• Preventive Nutrition and Food Science
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• v.8 no.1
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• pp.66-69
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• 2003

An angiotensin converting enzyme (ACE) inhibitory peptide was isolated and purified from the hydrolysates of duck meat protein. Duck meat protein was hydrolyzed using trypsin at 37$^{\circ}C$ for 2 hrs. An ACE inhibitory peptide was purified using membrane filtration, anion exchange chromatography, gel permeation chromatography, fast protein liquid chromatography, normal phase HPLC. The purified inhibitory peptide was identified to be a tetrapeptide, Glu-Asp-Leu-Glu having $IC_{50}$/ value of 85.9 $\mu$M.

• 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.34 no.1
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• pp.1-6
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• 2014

Pidan and salted duck eggs are of nutritional rich alternative duck egg products which are predominantly consumed in China, Thailand, South Korea and other Chinese migrated countries. Both eggs are rich in proteins, lipids, unsaturated fatty acids and minerals. A Pidan whole egg contains 13.1% of protein, 10.7% of fat, 2.25% of carbohydrate and 2.3% of ash, whereas the salted duck egg contains 14% of protein, 16.6% of fat, 4.1% of carbohydrate and 7.5% of ash. The fresh duck egg contains a range of 9.30-11.80% of protein, 11.40-13.52% of fat, 1.50-1.74% of sugar and 1.10-1.17% of ash. Proteins, lipids, and ash contents are found to be greatly enhanced during the pickling and salting process of pidan and salted duck eggs. However, the alkaline induced aggregation of pidan leads to degradation and subsequent generation of free peptides and amino acids. Very few amino acids are found to be lost during the pickling and storage. However, no such losses of amino acids are reported in salted duck eggs during the salting process of 14 d. Phospholipids and cholesterol contents are lower in pidan oil and salted duck egg yolk oil. Thus, the pidan and salted duck eggs are nutritionally rich alternatives of duck egg products which will benefit the human health during consumption.

• Journal of Veterinary Clinics
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• v.36 no.1
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• pp.85-87
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• 2019

Eight-week-old Spot-billed duck were presented with visible drooping of both of wings. On physical examination, the Spot-billed ducks revealed valgus deformity of the carpal joint resulting in the primary flight feathers protruding dorsally. The bird was in good body condition and there was no loss of motion in any of the joints in the wings. The bird was fed chicken pellet with 18.5% of protein level and reared in a cage. Based on the clinical presentation and physical examination 'angel wing' was diagnosed. Wing bandage and nutritional change to lower-protein diet with fresh vegetables were applied simultaneously. And duck was transferred to wider outside pen with small pond. Four-week afterward clinical signs of angel wing were improved.

• Journal of Animal Science and Technology
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• v.62 no.5
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• pp.628-637
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• 2020

In poultry diets, a requirement of crude protein is one of the most important factors in poultry productivity. Besides, the Pekin duck requirement of crude protein is still not clear. This experiment was conducted to determine the crude protein requirement of Pekin duck on diet formulation by investigation of growth performance, carcass trait, and analysis of blood parameter for a hatch to 21-day (d) of age. A total of 432 male White Pekin ducks were randomly allocated to six levels of crude protein (i.e., 15%, 17%, 19%, 21%, 23%, and 25%) to give six replicate pens per treatment with 12 ducklings per each pen. Body weight and feed intake were measured weekly by calculating feed conversion ratio and protein intake. Two ducklings each pen was euthanized via cervical dislocation for analysis of carcass trait and plasma blood on 21-d of age. Data were applied on both prediction linear-plateau and quadratic-plateau models by estimation of the crude protein requirements. Data were applied on both prediction linear-plateau and quadratic-plateau models by estimation of the crude protein requirements. The level of crude protein requirements of Pekin ducks for 21 days after the hatch was estimated to be 20.63% and 23.25% diet for maximum daily gain, and minimum feed conversion ratio, respectively.

• Journal of Nutrition and Health
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• v.14 no.1
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• pp.16-25
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• 1981

Commercially available duck-meat was subjected to proximate analysis. On a wet basis, the duck-meat contained 62.87, 17.05, 19.06 ana 1.02 percent of moisture, crude fat, crude protein and ash, respectively. Almost all the essential amino acids contained in the duck-meat protein, ana the tryptophan was the limiting one by amino acid analysis of GLC. An analysis of the fatty acid composition by GLC showed a relatively high concentration of oleic acid. There was also a considerable content of linoleic acid. The content of polyunsaturated fatty acids of duck-meat was 70.9% and the P/S ratio of fatty acids was 3.4. The cholesterol content in duck-meat was determined to be approximately 70. 5mg/100g ofm sample. According to blood analysis, it was understood that the content of phospholipids was relatively high, particulary in lecithin. ATP-phosphorus, at the higher temperature, was released faster than at the lower temperature, by two hours after postmortem. The ATPase activity of Myogibril was inhibited at the relatively high concentration of added EDTA and metallic ions, but the activity was very high in the lower concentrations. According to the cooking conditions, boiled duck-meat showed good digestion by pepsin. It was understood that the digestibility of duck meat was relatively high, so the duck-meat protein is good source of animal protein. Therefore, it is able to be recommended that duck-meat is good nitrogen source animal food.

