Introduction

Chicken cutlets are ready-to-eat, flat croquette of minced chicken meat and other ingredients like flours, pulses, shredded potato, condiments, and spices and are often coated with rusk crumbs. Though a highly desirable, nutritious and protein-rich meat product, chicken cutlets at the same time are also highly perishable because it provides the nutrients needed to support the growth of various types of microorganisms (Bhat et al., 2015). The interest in food rich in antioxidants increased in recent decades and the importance of these food constituents has led to the development of a large market for antioxidant rich products and ingredients. Food antioxidants are compounds or substances that are present naturally in some ingredients or are intentionally added as food additive with the aim of inhibiting product oxidation (Halliwell, 1996). Due to toxicological concerns of synthetic antioxidants (Ito, 1982 and Nakatani, 2000) there have been increasing interests in identifying phenolic compounds that comes from fruits, vegetables, spices, grains, and herbs. Natural antioxidants in foods are highly relished by consumers. Mango is a very common tropical fruit usually found in Southern Asia, especially in Eastern India, China, Burma, Andaman Islands and Central America. The mango is indigenous to the Indian subcontinent and Southeast Asia (Fowomola, 2010). India ranks first among worlds mango producing countries accounting for about 50% of world’s mango production. Most popular types of mangoes in India are Alphonsos, Totapuri, Chausa and Dasheri (Subramanyam, 1990). Ripe mangoes are processed into frozen mango products, canned products, dehydrated products and ready-to-serve beverages (Ramteke and Eipeson, 1997). After consumption or industrial processing of the fruits, peel and seeds are discarded, resulting in high economic loss to the manufacturer, as well as an impact to the environment (Puravankara et al., 2000). For example, in India the mango-processing industry annually generates 3 x 10⁵ tons of seed, approximately (Soong and Barlow, 2004). Therefore, it is necessary to consider alternative uses for these mango byproducts, in order to avoid environmental problems and to create new revenue sources, providing greater economic returns to the agribusiness (Ayala-Zavala et al., 2011). It is well documented that mango peel is found to be a good source of bioactive compounds such as polyphenols, carotenoids, vitamins, enzymes and dietary fibers (Ajila et al., 2007). In addition, polyphenols from mango seed kernels were found to contain tannins, gallic acid, coumarin, ellagic acid, vanillin, mangiferin, ferulic acid, cinammic acid (Arogba, 1997). Mango byproducts have more antioxidant activity and phenolic content, than the byproducts of tamarind, avocado, longan and jackfruit (Kittiphoom, 2012). This suggests that the fruit seeds and peels should be further utilized rather than just discarded as waste. Keeping in view that phytochemicals present in mango byproducts are bioactive compounds and are useful in promoting health benefits, it seems appropriate to harness their functionality in meat products which is invariably alleged for health intricacies on ground of high saturated fats, cholesterol, low dietary fibers and oxidation prone status. Therefore, the present study was undertaken to unravel the effect of different levels of mango peel powder (MPP) on the storage quality of chicken cutlets.

Material and Methods

Raw Materials

Broilers were purchased from local market of Chomu, Jaipur. The birds were slaughtered using halal method. The body fat was trimmed and deboning of dressed chicken was done manually removing all tendons and separable connective tissue. The lean meat was packed in polythene bags and frozen at -18±2⁰C until use. Refined cottonseed oil of brand name ‘Ginni’ containing energy (900 Kcal/100 gram), saturated fatty acids (24%) and cholesterol 0% was purchased from local market used. Condiments used were fresh onion, garlic and ginger in a ratio of 3:2:1 and ground in a mixer to the consistency of fine paste. The spice mix formula used for preparation of the chicken cutlets was standardized in the laboratory and contained aniseed (Pimpinalla anisum) 12%, coriander (Coriandrum sativum) 20%, cumin seed (Cuminum cyminum) 15%, black pepper (Piper nigrum) 10%, red chilli (Capsicum frutescens) 8%, green cardamom (Elettaria cardamomum) 6%, white pepper (Piper nigrum) 5%, Black cardamom (Amomum subulatum) 5%, cinnamon (Cinnamomum zeylanicum) 6%, degi mirch (Capsicum annum) 5%, bay leaves (Laurus nobilis) 2%, cloves (Syzygium aromaticum) 2%, mace (Myristica fragrans) 2% and nutmeg (Myristica fragrans) 2%. Mangoes (Mangifera indica) were purchased from local market of Chomu, Jaipur and after washing properly, the peels were removed, cut into 2-3cm small pieces. The peels were spread in a single layer in oven pan and dried in the oven at 50°C for 16 hours to a moisture content of 10%. After drying, the peels were cooled at room temperature and then ground in grinder to convert it into powder form. The mango peel powder obtained from peel was incorporated at 1%, 2% and 3% level in the formulation replacing lean meat.

