment film for the liquid
crystal to achieve uniform optical properties and to
increase the stability of product36.
Fibroin and sericin, when sulphonated show anti-
thrombotic effect37. One stage condensation of
salicylic acid, formaldehyde, and sericin creates a co-
polymer with a molecular mass of 6000-8000 Da. A
concentration of 0.01-1 mg/mL in blood exhibits anti-
coagulant, fibrinolytic, and anti-aggregation activity
towards thrombocytes at 0.5 mg/mL (ref. 38). Sericin
with molecular weight of 1,00,000 shows an
inhibitory action for tyrosinase and lipid per
oxidation with rat brain homogenates39,40. The
addition of 0.1-2 mg/mL of sericin into the aqueous
solution shows heat resistant DNA polymerase
activity41. Sericin has been found to possess wound-
healing property and can be used as wound healing
covering material in the form of film42. Sericin also
has adhesive property due to its chemical
composition. It has affinity to keratin7. Silk threads
obtained from mulberry silkworm can be used for
making surgical sutures43. Silk sericin membranes are
good bandage materials and the film has adequate
flexibility and tensile strength. Due to its good
biocompatibility and infection resistant nature, it is a
novel wound coagulant material. Additionally, its
flexibility and water absorption properties promote
smooth cure for defects in the skin and do not cause
any peeling of the skin under regeneration when
detached from the skin44.
Kurioka45 has explained silk sericin as a
biomaterial. The silk sericin has the potential to find
application in the development of contact lenses. The
graft polymers are prepared with methyl methacrylate
or styrene and are also biocompatible46,47.
Intake of sericin containing food relives
constipation, suppresses development of bowel
cancer and accelerates the absorption of minerals. In
rats, consumption of sericin elevates the apparent
absorption of zinc, iron, magnesium, and calcium by
41, 41, 21, and 17 per cent, respectively48. A dietary
supplementation of 4 per cent of sericin suppresses
induced constipation in rats because of its low
digestibility along with water holding capacity49.
Sericin, when given orally, causes a dose dependent
decrease in the development of colonic aberrant crypt
foci. The incidence and the number of colon tumours
are suppressed by consumption of sericin. Sericin
have anti-tumor activity50-52.
Oxygen permeable membranes are made up of
fibroin and sericin with 10-16 per cent water and are
used for contact lenses, and as artificial skin53. Agar
and/or compounds containing agarose and sericin are
mixed with water to form sheet shaped gels and
which when dried at 0-40°C under load of 0.01-2
kg/cm2 give the polymer membranes54.
Cosmetic Applications
In addition to above-mentioned medical and
pharmaceutical uses of sericin, it has been used as
component of cosmetics. Sericin alone or in
combination with silk fibroin has been used in skin,
hair, and nail cosmetics. Sericin when used in the
form of lotion, cream and ointment shows increased
skin elasticity, antiwrinkle, and antiaging effects7,55-57.
Padamwar et al.58 have shown the moisturizing
property of the sericin gel, evaluated by
hydroxyproline assay, impedance measurement,
trance epidermal water loss (TEWL), and scanning
electron microscopy (SEM). Sericin gels increase the
hydroxyproline content in stratum corneum and
decrease skin impedance, which reveals moisturizing
property of sericin. Sericin gels with pluronic and
carbopol, act as moisturizer by repairing natural
moisturizing factor (NMF) as well as prevent TEWL
by preventing water loss from the skin. SEM has
shown the decrease cracking and flaking as compare
to dry skin and normal skin replicas.
Powder containing 5-30 per cent sericin with
average molecular weight 7,000-3,00,000 and 70-95
per cent silk fibroin when applied as film shows
antistaticity and moisture absorbability59. Sericin
hydrolysate solution shows that dermatitis is
controlled60. Sweat and sebum absorbing type of
cosmetics containing cellulose fibres impregnated
with fibroin dispersion and aqueous sericin solution
are also reported61. Lotion containing 1 per cent w/w
sericin and 4 per cent w/w D-glucose shows
moisturizing and conditioning effect62. Creams
containing 0.001-30 per cent w/w of sericin have
improved cleansing properties with less skin
irritation63. Sericin powder in the form of sericin
hydrolysate coated talc, mica, titania, iron oxide, and
nylon have been used to formulate foundation cream
and eyeliners64. The microcapsules or nanocapsules
consisting of polysiloxane gel, UV absorbent core
and UV scattering agent, silicone treated mica, silicon
treated titanium dioxide, silicon treated iron oxides,
squalene, glycerin trioctanoate, and talc have resulted
in cosmetic foundation having a SPF value of 25.7.
Sericin in sunscreen composition enhances the light
screening effect of UV filter like triazines, and
cinnamic acids ester65.
