Department of Food Engineering, Yüzüncü Yil University, Van, Turkey.
Gelatin is a multifunctional ingredient used in foods, pharmaceuticals, cosmetics, and photographic films as a gelling agent, stabilizer, thickener, emulsifier, and film former. As a thermoreversible hydrocolloid with a narrower gap between its melting and gelling temperatures, both of which are below human body temperature, gelatin provides unique advantages over carbohydrate-based gelling agents. Gelatin is mostly produced from pig skin, and cattle hides and bones. Some alternative raw materials have recently gained attention from both researchers and the industry not just because they overcome religious concerns shared by Jews and Muslims but also because they provide, in some cases, technological advantages over mammalian gelatins. Fish skins from a number of fish species are among the other sources that have been comprehensively studied as sources for gelatin production. Fish skins have a significant potential for the production of high-quality gelatin with different melting and gelling temperatures over a much wider range than mammalian gelatins, yet still have a sufficiently high gel strength and viscosity. Gelatin quality is industrially determined by gel strength, viscosity, melting or gelling temperatures, the water content, and microbiological safety. For gelatin manufacturers, yield from a particular raw material is also important. Recent experimental studies have shown that these quality parameters vary greatly depending on the biochemical characteristics of the raw materials, the manufacturing processes applied, and the experimental settings used for quality control tests. In this review, the gelatin quality achieved from different fish species is reviewed along with the experimental procedures used to determine gelatin quality. In addition, the chemical structure of collagen and gelatin, the collagen-gelatin conversion, the gelation process, and the gelatin market are discussed.
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Meat Sci. 2012 May 24;:
22682071
Department of Food and Nutrition, and Research Institute of Human Ecology, Seoul National University, Seoul 151-742, Republic of Korea.
This study was conducted to determine if glutinous rice flour (GRF) could be a functional food additive to potentially replace corn starch (CS), soy protein isolate (SPI) and/or sodium tripolyphosphate (STPP) to improve the physicochemical and organoleptic characteristics of seasoned beef patties. GRF had a lower cook loss among the treatment groups due to an increase in fat and moisture retentions (p<0.05). GRF lowered texture profile values for hardness, gumminess, springiness, and chewiness (p<0.05) of the patties, which are generally beneficial for this product. The beef patties with GRF were juicier and more tender than the control and other treatments (p<0.05). Hedonic scores for juiciness, tenderness and overall acceptability were the highest for the beef patties with 1 and 3% GRFs, suggesting that GRF may be an effective functional ingredient to improve the textural quality of seasoned beef patties.
Department of Poultry Science, Texas A & M University, College Station, TX 77843-2472, USA.
BACKGROUND The objective of this study was to evaluate the effects of low storage temperatures on shell egg quality. RESULTS Approximately 2100 shell eggs were collected and stored at - 1.1, 0.6, 2.2, 3.9, 5.6 and 7.2 °C for up to 4 weeks. Eighteen eggs at each storage temperature were evaluated after 0, 2, 7, 14, 21 and 28 days of storage. Haugh units (HU), yolk index (YI), albumen pH (pHA), yolk pH (pHY) and angel food cake density (CD) were measured. Shell egg quality tended to be preserved better at below 2.2 °C, as high HU and YI values relative to eggs stored at 7.2 °C were determined on day 28. However, storage at - 1.1 °C tended to cause the opposite effect, especially highly declined HU values over time. Significantly different HU values of shell eggs were measured after 14 days of storage, with eggs stored at 0.6 and 2.2 °C having the highest HU values, 80.42 and 77.97 respectively. CONCLUSION A lower temperature limit for shell egg storage could be established between 0.6 and 2.2 °C, as both temperatures showed the highest HU values, 77.88 and 77.60 respectively, after 28 days of storage.
College of Light Industry and Food Sciences, South China University of Technology, Guangzhou 510640, China.
