J. Chem. Chem. Eng. 6 (2012) 1029-1032
FTIR Characterization of Gelatin from Chicken Feet Poliana Fernandes de Almeida1, 2, Suzana Caetano da Silva Lannes2, Felipe Araújo Calarge3, Thiago Michel de Brito Farias3 and José Carlos Curvelo Santana3* 1. Federal Institute of Education of Mato Grosso, São Vicente Campus, Cuiabá 78106-000, Brazil 2. Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo 05508-000, Brazil 3 Laboratory of Biotechnology and Quality Control, Nove de Julho University, São Paulo 05001-100, Brazil Received: September 27, 2012 / Accepted: October 19, 2012 / Published: November 25, 2012. Abstract: The objective of this study was characterizing the gelatin from the chicken feet by FTIR (Fourier transform infrared) spectroscopy. Two gelatin samples were prepared for the experiment which were extracted of 200 g of chicken feet by a thermal bath of 4% acetyl acid solution at 60 °C. A commercial gelatin was used to compare the results. FTIR spectra of gelatin samples were recorded using a Nicolet iS5 FTIR spectrometer equipped with an ATR/iD3 with argon horizontal cell in which the spectra were varied in the range of 400-4,000 cm-1 at 16 °C. The results showed that FTIR spectra of the chicken feet gelatin had the most with the vibration peak at wave numbers of 1,652.01 cm-1 to the amide I, of 1,539.87 cm-1 to the amide II, of 1,241.29 cm-1 to the amide III, of 2,923.72 cm-1 to the amide B and of 3,399.56 cm-1 to the amide A. The collagen composition of the chicken feet gelatins was twotimes larger than the commercial gelatin and the vibration bands to beef gelatin have been different from chicken feet gelatins. This demonstrates that chicken feet gelatins are very good nutritional quality when compared to the commercial gelatin. Key words: FTIR, gelatin, chicken feet, collagen, composition.
1. Introduction The development of new food products has been studied, through the discovery of new sources of food or the reuse of by-products or wastes. For this, nutritional and sensory aspects should be taken into account, so they could supply some vitamin or minerals without rejection the product by the consumers. In this context, there are the so-called functional foods [1-3]. Food and pharmaceutical industries throughout the world are observing a growing demand for collagen and gelatin. The most popular and used is the gelatin of mammals (pigs and cattle) that are subjected to greater restrictions and skepticism among consumers, by socio-cultural and health concerns [3-6]. Gelatin is a denatured fibrous protein derived from *
Corresponding author: José Carlos Curvelo Santana, D.Sc. /Ph.D., research field: chemical engineering. E-mail: [email protected]
collagen by partial thermal hydrolysis. It is an important functional biopolymer that has a very broad application for food, material, pharmacy and photography industries [5, 6]. This demand for new gelling agents to replace the gelatin of mammals has guided several studies on different raw materials, such as the gelatin of marine origin (fish skin, bone, and fins), and other surveys focusing on the extraction and classification of gelatin from fishes [4, 5, 7, 8], however, it is an underused source. FTIR (Fourier transform infrared) spectroscopy has increasingly been adopted as an analytical tool in various fields, such as the petrochemical, pharmaceutical, environmental, clinical, agricultural, food and biomedical sectors during the past 15 years. The increasing importance of this technique in food technology is obvious from the recent increase in numbers of publications, as well as from the fact that many manufacturers of on-line grading lines have now implemented FTIR systems to measure various
FTIR Characterization of Gelatin from Chicken Feet
quality attributes [9-12]. There are reports in the literature which analyzes the qualities of apple (Malus domestica Borkh.), apricot fruit (Prunus armeniaca L.), avocado (Persea americana Mill.), banana (Musa acuminata Colla), carrot (Daucus carota L.), cherry (Prunus serotina L.), grape (Vitis vinifera L.) juice, green beans (Phaseolus vulgaris L.), kiwifruit (Actinidia deliciosa A. Chev.), mango (Magnifera indica L.), melon (Cucumis melo L.), onion (Allium cepa L.), peach (Prunus persica (L.) Batsch), tangerine (Citrus reticulata L.), tomato (Lycopersicon esculentum L.), unicorn leatherjacket (Aluterus monoceros) and Nile perch (Lates niloticus) gelatins and others [8-13]. The objective of this study was to characterize the gelatin from the chicken feet by FTIR spectroscopy and to compare the results with a commercial gelatin from ox leather.
