Applied Microbiology and Biotechnology

, Volume 93, Issue 1, pp 17–29

Efficient use of shrimp waste: present and future trends

Authors

    • Department of Biotechnology, GITAM Institute of TechnologyGITAM University
  • Murali Mohan Challa
    • Department of Biotechnology, GITAM Institute of TechnologyGITAM University
  • Hemalatha Kalangi Padma Jyothi
    • Department of Biochemistry, College of Science & TechnologyAndhra University
Mini-Review

DOI: 10.1007/s00253-011-3651-2

Cite this article as:
Kandra, P., Challa, M.M. & Kalangi Padma Jyothi, H. Appl Microbiol Biotechnol (2012) 93: 17. doi:10.1007/s00253-011-3651-2

Abstract

The production of shrimp waste from shrimp processing industries has undergone a dramatic increase in recent years. Continued production of this biomaterial without corresponding development of utilizing technology has resulted in waste collection, disposal, and pollution problems. Currently used chemical process releases toxic chemicals such as HCl, acetic acid, and NaOH into aquatic ecosystem as byproducts which will spoil the aquatic flora and fauna. Environmental protection regulations have become stricter. Now, there is a need to treat and utilize the waste in most efficient manner. The shrimp waste contains several bioactive compounds such as chitin, pigments, amino acids, and fatty acids. These bioactive compounds have a wide range of applications including medical, therapies, cosmetics, paper, pulp and textile industries, biotechnology, and food applications. This current review article present the utilization of shrimp waste as well as an alternative technology to replace hazardous chemical method that address the future trends in total utilization of shrimp waste for recovery of bioactive compounds.

Keywords

Shrimp wasteToxic chemicalsChitinPigmentsTherapies

Introduction

Aquaculture is the world's fastest growing food-production sector in the recent years, providing an acceptable, protein rich supplement to, and substitute for, wild aquatic animals and plants. Asia plays a leading role in shrimp farming, accounting for almost 80% of world shrimp production (Fuchs et al. 1999; Rosenberry 1998). Shrimp is a high-value aquacultural product, and is processed for the meat, leaving the carapace and head as waste products (Omum 1992; Knorr 1991). Shrimp landed by large trawlers are, however, deheaded at sea or supplied to processing industries. The main unutilized source of marine protein and oils is heads of shrimp from packaging and processing industry. Heads are usually removed in peeling sheds near the landing or at packing plants. Generally, shrimp is exported in frozen form without exoskeleton. About 45–48% by weight of shrimp raw material is discarded as waste depending on species (Sachindra et al. 2005).

An inevitable increase in waste produced by the processing industry is of no use (Subasinghe 1999).The biomaterial or biowaste contains many valuable compounds that after appropriate processing can add substantially to overall profitability. This shrimp biomaterial can be valorized without fractionation. Usually, it is applied as such for feeding in veterinary practice and aquaculture. Medium- and large-scale processing has been developed to dry the waste and to mix it with other agricultural raw materials to produce animal feed. The most common technique for shrimp waste utilization is the artisan practice of sun drying. This procedure has low hygienic control and the products are limited for animal consumption. Shrimp waste is then considered in landfills, soil dumping, and discarded in sea water resulting in the major surface pollution, unpleasant smell in coastal areas, and constituting an important concern of environmental pollution. Usually, shrimp waste is dried on the beaches which encourage environmental problems (Mathew and Nair 2006).

In particular, discarding of shrimp waste is a serious environmental problem because valuable living resources are wasted. Populations of endangered species are threatened due to environmental pollution (Morgan and Chuenpagdue 2003). In any case, it is widely accepted that ecological impact is significant by discarding shrimp waste (Kelleher 2005). Coastal aquaculture is diverse in terms of the resources used; the scale and nature of the practices adopted and varied environmental characteristics. A major problem with shrimp biomaterial valorization is the high perishability of the material (Anonymous 1997). Under tropical climatic conditions, decay starts within an hour after processing and leads to the production of biogenic amines with a very offensive smell. If this decay is unavoidable or not prevented, the biomaterial turns into real waste, and due to its high protein content, it becomes a real threat to the environment and a financial burden if not discarded properly.