Loach protein hydrolysates (LPH) prepared by papain digestion were fractionated into four fractions, LPH-I (MW > 10 kDa), LPH-II (MW = 5-10 kDa), LPH-III (MW = 3-5 kDa), LPH-IV (MW < 3 kDa), and the in vitro antioxidant and antiproliferative (anticancer) activities of all fractions were determined. LPH-IV showed the lowest IC(50) value (16.9 ± 0.21 mg/mL) for hydroxyl radical scavenging activity and the highest oxygen radical scavenging capacity (ORAC) value (reaching 215 ± 5.9 mM Trolox/100 g loach peptide when the concentration was 60 μg/mL). Compared with other fractions, LPH-IV also exhibited stronger antiproliferative activity for human liver (HepG2), breast (MCF-7), and colon (Caco-2) cancer cell lines in a dose-dependent manner. When the protein concentration was 40 mg/mL, the HepG2 and MCF-7 cell proliferation of LPH-IV reached 7 and 4%, respectively, with no significant difference from those of LPH (8 and 7%, p > 0.05), with significantly less growth than those of LPH-I, LPH-II, and LPH-III, respectively (p < 0.05). The Caco-2 colon cell proliferation of LPH-IV was 12.8- and 8.7-fold smaller than those of LPH-I and LPH-II, respectively (p < 0.05). All of the fractions had a greater ability to inhibit Caco-2 colon cancer cell proliferation than to inhibit HepG2 liver cancer and MCF-7 breast cancer cell proliferation. The ORAC values of most of the fractions correlated (R(2)> 0.86, p < 0.01) with the antiproliferative activity of the three cancer cell lines, suggesting that higher antioxidant activity leads to better antiproliferative activity. However, further mechanistic and human clinical studies of the anticancer activity of loach protein hydrolysate fractions are needed.
South China University of Technology, Guangzhou 510640, China.
In this study, sodium caseinate hydrolysates produced by papain with strong growth-stimulating activity for Streptococcus thermophilus (St) and Lactobacillus delbrueckii subsp. bulgaricus (Lb) were obtained. A series of separation methods including ultrafiltration, macroporous adsorption resin chromatography, gel filtration chromatography, and reverse-phase high-performance liquid chromatography (RP-HPLC) were applied to isolate and purify the peptide(s), which were mainly responsible for the activity. Finally, three novel growth-stimulating peptides, H-2-A, F2-c, and F2-b, corresponding to amino acid residues 29-35 and 103-108 of bovine α(S2)-casein and 181-186 of bovine α(S1)-casein, respectively, were obtained. With supplementation of H-2-A, F2-b, or F2-c at a protein concentration of 0.3%, the biomass yield of these two lactic acid bacteria (LAB) was enhanced by 193.3, 166.7, or 151.7%, respectively. In addition, there were significant (p < 0.05) increases in viable counts of St and lactic acid production of LAB in the presence of the purified peptides.
J Food Sci. ;75 (9):C731-9
21535584
Faculty of Agricultural Technology, Burapha Univ., Sakaeo Campus, Watthananakhon, Sakaeo 27160, Thailand.
The addition of microbial transglutaminase (MTGase) generally increased the gel strength of lizardfish (Saurida spp.) scale gelatin gels (P≤0.05) with an increase in gel strength with the addition of MTGase up to 0.5%(w/v). The texture profile analysis compression tests of lizardfish scale gelatin gel with and without MTGase were studied to determine their effects on gel characteristics. MTGase added to the gels decreased the band intensity of the β- and α-components with increasing concentrations of enzyme. Gel microstructures with various concentration of MTGase showed denser strands in the gels with enzyme compared with the looser stands in non-enzyme-treated gel samples. Films cast from lizardfish scale gelatin with and without 0.5% MTGase and bovine gelatin films were transparent and flexible. The lizardfish gelatin films were all slightly yellowish while the bovine gelatin films were clearer. The L value of bovine gelatin films had the highest value (P≤0.05) whereas lizardfish scale gelatin films with and without enzyme were not significantly different (P>0.05) for L, a, and b values and ΔE. The film's mechanical properties included tensile strength (TS) and elongation at break (E) were not significantly different (P > 0.05) for E and the films of lizardfish scale gelatin showed higher TS than the films without enzyme added (P ≤ 0.05). The water vapor permeability of films from lizardfish scale gelatin with and without 0.5% MTGase and bovine gelatin films were 21.0 ± 0.17, 26.3 ± 0.79, and 25.8 ± 0.09 g·mm/m(2)·d·kPa, respectively, while the oxygen transmission rate of all 3 types of films were less than 50 cc O(2)/m(2)·d.
J Food Sci. 2010 Aug 1;75 (6):C582-7
20722914
Dept. of Food Science, Cornell Univ., Ithaca, NY 14853-7201, USA.
