ASSESSMENT OF THE PRESERVATIVE EFFICACY OF EXTRACTS OF Trametes elegans ON PAWPAW AND BANANA FRUITS

Abstract

The preservative efficacy of Trametes elegans extracts on pawpaw and banana fruits were investigated. Trametes elegans was collected on decaying wood at Ilara Mokin farm (Latitude: 7° 20′ 33.9″ N and Longitude: 5° 6′ 21.1″ E), Ondo State, Nigeria. The macrofungus (Trametes elegans) was pulverized and extracted with methanol, acetone and n-hexane respectively for 72 hours. Phytochemical properties of the extracts were determined using standard methods. Phytochemical screening of T. elegans extracts revealed the presence of saponin, tannin, steroid, terpenoid and flavonoid. The antimicrobial effect of extracts and commercial antibiotics was investigated against microbial isolates earlier obtained from spoilt pawpaw and banana fruits. The antimicrobial activity of T. elegans extracts revealed that fungi isolates were more susceptible than bacteria isolates, having higher zones of inhibition. The fruits samples (pawpaw and banana) were coated with the extracts and stored under different conditions (ambient and refrigeration temperatures). The proximate and mineral composition of the fresh and preserved pawpaw and banana fruit samples were determined using standard methods. Preservative study revealed that the three extracts (methanol, acetone and n-hexane) used extended the shelf life of pawpaw beyond 5 days to 8 days and beyond 8 days to 11 days at 26 ± 2°C and 5 ± 1°C respectively. Musa ‘gros michel’ was preserved beyond 6 days to 9 days and beyond 12 days to 16 days at 26 ± 2°C and 5 ± 1°C and Musa sapientum beyond 9 days to 12 days and beyond 16 days to 21 days at 26 ± 2°C and 5 ± 1°C respectively. The control samples showed rapid deterioration in colour, texture and odour within 5 and 8 days for pawpaw, 6 and 12 days for Musa ‘gros michel’ and 9 and 16 days for Musa sapientum. There was significant difference in the proximate and mineral composition between the control samples of Musa sapientum, Musa ‘gros michel’ and pawpaw compared to the treated fruit samples under both storage conditions. Calcium content of Musa ‘gros michel’ rangef from 161.00 to 170.29 mg/ kg and 149.08 to 159.01 mg/ kg and potassium content from 400.00 – 43.11 mg/kg and 342.00 – 436.00 mg/ kg at 26 ± 2°C and 5 ± 1°C respectively. Calcium content of Musa sapientum ranged from 49.90 – 165.01 mg/kg and 150.0 – 233.36 mg/ kg and potassium content from 270.06 – 335.00 mg/ kg at 26 ± 2°C and 5 ± 1°C respectively. The iron content of pawpaw ranged from 0.55 – 1.01 mg/ kg and 0.65 – 1.54 mg/kg and calcium content from 40.05 – 69.89 mg/ kg and 40.10 – 62.02 mg/ ml at 26 ± 2°C and 5 ± 1°C respectively. This study shows that Trametes elegans extract could be used to extend the shelf life of pawpaw and banana by surface coating. The study also gives an insight into the potential use of T. elegans as a natural means of preservation.