It is obvious for both environmental and economic reasons that, wherever possible, appropriate technology should be applied to prevent decay and to convert the biomaterial into valuable products. Technology should provide systems for the delay or prevention of decay and procedures for fractionation. Therefore, there is a significant interest regarding recycling of shrimp waste. This review focuses on present utilization and recent findings; well-known biotechnologies commonly used for the treatment of shrimp waste that address the future trends in total utilization of shrimp waste for recovery of bioactive compounds. However, before presenting the specific features of selected technologies, it is first necessary to briefly summarize the existing chemical method for degradation of shrimp waste.

Present utilization of shrimp waste

The higher protein content used in Asian diets fits with the more carnivorous feeding habits of the main shrimp species cultured. Moreover, carnivorous shrimp species are less able to harness the natural pond biota than their more omnivorous or detrivorous counterparts (Tacon and Akiyama 1997). Shrimp for human food represents around 78% both in developed and developing countries, leaving about 22% for non-food uses (Vannuccini 2004). Therefore, shrimp and it's derived byproducts are considered important from the nutritional point of view. The amount of shrimp waste (40–48%) contains head and body carapace (Sachindra et al. 2005). Only 5% of shrimp waste is used mostly for animal feed. The shrimp waste composed mainly of protein (40%), minerals (35%) and chitin (14–30%) (Synowiecki and Al-Khateeb 2000) and is very rich in carotenoid pigments mainly Astaxanthin (Britton 1997; Gimeno et al. 2007). In efficient utilization of these marine shrimp waste becomes an accumulation from processing plants.

Shrimp head waste fermented in the presence of sugar molasses by using Lactobacillus plantarum was co-dried with 15% feather meal is used as silage meal. Fermented shrimp head waste meal can be used to replace fish meal (30%) for feeding to African catfish Clarias gariepinus (Nwanna and Daramola 2001). Use of fish silage for partial or complete replacement of fish meal in diets of Nile tilapia (Oreochromis niloticus) and African catfish (C. gariepinus) (Al-Azab 2005; Soltan et al. 2008). Shrimp head waste is also currently used in the preparation of prawn head soup (B.B.C. Food recipes).

Chitin

Chitin is one of the most abundant renewable biopolymers on earth that can be obtained as a cheap biopolymer from marine sources (Muzzarelli 1997). After cellulose, chitin is the most abundant polysaccharide in nature and is primarily present in the exoskeletons of crustaceans (such as crabs, shrimp, lobsters, etc.) and also in various insects, worms, fungi, and mushrooms in varying amount (Arcidiacono and Kaplan 1992). It is biocompatible, biodegradable, and bio-absorbable, with antibacterial and wound-healing abilities with low immunogenicity. Therefore, there have been many reports on its biomedical applications (Jollès and Muzzarelli 1999). Accordingly, a very broad range of applications in different fields such as food technology, material science, microbiology, agriculture, wastewater treatment, drug delivery systems, tissue engineering, and bionanotechnology have been reported (Feisal and Montarop 2010).

Henri Braconnot, a French professor of natural history, discovered chitin in 1811 after the discovery of a material particularly resistant to usual chemicals by Hachett, an English scientist in 1799. In 1843, Lassaigne demonstrated the presence of nitrogen in chitin (Jeuniaux 1996). Henri Braconnot named it as fungine. In 1823, Odier found the same material in insects and plants and named it as chitine (Muzzarelli and Mozzarelli 2009). Chitin is not only an essential component of invertebrates but may also be present in vertebrates. Unlike cellulose, chitin can be a source of nitrogen as well as carbon (C:N = 8:1) (Struszczyk 2006).