Nail cosmetics, containing 0.02-20 per cent sericin
are reported to prevent nail from chapping,
brittleness, and imparting the inherent gross to nails66.
Hair and bath preparations, containing 0.02-2 per cent
sericin and 0.01-1 per cent olive oil, fatty acid or their
salts show reducing damage of hair surface by
binding of sericin to hairs67. Sericin hydrolysates with
average molecular weight 300-3000 are used as
conditioners for skin and hair68. Shampoo containing
sericin and pelarogenic acid of pH less than six are
useful for the care and cleaning of hairs69.
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... The use of SER has grown rapidly in the cosmetics industry. It inhibits the water loss from the skin's epidermal layer, which confers a smoother surface to the skin [236]. Many skin lotions have been widely utilized to overcome the skin dryness caused by excessive transepidermal water loss. ...
... It has been reported that SER offers a synergic effect for mineral ingestion in the intestine, e.g. magnesium, zinc, iron, and calcium [199,235,236]. Another property of SER has been discussed, highlighting the emulsifying impact when SER is used as a salad dressing by observing the emulsion stabilization for two days [249]. ...
Silks are natural polymers that have been widely used for centuries. Silk consists of a filament core protein, termed fibroin, and a glue-like coating substance formed of sericin (SER) proteins. This protein is extracted from the silkworm cocoons (particularly Bombyx mori) and is mainly composed of amino acids like glycine, serine, aspartic acid, and threonine. Silk SER can be obtained using numerous methods, including enzymatic extraction, high-temperature, autoclaving, ethanol precipitation, cross-linking, and utilizing acidic, alkali, or neutral aqueous solutions. Given the versatility and outstanding properties of SER, it is widely fabricated to produce sponges, films, and hydrogels for further use in diverse biomedical applications. Hence, many authors reported that SER benefits cell proliferation, tissue engineering, and skin tissue restoration thanks to its moisturizing features, antioxidant and anti-inflammatory properties, and mitogenic effect on mammalian cells. Remarkably, SER is used in drug delivery depending on its chemical reactivity and pH-responsiveness. These unique features of SER enhance the bioactivity of drugs, facilitating the fabrication of biomedical materials at nano- and microscales, hydrogels, and conjugated molecules. This review thoroughly outlines the extraction techniques, biological properties, and respective biomedical applications of SER.
... The silk fibre has fibrous core protein fibroin, and this core protein is coated with glue-like protein sericin [16]. Sericin is an amorphous, globular, and hydrophilic polymer, which consists of 18 different amino acids [17]. These amino acids have made by a bulkier strong polar group, such as carboxyl, hydroxyl, and amino groups [17]. ...
... Sericin is an amorphous, globular, and hydrophilic polymer, which consists of 18 different amino acids [17]. These amino acids have made by a bulkier strong polar group, such as carboxyl, hydroxyl, and amino groups [17]. The silk industry produces sericin as a by-product and produced after the process of silk degumming [18]. ...
... The silk fibre has fibrous core protein fibroin, and this core protein is coated with glue-like protein sericin [16]. Sericin is an amorphous, globular, and hydrophilic polymer, which consists of 18 different amino acids [17]. These amino acids have made by a bulkier strong polar group, such as carboxyl, hydroxyl, and amino groups [17]. ...
... Sericin is an amorphous, globular, and hydrophilic polymer, which consists of 18 different amino acids [17]. These amino acids have made by a bulkier strong polar group, such as carboxyl, hydroxyl, and amino groups [17]. The ...
... Silk consists of two non-sticky, sericin-coated and glued fibers that surround the cocoon of the silkworm. Silk contains two types of proteins, fibroin and sericin [1,2]. The content of sericin in raw silk fiber is 20-30%. ...
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Sericin protein was extracted from silk using a water-based method. The impact of sericin on the aquatic environment and its behavior under various temperature conditions were thoroughly investigated. To assess the total protein content in the solutions derived from silk at different temperatures, the Lowry method was employed. Subsequently, sericin protein was isolated in its pure form. In order to gain deeper insights into the characteristics of sericin, both IR-spectrometric and UV-spectrometric analyses were conducted. These analyses provided valuable information about the molecular structure and properties of the sericin protein. Additionally, the study focused on determining the composition of amino acids present in the sericin protein. For this purpose, high-performance liquid chromatography (HPLC) was employed, allowing for precise quantification and identification of individual amino acids within the protein. Through these comprehensive analytical techniques and experiments, researchers aimed to unravel the properties, behavior, and potential applications of sericin protein, contributing to a better understanding of its role and impact in various environmental and temperature conditions.
