Dietary Influence of Roselle (Hibiscus sabdariffa L.) Calyx Extract on Oxidative Stability and Microbiological Quality of Cooked Chicken
Isaiah A. Okere *
Livestock Improvement Programme, Agriculture Value Addition Programme, Institute of Agricultural Research and Training, Obafemi Awolowo University, Moor Plantation, P.M.B. 5029, Ibadan, Nigeria.
Olubunmi O. Olusola
Department of Animal Science, University of Ibadan, Ibadan, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
This study investigated the dietary impact of roselle calyx extract (RCE) offered to broiler chickens on oxidative and microbial condition in their cooked meat during cold storage. Four concentrations of RCE excluding plain (T1) were prepared by hot water extraction at 100°C for 10 minutes using 5 (T2), 10 (T3), 15 (T4) and 20g roselle calyx/L (T5) which were assayed for total phenol and Ascorbic Acid-AA (mg/100mL) and were offered as drinking water to 28-day-old broiler chickens (n=210, r=6) until day 49; on which two birds per replicate were sacrificed and breast meat excised. The cooked breast meat samples were assayed for Lipid oxidation-LO (mg MDA/kg) and microbial load [Total Bacterial count-TBC and Mould count-MC (log10 Cfu/g)] on days 0, 15, 30, 45 and 60 of storage (-4oC). Total phenol of 11.8±0.16 (T5) and 11.00±0.12 (T4) were similar and significantly (p<0.05) higher than 9.65±0.17 (T3) and 8.8±0.10 (T2). The AA ranged from 56.99±0.02 (T2) to 65.51±0.01 (T5). At day 60, LO of 0.45±0.05 (T5) was significantly lower than 0.65±0.02 (T4), 0.68±0.03 (T3), 0.86±0.04 (T2) and 1.31±0.31 (T1); with percentage reduction of 65.65% in T5 for lipid oxidation relative to the control T1. The TBC of 0.23±0.07 (T5) on day 60 was significantly lower than 0.48±0.06 (T1), 0.37±0.09 (T2), 0.36±0.00 (T3) and 0.31±0.03 (T4); with percentage reduction of 52.08% in T5 for TBC relative to the control T1. The MC of 0.14±0.02 (T5) on day 60 was significantly lower than 0.30±0.01 (T1), 0.23±0.02 (T2), 0.20±0.02 (T3) and 0.19±0.02 (T4); with percentage reduction of 56.67% in T5 for MC relative to the control T1. The LO, TBC and MC on day 60, in the cooked meat obtained from broiler chickens offered RCE (treatments: T2-T5) were significantly (p<0.05) lower than the control T1; indicating improved oxidative stability and antimicrobial potential of RCE. It was evident that offering aqueous roselle calyx extract to broiler chickens conferred oxidative stability and antimicrobial potential to the chicken meat in reducing lipid oxidation and microbial load during storage. Thus, cooked meat from broiler chickens offered with 5 to 20g roselle calyx/L extract had better oxidative stability and reduced microbial load during storage.
Keywords: Broiler chicken meat, antioxidant, microbial load, roselle calyx extract, phytochemicals