Recovery of astaxanthin from shrimp (Penaeus vannamei) waste by ultrasonic-assisted extraction using ionic liquid-in-water microemulsions

Ultrasound-assisted extraction and antioxidant activity of polysaccharides from Tenebrio molitor

Tenebrio molitor, which is rich in various nutrients, and its polysaccharides, as significant bioactive substances, exhibit strong antioxidant effects. This study utilized defatted T. molitor as raw material and employed an ultrasound-assisted extraction method. The factors considered include extraction temperature, time, ultrasound power, and liquid-to-feed ratio, with the yield of T. molitor polysaccharides as the response value. Based on single-factor experiments and response surface methodology, the optimal extraction parameters for T. molitor polysaccharides were determined. Following purification, protein removal, and dialysis to eliminate impurities, the structure of the extracted polysaccharides was preliminarily investigated using infrared spectroscopy. Their antioxidant activities were explored by measuring their DPPH·, OH·, and ABTS+· radical scavenging abilities and Fe3+ reducing power. The results indicated that the optimal conditions for ultrasound-assisted extraction were an extraction temperature of 75 °C, an extraction time of 150 min, an ultrasound power of 270 W, and a liquid-to-feed ratio of 15:1 mL/g, yielding a polysaccharide extraction rate of 9.513%. Infrared spectroscopy analysis revealed the presence of pyranose sugars with main functional groups including C-O, C=O, and O-H. Antioxidant activity tests showed that within a certain concentration range, the higher the polysaccharide concentration, the stronger its radical scavenging abilities. Compared with Vitamin C(Vc), the polysaccharides had stronger scavenging abilities for DPPH· and OH·, some scavenging ability for ABTS+·, and Fe3+ reduction ability, and corresponding to IC50 values of 0.9625, 9.1909, and 235.69 mg/mL respectively. The Fe3+ reducing power reached a maximum absorbance of 0.38899 at a concentration of 1.6 mg/mL. T. molitor polysaccharides demonstrate promising antioxidant activity and potential as functional ingredients in food, health products, and pharmaceuticals, providing new technical references for the development and utilization of T. molitor resources.

Applications of high-intensity ultrasound on shrimp: Potential, constraints, and prospects in the extraction and retrieval of bioactive compounds, safety, and quality

The global shrimp market holds substantial prominence within the food industry, registering a significant USD 24.7 billion in worldwide exportation in 2020. However, the production of a safe and high-quality product requires consideration of various factors, including the potential for allergenic reactions, occurrences of foodborne outbreaks, and risks of spoilage. Additionally, the exploration of the recovery of bioactive compounds (e.g., astaxanthin [AX], polyunsaturated fatty acids, and polysaccharides) from shrimp waste demands focused attention. Within this framework, this review seeks to comprehend and assess the utilization of high-intensity ultrasound (HIUS), both as a standalone method and combined with other technologies, within the shrimp industry. The objective is to evaluate its applications, limitations, and prospects, with a specific emphasis on delineating the impact of sonication parameters (e.g., power, time, and temperature) on various applications. This includes an examination of undesirable effects and identifying areas of interest for current and prospective research. HIUS has demonstrated promise in enhancing the extraction of bioactive compounds, such as AX, lipids, and chitin, while concurrently addressing concerns such as allergen reduction (e.g., tropomyosin), inactivation of pathogens (e.g., Vibrio parahaemolyticus), and quality improvement, manifesting in reduced melanosis scores and improved peelability. Nonetheless, potential impediments, particularly related to oxidation processes, especially those associated with lipids, pose a hindrance to its widespread implementation, potentially impacting texture properties. Consequently, further optimization studies remain imperative. Moreover, novel applications of sonication in shrimp processing, including brining, thawing, and drying, represent a promising avenue for expanding the utilization of HIUS in the shrimp industry.

