Physicochemical Properties of Quail Bone Gelatin Extract with Hydrochloric Acid and Citric Acid

Gelatin is a translucent, colorless and flavorless food that was derived from hydrolysis of collagen that was found in animal skin, bone and connective tissue of animals such as domestic cattle, pig, poultry and fish. The objective of the present study is to extract gelatin from quail bone by using acid pretreatment method which is hydrochloric acid (HCl) and citric acid (C6H8O7) and to determine the physicochemical properties of quail bone gelatin. The quail bone gelatin (QBG) was compared with commercial bovine gelatin (CBG) and commercial fish gelatin (CFG). Chemical composition (protein, moisture and ash), bloom strength, pH, color, melting temperature and Fourier Transform Infrared Spectroscopy (FTIR) were evaluated. The most important parameter to determine the quality of gelatin is bloom strength. QBG extracted with hydrochloric acid (QBGHCl) has the highest (165.36 g) value followed by citric acid (QBGc.a) which was 149.48 g, while CBG and CFG have bloom value 136.28 g and 91.69 g respectively. There was no significant difference (p>0.05) between QBGc.a and CBG but there was significant difference (p<0.05) between QBGHCl and CFG. The pH and melting temperature value has range value between 4.84 to 5.46 and 29.34˚C to 38.69˚C. QBGHCl and QBGc.a possesed a similar band (Amide A, Amide B, Amide I, II and III) with CBG and CFG for FTIR. Overall, the physicochemical properties of QBGHCl and QBGc.a has similar quality to CBG which have better quality than CFG. The result has been proven that QBG have a good quality of gelatin, therefore it can be an alternative to gelatin production in the future.

Antioxidant activity of bioactive peptide derived from Pekin duck feet gelatin hydrolysate

Malaysia is one of the main producers of duck meat globally with increasing demands. Increasing in duck production will also increase the number of duck by-products such as skin, feet and bones. Pekin duck (Anas platyrhyncos domestica) is one of the famous duck breeds. Gelatin that was extracted from Pekin duck feet has shown a potential raw material for the production of bioactive peptide that can involve in various functions of the organism physiologically for example antioxidant effects. Pekin Duck feet gelatin was hydrolyzed by using five commercial enzymes (Alcalase, Esperase, Flavourzyme, Neutrase and Protamex) to identify radical scavenging potencies of derived bioactive peptides. All the five enzymes were studied under three different enzyme-substrate ratio (1:10, 1:15, 1:20) with every enzyme optimum pH and temperature. Scavenging activities studied included DPPH radical scavenging activity and ABTS radical scavenging activity. In DPPH radical scavenging activity, all the five enzymes showed the highest percentage of radical scavenging activity at (1:20) enzyme-substrate ratio condition. Among the five enzymes studied, gelatin hydrolyzed with Protamex showed the highest activity (54.83%), followed by Alcalase (53.12%), Esperase (49.81%), Flavourzyme (49.32%) and lastly Neutrase (47.49%) at sample concentration 4.5 mg/ml. The half-maximal inhibitory concentration (IC50) value of the bioactive peptide for ABTS radical scavenging activity was measured. Alcalase has produced the duck feet gelatin hydrolysate that has the lowest IC50 value against ABTS radical scavenging activity with value (0.45%) followed by Esperase (0.54%), Neutrase (0.57%), Protamex (0.60%) and lastly Flavourzyme (0.74%)

Physichochemical properties of Khaki Campbell, Muscovy and Pekin duck feet gelatin extracted with acetic acid

Gelatin is a high molecular weight polypeptides with water soluble properties that was derived from collagen by thermal treatment hydrolysis (Bailey & Light., 1989; Kuan et al., 2016). The major source of gelatin production in Europe is 60% from pigs and another 40% of gelatin production are from bones and skin of cattle and other animal (Aykin-Dinçer et al., 2017). Nevertheless, the market for non-porcine and non-bovine gelatin has been increased recently by Kosher, Muslims and Vegetarian regarding the halal food issue and occurrence of diseases from bovine such as Bovine Spongiform Encephalopathy (BSE) and food and mouth diseases (FMD) (Karim & Bhat., 2009; Samsudin et al., 2018). Hence, another alternatives to gelatin is from mammalian-derived source such as avian sources for example from duck feet (Kuan et al., 2016)

Physicochemical Properties of Duck Feet Gelatin Powder Extracted with Acetic Acid

Physiochemical properties such as colour, amino acid composition, melting temperature and hydroxyproline content determines the quality of gelatin. In this study, 4% of acetic acid was used to produce gelatin powder from Pekin, Muscovy and Khaki Campbell duck feet. The duck feet gelatin powders were analysed for their physiochemical properties and compared with commercial bovine gelatin. For colour analysis, Pekin duck feet gelatin (PDFG) had the highest L* value (21.41), followed by Khaki Campbell duck feet gelatin (KCDFG, 20.57) and Muscovy duck feet gelatin (MDFG, 17.85). KCDFG and PDFG had the same a* values (redness) which was -0.05, while the a* value of MDFG was -1.49. Lastly, the b* values of duck feet gelatin powder were 6.17, 8.47 and 9.47 for PDFG, MDFG and KCDFG, respectively. Duck feet gelatin powder had a melting temperature value of 61.91°C, 48.62°C and 44.81°C for KCDFG, MDFG and PDFG, accordingly. PDFG had the highest hydroxyproline content, which was followed by KCDEG and MDFG with the values of 9.15, 8.00 and 7.63 g/100g, respectively. The main amino acids present in the duck feet gelatin powder were glycine (21.73%, 13.62%, 13.46% and 15.33%), proline (13.08%, 8.71%, 8.39% and 9.34%), hydroxyproline (12.57%, 8.05%, 7.84% and 9.39%) and alanine (8.79%, 5.77%, 6.03%, 6.65%) for CBG, KCDFG, MDFG and PDFG, respectively. Furthermore, the lowest amino acids observed were tyrosine, histidine, methionine and isoleucine. No trace of cysteine was observed. Pekin duck feet produced the best quality gelatin compared to Khaki Campbell and Muscovy duck feet