Browsing by Author "Marapana, R. A. U. J."

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Determination of polycyclic aromatic hydrocarbons in black tea at different processing stages.
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Sithara, T. A. H.; Marapana, R. A. U. J.; Liyanage, R.; Senanayaka, S.
Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous organic molecules considered as environmental pollutants, generally enter to the environment during incomplete combustion of organic materials. Various foods have been contaminated from PAHs during preparation, processing or from the environment. The present study was carried out to investigate the occurrence of 16 priority PAHs, in black tea, collected from a tea factory. There were six samples of tea from the same batch and same grade at different processing stages that were analyzed. The Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method was followed to prepare samples and the analysis was done by using gas chromatography- mass spectroscopy. The total PAHs contents of fresh tea leaves, withered, rolled, fermented, dried, graded tea were 26631.84, 59716.89, 43517.76, 11584.72, 7151.88, 16726.77 μg/kg respectively. The results showed that the PAHs were high in withering and rolling steps than the other steps and high PAHs count in graded tea than dried black tea. Since the withering, rolling and tea grading steps are carried out close to the unloading bay and machinery, they could be contaminated from smoke of vehicles and factory smoke effluent. The fermented tea showed less PAHs content and that decrement could be due to volatilization and degradation of PAHs during fermentation. The PAHs contamination of tea leaves depend on the manufacturing premises, environmental condition, thermal energy type, dryer type and raw material conditions etc. The majority of detected PAHs in tea samples were of low molecular weights. According to International Agency for Research on Cancer, 2 and 3 ring PAHs were classified into group 2B and 3 according to the carcinogenicity; the agent possibly carcinogenic and not classifiable as to its carcinogenicity to humans respectively. Even though, tea was contaminated from PAHs, these PAHs are not harmful to the human health. Therefore, the consumption of black tea is safe to the humans
Effect of ethephon and acetylene treatments on chlorophylls and carotenoids pigments in banana (Musa acuminata, AAB)
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Maduwanthi, S. D. T.; Marapana, R. A. U. J.
The present study was conducted to analyze the effects of selected induce ripening agents on major pigments in peel and flesh of Ambul banana (Musa acuminata, AAB). Freshly harvested mature green banana obtained from Dankotuwa, Sri Lanka which are in same maturity stage were subjected to 1000 ppm ethephon and 1000 ppm acetylene and kept at 20 ℃, 80-85% RH for ripening. Chlorophyll a, chlorophyll b and β-carotene were analyzed in peel while β-carotene and lutein were analyzed in flesh at fully yellow stage (Stage 6) using spectrophotometric methods. Analytical standards of each pigment was used for quantification. Peel colour was measured using L*a*b* scale. According to the results obtained chlorophyll a in banana peel at stage 6 were 0.64±0.01, 0.64±0.00 and 0.86±0.03 μg/cm2 respectively in naturally ripened, acetylene and ethephon treated samples while Chlorophyll b levels were 1.09±0.02, 1.34±0.04 and 1.47±0.00 μg/cm2 respectively in those samples. Higher values of chlorophylls in ethephon treated samples at stage 6, corresponds with significantly lower value of a* (1.93 ± 0.03) of those samples. The highest β-carotene levels in both peel and flesh were recorded in naturally ripened samples where those values were 553.70±52.04 and 314.89±1.75 μg/100g respectively. β-carotene and lutein contents were significantly low (P<0.05) in flesh of ethephon treated banana where the recorded values were 146.74±0.72 and 189.87±2.27 μg/100g respectively. Lutein content was significantly (P<0.05) high in flesh of naturally ripened banana comparing to treated banana. Ethephon and acetylene treatments can significantly affect the pigment content in banana peel and flesh.