• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.2
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• pp.209-214
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• 2016

The aim of this study was to investigate the effects of pork skin gelatin on the physicochemical properties (pH, CIE color value, water holding capacity, cooking yield, viscosity, proximate composition, and texture profile analysis) of emulsion-type sausage. Emulsion-type sausages were manufactured with 0% (control), 1%, 3%, and 5% pork skin gelatin. Moisture contents of samples containing 3% and 5% pork skin gelatin were significantly higher than those of the control and samples containing 1% pork skin gelatin (P<0.05). Protein contents were the highest in samples containing 5% pork skin gelatin (P<0.05). The pH values of uncooked and cooked samples increased with increasing pork skin gelatin level (P<0.05). The lightness and yellowness values of cooked samples containing pork skin gelatin were higher than those of the control (P<0.05). In addition, redness values of cooked samples containing 3% and 5% pork skin gelatin were significantly lower than those of the control and samples containing 1% pork skin gelatin (P<0.05). Water holding capacity (WHC) was the lowest in control, and samples containing 3% and 5% pork skin gelatin had significantly higher WHC compared to the other samples (P<0.05). Cooking yield of samples increased with increasing concentration of pork skin gelatin (P<0.05). Samples containing 3% and 5% pork skin gelatin showed higher viscosity than the control and sample containing 1% pork skin gelatin (P<0.05). Springiness, cohesiveness, and chewiness of samples were not significantly different among the samples. Hardness values of the control and sample containing 1% pork skin gelatin were lower than those of other samples (P<0.05), and samples containing 5% pork skin gelatin had the highest hardness (P<0.05). Gumminess of sample containing 5% pork skin gelatin was significantly higher than that of the control (P<0.05). The results show that pork skin gelatin could improve the potential of emulsion-type sausage physicochemical properties.

• Food Science of Animal Resources
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• v.39 no.4
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• pp.576-584
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• 2019

This study was performed to evaluate the physicochemical properties of myofibrillar protein (MP) gels containing pork skin gelatin at different salt concentrations. MP gels were prepared to the different salt levels (0.15, 0.30, and 0.45 M) with or without 1.0% of pork skin gelatin. Cooking yield (CY), gel strength, shear stress were measured to determine the physical properties, and SDS-polyacrylamide gel electrophoresis, scanning electron microscopy, fourier transform infrared spectroscopy, sulfhydryl group and protein surface hydrophobicity was performed to figure out the structural changes among the proteins. The addition of gelatin into MP increased CYs and shear stress. MP at 0.45 M salt level had the highest CY and shear stress, as compared to MPs at lower salt concentrations. As the salt concentration of MP gels increased, the microstructure became the compact and wet structures, and decreased the amount of ${\alpha}-helix$/unordered structures and ${\beta}-sheet$. MP with gelatin showed a decreased amount of ${\alpha}-helix$/unordered structures and ${\beta}-sheet$ compared to MP without gelatin. The addition of gelatin to MP did not affect the sulfhydryl group, but the sulfhydryl group decreased as increased salt levels. MP mixtures containing gelatin showed a higher hydrophobicity value than those without gelatin, regardless of salt concentration. Based on these results, the addition of gelatin increased viscosity of raw meat batter and CY of MP gels for the application to low salt meat products.

• Korean Journal of Food Science and Technology
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• v.49 no.1
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• pp.80-84
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• 2017

Physicochemical properties of spent hen chicken-thigh sausage manufactured with 0 (control), 1, 3, and 5% pork skin gelatin were determined. The moisture contents of samples containing pork skin gelatin were higher than control samples. The pH value of cooked samples increased with increasing pork skin gelatin level (p<0.05). The lightness and yellowness values of cooked samples containing gelatin were higher than lightness and yellowness values of the control (p<0.05). The cooking yield of samples increased with increasing concentration of pork skin gelatin (p<0.05). The samples containing 3 and 5% pork skin gelatin showed higher viscosity than control and gelatin 1% sample (p<0.05). Hardness values were lowest in the of control group and highest in samples containing 5% pork skin gelatin (p<0.05). Overall acceptability of 5% gelatin samples was higher than acceptability of the control samples (p<0.05). The results showed that the pork skin gelatin could improve the physicochemical properties of spent hen chicken-thigh sausage.

