Correction: Extraction and physicochemical properties of gelatin from chicken feet of different ages and its effect on sensory evaluation of the developed yogurt
Year: 2025
Type: erratum
Abstract: Introduction Gelatin and its functional properties Gelatin is a protein derived from collagen, which is abundant in the connective tissues of all animals, including bones, cartilage, skin, and muscle tendons (Ahmad et al., 2023). It can be obtained by partial hydrolysis/thermal denaturation (Siburian et al., 2020). Gelatin has several critical functional properties ( Ghorani et al., 2020, Alipal et al., 2021). In addition to its role as a protein, gelatin is used in a variety of food industries due to its functional properties such as high water-binding capacity, emulsifying power, foaming ability, viscosity enhancement, elasticity, and formation of a protective layer around food (Luo et al., 2022). It has distinct properties when compared to other gel-forming polymers such as pectin and starch (Choe and Kim, 2018). When heated, gelatin transforms into a gel and can melt and solidify repeatedly without fracture (Torrejon et al., 2022). Gelatin uses and applications Technically, it may be used as a component to improve the flexibility, thickness, texture, and stability of food products, particularly in the manufacture of dairy, meat products and confections (Ahmad et al., 2024, Zhang et al., 2024), It is also used for packaging and film production, which provides substantial benefits in industrial applications. It is also utilized as a unique functional material in pharmaceutical, medicinal, and cosmetic products (Milano et al., 2023, Shakila et al., 2012, Ahmad Anuar et al., 2023). Gelatin is not a complete protein because it lacks tryptophan one of the 10 necessary amino acids required (Mikhailov, 2023). Gelatin from chicken feet Many research works have been dedicated recently with the objectives of extracting and studying the properties of gelatin from chicken feet (Bagal‐Kestwal et al., 2019, Abedinia et al., 2020; Fatima et al., 2022, Aidat et al., 2023, Goudie et al., 2023, Harini et al., 2023, Sedaghat and Mohsenzadeh, 2022, Rather et al., 2022, Lu et al., 2022, Lamers et al., 2024, Usman et al., 2024, Al-Gheethi et al., 2021, Zambuto et al., 2024). Waste from slaughterhouses pollutes the environment and has negative effects on human health (Arshad, 2023, Ragasri and Sabumon, 2023, Wang et al., 2024). It is very important to treat the slaughterhouse waste by recycling and turning them into secondary materials that can be used (Philipp et al., 2021, Chowdhury et al., 2022, Ungureanu et al., 2024). It can be used in various food products such as yoghurt, beverages, bakery, meat, and dairy products as thickening, binding, stabilizing and emulsifying agent (Usman et al., 2023, Gao et al., 2024). Saudi Arabia has a significant poultry industry, leading to abundant chicken feet as a byproduct. However, utilizing these chicken feet for gelatin extraction can reduce waste and create an alternative gelatin product. Properties of chicken feet gelatin The physicochemical properties of gelatin extracted from these chicken feet could vary based on chicken ages and the yoghurt containing chicken feet gelatin will have enhanced sensory attributes properties such as taste, texture, color, and overall quality of the developed yoghurt. Therefore, the objective of this research was to investigate the physicochemical properties of gelatin extracted from chicken feet of varying ages from a local poultry slaughterhouse in Saudi Arabia. Additionally, the study aimed to evaluate the impact of the extracted gelatin on the sensory properties of the developed yoghurt. 2. Materials and Methods 2.1. Materials Fresh chicken feet of the ROSS strain were obtained from slaughterhouse of Al-watania Poultry Company, Buraidah, Qassim, Saudi Arabia and transported to the meat laboratory, Faculty of Agriculture and Food, Qassim University for gelatin extraction purpose. Chicken feet from the mentioned strain at three different ages (12, 14, and 16 weeks) which are produced and available in Al watania Poultry Compony, Saudi Arabia were chosen for extraction. Bovine standard gelatin, hydrochloric acid, sodium hydroxide and acetic acid were purchased from Sigma-Aldrich, Saudi Arabia. 