Variation of carotenoids, total phenolics and antioxidant activity levels in ananas comosus from different counties in Kenya with duration of storage
Obumba, Maxwell Ouma
MetadataShow full item record
Epidemiological studies have repeatedly shown the apparent association between high fruit intake and lower incidence of chronic degenerative diseases. The chemo protective properties of fruits have been partly attributed to the antioxidants including phenolic compounds and carotenoids. Despite numerous reports of commonly available tropical fruits on their antioxidants and antioxidant activity, no information is available for the smooth cayenne, a common variety of Ananas comosus grown in Kenya. The concern on the perishability of the fruit also calls for investigation on the variation of the levels of antioxidants with duration of storage. The antioxidant activity, carotenoid content (lutein, beta-carotene and lycopene) and total phenolic content of fruit samples of smooth cayenne sourced from five Counties were studied. Samples were obtained from Kiambu, Homabay, Kilifi, Kericho and Nyamira and analysed for 7 days of storage under room temperature (21°C-25°C). The carotenoids were determined using high performance liquid chromatography method, Folin-Ciocalteu reagent used to measure total phenolic content and expressed as gallic acid equivalents. The in vitro antioxidant activity was assessed by DPPH Assay and expressed as ICso. One way ANOV A was employed for statistical data analysis. The levels of beta-carotene and lycopene were below detection limit in all samples while lutein levels ranged between 107.52±1.25 )..I.g/IOOgand 233.55±5.77)..1.g/100g.The antioxidant capacity ranged between 45.00 ug/l Oug and 88.15 )..I.g/IOOgwhile total phenolic content ranged from 82.64±0.28 ~lg/lOOgto 164.64±0.28 )..I.g1O/ Og, expressed as gallic acid equivalents. The Kilifi sample showed the highest radical scavenging activity with ICso value of 45.00±1.13)..1.g/100gwhile the Nyamira sample showed the highest content of phenolic compounds (160.79±0.28 to 164.64±0.28). Findings not only showed that levels of lutein, phenolics and antioxidant activity differed significantly among samples but there also was generally a significant increase in the levels of lutein and total phenolic content during storage from day 1 to 7 (p<0.05), indicating the effect of storage on the nutritional value of the fruit. Findings pointed out that storage beyond the fourth day had no significant change in the antioxidant activity of samples from Homabay, Kilifi, Kericho and Nyamira. There were notable strong positive correlations between total phenolic content and the antioxidant activity (r> 0.875) attributing the phenolic compounds to the antioxidant activity. The findings indicated that the smooth cayenne variety of Ananas comosus contains sufficient levels of lutein and phenolic compounds that increase with fruit storage and would be of nutritional value. The fruit should therefore be promoted for consumption with a particular focus on reducing incidences of chronic degenerative diseases.