Gelatin Extraction Research Articles

Extraction of catfish bone waste (pangasius hypophtalmus) by utilizing an organic liquid of pineapple peel waste (ananas comosus) into gelatin

This study aims to determine how to extract the gelatin from catfish bones by using pineapple peel waste as a soaking material in the pre-treatment stage and examining the physicochemical properties of the gelatin produced. Kampung Patin in Kampar Regency, Riau Province, is one of the catfish cultivations in Indonesia. It is a center for producing catfish that produces fish bone waste. In this study, gelatin extraction will be undertaken in several stages: the preparation of pineapple waste liquid extract and gelatin extraction (pre-treatment and main extraction stages). Catfish bones will be soaked in 1:5 (m/v) pineapple waste liquid at the pre-treatment stage for 24 hours. While in the central extraction, ossein will be immersed in water at a temperature of 750C for 5 hours. The analysis results for physicochemical characteristics of gelatin obtained include yield of 2.55, pH of 4.58, water content; 11.66%, ash content; 17.71%, crude fat content; 0.17%, protein content; 64.71%. It can be inferred that it meets the established gelatin quality standards from various physicochemical characteristics of gelatin in this study.

Valorization of discarded industrial processing wastes of Siboga squid (Doryteuthiis sibogae) for the extraction and physico-chemical characterization of gelatin

A growing concern on the accumulation and disposal of fish processing discards and environmental degradation induces a profound attraction on the development of valuable byproducts for human purposes. Gelatin was isolated from Siboga squid ( Doryteuthiis sibogae ) skin through cold maturation process and its physico-chemical as well as structural properties viz . Water Holding Capacity (WHC), emulsifying capacity, emulsifying stability and viscosity were analyzed. The alkaline treatment of skin yielded 7.5 % gelatin powder. Extracted gelatin was characterized using UV-visible spectroscopy, 1 H NMR, FT-IR and Raman analyses. Based on FT-IR and Raman fingerprints, peak located at 1664 cm -1 (C=O stretch Amide I band) could be inferred that secondary structure of proteins as well as coiled structure of gelatin. Topographic analysis by AFM showed presence of aggregates of the polymer. The results suggest that the Siboga squid gelatin is an alternative source of gelatin and its potential applicability at industrial scale.

Self-assembled hydrolyzed gelatin nanoparticles from silver carp spine bones for Pickering emulsion stabilization

In this work, enzymatic hydrolysis modification was combined with silver carp spine bone gelatin extraction process to obtain pepsin enzyme hydrolyzed gelatins (PEHGs) for emulsion development. Using pepsins at ratios of 6–24 U/g of silver carp vertebrae, PEHGs were obtained with molecular weights of mainly <5 KDa and the production yields were 12.6%–13.3%. The obtained PEHGs at different pepsin/vertebrae ratios showed similar secondary structure percentages. They could self-assembled into pH-stable nanoparticles. PEHGs had higher fat-binding capacity values (16.2–21.5 g of oil/g of PEHG) and higher emulsion stabilization ability (creaming index values < 11% after 28-day storage at 4 °C) than silver carp scale gelatins, bovine bone gelatin, cold-water CFG and tilapia skin gelatins. With the decrease of pepsin/vertebrae ratios in the PEHG preparation process, the nanoparticle numbers and sizes increased, the turbidities of PEHG solutions increased, the gel strengths (164–314 g) of PEHG gels increased, the initial droplet sizes of Pickering emulsions decreased, and creaming stability of Pickering emulsions increased. This work provided useful information to analyze the effect of enzymatic hydrolysis modification on the structural, functional, and emulsifying properties of a protein. It also provided an efficient way to prepare protein self-assembly nanoparticles from animal tissues.

Rheological and functional characterization of gelatin and fat extracted from chicken skin for application in food technology.