2.2. Sample preparation Chicken feet were prepared at the Meat Laboratory, College of Agriculture and Food, Qassim University according to the slightly modified method of Potti and Fahad (2017). The samples of chicken feet were first cleaned by removing the skin and fat. The samples were immersed in boiling water at 100°C for 40 min and then dried in an oven for 18 h at 50°C. Alkaline pretreatment was performed using sodium hydroxide solution (NaOH) with a concentration of 0.2% (wt/vol) to remove the non-collagenous material and mineral ions and dried in the oven. The dried samples were soaked in hydrochloric acid solution with a concentration of 89 0.2% (wt/vol at room temperature (27 ± 1°C). The soaking solution was changed every three days for nine days. 2.3. Extraction of gelatin Gelatin extraction was carried out according to the method of Ab Rahim et al. (2021). The pre-treated chicken feet were cut into small pieces and were immersed in distilled water at a temperature of 70°C in a ratio of 1:9 (w/v) in a shaking water bath and shaken for 90 min. This process was repeated three times until the chicken feet became soft and ready for extraction. After that, the samples were soaked in acetic acid at a concentration of 0.2% (v/v) for 40 min. The resulting acidic extract was then dried and washed with distilled water until the pH became neutral. The extract was filtered using two layers of cheese cloth, pour it sanitized trays individually and dried in the oven at 105°C for 24 h. The dried gelatin obtained was ground individually using electric grinder model Moulinex, AR110027, France. The powders of the final gelatin of the different ages were obtained. 2.4. Gelatin yield Gelatin yield (GY) was calculated using the following equation according to the method of Balaji Wamanrao and Tanaji (2022) according to equation 1 below: GY = Weight of extarcted gelatin (g) Weight of whole chicken feet (g) × 100 (Equation (1) 2.5. pH measurement The gelatin solution was prepared individually by dissolving the gelatin powder in the ratio of 1:10 gelatin: distilled water (w/v). A pre-calibrated pH meter (pH meter HI 2211 - pH Meter HANNA) was used for pH measurement. 2.6. Gel strength The gel strength was determined using the method of Hirbo et al. (2023). Gelatin solution was prepared by mixing the dried gelatin with distilled water. The mixture was left at room temperature for 30 min, pre - heated at a temperature of 65°C for 20 min until the gelatin was completely dissolved. The samples were stored at a refrigerator adjusted at a temperature of 4°C for 16±2 h. To determine the gel strength the gelatin sample was transferred to a cylindrical mold measuring 3 cm in diameter and 2.5 cm in height to assess gel strength. A texture analyzer (Stable Micro System, Surrey, UK) with a 5 kg load cell, a crosshead speed of 1 mm/s, and a 1.27 cm diameter flat-faced cylindrical teflon plunger was used to evaluate gel strength. When the plunger penetrated 4 mm into the gelatin gels, the maximum force (in grams) was recorded. 2.7. Gel viscosity The gel viscosity was measured according to the modified method of Muñoz, et al. (2004). Gelatin powder was dissolved in distilled water in a ratio of 1:10 (W: V) and heated to 60°C. The viscosity was measured using a Brookfield digital viscometer model RVDV-I with spindle No. 1 at a speed of 60 rpm and a temperature of 40 ± 1°C. 2.8. Melting point (MP) The melting point was measured according to the modified method of Choi and Regenstein (2000). The gelatin solution used in gel viscosity test was used in this measurement. It was placed in a screw cap test tubes. The samples were tightly closed and stored in the refrigerator at 7°C for 16 to 18 h. After that, the sample was transferred to a water bath at 10°C and placed upside down inside the water bath so that the temperatures were controlled. The heating process was carried out in stages by increasing the temperature by 1°C per min, and the melting point (MP) of the extracted gelatin was obtained by averaging the temperatures between the starting and ending melting points as follows (equation 2): MP (°C) = starting melting temperature + ending melting temperature/2 (Equation 2) 2.9. Water holding capacity (WHC) Modified method described by Warner (2014) was used to determine the WHC of the gelatin. One gram of the extracted gelatin was