Method of Preparation of Chicken Cutlets

Several preliminary trials were conducted to optimize the basic formulation and processing conditions for the preparation of chicken cutlets. The standardized formulation contained lean meat 75%, added water 2%, shredded potato 6%, condiment mixture 9%, gram flour 3%, whole egg liquid 1%, spice mixture 2%, common salt 1.75%, sugar 0.25% and sodium nitrite 120ppm. Lean meat from round part of chicken was cut into smaller chunks and minced in a mincer. The common salt, sugar, sodium nitrite and added water in the form of crushed ice was added to weighed meat according to above formulation and was kept at refrigeration temperature (4±1⁰C) for 15-20 minutes. The mixture was shallow fat fried in 2.5 percent w/w refined oil for 8 minutes. The condiment and spice mixture was fried separately till golden brown colour. The fried meat, condiment and spice mixture, gram flour, shredded potato and whole egg liquid were mixed in a domestic mixer. The batter so formed was used in the preparation of raw cutlets by using moulds. The raw cutlets were kept at refrigeration temperature for 15-20 minutes and dipped in whole egg liquid and then rolled in rusk powder till uniform coating was formed on the surface and were deep fat fried at the temperature of 150⁰C in refined oil till golden brown colour. The internal core temperature was measured with the help of a thermometer (80±2⁰C) and the excess fat was removed from the fried cutlets by using tissue paper.

Analytical Procedures

The storage studies were carried out for a period of 15 days and were based on following physicochemical and microbiological properties.

Physicochemical Properties

The pH of chicken cutlets was determined by the method of Keller et al., 1974 using a digital pH meter. Free fatty acid value was determined by method of US Army laboratories (Natick) described by Koniecko (1979).Thiobarbituric acid reactive substances (TBARS) value of cooked products during storage was determined as per Witte et al., 1970.

Microbiological Properties

Total plate count, psychrophilic count, coliform count and yeast and mold count were determined by methods of APHA (1984).

Analysis

The results were analyzed statistically for analysis of variance and least significant difference tests as per Snedecor and Cochran (1980). In significant effects, least significant differences were calculated at appropriate level of significance for a pair wise comparison of treatment means.

Results and Discussion

Physicochemical Properties

The mean values of various physicochemical parameters of chicken cutlets incorporated with 1%, 2% and 3% levels of mango peel powder along with control during refrigerated storage (4±1⁰C) are presented in Table 1.

pH

In the present study, incorporation of MPP had a significant (P<0.05) effect on the pH values in all treated samples and an increasing trend in pH values was observed in both control and treated cutlets from day 0 to 15. The mean pH value of all the treated products were significantly (P<0.05) lower at almost all days of storage as compared to control. Chandralekha et al., 2012 also reported an increase in pH values of chicken meat balls during refrigerated storage for 8 days. The increase in pH on subsequent days of storage might be attributed to formation of volatile basic nitrogen components as affected by biochemical changes under low temperature (Ibrahim and Desouky, 2009) and to microbial load which may cause protein hydrolysis with the appearance of alkyl groups (Yassin, 2003).