Statistical Tools to Optimize the Recovery of Bioactive Compounds from Marine Byproducts

Techniques for extracting important bioactive molecules from seafood byproducts, viz., bones, heads, skin, frames, fins, shells, guts, and viscera, are receiving emphasis due to the need for better valorization. Employing green extraction technologies for efficient and quality production of these bioactive molecules is also strictly required. Hence, understanding the extraction process parameters to effectively design an applicable optimization strategy could enable these improvements. In this review, statistical optimization strategies applied for the extraction process parameters of obtaining bioactive molecules from seafood byproducts are focused upon. The type of experimental designs and techniques applied to criticize and validate the effects of independent variables on the extraction output are addressed. Dominant parameters studied were the enzyme/substrate ratio, pH, time, temperature, and power of extraction instruments. The yield of bioactive compounds, including long-chain polyunsaturated fatty acids, amino acids, peptides, enzymes, gelatine, collagen, chitin, vitamins, polyphenolic constituents, carotenoids, etc., were the most studied responses. Efficiency and/or economic and quality considerations and their selected optimization strategies that favor the production of potential bioactive molecules were also reviewed.

Tailor-made solvents for microbial carotenoids recovery

In recent years, microbial carotenoids have emerged as a promising alternative for the pharmaceutical and food industries, particularly in promoting human health due to their potent antioxidant and antimicrobial properties. Microbial carotenoids, particularly those produced by yeast, bacteria, and microalgae, are synthesized intracellularly, requiring the use of solvents for their effective extraction and recovery. The conventional use of toxic volatile organic solvents (VOCs) like hexane, petroleum ether, and dimethyl sulfoxide in the extraction of microbial carotenoids has been common. However, ongoing research is introducing innovative, non-toxic, environmentally friendly tailor-made solvents, such as ionic liquids (IL) and deep eutectic solvents (DES), indicating a new era of cleaner and biocompatible technologies. This review aims to highlight recent advancements in utilizing IL and DES for obtaining carotenoids from microorganisms. Additionally, we explore the utilization of in silico tools designed to determine the solubilities of microbial carotenoids in tailor-made DES and ILs. This presents a promising alternative for the scientific community, potentially reducing the need for extensive experimental screening of solvents for the recovery of microbial carotenoids in the separation processing. According to our expert perspective, both IL and DES exhibit a plethora of exceptional attributes for the recovery of microbial carotenoids. Nevertheless, the current employment of these solvents for recovery of carotenoids is restricted to scientific exploration, as their feasibility for practical application in industrial settings has yet to be conclusively demonstrated. KEY POINTS: • ILs and DES share many tailoring properties for the recovery of microbial carotenoids • The use of ILs and DES for microbial carotenoid extraction remains driven by scientific curiosity. • The economic feasibility of ILs and DES is yet to be demonstrated in industrial applications.

Intelligent and active biodegradable biopolymeric films containing carotenoids

There is growing interest in the use of natural bioactive compounds for the development of new bio-based materials for intelligent and active food packaging applications. Several beneficial effects have been associated with the antioxidant and antimicrobial potentials of carotenoid compounds. In addition, carotenoids are sensitive to pH changes and oxidation reactions, which make them useful bioindicators of food deterioration. This review summarizes the current research on the application of carotenoids as novel intelligent and active biodegradable food packaging materials. Carotenoids recovered from food processing by-products can be used in the development of active food packaging materials due to their antioxidant properties. They help maintain the stability of lipid-rich foods, such as vegetable oils. Additionally, when incorporated into films, carotenoids can monitor food oxidation, providing intelligent functionalities.

Selectively extraction of astaxanthin from Haematococcus pluvialis by aqueous biphasic systems composed of ionic liquids and deep eutectic solutions

Haematococcus pluvialis is rich in astaxanthin ester (Ast1) and free astaxanthin (Ast2). The astaxanthin is natural antioxidant, and shows higher biodegradability and eco-friendly characteristics than commercial astaxanthin. However, the existing extraction technology is difficult to achieve selectively separation of Ast1 and Ast2. Novel aqueous biphasic systems (ABSs) composed of ionic liquids (ILs) and deep eutectic solvents (DESs) were developed to selectively extract Ast1 and Ast2. The results showed that the ABS composed of tributyloctylphosphine chloride ([P4448]Cl) and choline chloride:d-fructose ([ChCl][Fru]) performed best. The yield and partition coefficient of astaxanthin was 2.35 mg·g-1 and 103.59, respectively. Moreover, Ast1 and Ast2 could be selectively separately with the highest coefficient of specificity of 48.31. Furthermore, the ABS maintained an excellent extraction capacity after three cycles of recycling. As compared with organic solvent extraction and prior methods, the IL-DES ABS is more efficient, recyclable, and environmentally friendly for selectively extraction of astaxanthin.

