Chicken Products from Chennai: Effect of Different Cooking Methods on Physicochemical and Microbial Quality from Different Retail Outlets

In India poultry industry has come a long way from a backyard activity to a well organized, scientific and vibrant sector due to higher demand for meat and egg production. India is the world’s sixth largest producer of poultry meat and the country produces 5.3 million metric tons (MT) of chicken which shares around 51.44% of total meat production (BAHS, 2022). Though a significant increase in poultry production was achieved, concomitant increase in processing and marketing of poultry products has not been attained.
       
Generally, the poultry is relatively cheaper source of protein as compared to beef, mutton and fish meat; and the demand of poultry meat is continuously increasing. Under these circumstances, it is imperative to consumers of poultry meat and its products to have quality meat products in the market (Barbut, 2002). Generally, meat cooking methods were categorized into dry, moist and novel heating i.e. microwave and infrared (Tiwari and O’Donnell, 2012). Changes in the physicochemical characteristics during cooking (e.g. weight loss, water-holding capacity modification, color and aroma development and muscle fiber shrinkage) are highly based on the muscle composition, its characteristics and different heating methods in which time-temperature combination during cooking, which eventually influence the quality parameters and palatability of meat and meat products (Lee et al., 2017; Chumngoen et al., 2016). However, published data on the effects of moist and dry heat cooking on the quality of poultry meat products was also very limited.
 
The chicken products such as grilled chicken, chicken 65, chicken biryani and chicken gravy are most commonly available in different outlets in and around Chennai. Also, research work quality standards of chicken products, which are available or market in major metropolitan cities was meagre. So, in previous study, we evaluated the effect of different cooking methods on the proximate composition of chicken products sold at different retail outlets in and around Chennai (Vanathi et al., 2022). Hence, the study was conducted to evaluate the physicochemical and microbial quality of chicken products available at different retail outlets in and around Chennai.

The studies were carried out in the Department of Livestock Products Technology (Meat Science), Madras Veterinary College, Chennai-600 007, TANUVAS during the year 2020 to 2021.
 
Source of materials
 
A total of 120 nos. of chicken products, based on cooking methods such as dry heat (chicken 65 and grilled chicken) and moist cooked (chicken biryani and chicken gravy) samples were collected from different retail outlets located at 12 different zones in Chennai such as Vepery, Purasaiwakkam, Chennai Central, Perambur, Erukkancheri, Egmore, Periamet, Valasaravakkam, Shozhinganallur, Perungudi, Annanagar and Koyembedu were presented in Table 1. Chicken products samples were placed in UV sterilized polythene bags and transported hygienically to Department of Livestock Products Technology (Meat Science), Madras Veterinary College, Chennai -7 in clean insulated box with ice packs. The collected samples were immediately used for analysis of quality characteristics.
 

 
Chemicals
 
The chemicals used for analysis of chicken products were of analytical grade was obtained from standard firms (M/S Sigma Aldrich, M/S Hi-Media and M/S Loba Chemie).
 
Estimation of physico-chemical qualities
 
pH
 
pH of the sample was measured by using a digital pH meter (Cyberscan pH 510, Merck). About 5 gm of sample was homogenized with 45 ml of distilled water in a warning laboratory blender for 1 min. The pH recorded by immersing the combined electrode of digital pH meter into the homogenate.
 
Estimation of thiobarbituric acid value (TBA)
 
The TBA value is the measured as the oxidative rancidity of food and is generally expressed as a value or number. Rancidity of fat in stored food is defined as the development of state off flavor as a result of oxidation of unsaturated fatty acid. The TBA value of chicken products was assessed in triplicates as per the procedure mentioned by Tarladgis et al., (1960).
 
Estimation of tyrosine value (TV)
 
The tyrosine value can be effectively used as an indication for proteolysis and to measure the amino acid tyrosine and tryptophan present in nonpolar extract of the meat product. The TV of chicken products was assessed in triplicates as per the procedure mentioned by Strange et al., (1977).
 
Munsell colour analysis
 
The Munsell color-order system is the best way of detecting specific colors as well as showing the relationships among different colors. Every color has three specific qualities or color attributes: such as hue, value and chroma. Munsell established numeric scales along with visually uniform steps for each of these attributes. The Munsell Book of Color, which had collection of colored chips and were arranged according to these scales. Each chip is identified numerically using these scales. The color of any surface can be identified by comparing it to the chips, under proper illumination and viewing conditions. The color is then identified by its H (hue), V (value) and C (chroma).
 
Estimation of microbial qualities
 
Microbial qualities such as standard plate count, coliform count and yeast and mould counts in chicken products were determined following the standard method of APHA (1984).
 
Statistical analysis
 
The data obtained from each experiments were subjected to statistical analysis (Snedecor and Cochran, 1994) for Analysis of Variance (ANOVA) and Duncan’s multiple range test to compare the means by using SPSS software for window (Version 17.0, SPSS Inc., Chicago, IL, USA). The level of significant effects, least significant differences were calculated at appropriate level of significance of 0.05 was used for comparison of means.