2. Experiment 2.1 Gelatins Three gelatin samples were used in this study, two prepared from chicken feet and a commercial gelatin (ox leather) which was used to compare the results for the experiment. The chicken feet are provided by Brazilian markets. The chicken feet were washed; the nails were removed, again washed with cold water to remove any residue of dirt. Afterwards 200 g of chicken feet by a thermal bath of 4% acetyl acid solution at 60 °C for 4 h, in order to extract the collagen [2-6]. 2.2. FTIR Procedure FTIR spectra of gelatin samples were recorded using a horizontal ATR. Trough a Nicolet iS5 FTIR spectrometer equipped with an ATR/iD3 with argon horizontal cell (Thermo Scientific®, EUA) at room temperature. The spectra in the range of 400-4,000 cm-1 were rationed and automatic signals gained were collected in 32 scans at a resolution of 4 cm-1 against a background spectrum recorded from the clean empty cell at 16 °C [8-10].
3. Results and Discussion Fig. 1 shows the FTIR spectra of gelatin from chicken feet for the first and second extraction processes on a thermal bath of 4% acetyl acid solution at 60 °C for 4 h. Also, Fig. 1 shows the FTIR spectra for the commercial gelatin from ox leather. FTIR spectra of gelatin extracted from the chicken feet showed the major peaks in amide region. Chicken gelatins showed the vibration peak at the wave numbers of 1,652.01 cm-1 to the amide I, of 1,539.87 cm-1 to the amide II, of 1,241.29 cm-1 to the amide III, of 2,923.72 cm-1 to the amide B and of 3,399.56 cm-1 to the amide A. The FTIR spectra of commercial gelatin showed amide II at 1,556.53 cm-1, amide I at 1,651.32 cm-1, amide B at 2,921.49 cm-1, amide A in a range of 3,391.84-3,467.09 cm-1 and it had not found the amide III. However, a high protein content of low molecular weight has been found. For Fig. 1, the unicorn leatherjackets were observed values of vibration bands of amide I are between 1,634.73-1,649.11 cm-1 . Muyonga et al.  have been found for Nile perch at amide I at vibration bands are between 1,600-1,700 cm-1, because its structural in spiral form. According to Ahmad and Benjakul , the vibrantion bands of amide II are between 1,539.69 and 1,549.87 cm-1, while the low amplitude is due to N-H linkages on α-helices. For amide III, Muyonga et al.  have been found values of vibration band about 1,240 cm-1 and for the unicorn leatherjackets at a vibration band range of 1,237.74-1,206.06 cm-1 . For unicorn leatherjackets, Ahmad and Benjakul have been found its vibration bands for the amide B between 3,073.13 and 3,165.97 cm-1 and for the amide A between 3,293.18 and 3,300.66 cm-1. From Fig. 1 it is possible to make the following observations: the amide I vibration mode is primarily a C=O stretching vibration coupled to contributions from the CN stretch, CCN deformation and in-plane NH bending modes. The amide II vibration modes are attributed to an out-of-phase combination of CN stretch and in-plane NH deformation modes of the peptide
FTIR Characterization of Gelatin from Chicken Feet
Fig. 1 FTIR spectra of gelatins: (a) first sample of chicken gelatin, (b) second sample of chicken gelatin and (c) sample of commercial gelatin (ox leather).
group (glycine backbone and proline side-chains). The amide III represented the combination peaks between C-N stretching vibrations and N-H deformation from amide linkages as well as absorptions arising from wagging vibrations from CH2 groups from the glycine backbone and proline side-chains. Moreover, the amide a band arises from the stretching vibrations of N-H group. The amide A
also tends to join with the CH2 stretch peak when carboxylic acid groups exist in a dimeric inter-molecular interaction and it may change stretching its peak with the CH2 groups. The amide B peak suggests the interaction of -NH3 group between peptide chains. Thus, it can be concluded that the secondary structure of gelatins obtained from the chicken feet was affected by acid pretreatment and
FTIR Characterization of Gelatin from Chicken Feet
extraction time. The low molecular weight peptides formed during the extraction for long time were more likely able to form covalent cross-links during freeze-drying process [8, 9, 11-14]. The vibration picks below of wave numbers of 1,000 cm-1 are characteristics of the low molecular weight peptides formed during the extraction for long time which were more likely able to form covalent cross-links during freeze-drying process . ThE was affecting on the collagen content from commercial gelatin and reduce one of the main qualities expected in gelatins. The process used in this work had not affecting the chicken gelatin. The results showed that collagen composition of the chicken feet gelatins was greater than 70% while for the beef gelatin (commercial) was only 35% and the vibration bands to beef gelatin have been different from chicken feet gelatins.
4. Conclusions FTIR characterization showed that collagen composition of the chicken feet gelatins is two-times the beef gelatin (commercial) and the vibration bands to beef gelatin have been different from chicken feet gelatins. FTIR spectra of gelatin extracted from the chicken feet showed the major peaks in amide region and all amides have been characterized. Thus, it is concluded that the production of jelly using chicken feet would add value to this poultry industry waste, because the chicken gelatins have better nutritional quality when compared to the commercial gelatin.
Acknowledgments The authors thank to CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior), FAPESP (Fundação de Apoio à Pesquisa do Estado de São Paulo) and UNINOVE (Nove de Julho University) for the financial supports.
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