• 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.

• Journal of Animal Science and Technology
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• v.62 no.4
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• pp.553-564
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• 2020

The present study investigated the effects of duck skin gelatin and carrageenan on the quality of semi-dried restructured jerky. Restructured jerky was prepared as follows: G0 (control, without duck skin gelatin and carrageenan), G0C (0.3% carrageenan), G0.5 (0.5% duck skin gelatin), G0.5C (0.5% duck skin gelatin and 0.3% carrageenan), G1 (1.0% duck skin gelatin), and G1C (1.0% duck skin gelatin and 0.3% carrageenan). The moisture content was the highest for the semi-dried restructured jerky from G0.5C and G1C groups, which showed the lowest for shear force value (p < 0.05). The processing yield of semi-dried restructured jerky with carrageenan was higher compared to that of the control group (p < 0.05). The rehydration capacities of G0.5, G0.5C, and G1C groups were significantly higher than the rehydration capacity of the control group (p < 0.05). Water activity, lightness, yellowness, flavor score, texture score, and overall acceptability were the highest (p < 0.05) for the semi-dried restructured jerky from the G1C group. No significant (p > 0.05) difference was observed in appearance score among restructured jerky prepared from duck skin gelatin and carrageenan. Thus, the addition of 1.0% duck skin gelatin and 0.3% carrageenan to semi-dried restructured jerky formulations results in the optimization of quality characteristics.

• 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.37 no.2
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• pp.85-93
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• 1994

The fish skin gelatin hydrolysates were produced using a continuous two-stage membrane (MWCO 10,000, MWCO 5,000) reactor, and molecular weights, amino acids and functional properties of the hydrolysates were investigated. The major molecular weights distribution of the major fractions were $8{\sim}10\;KDa$ and $4.5{\sim}6.5\;KDa$ in the 1st-step hydrolysates, $2{\sim}6\;KDa$ and $0.5{\sim}2\;KDa$ in the 2nd-step hydrolysates. Among the amino acids in the hydrolysates, glycine, proline, serine, alanine, hydroxyproline, glutamic acid and aspartic acid having sweet taste were responsible for $68{\sim}72%$ of the total amino acids. But valine, methionine, isoleucine, leucine, phenylalanine and histidine having a bitter taste were only $23{\sim}25%$ Taste evaluations show that the gelatin hydrolysates have a brothy and sweet taste, 2nd-step hydrolysate have more a favorable taste than 1st-step hydrolysate. The hydrolysates were completely soluble and clear over the entire pH range. Moisture sorption at intermediate water activities of the 2nd-step hydrolysate was much higher than the unmodified fish skin gelatin, but foaming and emulsification properties were poor. Buffer capacity of the 2nd-step hydrolysate was higher than the fish skin gelatin and 1st-step hydrolysate, while viscosities of the hydrolysates were lower than the fish skin gelatin.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.11 no.4
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• pp.189-195
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• 1978

Using the skins of conger eel, Astroconger myriaster, and hagfish, Eptatretus burzeri, from fillet manufactory, the optimum conditions of skin glue processing were investigated and physical ana chemical properties of the product were also determined. The yields of conger eel and hagfish skin to the total body weight were $10.6\%$ and $11.4\%$, respectively. The optimum processing conditions for conger eel skin glue were the extraction of skins which were previously tinted with $0.3\%$ calcium hydroxide solution for one hour, in water at pH 5.5 and $60^{\circ}C$ for four hours. The additional water was six times sample weight. In case of the hagfish skin glue, the liming time with $0.3\%$ calcium hydroxide solution was suitable for three hours, and the skins were extracted with water as much as nine times sample weight at pH 5.0 and $60^{\circ}C$ for three hours. The contents of crude protein of conger eel and hagfish skin glue were $91.5\%$ and $90.2\%$, respectively. The content of crude lipid was slightly higher than that of chemical grade gelatin. Relative viscosity, melting point, gelation temperature and jelly strength of conger eel skin glue were 13.6, $15.2^{\circ}C$, $6.2^{\circ}C$ and 13.0g respectively and those of hagfish skin glue were 12.9, $14.8^{\circ}C$, $4.3^{\circ}C$ and 23.3g respectively. The turbidity of conger eel skin glue and hagfish skin glue were slightly superior to those of dry glue.

• Journal of Animal Science and Technology
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• v.62 no.4
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• pp.587-594
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• 2020

In this study, we examined the effects of various hydrocolloid (alginate, carrageenan, and konjac) treatments on the quality characteristics of cold-cut duck meat jelly. Seven different types of cold-cut duck meat jelly were prepared: control, without hydrocolloids; T1, 0.5% alginate; T2, 0.5% carrageenan; T3, 0.5% konjac; T4, 0.25% alginate + 0.25% carrageenan; T5, 0.25% carrageen + 0.25% konjac; and T6, 0.25% alginate + 0.25% konjac. The pH and moisture content of the cold-cut duck meat jelly with hydrocolloids was higher (p < 0.05) than that of the control. The highest lightness value was recorded for T4 and T6 (p < 0.05), and the hardness was lower (p < 0.05) in the meat jelly with hydrocolloids than in the control, except for T2 and T5. The springiness of the meat jelly was the highest (p < 0.05) in T1 and T4. The onset, peak, and end temperatures were the lowest (p < 0.05) in the control. The highest appearance score of the meat jelly was observed in T6, and its overall acceptability was higher (p < 0.05) than that of the control, indicating that, of all the treatments, 0.25% alginate + 0.25% konjac yielded the most desirable results. Thus, the combined use of duck skin and gelatin with alginate and konjac is potentially applicable for the development of new cold-cut duck meat products.