Fish skin gelatin was hydrolyzed with papain to produce antioxidant peptides. Response surface methodology (RSM) was applied to optimize the hydrolysis conditions (including enzyme to substrate ratio [E/S], hydrolysis time, and temperature). The highest degree of hydrolysis (DH)(50.1 +/- 1.1%) was obtained at an E/S of 2% at 56.8 degrees C, 2.11 h, and was not significantly different from the predicted values within a 95% confidence interval. The highest 1,1-diphenyl-2-picrylhydrazyl (DPPH)(96.8 +/- 0.9%) and 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS(*+))(9.80 +/- 0.11 mM Trolox [6-hydroxy-2,5,7,8-tetramethychroman-2-carboxylic acid]) radical-scavenging activities of fish gelatin hydrolyzates were obtained at an E/S of 3% at 52.1 degrees C, 2.65 h, and both DPPH and ABTS(*+) radical-scavenging activities were not significantly different from the predicted values 97.3% and 9.86 mM Trolox within the 95% confidence interval. Therefore, RSM is an efficient way to optimize fish gelatin hydrolysation and the resultant hydrolyzates show promise as antioxidant peptides. Practical Application: There is a growing interest in the use of fish gelatin as an alternative to mammalian gelatin. One potential use is as a source of widely acceptable functional compounds. In this study, a search for antioxidant peptides from fish gelatin prepared by an enzymatic method has been successfully done. This suggests that this is a practical way to obtain bioactive peptides.
Research Center for Quality Supervision and Testing of Foods and Cosmetics, China National Center for Food Quality Supervision and Testing, Shanghai Inst. of Quality Inspection and Technical Research, Shanghai, China.
Pretreatments with different chemicals at different concentrations to remove Ca compounds were studied to determine their effects on gelatin extraction from silver carp (Hypophthalmichthys molitrix) scales. During Ca removal with HCl, citric acid, and EDTA, all 3 chemicals were able to decalcify (>90%) scales; however, protein losses with EDTA were lower than with HCl and citric acid (P < 0.05), and protein losses with citric acid were lower than with HCl (P < 0.05). Ca removal with HCl yielded a solution where 4% to 5% of the protein was Hyp, with estimated gelatin losses from 0.9% to 2.5%. After 0.20 mol/L HCl was used for Ca removal, the extracted gelatin solution was 15.4% of the initial scales weight and gave a gel strength of 128 g. After using 1.2 g/L citric acid for Ca removal, the extracted gelatin solution was only 9% of the scales and the gel strength was 97 g. Using 0.20 mol/L EDTA for Ca removal gave a yield of 22% and a gel strength of 152 g. These data suggest that EDTA at 0.20 mol/L provides the best Ca removal with minimal collagen/gelatin removal (estimated gelatin loss was less than 0.013%) during the Ca removal step, and subsequently gave a high gelatin yield and gel strength. Fish gelatin has generally been extracted from fish skins and occasionally fish bones. This article focuses on removing the Ca compounds in fish scales and then producing fish gelatin with a good gel strength and yield. With further studies, this study may help the fish industry to have a new source of fish gelatin for food and pharmaceutical applications.
Dept. of Food Science, College of Agriculture and Life Sciences, Cornell Univ., Stocking Hall, Ithaca, NY 14853, USA.
The objective of this study was to compare water gel desserts from various gelatins using instrumental measurements. The puncture test and texture profile analysis (TPA) with compression were determined at 25% and 75% deformation; the melting properties were determined rheologically by monitoring the change of storage modulus (G') with increasing temperature. The measurements with 25% deformation were always nondestructive, while measurements with 75% deformation were mostly destructive. Desserts made from Alaska pollock gelatin (AG) or gelatin mixtures containing AG were more resistant to the destruction caused by the large deformation than tilapia gelatin and pork gelatins. In addition, the gel dessert made from AG melted at a lower temperature than those from tilapia skin gelatin and pork gelatins, while desserts made from gelatin mixtures reflected the melting properties of the separate gelatins.
Biosystems Engineering Dept., Auburn Univ., 200 Tom E. Corley Building, Auburn, AL 36849-5417, USA.
To determine the nanostructure of gelatin from catfish (Ictalurus punctatus) skin, atomic force microscopy (AFM) was used to study gelatin aggregates. The gelatin was extracted at an optimized acid concentration after alkaline processing. First, the AFM imaging parameters were optimized to obtain high-quality images. Then height mode with a 2-dimensional plane, 3-dimensional topographical images, and error signal mode images, which removed slow variations in surface topography but highlighted the edges of sample features, were used to analyze the structure of particles. The results describe fish gelatin at a nanoscale level for the first time and are compared with AFM images of mammalian gelatins. Both annular pores with diameters averaging 118 nm and spherical aggregates with an average diameter of 267 nm were seen in the AFM images of fish gelatin. From the AFM images, we propose that the structures formed were determined by whether the solution penetrated into the gelatin molecules evenly or not during hydrolysis. A scheme for the formation of annular pores and spherical aggregates is proposed.
