Freshly harvested fruits of Water chestnut (Trapa sp.) were collected on July 2010-September 2010 from the Fruit Research Substation, Shyampur, Rajshahi, Bangladesh for experimental purpose. The physical and chemical parameters were studied from July 2010-January 2011 by the following methods. The chemicals and reagents used in this study were of analytical grade.
Determination of pH:
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Extraction of juice from water chestnut (Trapa sp.): About 70-90 g of water chestnuts (Trapa sp.) was taken in a mortar. The fruits were crushed thoroughly in a mortar with a pestle and then filtered through two layers of muslin cloth. The filtrate was then centrifuged for 10 min at 3000 rpm and the clear supernatant was collected |
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Preparation of standard buffer solution: Buffer tablets (BDH Chemicals Ltd. Poole, England) of pH 7.0 or 4.0 was dissolved in distilled water and made up to the mark of 100 mL with distilled water |
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Procedure: The electrode assembly of the pH meter was dipped into the standard buffer solution of pH 7.0 taken in a clear and dry beaker. The temperature correction knob was set to 28°C and the fine adjustment was made by asymmetry potentially knob to pH 7.0. After a wash the electrode assembly was then dipped into a solution of standard pH 4.0 and adjusted to the required pH by fine asymmetry potentially knob. The electrode assembly was raised, washed twice with distilled water, rinsed off with the juice of the cultivars and then dipped into the juice of the water chestnut (Trapa sp.). The pH of the juice was noted |
Determination of total titratable acidity (TTA): TTA was determined by the Folin method.
Determination of moisture content: The moisture content was determined by the conventional procedure.
Determination of dry matter: Dry matter content was calculated from the data obtained from percentage of moisture content.
Determination of ash: Ash content was determined as followed by the method of AOAC.
Determination of water-soluble protein: Water-soluble protein concentration was determined following the method of Lowry et al. using BSA as standard. The extraction was carried out with distilled water.
Determination of lipid: Lipid content of the water chestnuts (Trapa sp.) was determined as described by Bligh and Dye.
Determination of total sugar: The total sugar content of water chestnuts (Trapa sp.) was determined colorimetrically by the anthrone method as described in Laboratory Manual in Biochemistry.
Extraction of sugar: Extraction of sugar from water chestnuts (Trapa sp.) was done as described by Loomis and Shull.
Determination of reducing sugar: Reducing sugar content of the water chestnuts (Trapa sp.) was determined by dinitrosalicylic acid method.
Determination of non-reducing sugar or sucrose: Non-reducing sugar or sucrose content was determined by using the formula.
Determination of starch: The starch content of the water chestnuts (Trapa sp.) was determined by the Anthrone method, as described in Laboratory Manual in Biochemistry.
Determination of vitamin-C: Vitamin-C content of water chestnuts (Trapa sp.) was determined by the titrimetric method.
Determination of β-Carotene: β-Carotene content of water chestnuts (Trapa sp.) was determined according to the procedure reported in methods of Biochemical Analysis.