Chitin is a poly-beta-1, 4-N-acetylglucosamine (Roberts 1992). Chitosan is a modified, natural carbohydrate polymer derived by deacetylation of chitin. Chitin is insoluble in water due to its intermolecular hydrogen bonds (Minke and Blackwell 1978), but water-soluble chitin-based derivatives such as chitosan or carboxymethyl chitin can be obtained. One of their most important features is the ability (flexibility) to be shaped into different forms such as fibers, hydrogels, beads, sponges, and membranes (Mano et al. 2007). The origin of chitin affects its crystallinity, purity, polymer chain arrangement, and dictates its properties (Rinaudo 2006). Chitin contains 6–7% nitrogen and in its deacetylated form, chitosan contains 7–9.5% nitrogen. In chitosan, 60% to 80% of the acetyl groups available in chitin are removed (Mathur and Narang 1990). There are three forms of chitin: α, β, and γ chitin. The α-form, which is mainly obtained from crab and shrimp shells, is widely distributed. Both α and β chitin/chitosan are commercially available. The α-chitin chains are aligned in anti-parallel fashion. The anti-parallel arrangement in α-chitin gives rise to strong hydrogen bonding and consequently makes it more stable (Sikorski et al. 2009). According to Synowiecki and Al-khateeb (2003), shrimp waste contains approximately 14–30% chitin on dry weight basis depending on the processing method. The traditional sources of chitin are from shrimp, Antarctic krill, crab, and lobster processing (Muzzarelli 1997; Shahidi and Synowiecki 1991). Chitin is an environmentally friendly material (Mahmoud et al. 2007). Controlled deacetylation produce chitosan with approximately 50% free amine (Knorr 1991).

The various technologies that can be used in shrimp waste bioremediation are summarized along with the existing chemical method for degradation of shrimp waste.

Chemical process

Several researchers have reported a chemical process for demineralization and deproteinization by treatment with acid and alkali to remove calcium carbonate and protein. In traditional chemical methods for isolating chitin from shrimp waste 4% NaOH is used for deproteinization and 4% HCl for demineralization. Using of strong acid results in detrimental effects on molecular weight and negatively effect on intrinsic properties of the purified chitin (Percot and Viton Domard 2003). Although traditional chitin production methods are efficient in recovering chitin, they render other biomolecules like proteins and lipids including carotenoids useless, during protein removal and demineralization (Healy et al. 2003; Rao and Stevens 2005). Acid ensilage with milder organic acids has been reported to stabilize carotenoids and their further recovery (Sachindra et al. 2007).

Deproteination

In the first step, the waste is treated with 4% sodium hydroxide (NaOH) at elevated temperatures 70–120°C (Yang et al. 2000; Rao et al. 2000). Under these conditions, the protein becomes detached from the solid component of the shrimp waste. To prevent oxidation of the products, the process is usually carried out in a nitrogen atmosphere and in the presence of sodium borohydride (NaBH4). After completion of the deproteination step, the protein hydrolysate is removed easily by separation of the solids from the protein slurry by filtration. The protein hydrolysate can be dried and used in the form of a cake or powder as a protein supplement in feed. This protein hydrolysate also contains most of the shrimp flavor. The solid fraction consists mainly of chitin and calcium carbonate. It also contains most of the pigment. This process may not be considered as a good recovery option because it is expensive and non-environmental friendly process (Rao et al. 2002).

Demineralization

In the next step, the solid fraction is treated with 4% hydrochloric acid (HCl) which converts the insoluble calcium carbonate into soluble calcium chloride that can subsequently be removed by washing. With appropriate deproteinization and demineralization, the remaining product consists mainly of chitin with minor amounts of protein and calcium that can be judged from a weak Biuret reaction and a low weight after ashing, respectively. The use of acids harms physical and chemical properties of chitin results in harmful effluent wastewater and increase the cost of chitin-purifying process (Mahmoud et al. 2007). The chitin product should be white. It is insoluble in alkali and in most acids and organic solvents. Due to its low reactivity, chitin is usually deacetylated to chitosan.