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Lipo Chemicals Inc, Paterson NJ 07504, USA. n.dayan@lipochemicals.com
This study compared the genotoxic potential of a polymeric associative thickener used in topically applied emulsions preserved with three different preservative systems. The method used for the assessment of genotoxicity is the in vitro micronucleus test [Organization for Economic Cooperation and Development (OECD) guideline number 487]. When changing an additive such as a preservation system in a raw material, it is crucial to re-evaluate its toxicity potential because this change may significantly alter its properties. This study shows that at the levels tested neither of the systems evaluated demonstrated any cytotoxic or genotoxic effects. Skin exposure must take into consideration factors such as duration, skin condition and metabolism, but most importantly concentration. Although preservatives can be toxic at high concentrations, they are usually safe at the concentrations used in cosmetic raw materials and formulations. If used to preserve raw materials, they undergo further dilution when added to the formulation.
J Food Sci. ;75 (9):S469-76
21535620
Cornell Univ., Dept. of Food Science, Stocking Hall, Ithaca, NY, 14853-7201, USA.
Fish skin gelatin has recently been of interest as a product that eliminates religious concerns (Jewish and Muslim) and could be an alternative value-added product from fish waste. Recent research has shown that extraction conditions affect gelatin quality. In this study, gelatin from Asian silver carp skin and extracted under different conditions have been studied sensory properties using descriptive analysis and time intensity testing to determine how extraction conditions affect gelatin sensory properties. Three pairs of gelatin samples were selected based on their gel strength, viscosity, and melting temperature. The impacts of different extraction conditions on instrumental methods were examined. Some functionality measurements were also done to determine how sensory measurements correlate with instrumental measurements. The gel strength varied between 60 ± 10 g and 590 ± 30 g while the viscosity varied between 1.9 ± 0.0 cP and 7.4 ± 0.2 cP. The hardness, melting and gelling temperature of the samples were well correlated with the gel strength (r > 0.90). The results indicated that the strongest correlation among all the sensory attributes was between firmness and melting temperature, which was a negative correlation (-0.75) suggesting that the firmer the gel samples the slower they melt. The viscosity was found to be very discriminative between samples in terms of sensory properties. The functional measurements were found to be strongly correlated within themselves while the sensory measurements were less so, which might be due to the greater variability when using sensory panelists or sensory parameters simply might not be related. The firmness, melting rate, and aftertaste were those sensory attributes most successfully discriminated by the panelists.
J Food Sci. ;75 (9):E620-6
21535597
Fish Processing Div., Central Inst. of Fisheries Technology (ICAR) Cochin-682 029, Kerala, India. george66jiji@rediffmail.com
Films of 0.11 to 0.13 mm thickness were prepared using gelatins from the skins of cultured freshwater carp species and mammalian gelatins viz., porcine and bovine skin gelatin. A comparative study was made on the physical, mechanical, and barrier properties of these films. The amino acid composition, gel strength, clarity, and gel setting point of the gelatins were also determined. Carp skin gelatins had a lower imino acid content (19.16% to 20.86%) than mammalian skin gelatins (22.91% to 23.7%). Grass carp gelatin had gel strength of 230.2 B that is comparable to the reported value for bovine skin gelatin (227.2 B). The bloom values of rohu and common carp skin gelatins were 188.6 B and 181.3 B, respectively, which were significantly lower than mammalian gelatins. Mammalian gels have significantly higher (P < 0.05) setting temperatures (23.7 to 24.2 °C) than carp skin gelatins. Tensile strength (TS) was lowest for films from common carp and rohu skin gelatin (490 and 497 kg/cm(2), respectively) and highest for porcine skin gelatin film. The degree of transparency (L*) was significantly higher for films from grass carp, bovine hide, and pork skin gelatin films. Carp skin gelatin films had significantly lower water vapor permeability (WVP) and oxygen permeability (OP) than mammalian skin gelatin films, which indicated that carp skin gelatin based films have superior barrier properties than mammalian skin gelatin films.
