Introduction

The importance of dietary polyphenols has been underlined because of their antioxidative activities (Fresco et al., 2006) and anticarcinogenic effects; they inhibit cancer cell proliferation in vitro (Scalbert et al., 2005). Fruits and vegetables contain many antioxidant compounds such as phenolic compounds, carotenoids, anthocyanins and tocopherols (Naczk and Shahidi 2006). Specially, fruit peels are rich in polyphenolic compounds, flavonoids, ascorbic acid, and many other biologically active components having positive influences on health (Leontowicz et al., 2003).

The mango plant has been the focus of attention of many researchers for potent antioxidants. Parts of the mango, such as stem bark, leaves and pulp are known for various biomedical applications, including antioxidative and free radical scavenging (Ajila et al., 2007a; Ribeiro et al., 2007), anti-inflammatory (Hernandez et al., 2007), and anticancer (Percival et al., 2006) activities. In a recent study, aqueous and ethanolic extracts of mango leaves were reported to be ideal antioxidants (Ling et al., 2009). Despite these reports, few scientific investigations have examined the importance of mango peels in terms of antioxidant and anticancer activities. However, mango is a seasonal fruit approximately 20% of fruits are processed for products, such as puree, nectar, pickles and canned slices that are popular worldwide (Loelillet, 1994). The polyphenol was reported in Irvin mango variety and this was higher in ripe peel compared to raw peel (Ueda et al., 2000). Peel is a major by-product of such processing, mango peels are not currently used commercially but are discarded as waste and are becoming a source of pollution (Ajila et al., 2007b). Peel has been found to be a good source of phytochemicals, such as polyphenols, carotenoids, vitamin E and vitamin C (Ajila et al., 2007a) and it exhibited good antioxidant properties (Ajila et al., 2007b). Polyphenol content of peel was reported to be more than that of flesh (Lakshminarayana et al., 1979). As it has been reported that different antioxidant compounds exhibit differential scavenging activity on various reactive oxygen species (Wang and Jiao, 2000) and that reaction with hydroxyl radicals is non-specific, while reaction with other radicals is more specific (Singh et al., 2009). Thus, the objective of this study was to examine the efficacy of mango peel as an antioxidant on chicken meat products. The quality and acceptability of the products were determined.

Materials and Methods

Fresh Broilers of six week old was procured from the local market were slaughtered and dressed following traditional halal method. The body fat, tendons and separable connective tissues as well as skin were trimmed off. Skin was utilized for this study. The dressed meat was packed in LDPE pouches and kept in refrigerator at 4+1^oC over night which was then subsequently used for product formulation. Mango peel powder was prepared from dried peels of mango which were procured from local market. The fruits were washed with distilled water, it was peeled and their edible portions of mango were carefully separated. The peels were dried separately in a hot air oven at 50°C for 48 h and ground to a fine powder and passed through a 24-mesh sieve. For estimation of antioxidant potential of MPeE extract, 5 gm of powder were taken separately and added in 100 ml each distilled water after boiling at 100^oC. After 1hr, the extract was obtained by filtering through Whatman filter paper No.1 and extract were added according to the level emulsion.

Preparation of Chicken Nuggets

Chicken nuggets were prepared from the following procedure of Verma et al., 2013.

Estimation of Total Phenolics, Proximate Analysis, pH and Cooking Yield

The concentration of phenolic compounds in the mango peel powder extract was determined by the F-C method as described by Singleton and Rossi (1965). The pH and proximate compositions (moisture and fat) of chicken nuggets was measured using digital pH meter (Systronics Digital pH meter 802) as suggested by (AOAC, 1995). The cooking yield of the product was calculated on the basis of Weight of cooked loaf and emulsion.

Sensory Evaluation

The nuggets samples were then arranged on a white porcelain dish and immediately subjected to sensory evaluation by a panel comprising of semi-trained members (Keeton 1983).

Statistical Analysis

The data obtained during the experiment were analyzed as per following the procedure described by Snedecor and Cochran (1989).

Results and Discussion

The total phenolic contents (TPC) of the mango peel powder obtained from fruit are presented in Table 1.