Trash to Treasure: An Up-to-Date Understanding of the Valorization of Seafood By-Products, Targeting the Major Bioactive Compounds

Fishery production is exponentially growing, and its by-products negatively impact industries' economic and environmental status. The large amount of bioactive micro- and macromolecules in fishery by-products, including lipids, proteins, peptides, amino acids, vitamins, carotenoids, enzymes, collagen, gelatin, chitin, chitosan, and fucoidan, need to be utilized through effective strategies and proper management. Due to the bioactive and healthy compounds in fishery discards, these components can be used as functional food ingredients. Fishery discards have inorganic or organic value to add to or implement in various sectors (such as the agriculture, medical, and pharmaceutical industries). However, the best use of these postharvest raw materials for human welfare remains unelucidated in the scientific community. This review article describes the most useful techniques and methods, such as obtaining proteins and peptides, fatty acids, enzymes, minerals, and carotenoids, as well as collagen, gelatin, and polysaccharides such as chitin-chitosan and fucoidan, to ensure the best use of fishery discards. Marine-derived bioactive compounds have biological activities, such as antioxidant, anticancer, antidiabetic, anti-inflammatory, and antimicrobial activities. These high-value compounds are used in various industrial sectors, such as the food and cosmetic industries, owing to their unique functional and characteristic structures. This study aimed to determine the gap between misused fishery discards and their effects on the environment and create awareness for the complete valorization of fishery discards, targeting a sustainable world.

A switchable temperature-responsive ionic liquid-based surfactant-free microemulsion for extraction and separation of hydrophilic and lipophilic compounds from Camptotheca acuminata and extraction mechanism

In this study, a switchable temperature-responsive ionic liquid-based surfactant-free microemulsion (TRIL-SFME) for extraction and in-situ separation of hydrophilic and lipophilic compounds from Camptotheca acuminata was firstly developed and systematically characterized. This TRIL-SFME was obtained using 1-hexyl-3-methylimidazolium tetrafluoroborate ([HMIM][BF₄]), 1,2-propanediol and H₂O. The prepared TRIL-SFME presented low viscosity and rapid response to temperature. Firstly, the effect of temperatures on TRIL-SFME phase behavior was studied followed by determination of effect of liquid/solid ratio and extraction time on the extraction yields of the targeted compounds. The TRIL-SFME demulsified rapidly by thermal stimulus, resulting in in-situ separation and enrichment of compounds with varying polarity. The results of present study revealed that TRIL-SFME had higher extraction yields (1.50-5.79 folds) compared to traditional solvents and individual components of TRIL-SFME. Besides, in-situ separation and enrichment of hydrophilic compounds (phenolic acids) and lipophilic compounds (alkaloids) was accomplished in short time (within 3 min) by cooling the system to 4 ℃. Furthermore, the mesoscopic behavior between TRIL-SFME and targeted compounds was simulated by dissipative particle dynamics (DPD) to explore the extraction mechanism for the first time. The results illustrated the formation of W/IL structure of TRIL-SFME and clarified solubilization mechanism of TRIL-SFME system for targeted compounds, which is related to its special "water pool" structure. This novel and switchable TRIL-SFME is an environmentally friendly and promising alternative to simultaneously extract, in-situ separate and enrich the natural active compounds with different polarity from plant matrices.

Biocolorants in food: Sources, extraction, applications and future prospects

Color of a food is one of the major factors influencing its acceptance by consumers. At presently synthetic dyes are the most commonly used food colorant in food industry by providing more esthetically appearance and as a means to quality control. However, the growing concern about health and environmental due to associated toxicity with synthetic food colorants has accelerated the global efforts to replace them with safer and healthy food colorants obtained from natural resources (plants, microorganisms, and animals). Further, many of these biocolorants not only provide myriad of colors to the food but also exert biological properties, thus they can be used as nutraceuticals in foods and beverages. In order to understand the importance of nature-derived pigments as food colorants, this review provides a thorough discussion on the natural origin of food colorants. Following this, different extraction methods for isolating biocolorants from plants and microbes were also discussed. Many of these biocolorants not only provide color, but also have many health promoting properties, for this reason their physicochemical and biological properties were also reviewed. Finally, current trends on the use of biocolorants in foods, and the challenges faced by the biocolorants in their effective utilization by food industry and possible solutions to these challenges were discussed.