Chicken skin is a major byproduct of the poultry industry. This study was undertaken to extract and characterize fat and gelatin from chicken skin. To do this, the chicken skin was wet‐rendered at different temperature–time combinations and the yield and properties of the extracted gelatin and fat were determined. Gelatin and fat were recovered at yield ranges of 0.74%–2.03% and 24.01%–27.91%, respectively. The time and the interaction of time–temperature had a positive effect on gelatin yield (p < .05); however, the fat yield was not affected by the extraction condition. Protein, ash, and hydroxyproline content of gelatin and unsaponifiables and free fatty acids contents, peroxide value, and induction period of oxidation of the fat were affected by the extraction condition. Functional and rheological analyses showed chicken skin gelatin gel/solution had a higher bloom value, viscosity, foaming capacity, storage and loss moduli, and melting and gelling points than the commercial bovine gelatin. Oleic (42.13%), palmitic (24.6%), and linoleic (17.53%) acids were the main fatty acids of chicken skin fat. The storage modulus of chicken skin fat was higher than the loss modulus up to 31°C; however, because of a low slip melting point (22.74°C) and solid fat content, it was fluid at room temperature. The findings of this research can be useful in the development of processes for the extraction and application of chicken skin gelatin and fat.

Production and characterization of gelatin from rabbit bone as bioplastics material by acid pre-treatment

This study aims to find out the effect of hydrochloric acid curing concentration on the characteristics of rabbit bone gelatin and determine the level of hydrochloric acid concentration for the soaking process to produce the best characteristics of rabbit bone gelatin. The material used was 50 kg of Rex rabbit bones obtained from rabbit farms, HCl 4, 5 and 6% and distilled water. The rabbit skin was soaked in hydrochloricacid (4, 5 and 6%) for 4 d as treatment and replicated three times. Gelatin extraction was performed three times at temperatures of 65, 75 and 85°C for 4 h each time and the results obtained were filtered through filter paper. The filtrate was concentrated at 50°C for 5 h. The concentrated filtrate was then poured into a tray before drying in an oven at 50°C until dry. Milling was carried out until it became gelatin powder. This study used a completely randomised design with a unidirectional pattern, and if there was a significant difference, continued with Duncan’s multiple range test. The results showed that the rabbit bone gelatin yield was between 6.18-8.52%, moisture 8.08-8.45%, ash content 8.15-10.93%, pH 3.85-4, protein content 57.09-62.84%, fat content 0.04-0.27%, gel strength 74.47-129.09 bloom, viscosity 3.06-4.26 cP, thick point 10-12°C, melting point 33-35°C and the molecular weights were 85, 120, and 212.5 kDa. The characteristics of rabbit bone gelatin still meet the Standar Nasional Indonesia gelatin range. Curing treatment with 6% HCl gave the best gelatin characteristics.

The differences between glazing with solutions, coating with fish waste extracted gelatin and polyethylene-packaging of common carp fish fil-lets and their effects on qualitative and sensory characteristics during different freezing storage periods

The study was conducted to choose the best way to store the fillets of common carp fish. Samples were divided into five treatments (T1 control treatment), (T2 glazing with saline solution 2%), (T3 glazing with acid solution 2%), (T4 coating with fish ex-tracted Gelatin), (T5 normal polyethylene- packaging). These five groups (treat-ments) have been stored in freezing conditions at four periods 2,4,6,8 weeks respectively. The qualitative and sensory properties of fish fillets were studied and the best results was belonging to T4 (gelatin coating treatment). The study included the process of gelatin extraction from fish waste as well.

Optimization Chicken Bones Gelatin Extraction Using Hydrochloric Acid Immersion and Multi-Stage Thermal Treatment

The growing poultry consumption rate yearly includes chicken with significantly increased amounts of by-products like skin and bones. Chicken bones are unused properly even if the bone is rich in collagen which is the primary material to produce gelatin. Gelatin usually is generated by bovine and porcine, but some health and religious issues have successfully forbid using both resources. Chicken bones could be an alternative material for gelatin production. This research aimed to investigate chicken bones as a substitute resource for gelatin manufacturing using hydrochloric acid submersion in collaboration with multi-stage thermal treatment. Chicken bones were proceeded in several steps such as degreasing, decontamination, resizing, demineralization using a hydrochloric acid immersion (1.50, 3.00, 4.50, and 6.00% v/v) for 24 and 48 hours, addition gelatin extraction using multi-stages thermal process (55, 65, and 75°C) for 4 hours each temperature subsequentially, evaporating, drying, and shaping a gelatin powder. This study produced type A gelatin which investigated yield number, moisture and ash content, gel strength, acidity level, and functional group using Fourier-transform Infrared (FTIR) spectroscopy. The sample gelatin has obtained at least 2% up to 8% yields. The moisture and ash contents were suitable to the commercial specification range, 4-12%, and 0.1-0.4%, respectively. The acid conditioning process has an impact on acidity with pH levels 4.40-5.44. Based on gelatin standards, this study declared that processing chicken bones using 6.00% hydrochloric acid submersion for 24 hours was optimal for gelatin extraction. Those optimal condition has formed gelatin with more than 8% yields. It was considered great gelatin with 260.57 g Bloom of gel strength and 90.18% of emulsion stability. Sample gelatin has a quite reasonable acidity level at 4.5. Protein structures confirmation using the vibration of the best gelatin sample has also shown essential components such as O-H, N-H, and C=O on the FTIR spectrum.Keywords: chicken bones (Gallus domesticus), hydrochloric acid immersion, gel strength, emulsion stability, FTIR spectroscopy