placed in a centrifuge tube using a device (SIGMA 3K30) and centrifuged at a speed of 920 rpm for 10 min. The percentage of centrifuged water was calculated by subtracting the weight of gelatin after the centrifugation process from the first basic weight (1.0 g), then the result was calculated as a percentage. The WHC values were calculated according to the following equation (equation 3): WHC % = (basic weight of gelatin−weight of gelatin after centerfugation) basic weight × 100 (Equation (3) 2.10. Color measurement The gelatin solution was prepared and cooled at 10 ± 1 °C for 18 h. The color of the gelatin was determined according to Kim et al.(2020). The colorimeter (Hunter lab, model 16, Minolta Ltd., Japan) was used in the measurement. The device was calibrated using a white plate; L* = +97.83, a* = −0.43, and b* = +1.98). The following colors values were obtained (Lightness L*, redness a* and yellowness b*) which represent the mean intensity of lightness, redness, and yellowness, respectively. 2.11. Proximate analysis The proximate analysis values (moisture, protein, fat and ash) of the extracted gelatin were determined according to the method of AOAC (Horwitz and Latimer, 2000) and carbohydrates were obtained by subtraction from 100. 2.12. Preparation of the yoghurt for sensory evaluation The yoghurt samples were prepared according to the modified published method of Arioui et al. ( 2018). Fresh cow milk was used in yoghurt preparation. The total soluble solids and fats were maintained to be 15% and 3%, respectively. The milk was homogenized and heated to 90℃ for 3 min for pasteurization. Once cooled to 45℃, the gelatin powder was incorporated individually in percentages of 0%, 1%, 2%, 3% into the pasteurized milk and stirred until completely dissolved in the milk. The starter ((Streptococcus thermophilus (YC-X16) and Lactobacillus bulgaricus (C H N-1 1), CHR HANSEN Denmark)) was added the incorporated milk at a percentage of 3%. The treated milk samples were poured into yoghurt cups and distributed randomly using different three-digit numbers and kept into incubation room set at 45℃ for 4 h. The yoghurt samples incorporated with the gelatin were then cooled to 4℃ overnight for sensory evaluation. 2.13. Sensory evaluation studies The prepared yoghurt samples were evaluated the following day by 25 untrained faculty members and students from the College of Agriculture and Food, Qassim University, KSA, who regularly consume yoghurt. This evaluation followed the guidelines and protocols established by the university's ethical committee of the university (details provided in the declarations). The yoghurt samples were evaluated to the following attributes: taste, smell, color, texture, and overall acceptability. The panelists were asked to indicate how much they liked or disliked the prepared yoghurt using a hedonic scale [1= dislike extremely, 9 = like extremely]. The scores were obtained and statistically analyzed. Statistical analysis The data obtained from 3 replicates were statistically analyzed. The statistical analysis was performed using Two – way analysis of variance (ANOVA) followed by Duncan's Multiple Range Test with P ≤ 0.05 significance level. Minitab Statistical Software version 17 was used for data analysis. 3. Results and Discussion 3.1. Gelatin yield Figure 1 shows the yield of the gelatin. The percentage was 3.4%, obtained from the chicken feet of 16 weeks, followed by 2.7%, obtained from chicken feet of 14 weeks and 2.2%, obtained in the chicken feet of 12 weeks' age. It was noticed that the yield of the gelatin obtained increased as the age of the chicken increased. This result suggests a correlation between the yield of the gelatin and the age of the chicken extracted from their feet which means that older chicken feet produce higher gelatin yield. This finding agreed with the earlier finding observed by Rana et al. (2015). They found that older chickens (42 days old) yielded more gelatin compared to younger ones (21 and 35 days old). Specifically, the gelatin yields on a dry weight basis were 0.132% for 21-day-old chickens, 0.182% for 35-day-old chickens, and 0.215% for 42-day-old chickens. Older chicken develops tougher connective tissues which may be more abundant and denser offering more collagen to convert into gelatin when the extraction condition