Sustainable Food Systems: The Case of Functional Compounds towards the Development of Clean Label Food Products

The addition of natural components with functional properties in novel food formulations confers one of the main challenges that the modern food industry is called to face. New EU directives and the global turn to circular economy models are also pressing the agro-industrial sector to adopt cradle-to-cradle approaches for their by-products and waste streams. This review aims to present the concept of “sustainable functional compounds”, emphasizing on some main bioactive compounds that could be recovered or biotechnologically produced from renewable resources. Herein, and in view of their efficient and “greener” production and extraction, emerging technologies, together with their possible advantages or drawbacks, are presented and discussed. Μodern examples of novel, clean label food products that are composed of sustainable functional compounds are summarized. Finally, some action plans towards the establishment of sustainable food systems are suggested.

Astaxanthin Extract from Shrimp (Trachypenaeus curvirostris) By-Products Improves Quality of Ready-to-Cook Shrimp Surimi Products during Frozen Storage at -18 °C

The effects of astaxanthin extract (AE) from shrimp by-products on the quality and sensory properties of ready-to-cook shrimp surimi products (RC-SSP) during frozen storage at −18 °C were investigated. Changes in 2-thiobarbituric acid reactive substances (TBARS) value, sulfhydryl groups, carbonyls, salt-soluble protein content, textural properties, color, and sensory quality over specific storage days were evaluated. The AE from shrimp by-products contained 4.49 μg/g tocopherol and 23.23 μg/g astaxanthin. The shrimp surimi products supplemented with 30 g/kg AE had higher redness values and greater overall acceptability and texture properties after cooking (p < 0.05). AE showed higher oxidative stability in RC-SSP than the control, as evidenced by lower TBARS and carbonyl content, and higher sulfhydryl and salt-soluble protein content. AE from shrimp by-products had positive effects on the antioxidant activity and color difference of RC-SSP, and could be used as a potential multifunctional additive for the development of shrimp surimi products.

Improvement of solubility, stability and antioxidant activity of carotenoids using deep eutectic solvent-based microemulsions

Natural carotenoids have been widely used as colorants and antioxidants in process of food, medicine, and cosmetic. However, the carotenoids have low bioactivity in vivo due to poor water-solubility. To enhance the solubility, stability and antioxidant activity of carotenoids, novel microemulsions (MEs) composed with deep eutectic solvents (DESs), tween 80 and water were developed as alternatives to organic solvents. The phase diagrams and physicochemical properties (viscosity, pH, and diameter) of the DES-based MEs were investigated at different temperatures. Then the solubility distribution, storage stability and DPPH free radical-scavenging activity of three carotenoids (astaxanthin, astaxanthin ester and lutein) in the MEs were evaluated. Compared with ethanol, methanol, and acetone, all the DES-based MEs studied significantly enhanced the solubility of the carotenoids due to the stronger hydrogen bonding and Van der Waals interactions. The highest solubilities of 0.27, 473.63, and 12.50 mg/mL for astaxanthin, astaxanthin ester and lutein, respectively, were observed in the MEs containing DES (DL-menthol:acetic acid = 1:2) at 35 ℃. Moreover, astaxanthin ester can be well preserved in the MEs containing DES (DL-menthol:octanoic acid = 1:2) with a half-life of more than 69 days. In addition, the DPPH scavenging capacities of the three carotenoids in all the MEs were higher than the organic solvents. The results revealed that the DES-based MEs with low viscosity (<0.2 Pa•s) and mild acidic pH (4-5) are potential solvents for natural carotenoids in food processing and storage, medicine making, as well as biomaterials processing.

Ultrasound-Assisted Extraction of Natural Pigments From Food Processing By-Products: A Review

Ultrasound is an emerging technology, which has been highly explored in the food area to improve processes and products. When ultrasound is applied to a product with solid or fluid characteristics, the passage of acoustic waves and acoustic cavitation generates different mechanisms responsible for modifications in the original matrix of the sample. These effects of ultrasound can also be used to take advantage of by-products, for example by extracting compounds of interest, including natural pigments. Natural pigments or colorants are being highly demanded by different industries not only for color purposes but also due to their healthy properties, the greater demands in regulations and new consumer preferences. This review presents an updated critical analysis of the application of ultrasound-assisted extraction (UAE) to obtain natural pigments from food processing by-products. Initially, the ultrasound effects and mechanisms that improve the extraction of natural pigments in a fluid medium, as well as the factors that influence the extraction and the energy consumption of UAE are analyzed and described. Subsequently, the UAE application to obtain pigments belonging to the groups of carotenoids, chlorophyll, anthocyanins and betalains is evaluated. These sections detail the processing conditions, positive and negative effects, as well as possible applications of the extracted pigments. This review presents relevant information that may be useful to expand and explore new applications of ultrasound technology as well as promote the revaluation of by-products to obtain pigments that can be used in food, pharmaceutical or cosmetic industries.