Deacetylation

Deacetylation of chitin into chitosan requires strong chemical conditions, 50% NaOH, and elevated temperatures as high as 70–90°C. The highest degree of deacetylation possible is desired, and several treatments are usually required to reach a sufficient degree to obtain a marketable product. Chitin deacetylated by 70–90% (also referred to as 30–10% acetylated chitosan) is considered to be a good end product (Fig. 1). The material should be low in protein and ash. Chitosan can be dissolved in 1–2% acetic acid, and high viscosity of this solution is indicative of a well-prepared chitosan. If too rigorous conditions are applied during deacetylation, the main chain of the chitin breaks and this result in low viscosity of chitosan dissolved in acetic acid. In addition, the broken molecules cause discoloration and condensation, resulting in reduced transparency and solubility. A good chitosan preparation has a low ash content (<1%) and dissolves well in acetic acid giving high transparency (>90% transmission).
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Fig. 1

Production of chitin and chitosan by the chemical method

Alternative technology to replace hazardous chemical method

Enzymatic method for recovery of protein and chitin

A new process for deproteinization of chitin from shrimp head was studied (Maryam Mizani and Mahmood Aminlari 2007). Recovery of the protein fraction of the shrimp waste has been widely studied by enzymatic hydrolysis method (Simpson and Haard 1985; Cano-Lopez et al. 1987). Certain proteolytic enzymes such as alcalase (Maryam et al. 2005; Guerard et al. 2007) and trypsin (Synowiecki and Al-Khateeb 2000) have been used to extract the proteins from shrimp waste. Application of sodium sulfite, Alcalase (a commercial proteinase), Triton X-100, and combination of these reagents in association with mild chemical treatment improved quality and quantity of the protein as well as chitin. The enzymatic deproteinization process has limited value due to residual small peptides directly attached to chitin molecules ranging from 4.4% to 7.9% of total weight (Synowiecki and Al- Khateeb 2000). However, in this method, using chemical agents in combination with proteolytic enzyme significantly reduced proteinaceous fraction of precipitate (Maryam Mizani and Mahmood Aminlari 2007). This method is described in Fig. 2. As these processes are costly because of the use of commercial enzymes, there is now a need to develop an efficient and economical method for extracting proteins from shrimp head waste.
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Fig. 2

Two-stage method for chitin production (enzymatic method for deproteinization)

Microbial fermentation method

One interesting new technology for extraction of chitin that offers an alternative to the more harsh chemical methods is fermentation by using microorganisms. Fermentation has been envisaged as one of the most eco-friendly, safe, technologically flexible, and economically viable alternative methods (Rao et al. 2000; Shirai et al. 2001; Healy et al. 2003; Bhaskar et al. 2007; Prameela et al. 2010a, c, d). Fermentation of shrimp waste with lactic acid bacteria results in production of a solid portion of chitin and a liquor containing shrimp proteins, minerals, pigments, and nutrients (Rao and Stevens 2005; Prameela et al. 2010a). Deproteinization of the biowaste occurs mainly by proteolytic enzyme produced by Lactobacillus (Woods 1998). This process results in clean chitin fraction and liquor with high content of soluble peptides and free amino acids (Fagberno 1996). Ensilation can also be conducted by addition of organic acids combined with Lactobacillus treatment (Dapkevicius et al. 1998). The efficiency of lactic acid bacteria depends on the quality of inoculums, glucose, initial pH, and pH during fermentation (Mathew and Nair 2006). Lactic acid produced by the process of break down of glucose, creating the low pH condition of ensilation; suppress the growth of microorganisms involved in spoilage of shrimp waste (Legarrenta et al. 1996). The lactic acid reacts with calcium carbonate component in the chitin fraction leading to the fermentation of calcium lactate, which gets precipitated and can be removed by washing.

Deproteinization of shrimp head waste also occurs by autolysis phenomenon. The phenomenon of autolysis was found in many fishes and shrimp waste. The endogenous enzymes such as phosphorylases, lipases, cathepsins, and gut enzymes would degrade the tissues when they were dead (Mukundan et al. 1986). Autolysis of shrimp head waste occurs at different temperatures (40°C, 50°C, 60°C, and gradual temperature) with a protein recovery of 43.6%, 73.6%, 50.3%, and 87.4%, respectively, at its initial pH. Autolysis of shrimp head waste served best for the preparation of hydrolysate with the maximum degree of hydrolysis 48.6% and the maximum protein recovery of 87.4% (Wenhong et al. 2009). However, there is little information available about the autolysis of shrimp head waste.