... 22 Sericin has different properties such as UV light protection, antioxidant, anticancer, and antibacterial. 23,24 Silk sericin has good biocompatibility, hydrophilicity, excellent affinity for biomolecules, and biodegradability. 25 Sericin has mitogenic and cytoprotective effects on keratinocytes and fibroblasts as well as it attracts them to the skin for tissue repair and skin development. ...
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The present study was aimed to prepare the potent silk sericin-based hydrogels in combination with plant extracts (curcumin and banana peel powder) and silver nanoparticles (AgNPs) to accelerate the acute wound healing process. Experimental excision wounds were created in mice by biopsy puncture, and the wound healing potential of silk sericin (2%)-based hydrogel and its combinations with curcumin (2%), banana peel powder (2%), and AgNPs (2%) was estimated by calculating the percent wound contraction, healing time, histology of skin tissues, and different biochemical tests. The results showed that the mice treated with sericin-based hydrogels showed significantly (P < 0.001) high percent wound contraction as compared to negative control, and wounds were healed in 11 days. The histological evaluation also showed that wounds covered with hydrogels were healed more than the uncovered wounds. Furthermore, the results of biochemical tests revealed that the treatment groups showed a significant (P < 0.001) decrease in the serum level of pro-inflammatory cytokines (IL-6). A significant (P < 0.001) increase in anti-inflammatory cytokines (IL-10) and anti-oxidant enzymes was observed in treatment groups. The highest wound healing potential was observed by sericin-based hydrogel containing banana peel powder, leaving behind the commercially available ointment polyfax (positive control). It can be concluded that the silk sericin-based hydrogels in combination with plant extract and AgNPs can be used as natural biomaterials in wound dressing for the rapid healing of acute wounds.
... Noteworthy silk sericin protein is especially hydrophilic component of silk with molecular weight ranging from 20 to 400 kDa and incorporates 18 different amino acids with predominantly polar amino acid inclusive of threonine (6%), glutamic acid (5 %), serine (25 %) and aspartic acid (17 %) (Aramwit et al., 2009;Gimenes et al., 2014;Padamwar and Pawar, 2004;Wu et al., 2007). Polar groups (amino, hydroxyl and carboxyl) of the side chains of amino acids, their structural organization, organic composition and solubility make viable co-polymerization, crosslinking and combinations of sericin with other polymers. ...
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Sericulture is a labour-intensive, welfare-oriented and rural cottage industry being capable to engage amateurish family manpower for income generation via indoor activities. It has potential to provide a livelihood for the poor rural families and can play a crucial role to uplift the economy of our country. Unfortunately, this industry has not been on the list of priorities of our Government. Currently, Pakistan is importing silk from other countries to meet the demand of local market. Nutritional background of larval stage (1st, 2nd and 3rd instars etc.) significantly influences the status of the resulting larva, pupae, adult and fiber. For this purpose, sericulture productivity has been impressively modulated by fertilizing the silkworm’s diet with natural food supplements or exogenous nutrients like Amway protein, honey, bovine milk, sericin, probiotics (Bacillus cereus, B. subtilis, B. amyloliquefaciens, B. licheniformis, Lactobacillus casei, Saccharomyces cerevisiae and Spirulina), vitamins (C and E), royal jelly, ascorbic acid, cowpea seed powder, AgNPs, secondary metabolites (phenols flavonoids, phenolic amino acids and proline) and white hen’s egg at different larval instars. Economic parameters (pupal weight, shell ratio (%), cocoon weight, filament length, shell weight, denier, fibroin and sericin contents) and biological traits (fresh weight of each larva, silk gland, pupa and moth) of silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) have been enhanced with natural food supplements. The current review highlights details about the overview of sericulture, constrains of sericulture industry being faced by local farmers in Pakistan and impact of natural food supplements on silkworms growth and cocoon yield.
This review deals with the structural and functional properties of sericin and its application in the food industry to enhance the food preservation. Sericin is a globular protein that contains silk fibre from the bombyx mori silkworm case. It has 18 amino acids. The proteins had been utilized in space travel food. Sericin is hydrophilic in nature and shows a physiological impact on the gastrointestinal system. Sericin contains different microbiology properties which allow us to apply it to different fields. Sericin can be attributed to three structures such as sericin A, sericin B, and sericin C. Comparison of extraction methods, extraction with steam using autoclave method is more sustainable. Sericin joins with properties such a gelling property, sol-gel change, isoelectric pH, dissolvability of sericin, and sun–nuclear weight. Sericin inhibits the growth of microorganisms such as S.aureus as gram-positive microorganisms and E.coli as gram-negative microorganisms. It provides a major antioxidant property by inhibiting tyrosinase enzymes. Sericin is an intriguing contender to impede the browning impact in food items without the expansion of manufactured cell antioxidant compounds. Food products prepared with sericin helps in diabetics and keeping up with the diet. The utilization of edible coating or films using sericin not only imparts antibrowning, antimicrobial, and antioxidant properties but also improves the nutritional properties of the food product. Though the production rate of sericin is high in India, a very few attempts have been made to utilize sericin in food applications. Hence utilizing sericin in food applications provide several advantages and improves its scope in food industry.