J Food Sci. 2010 Oct ;75 (8):E565-71
21535497
Cornell Univ., Dept. of Food Science, Stocking Hall, Ithaca, NY 14853-7201, USA.
Gelatin is used as a functional ingredient in many foods, pharmaceuticals, and cosmetics as a stabilizing, thickening, and gelling agent. The rheological properties of gelatins are important in the potential functionality of gelatin. This study is designed to determine the rheological properties of gelatin extracted from the skins of silver carp (Hypophthalmichthys molitrix Valenciennes 1844). The extracted gelatin is compared with commercially available gelatins from different sources. The results indicate that the stress-strain relationship of gelatin gels remained in the linear region over a broad range of strains and stresses and gave similar elastic moduli at varying frequency, stress, and strain levels. One exception was a commercial high molecular weight fish skin gelatin that gave a lower elastic modulus indicating that its gel strength was low compared to the other gelatin samples studied. Gel strength varied between 220 and 1230 g while viscosity varied between 4.53 and 6.91 cP among the samples. Melting and gelling temperatures varied between 14.2 and 32.3 °C and 3.2 and 25.4 °C, respectively. Texture profile analysis was done at 2 deformation levels, 25% and 75%, and the results correlated well with gel strength. The correlations between hardness, cohesiveness, and gumminess and gel strength were 0.98, 0.82, and 0.99, respectively, at 25% deformation but lower at 75% deformation. The results suggest that rheological measurements might be used to quickly estimate gel strength using less material. In addition, the silver carp skin gelatin seemed to be of equal quality to some of the commercial gelatins.
J Food Sci. 2010 May ;75 (4):C317-21
20546388
Cindy K Bower,
Roberto J Avena-Bustillos,
Katie A Hietala,
Cristina Bilbao-Sainz,
Carl W Olsen,
Tara H McHugh
USDA Agricultural Research Service, Subarctic Agricultural Research Unit, Fairbanks, AK 99775-7200, USA. Cindy.Bower@ars.usda.gov
Alaska pollock (Theragra chalcogramma) is the U.S.A.'s largest commercial fishery, with an annual catch of over 1 million tons. During pollock processing, the skins are discarded or made into fish meal, despite their value for gelatin production. The absence of gelatin-processing facilities in Alaska necessitates drying of the skins before transport to decrease the moisture content, but conventional hot-air drying is expensive. This study evaluated a less energy-intensive technology, the use of desiccants for reducing water weight in pollock skins prior to shipment. To ensure that the functional properties of gelatin obtained from dried pollock skins were not affected during desiccation, gelatins were prepared from each skin-drying treatment and compared with gelatin extracted from air-dried pollock skins. None of the desiccation treatments decreased the gel strength of pollock skin gelatin, nor were there major differences in gelling temperature or viscosity among the gelatin solutions. This suggests that pollock skins can be economically stabilized for transport to a gelatin-processing facility through the use of regenerable desiccants that are already common in the food industry. PRACTICAL APPLICATION: Pollock skins destined for gelatin production can be stabilized using chemical desiccants prior to shipment. The dehydration process does not harm the functional properties of gelatin, such as gel strength, gelling temperature, and viscosity. This research suggests that fish skins can be economically stabilized for transport to a gelatin-processing facility through the use of regenerable desiccants that are already common in the food industry.
Bioresour Technol. 2010 Mar 24;:
20346650
Department of Food Science and Technology, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran.
Physico-chemical properties of gelatin extracted from rainbow trout (Onchorhynchus mykiss) skin were optimized using response surface methodology (RSM). Central rotatable composite design was applied to study the combined effects of NaOH concentration (0.01-0.21N), acetic acid concentration (0.01-0.21N) and pre-treatment time (1-3h) on yield, molecular weight distribution, gel strength, viscosity and melting point of gelatin. Regression models were developed to predict the variables. Predict values of multiple response at optimal condition were that yield=9.36%, alpha(1)/alpha(2) chain ratio=1.76, beta chain percent=32.81, gel strength=459g, viscosity=3.2mPas and melting point=20.4 degrees C. The optimal condition was obtained using 0.19N NaOH and 0.121N acetic acid for 3h. The results showed that the concentration of H(+) during pre-treatment had significant effect on molecular weight distribution, melting point and gel strength. The concentration of OH(-) had significant effect on viscosity and for extraction yield, pretreatment time was the critical factor.
Department of Chemistry, Food Chemistry, University of Hamburg, Hamburg, Germany.