Improvement of lactic acid fermentation has been generally accomplished by testing one variable at a time (Meraz et al. 1992). The fermentation of shrimp heads was tested in modified aeration conditions in presence of constant sugar and inoculum levels. In this case, the selection criteria used was low pH (Fagberno 1996; Prameela et al. 2010a, b). Many researchers have studied the lactic acid fermentation combined with chemical treatments (Healy et al. 1994; Shirai et al. 1997; Zakaria et al. 1998) and with different carbon sources as a natural energy source as well (Hall and Silva 1992; Fagberno 1996; Prameela et al. 2010b). Treatment of minced scampi waste by culture of Lactobacillus paracasei strain A3 was investigated by Zakaria et al. 1998. All these studies were on deproteinization of raw material and how demineralization was affected by various inoculum amounts (Meraz et al. 1992; Shirai et al. 2001; Rao et al. 2002; Prameela et al. 2010c).

Srinivas et al. (2006) studied fermentable shrimp waste under different salt concentrations with amylolytic and non-amylolytic Lactobacillus strains for chitin production. Mahmoud et al. (2007) found unconventional approaches for demineralization of deproteinized crustacean shells for chitin production. Synowiecki and Al-Khatab (2003) studied the essential amino acids index and protein efficiency ratio value of an Alcalase 2.4 L digestion of shrimp waste discards. The removal of protein and calcium from shells is by a combination of enzymatic activity and mineral solubilization by organic acid produced in bacterial growth (Luis et al. 2003; Prameela et al. 2010a). Growth and temperature of microorganisms in culture medium has an effect on chitin and astaxanthin recovery from shrimp waste (Carr et al. 2002; Neith et al. 2009). Microorganisms studied include Lactobacillus plantarum (Rao et al. 2000; Prameela et al. 2010a, b), Pseudomonas aeruginosa (Wang and Chio 1998), Pseudomonas maltophilia (Wang and Chio 1998), Bacillus subtilis (Yang et al. 2000; He et al. 2006), L. paracasei (Shirai et al. 2001), Lecanicilecium fungicola (Laura et al. 2006), Pencillium chrysogenum (Patidar et al. 2005), Pediococcus acidolactici (Bhaskar et al. 2007; Prameela et al. 2010d). Homemade natural probiotic (curd) was used in extraction of chitin and carotenoids from shrimp waste (Prameela et al. 2010c). The composition of natural probiotic was evaluated and found to be composed of Lactobacillus acidophilus, L. plantarum, Lactobacillus bulgaricus, Pediococcus acidilactici, and Streptococcus thermophilus (unpublished data). Kyung-Taek et al. (2007) studied demineralization of crab shell waste by P. aeruginosa F 722. Deproteinization of the biowaste occurs mainly by proteolytic enzymes produced by added microorganisms and protease present endogenously in the biowaste (Bautista et al. 2001; Shirai et al. 2001; Cira et al. 2002). An integrated bioconversion of shrimp was proposed, whereby protein, pigment, and main biopolymer chitin can be isolated for industrial for common use. In this context, a process which involves the total utilization of shell waste is highly valuable (Fig. 3).
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Fig. 3

Flow chart indicating fermentation of shrimp waste by using microorganisms

Chitin has an interesting property of converting itself to oligosaccharides because oligosaccharides are water soluble and possess versatile functional properties such as anti-tumor activity and antimicrobial activity (Suzuki et al. 1986; Wang et al. 2006, 2008; Liang et al. 2007). Chitin and its derivatives have many properties that make them attractive for a wide variety of applications, from food, nutrition and cosmetics to biomedicine, aquaculture, and the environment (Knapczyk and Brzozowski 1982; Lang and Clausen 1985; Holland 1986). Chitin has many applications including functional food ingredients, medicines, pharmaceuticals, cosmetics, textiles, fine chemicals, for water treatment and biodegradable packaging films (Park et al. 2005; Bautista et al. 2001; Yang et al. 2000). Their antibacterial, antifungal and antiviral properties make them particularly useful for biomedical applications such as wound dressing, weight loss agent, blood cholesterol control, surgical sutures and aid in cataract surgery and periodontal disease treatment (Stanford 1987; Rockway 2000; Taha and Swailam 2002). In the present review, a variety of applications are summarized in Table 1.
Table 1

Applications of bioactive compound chitin and chitosan from shrimp waste

Application

Product

Mechanism

Reference

Immunology

Chitin

Activation of complement and macrophages

Minami et al. 1998; Freier et al. 2005.

