Ruheea Taskin Ruhee
Waseda University, Graduate School of Sport Sciences, 2-579-15 Mikajima, Tokorozawa, Saitama 359-1192, Japan,
Samia Sams
University of Dhaka, Faculty of Biological Sciences, Institute of Nutrition and Food Science, Dhaka1000, Bangladesh
Amena Begum
Amena Begum, University of Dhaka, Faculty of Biological Sciences, Institute of Nutrition and Food Science, Dhaka-1000, Bangladesh
Mohammad Khairul Alam
Mohammad Khairul Alam, University of Dhaka, Faculty of Biological Sciences, Institute of Nutrition and Food Science, Dhaka-1000, Bangladesh,
Parveen Begum
University of Dhaka, Faculty of Biological Sciences, Institute of Nutrition and Food Science, Dhaka-1000, Bangladesh,
Maksuda Khatun
Department of Botany, University of Dhaka, Dhaka-1000, Bangladesh,
Mahbuba Kawser
University of Dhaka, Faculty of Biological Sciences, Institute of Nutrition and Food Science, Dhaka-1000, Bangladesh
Silvia Saberin
University of Dhaka, Faculty of Biological Sciences, Institute of Nutrition and Food Science, Dhaka1000, Bangladesh
Monira Ahsan
Department of Pharmaceutical Chemistry, University of Dhaka, Dhaka-1000, Bangladesh
Sheikh Nazrul Islam
University of Dhaka, Faculty of Biological Sciences, Institute of Nutrition and Food Science, Dhaka-1000, Bangladesh
Bangladesh; Dietary fibre; Ethnic vegetables and fruits; Unconventional vegetables
Quality and Nutrition
Vegetables, Minor fruits
Reagents Total dietary fibre assay kit (TDF-100) was purchased from Sigma-Aldrich (Saint Louis, MO, USA). Reagent grade ethanol, acetone, dibasic sodium phosphate, sodium phosphate, sodium hydroxide, hydrochloric acid was procured from Merck (Darmstadt, Germany). Food samples This study included analysis of total dietary fibre content for sixty-nine vegetables and fruits of ethnic and unconventional varieties grown in Chittagong Hill Tracts (CHTs) and in some specific plane lands. Ethnic group comprised twenty-eight leafy and seventeen non-leafy vegetables and six fruits; and unconventional group consisted of fifteen leafy and three non-leafy vegetables. Sample plan Multi-region sampling plan was employed for collection of the food sample. To conform to the representative sample principle- “what the mass people consume’ and from where they collect it” (Southgate and Greenfield, 2017), the ethnic samples were collected from weekly local markets at Rangamati and Bandarban, and the unconventional ones were collected from the specific local areas of Gazipur, Mymansingh and from some places of Dhaka, where they were grown. The samples were collected fresh, which were then water sprayed, packed into auto seal plastic poly bags and brought to the lab where the food samples were processed for analysis of dietary fibre. Depending on the availability, two to three samples were collected for each of the food from every market and growing area. These were then mixed to make three analytes or composite test samples.
Identification of vegetable sample A taxonomist (Dr. Maksuda Khatun) of the Department of Botany, University of Dhaka, who has also accompanied the collection team, and confirmed the sample identity with name and family. Sample processing Each of the collected samples was cleaned with tap water and then rinsed with distilled water, gently swabbed with tissue paper to remove traces of water and air dried. The air-dried sample was diced or cut into small pieces (peeled where needed) using a clean stainless steel knife on a dried clean plastic cutting board. The diced sample was mixed, and a weighted portion was spread in stainless steel plate(s) and then dried in air-oven at 100 – 105 ° C to constant weight (AOAC, 2007), which was then milled to 0.3 to 0.5 mm mesh powder. The powdered or milled sample was stored in desiccators for analysis of total dietary fibre. Analysis of total dietary fibre The total dietary fibre was estimated by the enzymatic and gravimetric method of the Association of the Official Analytical Chemists (AOAC, 2007) using a total dietary fibre assay kit (TDF-100A, Sigma-Aldrich, Saint Louis, USA). The assay procedure as described in the kit was strictly followed. In brief, the dried meshed sample was incubated with α-amylase at pH 6.0 for 15 min at 95 o C for gelatinization, which was then digested by incubation with protease at pH 7.5 for 30 min at 60 o C, then with amyloglucosidase at pH 4.5 for another 30 min at 60 o C to remove protein and starch present in the sample. Ethanol was added in excess to precipitate the soluble dietary fibre. The residue was filtered and washed with ethanol and acetone; which was then dried overnight in an air-oven until it reduced to constant weight or nearest 0.1 mg. After drying, half of the sample was analyzed for protein and the other half was burnt to ash.
Statistical analysis The analysis was carried out in triplicates. Descriptive statistics were performed and values were expressed as mean ± standard deviation. One-way analysis of variance (ANOVA) was employed to evaluate the differences among varieties for total dietary fibre content and was declared significant when p <0.05 at 5% level of significance. Minitab version 18.0. (Minitab Inc., State College, PA, USA) was used to analyze the data.
Potravinarstvo Slovak Journal of Food Sciences vol. 14, 2020, p. 33-41
Journal