Kinetic evaluation of gelatin extraction from chicken skin and the effect of some extraction parameters

AbstractKinetic models have been extensively studied for the prediction of yield and quality for plant‐sourced ingredients although that is very rare for animal‐sourced products. This study is designed to evaluate common kinetic models for the prediction of yield in gelatin extraction from chicken skin. Kinetic models used for comparison were the Peleg's, the first order, and the rate law models while extraction parameters studied were solvent pH, solid:liquid ratio, and sample size. Extraction is evaluated based on the protein and hydroxyproline (Hyp) concentrations of each extract. The success of the models is evaluated based on the root‐mean‐square error (RMSE) and the coefficient of determination (R2) values calculated for fittings of the models to the experimental data. The protein content of the dried and degreased skin was over 50% before gelatin extraction. Neutral pH led to the highest yield for both protein and Hyp, which were close to 2,100 and 200 mg per 10 g of skin, respectively. Similarly, smaller sample size or lower solid:liquid ratio resulted in a higher yield. In general, the first 60 min of the extraction was by rapid washing and later on by slow diffusion. Peleg's model is found to be the best fit to the experimental data with the highest R2 values between 0.97 and 0.99 and the lowest RMSE values compared to that of other kinetic models. This is the first report on the kinetics of gelatin extraction as well as one of the few studies on extraction kinetics of animal‐sourced products.Practical ApplicationsExtraction parameters including the size of the raw material and raw material:solvent ratio showed significant effects on extraction yield. The smaller the size and the ratio, the higher the yield. Kinetics of gelatin extraction is reported for the first time by this manuscript, dealing with the yield during the whole extraction process. Extraction parameters may create substantial variability in quality and yield; thus, the data presented here may be utilized in minimizing those potential variations, by minimizing the time, energy and solvent required. The gelatin industry may use this report in the design of the gelatin extraction process as the data presented concludes that a high‐rate extraction was completed within the first hour of the extraction, leading over 80% of the expected yield. Gelatin manufacturers and researchers in this field may find this manuscript useful as it provides valuable insights on gelatin extraction and its kinetics.

Optimization of Extraction Conditions of Gelatin from Grey Mullet (Mugilidae) Scale with RSM

ABSTRACT By-products from fish cleaning are rich sources of gelatin. Response surface methodology (RSM) with three parameters was conducted to determine the optimum extraction conditions of gelatin from grey mullet scale. A central composite rotatable design (CCRD) was used to study the combined effects of sodium hydroxide concentration (0.3-0.9 %), soaking time in sodium hydroxide solution (50-150 minute), and extraction temperature (30-60 ºC) were determined. gel strength (g),Viscosity (cp), L*, a*, and b* indices were chosen as responses. The results showed the optimum conditions were sodium hydroxide concentration 0.233 %, soaking time in sodium hydroxide solution of 96.457 minutes, and extraction temperature of 41.378 ºC. The predicted responses including viscosity, gel strength, L*, a*, and b* were 2.17 cp, 145 g, 6.039, 6.801, and 38.859 respectively. The response surface method was able to estimate the optimal conditions of extraction gelatin with high desirability (0.998).