Hemostasis

Chitin nano-fiber

Activation of platelets

Klokkevold et al. 1999

Wound healing

Chitosan membrane

Ability to protect skin by preventing bacterial invasion

Mi et al. 2001; Ong et al. 2008

Medical

Chitosan acetate bandage

Antibacterial activity when applied to burnt skin contaminated with P. aeruginosa

Dai et al. 2009

Scaffold for the regeneration of tissue

Chitin

(1)Ability to form temporary matrix, (2) ability to form porous structure for tissue to grow, (3) biodegradability, and finally (4) non-toxic byproducts from the digestion

Brandl et al. 2007

Nerve regeneration

Chitooligosaccharide

Used as neuroprotective material with an ability to improve injured peripheral nerve regeneration

Gong et al. 2009

Blood cholesterol control

Chitosan

It combines with bile acids in the digestive tract, and excretes them into the feces, thus decreasing the resorption of bile acids, so that the cholesterol pool in the body was decreased and the level of serum cholesterol consequently decreased

Maezaki et al. 1993

Drug delivery carriers

N-succinyl-chitosan, carboxymethyl chitin, chitosan hydrogel, hydroxyethyl chitin

These associated macromolecules have been shown to transport through mucosa and epithelia more efficiently

Janes et al. 2001

 

Cationic chitosan

With other natural polymers. It has been shown to enhance the drug encapsulation efficiency of liposomes via the layer-by-layer (L-b-L) self-assembly technique

Haidar et al. 2008

 

Nanoparticles of chitosan

In association with polyethylene oxide have been used as protein carrier

Calvo et al. 1997

 

Chitosan and tripolyphosphate.

Developed oral delivery system

Bodmeier et al. 1989

Antioxidant

Aminoethyl-chitin

Antioxidant activity against free radicals such as 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl, superoxide, and peroxyl groups

Je and Kim 2006

Antimicrobial activity

Chitosan

Ability of chitin and its derivatives to activate defense mechanisms of the host organisms such as inducing the accumulation of chitinases and other pathogenesis-related proteins

El Ghaouth et al. 1992

Gene therapy

Galactosylated chitosan

Can condense DNA and forms small discrete particles in particular conditions; hence it has many potential applications for gene delivery

Erbacher et al. 1998

Food technology

Chitosan-based films

To improve the preservation of vacuum-packaged processed meat and it could delay the growth of Entrobacteriaceae, which are indigenous bacteria in the food products

Ouattara et al. 2000

Agriculture

Chitin oligosaccharides

They could also promote carrot somatic embryos survival, to boost the defense system in rice

De Jong et al. 1993; Ito et al. 1997; Okada et al. 2001

 

Chitin fragments

Can desensitize the perception system of tomato, which can lead to improvement of the defense mechanism in tomato cells

Felix et al. 1998

 

Lipo-chitin

Can induce the formation of nodule in soybean root

Minami et al. 1996

Bio-nanotechnology

Graphitic carbon nanocapsules, tungsten carbide and tungsten carbides/graphitic carbon composites

The fabrication of bioinspired micro-electromechanical systems

Cheng and Pisano 2008; Wang et al. 2010

 

Chitin whiskers

3D networks

Gopalan and Dufresne 2003

Electrolyte

Chitin and H2SO4 electrolyte

High charge–discharge ability

Yamazaki et al. 2009

Heavy metals and other pollutants removal

Chitin phosphate

Absorb uranium in the presence of sodium carbonate solution

Sakaguchi et al. 1981

 

Chitosan-based chelating resins

Absorb mercury, Ti, Mo, W, U

Hakim et al. 2008a, b; Oshita et al. 2008

 