Free Fatty Acid (FFA)

Free fatty acids are the products of enzymatic or microbial degradation of lipids. Determination of FFA gives information about stability of fat during storage.

Table 1: Effect of Refrigerated Storage on Physio-Chemical Characteristics of Aerobically Packed Chicken Cutlets Treated With Different Levels of MPP (Mean ± SE)^*

*Mean± SE with different superscripts in a row wise (lower case alphabet) and column wise (upper case alphabet) differ significantly (P<0.05); n=6 for each treatment; MPP=Mango peel powder

FFA followed a significant (P<0.05) increasing trend from day 0 to 15 in treated products as well as control. FFA values were significantly (P<0.05) lower than control in chicken cutlets treated with 3% MPP on all days of refrigerated storage. However, on day 0, FFA values for chicken cutlets treated with 1% and 2% levels of MPP were comparable to control. The significant (P<0.05) increase in FFA content of meat products during storage might be due to growth of lipolytic microorganisms (Das et al., 2008). Sahoo and Anjaneyulu (1997) reported similar trend but with higher value of FFA content in buffalo meat nuggets. The decrease in FFA content in mango peel powder treated chicken cutlets may be attributed to lesser lipolytic count in the product.

Thiobarbituric Acid Reactive Substances (TBARS) Value (mg Malonaldehyde/kg)

TBARS value followed a significant (P<0.05) increasing trend from day 0 to 15 in case of both control and treated chicken cutlets. However, TBARS values of product treated with 3% MPP were significantly (P<0.05) lower than control at all intervals of storage. TBARS values of cutlets treated with MPP at 1% and 2% mg level were comparable at day 0, 5 and 10. The TBARS values of greater than 1 mg malonaldehyde/kg were recorded in control products on tenth day of storage while as its value was greater than 1 mg malonaldehyde/kg in both treated and untreated products on fifteenth day of refrigeration storage. This suggests that MPP incorporation in chicken cutlets prevented oxidative rancidity upto 10^th day of storage in its treatments as TBARS values greater than one are usually associated with rancid flavour/odour by sensory panelists (Tarladgis et al., 1960; Jayasingh and Cornforth, 2003). The decrease in TBARS value in mango peel powder treated products can be attributed to its antioxidant properties which reduced oxidative rancidity and formation of secondary oxidation products during refrigerated storage of chicken cutlets. Vega-Vega et al., 2013 demonstrated a significantly higher total antioxidant capacity of mango byproducts than of the edible portions. Several studies have shown that mango peel contain various phenolic compounds and can be a good source of natural antioxidants (Ajila et al., 2007; Abdeldaiem et al., 2013). The increase in TBARS values during the progressive storage period might be attributed to oxygen permeability of packaging material (Brewer et al., 1992) that led to lipid oxidation. A general trend of increased TBARS value during refrigerated and frozen storage of meat and meat products had been reported by (Devatkal et al., 2004; Salahuddin et al., 1989; Dushyanthan et al., 2000 and Kumar 2001).

Microbiological Properties

The mean values of various microbiological parameters of chicken cutlets incorporated with 1%, 2% and 3% levels of mango peel powder along with control during refrigerated storage (4±1⁰C) are presented in Table 2.

Total Plate Count (log cfu/g)

Total plate count followed a linear increasing trend from day 0 to 15 in control as well as treated products. Similar findings were reported by Kumar et al., 2007 and Nath et al.,1995 in chicken meat patties and according to them total plate count (TPC) increased at each storage interval both in control and extended patties. Total plate count of treated chicken cutlets was lower than control during entire period of storage. At day 5, total plate count of MPP 2% and 3% treated products were significantly (P<0.05) lower as compared to control. At day 10 and 15, the count of all the treated products was significantly (P<0.05) lower as compared to control. Total plate count of treated products was within permissible limits up to tenth day of storage. The microbial count of 5.33 x 10³ cfu/g for total plate count is considered to be indicative of un-acceptability of cooked meat products (Cremer and Chipley 1977). These findings are also in agreement with the findings of Abdeldaiem et al., 2013, who observed a significant (P<0.05) decrease in total plate count of irradiated mango (Mangifera indica) peel powder treated beef burgers. The decrease in total plate count can be attributed to phenolic content of mango byproduct powder, responsible for its antimicrobial activity. The antimicrobial mechanisms of these compounds are not well understood; however, it has been suggested that phenolic compounds will cause changes in the membrane through its interaction with the carboxyl groups of the hydrophilic amino acids of the protein in the cell membrane, thus altering its permeability (Raybaudi-Massilia et al., 2009).