Parvalbumins are well-known as major fish allergens. However, no quantitative analytical method is currently available for the determination of parvalbumins from different fish species. The aim of this study was the isolation of the various parvalbumins by the application of gel chromatography and dialysis and the development and validation of a competitive indirect ELISA for the determination of parvalbumins from various fish species. This ELISA method was applied to several fish gelatins and isinglass samples used in food production. The competitive ELISA was capable of detecting all tested parvalbumins within a range of 0.1-0.5 mg/L. No parvalbumin was detected in any of the investigated fish gelatins or in a fish skin used as raw material for fish gelatin production. Contrarily, isinglass was found to contain parvalbumin amounts of up to 414.7 +/- 30.6 mg/kg.
Department of Physiological Chemistry, Yale University, New Haven.
The Gates photographic film method for pepsin estimation as developed by Gilman and Cowgill measures an activity corresponding to that determined by the hemoglobin method of Anson and Mirsky rather than that resulting from the use of the gelatin viscosity technique. Therefore, the presence of gelatinase is not a source of great error in the gelatin film procedure.
Dept. of Food Science, Cornell Univ., Stocking Hall, Ithaca, NY 14853-7201, USA.
Fish skins are a by-product of the fish processing industry that can be successfully processed into gelatin. This study was designed to optimize the extraction process to obtain the highest yield, gel strength, and viscosity for gelatin production from silver carp skin. A fractional factorial design (2 levels, resolution III, 2(9-5)) was chosen to screen 9 parameters to determine the most significant ones. Those found to be significant were optimized to determine the maximum value for 3 dependent variables mentioned above. The hydroxyproline content and hydroxyproline/protein ratio of the skin were 1.7% and 6.5%, respectively. The protein content of the skin was 26%. The hydroxyproline content of the gelatin for the sample giving the highest hydroxyproline/protein ratio was 10.9%. This sample was arbitrarily called pure gelatin and the purity of the remaining samples was between 71.8% and 97%. The highest protein and gelatin recovery was 78.1% and 98.8% of the total available, respectively. The latter, gelatin recovery, is proposed to be used instead of protein yield. Four variables were determined as significant in screening and these variables were studied by a central composite rotatable design (4-factor and 5-level with 6 central points) to model the system and response surface methodology was used for optimization. The optimum extraction conditions were 50 degrees C for the extraction temperature, 0.1 N HCl for the acid concentration, 45 min for the acid pretreatment time, and finally 4 : 1 (v/w) for the water/skin ratio. The predicted responses for these extraction conditions were 630 g gel strength, 6.3 cP viscosity, and 80.8% gelatin recovery. The data suggest that silver carp skin gelatin is similar to those of fish gelatins currently being exploited commercially.
Research Center for Quality Supervision and Testing of Foods and Cosmetics, China National Center for Food Quality Supervision and Testing, Shanghai Inst. of Quality Inspection and Technical Research, Shanghai, China.
Pretreatments with different chemicals at different concentrations to remove Ca compounds were studied to determine their effects on gelatin extraction from silver carp (Hypophthalmichthys molitrix) scales. During Ca removal with HCl, citric acid, and EDTA, all 3 chemicals were able to decalcify (>90%) scales; however, protein losses with EDTA were lower than with HCl and citric acid (P < 0.05), and protein losses with citric acid were lower than with HCl (P < 0.05). Ca removal with HCl yielded a solution where 4% to 5% of the protein was Hyp, with estimated gelatin losses from 0.9% to 2.5%. After 0.20 mol/L HCl was used for Ca removal, the extracted gelatin solution was 15.4% of the initial scales weight and gave a gel strength of 128 g. After using 1.2 g/L citric acid for Ca removal, the extracted gelatin solution was only 9% of the scales and the gel strength was 97 g. Using 0.20 mol/L EDTA for Ca removal gave a yield of 22% and a gel strength of 152 g. These data suggest that EDTA at 0.20 mol/L provides the best Ca removal with minimal collagen/gelatin removal (estimated gelatin loss was less than 0.013%) during the Ca removal step, and subsequently gave a high gelatin yield and gel strength. Fish gelatin has generally been extracted from fish skins and occasionally fish bones. This article focuses on removing the Ca compounds in fish scales and then producing fish gelatin with a good gel strength and yield. With further studies, this study may help the fish industry to have a new source of fish gelatin for food and pharmaceutical applications.
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