Processing tactics for low-cost production of pure nuciferine from lotus leaf

Nuciferine is an important drug candidate for the treatment of many diseases. However, there is no general method for its low - cost production. In this work, a feasible method for the production of nuciferine from lotus leaf, using ultrasonic-assisted extraction-solid phase extraction (UAE-SPE) as extraction and cleanup procedure, was developed. Petroleum ether and silica gel have been successfully used as extraction solvent and adsorbent to integrate UAE with SPE, respectively. Except for filtration, no treatment (e.g. concentration and redissolution, etc) was needed on UAE extract before SPE and the effluents obtained in the loading process of SPE could be used as UAE extraction solvent without purification. No obvious decline in the extraction efficiency of UAE and adsorption capacity of SPE was observed at least for 5 runs, which provides a feasible way for the continuous production of nuciferine in industry, i.e. Cyclic UAE-SPE. Moreover, SPE column could be conveniently regenerated and reused without significant decline in its adsorption capacity at least for 5 cycles, which can be used to reduce the cost of the whole system further. In comparison with other cleanup procedures, Cyclic UAE-SPE showed apparent advantages in energy conservation and emission reduction. LLE and crystallization were applied to separate nuciferine from other impurities further. Under optimum conditions, the total recovery rate of nuciferine with a purity over 90.0% from lotus leaf reached 50.1%. All in all, the developed method has advantages in convenient operation, low cost, and high efficiency, thus, is fitting for the production of high purity nuciferine.

Comparison of the Proximate Composition and Nutritional Profile of Byproducts and Edible Parts of Five Species of Shrimp

The nutritional components of different parts (meat, head, shell and tail) of Litopenaeus vannamei (L.v), Macrobrachium rosenbergii (M.r), Penaeus monodon (P.m), Fenneropenaeus chinensis (F.c), and Penaeus japonicus (P.j) were analyzed and their nutritional values were evaluated. For the five species of shrimp, the meat yield was 37.47–55.94%, and the byproduct yield was 44.06–62.53%. The meat yields of L.v and F.c were the highest (55.94 and 55.92%, respectively), and the meat yield of M.r was the lowest (37.47%). The shrimp contain high amounts of crude protein, and the values of the amino acid score (AAS), chemical score (CS), and essential amino index (EAAI) were greater than or close to 1.00, indicating that shrimp protein had higher nutritional value. The shrimp head was rich in polyunsaturated fatty acids and the ratio of n-6 to n-3 PUFAs was from 0.37 to 1.68, indicating that the shrimp head is rich in n-3 PUFAs and is a good source of n-3 PUFAs. The five species of shrimp were rich in macro- and micro-minerals, especially in shrimp byproducts. The shrimp byproducts were also rich in other bioactive ingredients (astaxanthin), which are also very valuable for developing biological resources. Therefore, shrimp have many nutritional benefits, and their byproducts can also be used to develop natural nutraceuticals, which are considered to be one of the healthiest foods.

Influence of the Use of an Ionic Liquid as Pre-Hydrodistillation Maceration Medium on the Composition and Yield of Cannabis sativa L. Essential Oil