Table 2: Effect of Refrigerated Storage on Microbiological Characteristics of Aerobically Packed Chicken Cutlets Treated with Different Levels of MPP (Mean ± SE)^*

*Mean± SE with different superscripts in a row wise (lower case alphabet) and column wise (upper case alphabet) differ significantly (P<0.05); n=6 for each treatment; MPP=Mango peel powder

Phenolic compounds will cause an alteration of pH and electrical potential, causing the release of protons to the outside. Thus, there will be a coagulation of cytoplasmic content in the bacteria, accompanied by a loss of normal cell metabolism, leading to cell death (Raybaudi-Massilia et al., 2009). Vega-Vega et al., 2013 observed that most sensitive bacterial strains to the presence of mango by-product extract were the gram positives- L. monocytogenes and S. aureus, as compared against gram negative strains of E. coli O157:H7 and S. choleraesuis. Similar results have been reported by Kabuki et al., 2000, showing that extracts from mango seed are more effective against gram-positive bacteria than gram-negative bacteria.

Psychrophilic Count

Psychrophilic counts were not detected on day 0 and day 5 of storage in both control and MPP treated products. But, counts were observed on day 10 and day 15 of storage in all treated groups as well as control. However, the counts of treated products were significantly (P<0.05) lower as compared to control on day 10 and 15 of storage. The psychrophilic count always remained well below the maximum permissible limits in cooked meat products (Jay 1986). Cremer and Chipley (1997) described permissible level of psychrophilic count a 4.6 log cfu/g in cooked meat and meat products. A detectable count on day 10 while nil on preceding observations might be attributed to the fact bacteria generally need some lag phase before active multiplication is initiated. A gradual increase in psychrophilic counts during storage of chicken products had also been reported by Sen (1993), Nag et al., 1998 and Kalaikalan (1998) and Bhat et al., 2015.

Coliform Count

The count was not detected throughout the storage period in both control as well as MPP treated products. It could be due to destruction of these bacteria during cooking at 80°C much above their death point of 57°C. Further, hygienic practices followed during the preparation and packaging of chicken cutlets could also be one of the reasons for the absence of coliforms. Dawson (1975), Kumar (2001) and Bhat et al., 2015 also reported zero count of coliform for the product heated to such a high temperature.

Yeast and Mould Count

The yeast and mould count was detected only on day 15. However, the values for yeast and mold count were significantly (P<0.05) lower for the products treated with all levels of MPP as compared to the control. This is in agreement with Abdeldaiem et al., 2012, they observed that addition of Irradiated Mango (Mangifera indica) peels powder in beef burger had a significant (P<0.05) reducing effect on the mould and yeast counts.

Conclusions

The present study showed that the storage quality of chicken cutlets was within acceptable limits upto fifth day of refrigeration storage in both control and treated products. However, on tenth day of refrigeration storage, TBARS values and total plate count (TPC) was above permissible limits in control products but was within acceptable limits in all MPP treated chicken cutlets. Hence, mango peel powder (MPP) can be incorporated upto 3% level in chicken cutlets to maintain a shelf life of 10 days without affecting its quality under refrigeration storage (4±1⁰C).

Acknowledgements

The authors wish to express sincere thanks to Dean, staff and students of M.J.F. College of Veterinary and Animal Sciences for providing the support and technical assistance in completion of this study.

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