Chitin and chitosan

Have copper removal capability which could help to obtain more stable diesel oil

Peiselt et al. 2004

 

Chitosan

Adsorption of organic pollutants

Aksu 2005

Intelligent materials or composites

Chitin-based polyurethane

Shape memory materials can remember and regain their original shape after the removal of the stimulus

Zia et al. 2009

Energy production

Chitin

Chitin has also been utilized by Clostridium paraputrificum M-21 to produce hydrogen gas. This gas is considered to be a potential source of alternative energy

Evvyernie et al. 2000; Morimoto et al. 2005

Future trends in total utilization of shrimp waste

It is clear that the shrimp waste and discards utilization situation has changed dramatically since 1970s. Now, there are more possibilities for enhancing returns by extraction and utilization of shrimp byproducts (Gildberg 2002), but there are still more to come. The existing hazardous chemical method causes environmental pollution as well as great loss to the bioactive compounds that can be isolated from shrimp waste such as protein, pigments, and fatty acids. The enzymatic processes of extraction of chitin are costly for the high expenses in commercial enzymes. There is now a need to develop an efficient, simpler, eco-friendly, economical, and commercially viable method for extracting all the possible bioactive compounds present in shrimp head waste. Automation of the extraction process is an essential future trend for the minimization of expenses and safety of the labor involved in the process. In this section, we mention some of these new components that can be obtained from shrimp waste and could constitute an incipient industry or possibility of becoming so.

Bioactive compounds

New biologically active compounds have been isolated from shrimp discards. One discovery was antimicrobial activity representing a defense mechanism of the shrimp hemocyte histone proteins (Patat et al. 2004; Blanco et al. 2007).

Pigments

Valuable pigments have been found in a variety of shrimp waste material. Various studies have reported the presence and recovery of pigments such as astaxanthin and its esters, β-carotene (Shahidi et al. 1998). Carotenoids are a group of fat soluble pigments that can be found in many plants, algae, microorganisms, and animals. Carotenoids have been extracted using shrimp waste from processing head and shell of Penaeus indicus applying different organic solvents (Sachindra et al. 2005).

The occurrence of carotenoids in crustaceans is mainly due to the absorption of pigments from the diet, which they deposit as such or transfer metabolically to keto or hydroxyl derivatives (Davies 1985; Castillo et al. 1982). Carotenoids were also extracted from fish eggs as reported by Li et al. 2005 and from sea food industry wastewater using fish scales waste as an adsorbent (Stepnowski et al. 2004). The principal carotenoid is astaxanthin formed from ingested beta carotene through oxidative transformation (Katayama et al. 1971; Latscha 1990). Astaxanthin and its esters have been isolated as major pigments from temperate water, shrimp Pandalus borealis and Penaeus japonicus (Negre-Sadargues et al. 1993; Shahidi et al. 1998). The qualitative and quantitative distribution of carotenoids in different body components of four shrimp species Penaeus monodon, P. indicus, Metapenaeus dobsonii, and Prapenalopsis styliceru were studied (Sachindra et al. 2005). The highest total carotenoid content was observed in head than in carapace (Sachindra et al. 2005). These valuable pigments would be a cheaper alternative, applicable to a wide variety of industrial needs such as coloration of some surimi-based products or aquaculture feed formulations.

Furthermore, these pigments are important in medical and biomedical applications. Astaxanthin inhibits prostate cancer and modulating immune responses against tumor cells (Guerin et al. 2003). It also inhibits bladder carcinogenesis (Tanaka et al. 1994). The antioxidant activity has been reported to be ten times stronger than β-carotene (Naguib 2000). It has applications in functional food, feed for crustaceans and Salmonidae, and cosmetic industries (De Holanda and Netto 2006). This pigment is a precursor of Vitamin A and has a possible role in human health. Many studies have been conducted to extract astaxanthin from shrimp waste using various methods such as enzymatic process (Gildberg and Stenberg 2001; Armenta-López et al. 2002; De Holanda and Netto 2006), fermentation process (Sachindra et al. 2007), extraction using organic solvents (Sachindra et al. 2006), and extraction using vegetable oils (Sachindra and Mahendrakar 2005), since astaxanthin is an oil soluble pigment. Several vegetable oils such as sunflower oil, ground nut oil, ginger oil, mustard oil, soybean oil, coconut oil, rice bran oil, and cod liver oil have been used to extract this pigment from crustaceans and fish waste (Chen and Meyers 1982; Shahidi and Synowiecki 1991; Sachindra and Mahendrakar 2005). The amount of carotenoid present in P. monodon was 24%, saturated fatty acids 7.8%, and unsaturated fatty acids 31.7% (Sachindra et al. 2005). Minerals in shell fish waste usually consist of 90%, CaCo3/calcium phosphate and 10% in krill waste (Anderson 1975).

