Effect of fenugreek leaves powder on physicochemical, antioxidant and sensory properties of marinated broiler chicken

Introduction

Chicken meat is widely consumed because of its high-quality protein, favourable nutritional characteristics and versatility in preparation. Marination is an important processing technique used in poultry meat to improve flavour, tenderness, juiciness and overall sensory quality. Marinades generally contain salt, spices, herbs, oil and other functional ingredients that facilitate flavour development and improve the technological properties of meat. The increasing consumer interest in natural and healthier meat products has encouraged the use of herbs and plant-derived ingredients as functional components in meat processing. Natural herbs are rich in phenolic compounds, flavonoids and other bioactive constituents that possess antioxidant and antimicrobial properties. Incorporation of such herbs into meat products may improve their functional characteristics while reducing dependence on synthetic additives. Fenugreek (Trigonella foenum-graecum) is an important culinary herb widely used in Indian food preparations. Fenugreek leaves are rich in alkaloids, flavonoids, salicylates, nicotinic acid and polyphenols. The leaves also contain appreciable levels of phenolic compounds and tocopherols, which contribute to their antioxidant potential. Devatkal et al. (2011) [5] reported considerable phenolic content and free radical scavenging activity in fenugreek levels extract. Ahmad and Saleh (2019) [2] also reported improved flavour, tenderness, juiciness and overall acceptability in beef patties incorporated with fenugreek leaves powder. The functional properties of fenugreek may also influence the technological quality of meat products. Its soluble fibre, galactomannan and mucilaginous components possess waterbinding and thickening properties, which may contribute to improved moisture retention, marination uptake and cooking yield. Fenugreek has therefore attracted attention as a potential natural functional ingredient for meat products. However, the optimum level of fenugreek leaf powder in a standardized herbal marinade for broiler chicken has not been adequately established. Therefore, the present study was undertaken to determine the optimum level of fenugreek leaves powder in the marinade for marinated broiler chicken based on physico-chemical, antioxidant and sensory characteristics. Subsequently, the leaves were dried in a hot-air oven at 60 °C for 5-6 h. The dried leaves were ground using a mixer and sieved through a fine mesh to obtain a fine powder. The powder was packed in sterile polyethylene pouches and stored under refrigeration until further use.

Materials and Methods

Raw materials

Preparation of spice mix

The spice mix consisted of aniseed (10%), black pepper (10%), red chilli (13%), caraway seed (10%), cardamom (2%), cinnamon (5%), cloves (5%), coriander (20%), cumin seeds (10%), dried ginger (10%) and turmeric (5%). The ingredients were cleaned, dried at 50 °C for 4 h, ground and sieved before blending.

Formulation of basic marinade

A standardized basic marinade was prepared using salt (2.5%), onion powder (2.0%), garlic powder (1.0%), ginger powder (1.0%), dry spice mix (2.5%), Kashmiri chilli powder (1.0%), vegetable oil (5.0%) and water (20.0%).

The basic marinade ingredients and the required quantity of fenugreek leaves powder were homogenized in water and oil to obtain a uniform marinade.

Preparation of marinated broiler chicken

Fresh breast and thigh portions were cut into approximately 50 g pieces. The required quantity of marinade was thoroughly mixed manually with the chicken pieces. The marinated samples were packed in LDPE pouches and stored at 4 ± 1 °C for 2 h. Six trials were conducted. For sensory evaluation, an electric hot-air convection oven preheated to 180 °C was used. Cooking was standardized for 40 min and the internal temperature of the chicken was maintained at approximately 75 °C.

Analytical procedures Physico-chemical quality

The pH of fresh marinated chicken and cooked products was determined by homogenizing 10 g sample with 50 mL distilled water for 1 min and measuring with a calibrated digital pH meter. Marination yield was calculated from the weight of meat before and after marination. Marination retention was determined after storage at 4 ± 1 °C for 24 h. Water holding capacity was determined according to Wardlaw et al. (1973) [12] . Cooking yield was calculated from the weight before and after cooking, while moisture retention was calculated according to El-Magoli et al.

(1996) [6] . Drip loss was determined after 24 h storage at 4 ± 1 °C.

Antioxidant properties

Total phenolic content was determined by the Folin-Ciocalteu method and expressed as mg gallic acid equivalents (GAE)/g sample (Singleton et al., 1999) [10] . DPPH radical-scavenging activity was determined using the DPPH assay and expressed as percentage inhibition (Blois et al., 1958) [4] . Reducing power was estimated according to method described by Oyaizu (1986) [9] .

Sensory quality

Sensory characteristics including appearance and colour, flavour, juiciness, tenderness, texture and overall acceptability were evaluated using a nine-point hedonic scale, where 9 represented extremely desirable and 1 represented extremely undesirable. A trained and semitrained panel consisting of faculty members and postgraduate students of Veterinary College and Research Institute, Orathanadu, evaluated the samples.

Statistical analysis

Data generated from six trials were analyzed using SPSS version 20.0. Analysis of variance was performed following Snedecor and Cochran (1989) [11] and treatment means were compared statistically.

Results and Discussion

Physico-chemical characteristics

The results of physico-chemical characteristics of marinated broiler chicken incorporated with different levels of fenugreek leaves powder are presented in Table 2. The pH of fresh marinated meat increased significantly (P < 0.001) from 6.11 ± 0.01 in the control to 6.64 ± 0.01 in T3.