is optimized. However, the acid treatment and the temperature used in gelatin extraction process in this study may also affect the yield of gelatin. The difference in gelatin yield might be due to the different collagen contents in raw materials (Rao and Poonia, 2023). The variation in gelatin yield may result from varying amounts of collagen in the raw materials (Rao and Poonia, 2023). Sinthusamran et al. (2014) claimed that the gelatin yield was influenced by the raw material composition and the extraction conditions. However, Aykın-Dinçer, (2017) and Zou et al. (2024) stated that the different gelatin yields may result from variations in the length of the polypeptide chains caused by pretreatment, pH, temperature, and extraction time. Fatima et al (2022) found that a high yield of 7.5% can be obtained from chicken feet if the extraction conditions are optimized with pretreatment of the chicken feet with acetic acid in a concentration of 4.2% and an extraction temperature of 66°C for 4.2 h. In another study Usman et al. (2024) investigated gelatin extraction condition in native chicken feet gelatin using 1:3 (w/v) of distilled water at 55°C for 6 h. They found that the yield obtained from native and broiler chicken feet using 10% acetic acid was found to be 7.93% and 7.06%, respectively, on a dry basis. 3.2. pH measurement Figure 2 shows the pH values which range from 6.21 to 6.34. This result suggested that pH value of the gelatin was not influenced by NaOH pretreatments during extraction process (p ≥ 0.05). This finding disagreed with the finding of Saenmuang et al. (2019). They found that the pH of gelatin extracted from black-bone chicken feet and skin were acidic ranging from 3.71 to 4.81. the is for acid In the is an important in removing acid The pH of chicken were by Kim et al. and and In the pH of chicken was found to be to ranging from to which is in a with finding in this The pH from to in the treated The was by who that the feet in a mixture of sodium hydroxide and acetic acid and the process the of the gelatin. Gel strength The gel strength values of the gelatin are in Saenmuang et al. that gelatin is into three high g), g), and at values of gel strength in this study are ≤ different and were from to as gelatin. However, this result agreed with et al. who that gel strength of chicken feet gelatin gel strength value of The sample the value of followed by and in gelatin extracted from chicken feet 16, 14, and 12 weeks, respectively. The chicken feet from the chickens the gel strength It was that gelatin with has gel-forming and is used in food products such as yoghurt et al. a and and 2021). to et et al., this variation in the strength may be due to chicken feet pretreatment and and in chicken because and are of collagen and in stabilizing the protein et al., 2024). Gel viscosity The viscosity values are in The values range from to This result agreed with viscosity value et al. (2015). They found that gelatin viscosity values from 6 to et al. et al., claimed that high viscosity of gelatin may be due to the formation of gelatin because of the of from the However, viscosity the gelatin solution is and gelatin derived from poultry with viscosity may or when incorporated in food et al., 2023). It was observed that properties in gelatin such as viscosity affect the properties of the at the point of gel formation et al., It was that gelatin with viscosity values from 6 to in gelatin denser and et al., it for as for food products such as yoghurt et al., Melting point 1 shows the melting point of gelatin for age. The values of the melting point range from to The values are ≤ This finding is with that by Goudie et al. (2023). They that melting point of gelatin between and The value of the melting point was observed in followed by which in the gelatin obtained from the chicken feet of 16 weeks' age. Zhang et al., that the variation in the melting point of gelatin on the method of extraction and the gelatin However, was significant ≥ difference in the melting points values of the gelatin extracted from the chicken feet of respectively. et al., that gelatin when to or room This the finding in this research the values of melting Water holding capacity (WHC) 1 shows the WHC of the gelatin extracted from different chicken strain The values range from to was significant ≥ difference in the This finding is in a with that of and and it was observed that the to water increased from to with increasing chicken WHC that the gelatin can and more water and 2024, et al., 2024). for the high WHC of the gelatin may be the between protein and gelatin which may with protein in the which the of the protein leading to a high of the gel and a higher WHC et al., 2022). Color measurement 2 shows that all the obtained color values ≤ 0.05). The sample the gelatin the gelatin extracted from chickens at 14, and 12 yielded and respectively. The gelatin extracted from the feet of 12 weeks age the redness value followed by 14 weeks 16 weeks age and The yellowness values a It was that the color values of gelatin on the extraction and of as the color has on the functional properties of the gelatin, it its by the et al., It was that a higher L* value more gelatin. et al., found that gelatin derived from chicken higher L* and b* a* values compared to gelatin extracted from et al. (2017) observed increased L* and b* values a* values varying acid The of raw material and the extraction conditions the color of gelatin et al., However, a b* value which may be in gelatin. 2.8. Proximate composition 3 the of the proximate analysis of gelatin. The values were different ≤ with higher observed in older The sample the at The of the extracted gelatin from to The protein of the extracted gelatin in this study which is higher the protein percentage in the study by and the protein of chicken feet was found to be However, these with from studies on extracted from chicken which protein ranging from to et al., et al., and Additionally, and observed that the protein in chicken was The from to values were on the age of the as the age of the chickens the also significant were observed ≥ 0.05). disagreed with by Usman et al. who found that the in native and broiler chicken feet was and respectively. Sensory evaluation studies 4 shows the sensory evaluation attributes of the yoghurt prepared using the extracted gelatin. were significant ≤ in the attributes The the values for texture and The scores were and respectively. significant ≤ observed between yoghurt and samples prepared using 1 and of the extracted gelatin in of taste, color, texture and overall acceptability. The yoghurt prepared using 3% of the gelatin the values for taste, texture and overall of This finding agreed with that of et al. (2022) who the sensory evaluation properties of yoghurt with as for gelatin in concentration of and found that the total scores of This finding suggested that the percentage of gelatin was to improve sensory It has been that food based on gelatin the sensory quality of dairy This might be because the final products with gelatin have and et al., et al., et al., 2021, et al., 2023). In extraction color, gel melting water holding capacity and viscosity are important properties for applications of gelatin, with the 4 properties the to determine the quality of gelatin. The quality properties of gelatin extracted from the feet of ROSS strain chickens were influenced by the age of the chickens and the the it can be that the gelatin extracted from ROSS strain feet could be utilized as food to yoghurt and its sensory evaluation measured in the gelatin extracted from different chicken strain feet Gel strength Gel viscosity Melting point Water holding capacity % ± ± ± 12 ± ± ± ± 14 ± ± ± ± 16 ± ± ± ± the the significant ≤ 2. Color measured in the gelatin extracted from different chicken strain feet L* a* b* ± ± ± 12 ± ± ± 14 ± ± ± 16 ± 2.5 ± ± the the significant ≤ 3. Proximate composition of gelatin extracted from different chicken feet % ± ± ± ± ± available on from the 12 ± 9 ± ± ± ± 14 ± ± ± ± ± 16 ± ± ± ± 5 ± the the significant ≤ Sensory evaluation attributes of the yoghurt incorporated with chicken feet gelatin Color ± ± ± ± ± 12 ± ± ± ± ± 14 ± ± ± ± ± 16 ± a ± ± ± ± the the significant ≤ a 2.5 12 14 16 Gelatin Chicken ages Figure Gelatin yield extracted from chicken feet of The data with the are 12 14 16 pH value Chicken ages Figure 2. pH values of from chicken feet of ages The data with the the are not
Institutions: University of Jeddah, Qassim University
Language: English
Subfield: Biomaterials
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,353
Funder: University of Jeddah
OpenAlex ID: W4415403722