Cannabis sativa L. is a multi-purpose crop, whose resilience, adaptability and soil-enriching properties make it a low-impact production. In the last years, the cultivation of the "industrial" hemp varieties (THC < 0.2%) has been promoted by many Countries, opening a whole new market of hemp-derived products, such as its essential oil (EO). Its distillation might represent an effective method to exploit a residue of the hemp fiber production (flowers), complying with the guidelines of the circular economy. In the present work, different concentrations of an ionic liquid (IL; 1,3-dimethyl-1H-imidazol-3-ium dimethylphosphate) have been studied as a pre-hydrodistillation maceration medium. The EO yields have been evaluated, and their compositions have been analyzed by GC-EIMS. The use of 100% and 90% IL concentrations gave a hydrodistillation yield increment of 250% and 200%, respectively. The 200% yield increase was maintained when the 100% IL was recycled after the hydrodistillation. The lower IL concentrations incremented the cannabinoid and oxygenated sesquiterpene contents, while the opposite was true for sesquiterpene hydrocarbons. The proposed IL-enhanced hydrodistillation medium applied to hemp, studied for the first time in the present work, might be used to both (i) noteworthy increment the hydrodistillation yield and (ii) modulate the obtained EO composition based on the desired final product.

Emerging Green Techniques for the Extraction of Antioxidants from Agri-Food By-Products as Promising Ingredients for the Food Industry

Nowadays, the food industry is heavily involved in searching for green sources of valuable compounds, to be employed as potential food ingredients, to cater to the evolving consumers’ requirements for health-beneficial food ingredients. In this frame, agri-food by-products represent a low-cost source of natural bioactive compounds, including antioxidants. However, to effectively recover these intracellular compounds, it is necessary to reduce the mass transfer resistances represented by the cellular envelope, within which they are localized, to enhance their extractability. To this purpose, emerging extraction technologies, have been proposed, including Supercritical Fluid Extraction, Microwave-Assisted Extraction, Ultrasound-Assisted Extraction, High-Pressure Homogenization, Pulsed Electric Fields, High Voltage Electrical Discharges. These technologies demonstrated to be a sustainable alternative to conventional extraction, showing the potential to increase the extraction yield, decrease the extraction time and solvent consumption. Additionally, in green extraction processes, also the contribution of solvent selection, as well as environmental and economic aspects, represent a key factor. Therefore, this review focused on critically analyzing the main findings on the synergistic effect of low environmental impact technologies and green solvents towards the green extraction of antioxidants from food by-products, by discussing the main associated advantages and drawbacks, and the criteria of selection for process sustainability.

Microencapsulation of carotenoid-rich materials: A review

Carotenoids are natural pigments that present several bioactive properties, including antioxidant, anticarcinogenic and provitamin A activities. However, these compounds are susceptible to degradation when exposed to a number of conditions (e.g. light, heat, oxygen), leading to loss of benefits and hampering their application in food products. Their hydrophobicity also makes incorporation into water-based foods more difficult. Microencapsulation techniques have been applied for decades to provide stability to carotenoid-rich extracts under typical conditions of processing and storage of foods, besides offering several other advantages to the use and application of these materials. This work reviews the recent advances in the microencapsulation of carotenoid-rich extracts, oils and oleoresins from varying sources, evidencing the technologies applied to encapsulate these materials, the effects of encapsulation on the obtained particles, and the impact of such processes on the bioaccessibility and release profile of carotenoids from microparticles. Moreover, recent applications of carotenoid-rich microparticles in food products are discussed. Most of the applied processes were effective in improving different aspects of the encapsulated materials, especially the stability of carotenoids during storage, resulting in microparticles with promising properties for future applications in food products. However, the lack of information about the effects of microencapsulation on carotenoids during processing of model foods, the sensory acceptance of enriched food products and the bioaccessibility and bioavailability of microencapsulated carotenoids reveals gaps that should be explored in the future.

Optimized extraction of astaxanthin from shrimp shells treated by biological enzyme and its separation and purification using macroporous resin

The best enzymatic protease treatment of shrimp shells was identified by comparing the enzymatic hydrolysis effects of many different types of biological enzymes using fresh Arctic sweet shrimp as raw materials. The optimal enzymolysis conditions were determined using neutral protease as the best enzymatic protease. Among multiple macroporous adsorption resins, XDA-8 macroporous adsorption resin was preferable due to its static adsorption rate and desorption rate. The yield of astaxanthin (134.20 μg/g) after treatment with neutral protease was 3.7 times higher than that of the control group (36.03 μg/g). The yield of astaxanthin was obviously improved after enzymolysis of the shrimp shells. The purity of the astaxanthin was up to 87.34%, approximately 6508 times higher than that of the raw material. The production cost of astaxanthin would be greatly reduced by use of XDA-8 resin to obtain high-purity astaxanthin. This technique offers a high value-added utilization of shrimp shells.