Synthesis of gelatin and green tea based stretchable self-healing material of biomedical importance

Stimuli-responsive stretchable self-healing hydrogels of bio-based origin have gained extreme importance for the development of materials possessing numerous applications related to wound healing, preparation of electronic skin and many health monitoring issues. This paper highlights the synthesis of novel self-healing, stretchable hydrogel derived from gelatin and aqueous green tea extract (Gel-oxGTp-phen). The hydrogel Gel-oxGTp-phen was found to be biodegradable in phosphate buffer, urea solution and solutions of different pH. The synthesized material exhibited viscoelastic and self-healing properties. Self-healing occurred in the material after 2 h. Lastly, the blood containing Gel-oxGTp-phen hydrogel sample exhibited 1.47% percentage hemolysis ratio indicating non-hemolytic nature of the synthesized hydrogel and practical utility in the biomedical field.

Biodegradable Composites with Functional Properties Containing Biopolymers

There is a major focus on natural biopolymers of bacterial, animal, or plant origin as ecological materials, replacing petrochemical products. Biologically derived polylactide (PLA), polyhydroxybutyrate (PHB), and polyhydroxyalkanoates (PHA) possess interesting properties, but they are currently too expensive for most applications. Therefore, researchers try to find other biopolymers that are both durable and cheap enough to replace plastics in some applications. One possible candidate is gelatin, which can be transformed into a thin, translucent film that is flexible and has stable and high mechanical properties. Here, we present a method of synthesizing a composite material from gelatin. For preparation of such material, we used gelatin of animal origin (pig skin) with the addition of casein, food gelatin, glycerin, and enzymes as biocatalysts of chemical modification and further extraction of gelatin from collagen. Compositions forming films with homogeneous shapes and good mechanical properties were selected (Tensile strength reaches 3.11 MPa, while the highest value of elongation at break is 97.96%). After administering the samples to microbial scaring, the composites completely decomposed under the action of microorganisms within 30 days, which proves their biodegradation.

Study of the immunologic response of marine-derived collagen and gelatin extracts for tissue engineering applications

The host immunologic response to a specific material is a critical aspect when considering it for clinical implementation. Collagen and gelatin extracted from marine sources have been proposed as biomaterials for tissue engineering applications, but there is a lack of information in the literature about their immunogenicity. In this work, we evaluated the immune response to collagen and/or gelatin from blue shark and codfish, previously extracted and characterized. After endotoxin evaluation, bone marrow-derived macrophages were exposed to the materials and a panel of pro- and anti-inflammatory cytokines were evaluated both for protein quantification and gene expression. Then, the impact of those materials in the host was evaluated through peritoneal injection in C57BL/6 mice. The results suggested shark collagen as the less immunogenic material, inducing low expression of pro-inflammatory cytokines as well as inducible nitric oxide synthase (encoded by Nos2) and high expression of Arginase 1 (encoded by Arg1). Although shark gelatin appeared to be the material with higher pro-inflammatory expression, it also presents a high expression of IL-10 (anti-inflammatory cytokine) and Arginase (both markers for M2-like macrophages). When injected in the peritoneal cavity of mice, our materials demonstrated a transient recruitment of neutrophil, being almost non-existent after 24 hours of injection. Based on these findings, the studied collagenous materials can be considered interesting biomaterial candidates for regenerative medicine as they may induce an activation of the M2-like macrophage population, which is involved in suppressing the inflammatory processes promoting tissue remodeling. Statement of significanceMarine-origin biomaterials are emerging in the biomedical arena, namely the ones based in marine-derived collagen/gelatin proposed as cell templates for tissue regeneration. Nevertheless, although the major cause of implant rejection in clinical practice is the host's negative immune response, there is a lack of information in the literature about the immunological impact of these marine collagenous materials. This work aims to contribute with knowledge about the immunologic response to collagen/gelatin extracted from blue shark and codfish skins. The results demonstrated that despite some differences observed, all the materials can induce a macrophage phenotype related with anti-inflammation resolution and then act as immuno-modulators and anti-inflammatory inducible materials.

Tilapia wastes to valuable materials: A brief review of biomedical, wastewater treatment, and biofuel applications

Scale, skin, internal organs, viscera, trimmings, bone, tails, and fins are common fish wastes that are difficult to dispose of. Discarded fish wastes have become a global environmental concern. The conversion of fish waste into valuable materials, on the other hand, is currently in high demand around the world. In over 120 countries, there are numerous tilapia species available on the market. However, because of its low commercial value, tilapia wastes are discarded. This brief review summarises recent works on tilapia wastes utilisation in three areas: biomedical applications such as wound dressing treatment, synthesis of hydroxyapatite and gelatin extraction, wastewater treatment, and biofuel. The recovery of valuable materials from tilapia biowaste helps to reduce the environmental problems caused by discarded tilapia wastes.