Table 1: Effect of Different Levels of Mango Peel Extract on Certain Quality Characteristics of Chicken Nuggets (Mean ± S.E)

Mean ± SE with different superscripts in a row differ significantly (P<0.05)

The TPC of the mango peel powder, expressed as gallic acid equivalent, 590 mg/100 g, in the aqueous extractions. These values are within the broad range reported in the literature for peels of exotic fruit such as banana passion fruit (Passiflora mollissima) (246 mg GAE/ 100 g), cocona (Solanum sessiliflorum) (87.4 mg GAE/100 g), cupuaçu (Theobroma grandiflorum) (252 mg GAE/100 g) (Calderon et al., 2011) and in whole fruit such as zapote (Calocarpum zapota) (258 mg GAE/100 g), cherimoya (Annona cherimolia) (323 mg GAE/100 g), or strawberry (Fragaria ananasa) (238 mg GAE/100 g), (Vasco et al.,2008). The concentration and type of phenolic substances in fruit and fruit co-products depend on several factors; differences in varieties, ripeness and season; environmental factors, such as soil type and climate; genetic factors and processing and extraction methods (Rashid et al., 2016). The recovery of polyphenols from plant materials is influenced by the solubility of the phenolic compounds in the solvent used for the extraction process (Martinz et al., 2012).

Proximate Analysis, pH, Cooking Yield and Total Phenolics of the Product

No effect (p >0.05) on moisture or fat content was observed in cooked chicken nuggets containing mango peel extract. There were no significant differences (p<0.05) in the pH values between treated samples and control, indicating that the pH of the extracts did not affect the pH of the chicken product. No effect was observed from the interaction (p<0.05). Similar results were seen in cooked and refrigerated ground chicken meat (Brannan, 2009) and cooked and refrigerated chicken breast (Rababah et al., 2006), who also demonstrated no change in pH values of samples to which grape seed extract was added. The cooking yield was not significantly different in any of the formulations tested. Total phenolic content in MPeE incorporated nuggets was significantly (p<0.05) higher with respect to control. The average phenolics content was found to be in the following order- (0.75 %)> (0.50%)> (0.25%)> control. In the present study, the higher content of phenolics in chicken nuggets incorporated with mango peel extract might be due to proportionately higher content of phenolics present in mango fruit. Banerjee et al., 2012 and Kumar et al., 2013 also documented significantly higher total phenolics content with the increasing levels of incorporation of broccoli powder in nuggets prepared from chevon and emu respectively.Total phenolics (0.040±0.002) in control samples might have been contributed by incorporation of STPP, garlic, ginger and spices used during nuggets preparation (Tangkanakul et al., 2009).

Sensory Analysis

The appearance and juiciness of the products is not affected by the incorporation of different levels of MPeE (p<0.05) as compared to control (Table 2). Appearance scores of all products containing different levels of MPeE with control varied non-significantly (p<0.05). Similar trend was also recorded by Narkhede (2012), who reported non-significant (p<0.05) variations in appearance scores of chicken nuggets containing natural antioxidants as compared to control the decrease in appearance scores might be due to pigment and lipid oxidation. Juiciness of the product of product did not show any significant difference (p<0.05) between control and treatment. This could be due to the moisture retention (Sharma et al., 2014). Sensory scores of others attributes i.e., juiciness and appearance of the product treated with various levels of MPeE were found to be non significant (p<0.05) with control.

Table 2: Effect of Different Levels of Mango Peel Extract On Sensory Attributes of Chicken Nuggets (Mean ± S.E)

Mean ± SE with different superscripts in a column differ significantly (P<0.05).Mean values are scores on 8 point descriptive hedonic scale where 1=extremely poor and 8 extremely=desirable

The highest score for texture was evident for product containing MPeE 0.50% whereas the lowest score was recorded in control. Moreover, flavor and overall palatability scores of the products treated levels of MPeE 0.50% show significant (p<0.05) variations. Similar observations were also recorded by Pachpor (2014).Though the sensory scores of appearance and juiciness of the chicken nuggets was affected non- significantly (P<0.05) by the level of incorporation of MPeE, the scores of other attributes viz. proximate analysis and sensory scores were higher for treated with 0.50% MPeE.

Conclusion

The present study showed that Incorporation of MPeE 0.50% has substantial amounts of phenolic compounds with significant free radical scavenging activity and reducing power. The eating quality of chicken nuggets was unaffected by addition of MPeE. These results suggest that phytochemicals extracted from Mango peel may be used as a potential source of antioxidants to protect meat products against oxidative rancidity without any adverse effects on sensory attributes.

Acknowledgement

Authors are thankful to the Dean, Nagpur Veterinary College, MAFSU for providing necessary facilities.

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