• Food Science of Animal Resources
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• v.40 no.6
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• pp.1033-1043
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• 2020

This study investigated the impacts of gelatin hydrolysate addition on the technological properties and lipid oxidation stability of cooked sausage. Gelatin hydrolysate was prepared from pork and duck skin gelatin, through stepwise hydrolysis using collagenase and pepsin. The cooked sausages were formulated without gelatin (control) or with 1% pork skin gelatin, 1% duck skin gelatin, 1% pork skin gelatin hydrolysate, and 1% duck skin gelatin hydrolysate. The pH, color characteristics, protein solubility, cooking loss, and textural properties of cooked sausages were evaluated, and the 2-thiobarbituric acid reactive substances (TBARS) value was measured weekly to determine lipid oxidation stability during 4 wk of refrigerated storage. Enzymatic hydrolysis of gelatin decreased protein content and CIE L* but increased redness and yellowness (p<0.05). When 1% gelatin or gelatin hydrolysate was incorporated in cooked sausage, however, little to no impacts on pH value, moisture content, protein content, color characteristics, protein solubility, and cooking loss were found (p>0.05). The addition of 1% duck skin gelatin hydrolysate increased the cohesiveness and chewiness of cooked sausages. The inclusion of 1% duck skin gelatin accelerated lipid oxidation of cooked sausages during refrigerated storage (p<0.05), whereas duck skin gelatin hydrolysate caused a lower TBARS value in cooked sausage compared to duck skin gelatin. The results show comparable effects of gelatin and gelatin hydrolysate addition on the technological properties of cooked sausages; however, the oxidative stability of raw materials for gelatin extraction should be evaluated clearly in further studies.

• Food Science of Animal Resources
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• v.24 no.3
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• pp.266-272
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• 2004

The objective of this study was to investigate the physicochemical characteristics of gelatin extracted from pork skin under soaking in various acid solutions (lactic acid, acetic acid, and citric acid). Gelatin sol was extracted at 8$0^{\circ}C$, frozen at -2$0^{\circ}C$ and lyophilized it for 3 days to be completely dried in freeze drying unit. In the evaluation of gelatin quality, gelatin soaked in citric acid showed higher L- and a-values than those of any other gelatin (p<0.05). Gelatin treated by acetic acid showed the highest gel strength, cohesiveness, and brittleness. The content of hydroxyproline amino acid in gelatin treated by acetic acid was larger than one of gelatin treated in lactic and citric acid in order. From the experimental results, the highest quality of gelatin in all of period, which was soaked in acetic acid and lactic acid, has a more good quality than gelatin soaked in citric acid.

• Korean Journal of Food Science and Technology
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• v.26 no.6
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• pp.683-689
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• 1994

With a view to utilizing effectively fish skin wastes from marine manufactory, a gelatin solution extracted from yellowfin sole skin was fractionated by precipitation with ethanol, and then the functional and physico-chemical properties for the fractionated gelatin were determined. Ethanol was added up to 50% of ethanol content to a gelatin solution extracted from yellowfin sole skin, then the mixture was left to stand at $0^{\circ}C$ for 12 hours. Finally, the precipitates were dried by hot-air ($40^{\circ}C$). The gel strength and melting point of a 10% gel of gelatin prepared from yellowfin sole skin by precipitation with ethanol has 322.4g and $23.3^{\circ}C$, respectively. The physico-chemical properties of the ethanol treated fish skin gelatin were superior to those of fish skin gelatin prepared without ethanol treatment. Besides, the functional properties of the ethanol treated gelatin were lower in solubility and higher in water holding capacity, oil binding capacity, emulsifying activity, emulsifying stability, foam expansion and foam stability than those of pork skin gelatin sold on market as well as gelatin prepared without ethanol treatment. It may be concluded, from these results, that the fish skin gelatin prepared by precipitation with ethanol can be effectively utilized as a human food by improving the functional properties.