Influence of extraction times on physical and functional properties of gelatin from salted jellyfish by-products

By-products of the marine industry have gained attention for producing valuable food ingredients like gelatin, which might benefit food applications and decrease food waste. Gelatin is the only protein-based food hydrocolloid, mainly used for gelling, viscosity, or emulsifying in the food industry. So far, a number of researchers have reported that by-products of salted jellyfish can produce jellyfish gelatin. The quality of jellyfish gelatin gel depends on several factors including hydrochloric acid pretreatment, extraction temperature, and extraction time. However, the functional properties such as foaming and emulsifying of jellyfish gelatin are not well understood. This research was aimed at investigating the hydrochloric acid pretreatment effect of extraction times (12, 24, and 48 h) at 60 °C on the resulting gelatin's yield, physical, and functional properties. Results showed that jellyfish gelatin's yield, gel strength, and viscosity significantly increased with increasing extraction times. Jellyfish gelatin yields were 2.74-14.07%. The gel strength of jellyfish gelatin extracted for 48 h (325.97±2.84 g) was higher than that of jellyfish gelatins extracted for 12 h (210.46±3.97 g) and 24 h (261.60±3.25 g). All jellyfish gelatins can form gels at 4 °C. Viscosity values of jellyfish gelatin were 23.00-24.50 centipoise. The foaming capacity and foaming stability of jellyfish gelatin were 12.28-17.54% and 10.52-15.78%, respectively. The emulsification activity index of jellyfish gelatin was 13.11-13.30 m2/g, and the emulsification stability index was 39.19-56.42%. As a result, varied gelatin extraction periods influenced jellyfish gelatin's physical and functional properties, indicating that the extended extraction time of 48 h delivered the jellyfish gelatin that can be used as a foaming and emulsifying agent. Therefore, turning the jellyfish by-products into food ingredients like gelatin would increase product values and potential uses in the food and medical applications.

Application of Green Technology in Gelatin Extraction: A Review

Growing demands for green and sustainable processing that eliminates the utilization of toxic chemicals and increases efficiency has encouraged the application of novel extraction technologies for the food industry. This review discusses the principles and potential application of several green technology for gelatin extraction. Several novel technologies and their processing efficiency are discussed in this review. Furthermore, factors that affect the quality of the gelatin produced from different sources are also highlighted. The potential application of ultrasound-assisted extraction (UAE), subcritical water extraction, high-pressure processing, and microwave-assisted extraction (MAE) to improve gelatin extraction are addressed. These technologies have the potential to become an efficient extraction method compared to the conventional extraction technologies. Several combinations of green and conventional technologies have been reported to yield promising results. These combinations, especially using conventional pre-treatment and green technologies for extraction, have been found to be more effective in producing gelatin. Since gelatin could be produced from various sources, it exhibits different characteristics; thus, different approaches and extraction method should be identified for specific types of gelatin. Although these technologies have limitations, such as overhydration and sophisticated systems explicitly designed for large-scale production, they are nonetheless more efficient in the long run to safeguard the environment as they reduce solvent usage and carbon footprint along the way.

Edible active film based on gelatin and Malpighia emarginata waste extract to inhibit lipid and protein oxidation in beef patties

Active gelatin-based films and extract from Malpighia emarginata (Acerola cherry) bagasse (ABE) were used to inhibit changes in the quality of beef patties during storage. Four treatments of gelatin-based active films were elaborated: edible film without ABE (EF), EF incorporated with 2% ABE (AF2), EF incorporated with 4% ABE (AF4) and EF incorporated with 6% ABE (AF6). Polyvinyl chloride (PVC) plastic film (PF) was used as a control. The active films showed adequate physical and barrier properties, being effective in controlling color changes and oxidation reactions in lipids and proteins present in the evaluated samples. The addition of ABE to the gelatin film demonstrated a positive effect up to a concentration of 4%. The AF4 treatment reduced the formation of malonaldehyde and total carbonyl compounds by 23.58 and 60.14%, respectively. Therefore, the use of active gelatin-based film and ABE appears to be a good strategy for prolonging the shelf life of frozen beef patties.