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The removal and use of sericin could have a strong economic, social, and environmental impact, particularly in countries where sericulture is practiced, especially in Bangladesh. Because in our country Bangladesh, sericin is a waste material in the sericulture industry. Several techniques have been adopted for sericin extraction, but maintaining its chemical properties after extraction and environment-friendly extraction methods are still a major challenge. Sericin is fully or partially hydrolyzed and solubilized during the degumming of the cocoon. Consequently, it is important to create sericin extraction procedures that require less energy, don't release any chemicals, and don't harm the environment. Numerous research has been done to extract sericin but the differences in sericin content and chemical properties of Bivoltine and Multivoltine silkworm cocoon have not been studied yet. In this work, sericin was extracted from the silkworm cocoon of four different silkworm races at two different temperatures and durations. Significant differences were observed in yield% with different silkworm races and different treatments. Extracted sericin was characterized through SDS PAGE, FTIR & UV spectroscopy, and TGA.
A wound dressing material comprises an amorphous film having a crystallinity of less than 10% and containing fibroin and sericin as the main components.
The structure of sericin is related to the stripping resistance of cocoon filaments. When it was strong, the thermal absorption peak of DSC curve for sericin appeared at higher temperature region, indicating that both beta-structure and random coil structure were present in sericin. On the other hand, when the stripping resistance was weark, sericin had only the random coil structure. The adhesive strength of sericin closely depended on the phase of sericin, being strong when the sericin molecule in solution transformed from the random coil to the beta-structure.
This review covers literature dealing with the regeneration of silk polymer from silk fibre. The silk fibre used is that could not be used in the production of continuous thread, and waste collected during processing. The subjects covered include the classification of waste silk, separation of the polymer from the waste, properties of silk fibroil powder, the formation and properties of thin films and applications in fibres, films and membranes.
Gelation time decreased with rising temperature and increasing sericin concentration. - Chemical Abstracts, 111(4), 1989, abstract 24823
The molecular basis of sol-gel transformation of sericin extracted from cocoons with hot water was investigated by analyzing circular dichroism, infrared spectrum and X-ray analyses of sericin gels during the transformation. Results showed that sericin gel was reversible; it easily dissolved into sol at high temperatures and again returned to gel by cooling. This property was in contrast to the that of fibroin gel which was irreversible and did not become sol by heating. These difference between fibroin and sericin gels may mirror their structural divergence, which may be ascribed to their difference in β-structure, contents of polar amino acids (Ser, Thr, Asp) and mobility of moleules. © 1996, The Japanese Society of Sericultural Science. All rights reserved.
Silk consist of two types of proteins, silk fibroin and silk sericin. Fibroin contributes about 70-80% of total cocoon weight where as sericin contributes about 20-30% of total cocoon weight. About 50% of silk waste is generated during silk processing which has proved to be wide application in pharmaceutical and cosmetics applications including its textile application. Sericin is characterized by it's high content of serine (32%). Sericin can be removed by different methods. It has adhesive and gelling in between pH 6-7 make it suitable for preparation of mouth ulcer gel. FT-IR peaks at 1653 cm -1 and 1541 cm-1 for amide I and amide II respectively confirms the α-random coil of sericin and shifting of degradation peak in DSC thermogram confirms insolubility of brown coloured sericin. The sericin gels were prepared using pluronic was found to be sericin concentration dependent, where as sericin concentration independent with carbopol. The rheological and adhesive properties- of sericin are suitable for preparation of sericin gels containing Choline salicylate.
Rats were examined for the effect of consumption of silk protein, sericin on the intestinal absorption of Zn, Fe, Mg and Ca. Male Wistar rats were fed on the diet containing either 23% egg albumin or 20% egg albumin plus 3% sericin for 12 d. Consumption of sericin elevated the apparent absorption of Zn, Fe, Mg and Ca (41%, 41%, 21% and 17%, respectively), but did not affect serum concentrations of these elements. Urinary excretion of the elements was unaffected by dietary sericin. The results suggest that consumption of sericin enhances bioavailability of Zn, Fe, Mg and Ca in rats.
THE silk thread extruded by the lava of the silk moth of commerce (Bombyx mori) consists of two parts: a central core of two filaments of the protein fibre `fibroin', surrounded and cemented together by a layer of protein material called `sericin'.