• Food Science of Animal Resources
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• v.39 no.2
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• pp.229-239
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• 2019

The objectives of this study were to determine the interaction between porcine myofibrillar proteins and various gelatins (bovine hide, porcine skin, fish skin, and duck skin gelatins) and their impacts on gel properties of porcine myofibrillar proteins. Porcine myofibrillar protein was isolated from pork loin muscle (M. longissimus dorsi thoracis et lumborum). Control was prepared with only myofibrillar protein (60 mg/mL), and gelatin treatments were formulated with myofibrillar protein and each gelatin (9:1) at the same protein concentration. The myofibrillar protein-gelatin mixtures were heated from $10^{\circ}C$ to $75^{\circ}C$ ($2^{\circ}C/min$). Little to no impacts of gelatin addition on pH value and color characteristics of heat-induced myofibrillar protein gels were observed (p>0.05). The addition of gelatin slightly decreased cooking yield of heat-induced myofibrillar protein gels, but the gels showed lower centrifugal weight loss compared to control (p<0.05). The addition of gelatin significantly decreased hardness, cohesiveness, gumminess, and chewiness of heat-induced myofibrillar gels. Further, sodium dodecyl poly-acrylamide gel electrophoresis (SDS-PAGE) showed no interaction between myofibrillar proteins and gelatin under non-thermal conditions. Only a slight change in the endothermic peak (probably myosin) of myofibrillar protein-gelatin mixtures was found. The results of this study show that the addition of gelatin attenuated the water-holding capacity and textural properties of heat-induced myofibrillar protein gel. Thus, it could be suggested that well-known positive impacts of gelatin on quality characteristics of processed meat products may be largely affected by the functional properties of gelatin per se, rather than its interaction with myofibrillar proteins.

• Applied Biological Chemistry
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• v.36 no.6
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• pp.440-448
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• 1993

To utilize effectively fish skin wasted from fish processing, a dover sole skin gelatin was prepared by alkaline extraction method and the physico-chemical properties were examined. Conditions for the suitable pretreatment, extraction and decolorization for gelatin preparation from dover sole skin are as follows: the skin is limed with 1.0% calcium hydroxide solution at $5^{\circ}C$ for 4 days, washed thoroughly for 2 days with tap water, extracted with 5 volumes of water $(pH\;5.0{\sim}7.0)$ to dehydrated skin for 3 hours at $50^{\circ}C$, and then bleached with 3% activated carbon. Though dover sole skin gelatin was prepared under above conditions, physico-chemical property values such the melting point and gelling point of that were lower than those of yellowfin sole skin gelatin as well as the commercial pork skin gelatin. Therefore, the purified dover sole skin gelatin requires a suitable modification operation for better quality gelatin manufacture.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.716-723
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• 1993

To utilize effectively fish skin wasted from fish processing, a yellowfin sole skin gelatin was prepared by alkaline extraction method and the physico-chemical properties were examined. Conditions for the suitable extraction and decolorization for gelatin preparation from yellowfin sole skin are as follows: the skin is limed with 1.5% calcium hydroxide solution at $5^{\circ}C$ for 5 days, washed throughly with tap water, extracted with 6 volumes of water ($pH5.0{\sim}7.0$) to dehydrated skin for 3 hours at $50^{\circ}C$, and then bleached with 3% activated carbon. Though yellowfin sole skin gelatin was prepared under above condition, the physico-chemical property values such the melting point and gelling point of that were lower than those of pork skin gelatin. Therefore, the purified yellowfin sole skin gelatin requires a suitable modification operation for more a good quality gelatin manufacture.

• Applied Biological Chemistry
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• v.36 no.4
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• pp.290-295
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• 1993

In order to utilize effectively fish skin from fish processing, characteristics of the yellowfin sole and dover sole skins were investigated. In the yellowfin sole, the crude protein content and yield of fish skin used for the preparation of gelatin were 22.3% and 11.3%, respectively and in the dover sole, 17.2% and 8.9%, respectively. In the yellowfin sole skin, the soluble and insoluble collagen occupied 66.1% and 33.9%, respectively and in the dover sole skin, 78.8% and 21.1%, respectively. No difference in the amino acid composition between soluble and insoluble collagen was detected. The sum of proline and hydroxyproline content in the collagen extracted from fish skin was lower than that of those from pork skin or bone. The molecular weight of the two major subunits from the soluble collagen in the yellowfin sole skin were found to be 143 KDa and 202 KDa. Those in the dover sole skin were 142 KDa and 207 KDa. The physico-chemical properties such as the melting point and gelling point of yellowfin sole skin gelatin were superior to those of dover sole skin gelatin.