pH, thiobarbituric acid value and tyrosine value
 
The results for the effect of different types of cooking on the pH, thiobarbituric acid and tyrosine value of chicken products sold at different retail outlets in and around Chennai are shown in Table 2. Higher significant differences (P<0.01) was noticed in between chicken products prepared by dry and moist cooking sold at street outlets. In contrast to that no significant differences (P>0.05) was noticed between different cooking methods on chicken products sold in small hotels and restaurants. When compare with three different outlets, chicken biryani and chicken gravy showed higher significant differences (P<0.01), of which highest pH value was noticed in chicken biryani sold at street outlets, lowest pH value was observed in all the four products sold at restaurants. Thiobarbituric acid value of chicken products prepared by dry and moist cooking methods sold at street outlets had no significant differences (P>0.05), but higher significant differences (P<0.01), was noticed in case of small hotels and restaurants. But between different outlets except for grilled chicken all the chicken products showed higher significant differences. Chicken products sold at street outlets had higher thiobarbituric acid value when compare with small hotels and restaurants. Similarly, tyrosine value was found significantly higher (P<0.01), in chicken 65 and lower in grilled chicken and  chicken biryani in all the three outlets. But in comparison between three different retail outlets, chicken products sold at street outlets had significantly highest (P<0.05) tyrosine value for all the products except for chicken gravy. Similar reports on the pH of grilled beef tenderloin steak was higher than that of pan-fried, oven-roasted, or microwaved steak (Kim et al., 2001). Influence of cooking methods on the pH values of meat products might be associated with the heating rate. Also high temperature during cooking, increase the oxidation process in meat (O’Grady et al., 2008). However, some cooking methods did not produce this effect was also reported by Serrano et al., (2007). Pinthus and Saguy (1994) reported that fried croquettes had the highest oxidation level compared with moist-cooked nuggets and dry-cooked patties which was mainly due to increased porosity and uptake of oil. Generally during the process of frying, heat is transferred to the meat through hot oils or fat which causes oxidation changes in both meat as well as oil or fat.
 

 
Colour properties
 
The results for the effect of different types of cooking on the colour properties of chicken products sold at different retail outlets in and around Chennai are shown in Table 3. No Significant differences was noticed in the hue value of both dry and moist cooked chicken products sold in small hotels and restaurants. However, highly significant differences (P<0.01) was noticed between dry and moist cooked chicken products in street outlets. In contrast to that the hue value was found significantly higher (P<0.01) in chicken 65 sold at restaurants. Also there was no significant differences (P>0.05) was noticed in hue value of grilled chicken and chicken biryani sold at three different outlets. Chroma value revealed that highly significant differences (P<0.01) was noticed between dry and moist cooked chicken products in all the three outlets. In which chicken gravy sold at small hotels and grilled chicken sold at restaurants had highest chroma value. No significant differences (P>0.05) were noticed in the value of chicken products sold at street outlets and small hotels. Highly significant differences (P<0.01) were noticed between different cooking methods on chicken products sold at restaurants, of which chicken biryani showed highest score for value. Chicken 65 and chicken gravy showed highly significant differences (P<0.01) between three different outlets but no significant differences were noticed in grilled chicken and chicken biryani. Highest hue value in chicken 65 sold (8-Red) in restaurants implies that more natural or artificial colouring agents were included in the coating ingredients for attractiveness when compare with street outlets and small hotels (5-yellowish red). Choi et al., (2013) reported that redness and yellowness values of the chicken steaks were higher for the grilling when compare with other cooking methods and the lowest values were observed with superheated steam. Oh et al., (2014), found that the lightness value of chicken fillets cooked with superheated steam was higher than those cooked with convection oven. According to Jeon et al., (2013) and Kim et al., (2001), color of meat products after cooking varies according to cooking method.
 

 
Microbial quality
 
The results for the effect of different types of cooking on the microbial quality of chicken products sold at different retail outlets in and around Chennai are shown in Table 4. Among different types of cooking methods, moist cooked chicken products had significantly higher (P<0.01) standard plate count, of which chicken gravy had highest count in all three outlets such as street outlets, small hotels and restaurants. When compared with three different outlets, chicken product sold at street outlets had significantly higher (P<0.01) standard plate count in both dry and moist cooked chicken products. In case of coliform count, highly significant differences (P<0.01) were noticed among chicken products prepared by different cooking methods. Also coliform count was detected higher (P<0.05) in chicken biryani and gravy, lesser in chicken 65 and was not detected in grilled chicken in street outlets. But in small hotels coliform count was not found in dry cooked products such as chicken 65 and grilled chicken, no significant count (P>0.05) was noticed in moist cooked products such as chicken biryani and chicken gravy. Coliform count was not detected in both dry and moist cooked chicken products sold in restaurants of Chennai. Similarly, for yeast and mould count highly significant differences (P<0.01) were noticed between dry and moist cooked chicken products, of which chicken biryani had significantly highest yeast and mould count in street outlets and non significantly (P>0.05) in small hotels and restaurants. When compare with three different outlets, street outlets had significantly highest (P<0.01) yeast and mould count in both of the dry and moist cooked chicken products. Meat products is considered as spoiled when the microbial load was more than 6 log cycles (Frazier and Westhoff, 1978). Similarly, Shapton and Shapton (1991) and Dang et al., (2021) reported that SPC counts were within the limits of 6 log cfu/g is generally considered as  safe cooked meat products.
 

Thus it is concluded that dry type of cooking had reduced microbial load and TBA value was also as per the prescribed limitations. But microbial quality of moist cooked chicken products had higher standard plate count, coliform count and yeast and mould count were noticed among different types of cooking methods. But when compare with different type of retail outlets, chicken products sold in street outlets had higher microbial count and lipid oxidation properties, when compare with chicken products sold in small hotels and restaurants. In general, from the above study it was observed that chicken products prepared in restaurants had better physicochemical and microbial standards as per the specification when compare with street outlets and small hotels in and around Chennai.

The authors are thankful to the Director of Research, Tamil Nadu Veterinary and Animal Sciences University, Madhavaram Milk Colony, Chennai-51, for providing fund to carry out this research work under TANUVAS - Sub project.

The authors declares that they have no conflict of interest.