Extraction and Characterization of Gelatin from Skin By-Products of Seabream, Seabass and Rainbow Trout Reared in Aquaculture.

The expansion of fish filleting, driven by the increasing demand for convenience food, concomitantly generates a rising amount of skinning by-products. Current trends point to a growing share of aquaculture in fish production, so we have chosen three established aquaculture species to study the properties of gelatin extracted from their skin: rainbow trout, commonly filleted; and seabass and seabream, marketed whole until very recently. In the first case, trout skin yields only 1.6% gelatin accompanied by the lowest gel strength (96 g bloom), while yield for the other two species exceeds 6%, and gel strength reaches 181 and 229 g bloom for seabass and seabream, respectively. These results are in line with the proportion of total imino acids analyzed in the gelatin samples. Molecular weight profiling shows similarities among gelatins, but seabass and seabream gelatins appear more structured, with higher proportion of β-chains and high molecular weight aggregates, which may influence the rheological properties observed. These results present skin by-products of seabream, and to a minor extent seabass, as suitable raw materials to produce gelatin through valorization processes.

Gelatin extraction from fish waste and potential applications in food sector

AbstractFish solid wastes include different by‐products such as bones, scales and hides that are high in collagen content and account for up to 75% of the total body weight. These wastes can be utilised for the extraction of different products such as gelatin that can be used in different food and pharmaceutical industries. Fish gelatin can be used as a replacement for mammalian gelatin due to its nutritional profile as it contains all the amino acids: essential and non‐essential. Fish gelatin cannot only be used as a replacement for bovine and porcine gelatin but it also increases the utilisation of fish waste and reduces pollution. This review summarises the potential utilisation of different fish waste byproducts, extraction techniques and its application in different food products as an alternative to commercially available porcine and bovine gelatin.

Effect of microwave extraction temperature on the chemical structure and oil-water interface properties of fish skin gelatin

This study investigated the effect of microwave extraction temperature on the chemical structure and oil-water interface properties of fish skin gelatin. Results showed that increasing microwave extraction temperature from 55 to 75 °C led to the degradation of α subunits and breaking of the triple helical structure of gelatin, consequently exposing more hydrophobic groups and showing an improvement of amphiphilicity (58.35°-81.65°). Correspondingly, the interface pressure and adsorption also respectively increased from 8.00 to 8.90 mN/m and 43.70% to 93.66% due to its enhanced amphiphilicity. Furthermore, the volume-mean diameter and creaming index (CI) of emulsion obviously decreased, but the water holding capacity significantly increased, implying an improvement of emulsifying property. The rheological results showed the emulsion displayed a typical shear thinning behavior, and the apparent viscosity increased from 230 to 1339.4 Pa·s with the increase of microwave extraction temperature (55–75 °C) and concentration (1.0–3.0 wt%) at 0.1 s−1. The possible reason is that more gelatin molecules participated in the formation of dense network structure of continuous phase due to the higher amphiphilicity. This work would provide guiding significance for green extraction of fish skin gelatin and its application in stabilizing emulsion.

Characterization of codfish gelatin: A comparative study of fresh and salted skins and different extraction methods

The use of alternative sources for gelatin extraction is in demand in today's industries. Fish skins are an economical and sustainable source option. However, there is a lack of information about the preservation state of skins (fresh, frozen, salted, etc.) and how that affects the gelatin yield and properties, and therefore, compromise the final product.In this study we present a comparative analysis between different reported gelatin extraction processes for fresh and salted codfish (Gadus morhua) skins. The extracted products were characterized based on yield of extraction, amino acid composition, molecular weight distribution, rheological properties and gel strength, as well as the cell compatibility of the gelatins envisaging future biomedical applications.Results showed that extraction method affected the yield and gelatin properties within the same type of fish skin. Thus, it was found that water acidification step, demonstrated higher extraction yield, while other methods produced gelatins rich in OH-proline + proline, promoting enhanced gel strength and rheological properties. There is thus a compromise between yield and gelatin properties that industries need to understand before selecting their gelatin extraction method. Results, also showed that gelatins derived from salted skins demonstrated lower viscoelastic properties and gel strength, when compared with gelatins from fresh skins.Our research represents a unique comparative compilation of different extraction methods in cod skins differently conserved, as a tool on the quest for the sustainable valorization of fish by-products, included in a circular economy framework.