• Korean Journal of Veterinary Research
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• v.38 no.3
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• pp.467-473
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• 1998

The relative frequency and distribution of bovine chromogranin(BCG)-, serotonin-, somatostatin(SOM)-, and S-100 protein-immunoreactive cells in the proventriculus, gizzard and proventriculus-gizzard junction(P-G junction) of the duck(Anas platyrhynchos platyrhyncos, Linne) were studied using immunohistochemical methods. BCG-, and SOM-immunoreactive cells were detected in all ages of this study in the proventriculus and the gizzard, and BCG-immunoreactive cells were also detected in the P-G junction. SOM-immunoreactive cells were detected rarely on occasions only in 1 week, 2 weeks, 3 weeks and 9 weeks after hatching. But no S-100 protein-immunoreactive cells were detected in this study.

• Korean Journal of Veterinary Research
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• v.38 no.1
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• pp.1-8
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• 1998

The relative frequency and distribution of bovine chromogranin(BCG)-, serotonin-, somatostatin(SOM)- and S-100 protein-immunoreactive cells in the intestinal tract of the duck (Anas platyrhynchos platyrhyncos, Linne) with ages were studied using immunohistochemical methods. BCG-immunoreactive cells were detected in duodenum on 23 days of incubation. Thereafter these cells were occurred throughout the intestine. SOM-immunoreactive cells were detected in the small intestine from hatching to 9 weeks. Thereafter they were also observed in colon. Serotonin-immunoreactive cells were detected throughout the intestinal tracts after hatching. These immunoreactive cells were increased with ages except that BCG-immunoreactive cells were decreased with ages from 6 weeks after hatching. BCG- and serotonin-immunoreactive cells were most frequently detected in colon regions and SOM-immunoreactive cells in duodenum regions, but no S-100 protein-immunoreactive cells were detected in this study.

• Food Science of Animal Resources
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• v.33 no.1
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• pp.109-118
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• 2013

The objective of this study is to increase the utilization of duck by-products. The nutritional characteristics of four kinds of duck by-products (liver, heart, gizzard, and feet) were determined. The quality changes of four kinds of duck by-products were evaluated during frozen storage at $-20^{\circ}C$. The crude protein and cholesterol contents showed the highest level in liver while the crude fat content was determined to be the highest content in feet at 13.90%, and lowest in gizzard at 0.57%. Duck by-products contained USFA in the range of 48.69-77.66%, and the highest level in feet (p<0.05). During storage of duck by-products at $-20^{\circ}C$, the pH of duck by-products was in the range of 6.24-7.15, and there were no significant differences during the 4 mon storage period at $-20^{\circ}C$. Microbial counts of duck by-products except the gizzard were decreased significantly as storage time elapsed. In the sensory evaluation, overall acceptability of by-products (liver, heart, gizzard and feet) showed a tendency of decreasing value through storage, because off-flavor was increased with increased storage. Considering the combined results, one can conclude that duck by-products provide a good source of protein, and it was judged that the use of raw meat would be most appropriate within 3 mon of frozen storage.

• Food Science of Animal Resources
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• v.37 no.3
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• pp.360-367
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• 2017

This study was conducted to investigate the effect of duck skin on cooking loss, emulsion stability, pH, color, protein solubility, texture profile analysis (TPA), apparent viscosity, and sensory characteristics of press type duck ham with different ratio of duck breast meat and duck skin. Five duck ham formulations were produced with the following compositions: T1 (duck breast 70% + duck skin 30%), T2 (duck breast 60% + duck skin 40%), T3 (duck breast 50% + duck skin 50%), T4 (duck breast 40% + duck skin 60%), and T5 (duck breast 30% + duck skin 70%). The cooking loss and fat separation were lower in T1, and the total expressible fluid separations were lower in T1 and T2 than others. The pH ranged from 6.48 to 6.59, with the highest values in T4 and T5. T5 had the highest CIE $L^*$-value, and T1 and T2 had the highest CIE $a^*$-values; however, CIE $b^*$-values did not differ significantly between the duck ham samples. The protein solubility and TPA (hardness, springiness, cohesiveness, gumminess, and chewiness) were the highest in T1. T1 and T2 had higher scores for color, tenderness, and overall acceptability. T1, T2, and T3 showed significantly higher values, but there were no significant differences for flavor and juiciness. Regarding apparent viscosity properties, T1 and T2 had higher viscosity values than the other formulations. In conclusion, the T1 (duck breast 70% + duck skin 30%) and T2 (duck breast 60% + duck skin 40%) duck hams show the highest quality characteristics.