Essential amino acids

The amino acid composition of original shrimp waste and the powder obtained after lyophilization of fermented shrimp waste is having all the essential amino acids except tryptophan, which is absent in both original shrimp waste as well as fermented liquor (Bhaskar et al. 2010). When compared to different standard reference proteins, threonine was found to be most limiting in both original shrimp waste as well as fermented liquor. Barring tyrosine, the fermented liquor retained all the amino acids present in original shrimp waste, indicating the fact that fermentation had not adversely affected the amino acid composition (Bhaskar et al. 2010). Simpson and Haard (1985) studied the amino acid composition of carateno proteins isolated from shrimp waste by enzymatic methods and found to be dominated by glutamic acid and aspartic acid. The composition of fermented liquor is recommended for common carp juveniles (NRC 1993) as well as that of the reference protein recommended by FAO/WHO (1985). It can be used as a growth enhancer and immuno stimulant in aquaculture (Amar et al. 2000). Shrimp waste protein hydrolysates are known to be nutritionally superior as feed ingredients due to high amount of essential amino acids (Gildberg and Stenberg 2001). The amino acid composition of the fermented liquor obtained during degradation is also made up of essential amino acids required by marine Penaeus shrimp (Millamena et al. 1996a, b; 1997, 1998 and 1999). Sachindra and Bhaskar (2008) have evaluated and reported the in vitro antioxidant activities exhibited by the powder obtained after lyophilization of fermented liquor from fermented shrimp waste. These properties clearly indicate the potential value of this material as a health-promoting nutritional ingredient in the diets of juvenile fish and penaeid shrimps.

Fatty acids

The fatty acid composition of shrimp waste indicates that this product is rich in saturated fatty acids and also possess considerable quantities of mono- and poly-unsaturated fatty acids which account for 34% of total fatty acids. Guillou et al. (1995) have reported that acid ensilaging has minimal effect of fatty acid profile of shrimp waste, and the silage can be a good source of lipids in aquacultural diets. The fatty acid profile in marine organisms depends on the temperature of water in which they live. The acetone extract from the wastes and from the shrimps of tropical water of India was found to be rich in saturated fatty acids (Sachindra et al. 2005, 2006). The fatty acid composition of penaied shrimps from Brazilian water was found to be rich in unsaturated fatty acid (Bragagnolo and Rodriguez-Amaya 2001), indicating that the fatty acid composition varies with the species of shrimps.

Conclusion

Shrimp waste is usually dried on the beaches. It encourages not only environmental pollution but also reduces the recoverable components from their biowaste. Solid shrimp waste undergoes rapid putrefaction because of its alkaline nature (pH 7.5–8.0). Due to high perishability of shrimp waste, implemented processing is needed. This leads to the necessity to establish and implement protocols of byproduct separation and storage as well as proposals for conservation or pre-processing alternatives when possible, so as to maintain the maturities in the appropriate processing conditions. Improving the design and operation of biological treatment process for shrimp waste in real life application presents many challenges, including working within the following constraints: selection of microorganisms, the need for robust operation, environmental parameters, and low cost operation. Therefore, extensive research should be carried out to explore bioactive compounds and their activities from shrimp waste.

Acknowledgements

KP is grateful to Prof. K. Aruna Lakshmi and Prof. R. Sinha for helpful discussion.

Copyright information

© Springer-Verlag 2011