Tea (Camellia sinensis) cultivated in three agro-ecological regions of Bangladesh: Unveiling the variability of methylxanthine, bioactive phenolic compound, and antioxidant activity.

Tea (Camellia sinensis) is a widely consumed beverage known for its numerous health benefits, largely attributed to its rich content of quality determining secondary metabolites such as methylxanthine compounds and bioactive phenolic compounds. The goal of this study was to find out variations of the levels of methylxanthines, bioactive phenolic compounds, and antioxidant activity in methanolic and hot water extracts of 129 tea samples grown in three different ecological regions of Bangladesh named Panchagar, Sylhet, and Chattogram. Methylxanthine and bioactive phenolic compounds were determined by using HPLC-DAD, and the antioxidant profile was analysed by UV-vis spectrophotometric methods for methanol and hot water extracts of tea leaves. The IC50 values showed the trend as Panchagar > Sylhet > Chattogram and Sylhet > Chattogram > Panchagar for water and methanol extract, respectively. The results revealed significant (p < 0.05) variations in the levels of methylxanthines content: Panchagar > Chattogram > Sylhet. Caffeine was significantly higher (103.02 ± 5.55 mg/g of dry extract) in the methanolic extract of tea leaves of Panchagar district and lower (53.33 ± 4.30 mg/g of dry extract) in the hot water extract of Sylhet district. Panchagar and Chattogram possessed significantly (p < 0.05) higher catechin content for methanol (57.01 ± 5.50 mg/g dry extract) and hot water (55.23 ± 4.11 mg/g dry extract) extracts, respectively. The utilization of canonical discriminant functions yielded highly favorable outcomes in the classification of tea from three distinct cultivation origins in Bangladesh, relying on their inherent features. This study demonstrated the potential effects of geographical variations on the bioactive compounds and antioxidant properties of tea, emphasizing the importance of regional differences in tea cultivation for optimizing its health benefits as well as dispersing tea cultivation across the country.

Relative evaluation of in-vitro antioxidant potential and phenolic constituents by HPLC-DAD of Brassica vegetables extracted in different solvents.

Cabbage, cauliflower and broccoli are well-known vegetables from the Brassica family having functional effects on human health. This study was carried out to identify different antioxidant properties and to quantify phenolic compounds by HPLC-DAD in different extracts (methanol, ethanol and water: acetic acid: acetone) of these vegetables. The results showed that, the methanolic dry extract of cabbage possessed the highest antioxidant activity (549 ± 7.30 µg/g) and IC50 was 90 ± 2.52 µg/mL than others. Whereas the ethanolic dry extract of cauliflower had 348 ± 5.20 µg/g of flavonoid, which was the highest among all. The maximum levels of total tannin (414 ± 5.20 µg/g) and total phenolic content (465 ± 3.25 µg/g) was found in broccoli dry extract. Several polyphenolic compounds were identified in different extracts of the vegetables and they were Cauliflower (8) > Cabbage (10) > Broccoli (9) in total. Therefore, the use of total vegetables rather than extracts in the food industry would be more appropriate to get greater health benefit.

Determination of dietary exposure and extraction efficiency of nitrosamine from cooked meat.

Meat products are claimed to be a source of carcinogenic nitrosamines (NAs) exposure in food. In this study, dietary exposure of six nitrosamines: N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosopyrrolidine (NPYR), N-nitrosopiperidine (NPIP), N-nitrosodipropylamine (NDPA), N-nitrosodibutylamine (NDBA) were estimated by Gas chromatography method. Four types of processed beef products were collected from different restaurants of Dhaka city, Bangladesh and analyzed by Gas chromatography-Mass spectrometry (GC-MS) after extracting under different methods. Nitrosamines were extracted by three different methods: i) Ultrasonic, ii) Autoclave for 10 min, iii) Autoclave for 20 min, and mean recoveries were 73%, 85% and 62% respectively. The LOD (limit of detection) and the LOQ (limit of quantification) for the six nitrosamines were in the range of 0.05-0.3 µg/kg and 0.85-1.5 µg/kg, respectively. The total nitrosamine content in beef products were Shik kabab (20.87 µg/kg) > Burger patty (20.44 µg/kg) > Steak (15.84 µg/kg) >Chap (14.95 µg/kg). The daily dietary exposure for commonly consumed beef products ranged from 0.029 to 0.056 µg/kg body weight which was less than the limit set by World Health Organization (WHO). Simultaneous determination of six nitrosamines by Gas chromatography can be used for monitoring the content of nitrosamines in meat products to ensure food safety.