Similarly, product pH increased from 6.35 ± 0.01 in the control to 6.60 ± 0.01 in T3. The higher pH of fenugreektreated samples might be attributed to the presence of alkaloids, saponins and other nitrogenous compounds in fenugreek leaves. Similar observations were reported by Laila et al. (2024) [7] and Acharya et al. (2011) [1] . [3] reported that fenugreek galactomannan has strong water-binding properties and could improve moisture retention in meat products. Moisture retention increased significantly (P < 0.001) from 48.41 ± 0.16% in the control to 55.52 ± 0.87% in T3. This improvement might be attributed to the high water-holding capacity of fenugreek fibre and the formation of a hydrated gel by galactomannan.

The higher pH at greater levels of fenugreek might reduce protein denaturation, thereby improving moisture retention.

Marination retention increased significantly (P < 0.001) from 89.59 ± 0.27% in the control to 95.75 ± 0.17% in T3.

Similarly, marination yield increased from 91.42 ± 0.25 to 97.06 ± 0.14%. The increased marinade retention might be attributed to the viscosity, binding properties and hydrophilic nature of fenugreek, which enhance marinade uptake. The mucilaginous fibre might further improve the adhesion of the marinade to the meat surface. Fresh WHC increased numerically from 32.64 ± 0.48% in the control to 45.22 ± 1.24% in T3, while product WHC increased from 37.00 ± 10.90 to 51.83 ± 1.74%. However, the differences were not significant (P > 0.05). Drip loss decreased numerically from 3.27 ± 0.04% in the control to 2.86 ± 0.15% in T3, but the difference was also non-significant.

Antioxidant properties

DPPH inhibition increased significantly (P < 0.001) from 12.49 ± 0.54% in the control to 75.70 ± 5.03% in T3. The marked increase in radical-scavenging activity indicates the contribution of fenugreek phytochemicals to the antioxidant potential of marinated chicken. Total phenolic content increased significantly from 0.62 ± 0.33 mg GAE/g in the control to 3.30 ± 0.16 mg GAE/g in T3. This increase suggests that effective diffusion of fenugreek phenolic compounds into the meat matrix during marination. Devatkal et al. (2011) [5] reported 52.8 mg GAE/g phenolic content in fenugreek leaves extract, with 64.2% free radical scavenging activity. Naidu et al. (2011) [8] also reported substantial phenolic content and radical-scavenging activity in fenugreek extract. Reducing power increased significantly (P < 0.001) from 0.18 ± 0.01% in the control to 0.49 ± 0.02% in T3. The increase might be attributed to the electron-donating capacity of phenolic compounds and other antioxidant constituents present in fenugreek.

Sensory evaluation

The sensory results are presented in Table 3. All sensory attributes differed significantly (P < 0.001) among treatments. Appearance and colour scores increased from 7.61 ± 0.08 in the control to 8.34 ± 0.05 in T 2 , followed by a decrease at 3.5% fenugreek leaves powder. The improved score at 2.5% might be attributed to the favourable colour and appearance resulting from the moderate incorporation of fenugreek. The decline at 3.5% might be associated with the stronger greenish-brown colour imparted by the herb. Flavour scores increased from 7.58 ± 0.07 in the control to 8.36 ± 0.07 in T 2 . The improved flavour at the intermediate level might be associated with the characteristic pleasant aromatic compounds present in fenugreek. At the highest level, the stronger herbal flavour and bitterness might have masked the characteristic flavour of chicken. Previous research has also reported improved flavour and other sensory attributes with moderate fenugreek incorporation. Juiciness increased from 7.74 ± 0.07 in the control to 8.39 ± 0.07 in T 2 , which might be due to improved marinade uptake and moisture retention. Tenderness increased from 7.52 ± 0.07 to 8.50 ± 0.08, while texture increased from 7.42 ± 0.10 to 8.36 ± 0.07 at 2.5%. Improved moisture retention and marinade absorption might have contributed to better tenderness and texture. At higher levels, excessive fibre content and stronger herbal characteristics might have reduced sensory quality. Overall acceptability increased from 7.60 ± 0.10 in the control to 8.31 ± 0.11 in T 2 , followed by a decline to 7.84 ± 0.07 in T 3 . Thus, 2.5% fenugreek leaves powder provided the most favourable balance of sensory attributes. Although the 3.5% level produced the highest values for several physico-chemical and antioxidant parameters, the sensory scores declined at this level. The 2.5% treatment produced a desirable balance between technological functionality, antioxidant potential and sensory acceptability. It recorded 83.54 ± 0.26% cooking yield, 54.35 ± 0.91% moisture retention, 93.82 ± 0.32% marination retention, 95.10 ± 0.50% marination yield and an overall acceptability score of 8.31 ± 0.11. Therefore, 2.5% fenugreek leaves powder was selected as the optimum level for incorporation into the marinade for marinated broiler chicken. Sensory attributes of marinated chicken were evaluated on a 9-point hedonic scale (wherein 1 = extremely undesirable; 9 = extremely desirable). Means bearing different superscripts row-wise differ significantly (P < 0.05).

Conclusion

The incorporation of fenugreek leaves powder in the marinade improved the physico-chemical and antioxidant characteristics of marinated broiler chicken. Increasing the level of fenugreek leaves powder significantly enhanced cooking yield, moisture retention, marination retention, marination yield, DPPH inhibition, total phenolic content and reducing power. However, sensory quality decreased at the highest incorporation level of 3.5%. Among the treatments, 2.5% fenugreek leaves powder was found to be the optimum level, providing the best overall sensory acceptability along with desirable technological and antioxidant properties.

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