K. Nahar*
Bangladesh Council of Scientific and Industrial Research (BCSIR) Laboratories, Dhaka. BCSIR, Dhaka-1205, Bangladesh
M. Z. Haque
Institute of Food Science & Technology (IFST), BCSIR, Dhaka-1205, Bangladesh
K. Nada
Bangladesh Council of Scienti?c and Industrial Research (BCSIR) Laboratories, Dhaka. BCSIR, Dhaka-1205, Bangladesh
M. N. Uddin
Bangladesh Council of Scientific and Industrial Research (BCSIR) Laboratories, Dhaka. BCSIR, Dhaka-1205, Bangladesh
M. Abdullah Al-Mansur
Bangladesh Council of Scientific and Industrial Research (BCSIR) Laboratories, Dhaka. BCSIR, Dhaka-1205, Bangladesh
Pectin; Different mango cultivars; Buffer solution; Extraction condition; Biochemical properties; Protein content
Bangladesh Council of Scientific and Industrial Research (BCSIR) Laboratories, Dhaka. BCSIR, Dhaka-1205, Bangladesh
Quality and Nutrition
Mangoes (varieties: Amrapali, Fazlee, Langra and Kharsapat) were collected from Shaheb Bazar, Rajshahi, Bangladesh. Pectin extraction method Peels were removed from mangoes and chopped (1 sq.cm) and dried in oven at 90 ºC for 6 h and then powdered and sieved (mesh no. 80). The moisture content was 8-10%. Several extraction conditions were considered; 1) variable sources (Amrapali, Fazlee, Langra and Kharsapat)/ H2SO4-(NH4)2SO4 buffer/ pH 1.5/ 80 ºC/ 1h , 2) variable extractants (H2SO4-(NH4)2SO4 buffer, HCl-NaOH buffer and Citric acid buffer)/pH1.5 /80°C /1h /Amrapali, 3) variable pH( 1.5, 2.0, 2.5)/ HCl-NaOH buffer/ 80 °C1h/ Amrapali, 4) variable temperature (80 °C, 90 °C & 99.8 °C )/ HCl-NaOH buffer/ pH1./1h/ Amrapali, 5) variable extraction time (1h, 1.3 h, 2h, 2.3h)/ HCl-NaOH buffer/ pH1.5/ 80 °C/ 1h/ Amrapali. In all, 25 g of powder was mixed with 500 ml of extractant and processed following different extraction conditions. The extracts were filtered through a silk cloth and pectins were precipitated with double volume of methanol and dried at 60 °C in an oven for 4 hours and then powdered and stored at 25 ºC. The yields were 10.92-30.34 % on dry basis. Spectroscopical and structural investivation (FTIR, SEM) of Pectin Fourier Transform infrared analysis was carried out by ATR (Attenuated total reflection) method. The sample was scanned from 4000 to 400 cm–1 in a FTIR spectrophotometer (BRUKER, ATR crystal was germanium). The SEM micrograph of was taken by SEM (Hitachi-2600SN, Japan) by non-destructive method and the images were taken at voltage of 15.0 KV at 68.0 mm x 250 mm. Biochemical properties Equivalent weight (Eq. wt.) was determined by Ranganna’s method. About 0.5 g of sample was taken in a 250 ml conical ?ask and 5 ml of ethanol, 1 g of sodium chloride and 100 ml of distilled water were added. Penol red or Hinton’s indicator (6 drops) was added for sharpen the end point. The solution was titrated with 0.1 N NaOH. The end point was indicated by turning the yellowish color to purple color at pH 7.5. This neutralized solution was stored for determination of Methoxyl (MeO) content. The neutral solution was collected for determination of Eq.wt. and 25 ml of NaOH (0.25N) was added. The mixer was stirred thoroughly and kept at room temperature for 30 min. After then, 25 ml of 0.25N HCl was added and titrated against 0.1 N NaOH to the same end point as before like in Eq.wt. titration. Estimation of Anhydrouronic acid (AUA) content was essential to determine the purity and DE and to evaluate the physical properties (Mohamed and Hasan, 1995). The percentage of DE was determined on the basis of percentage of MeO content and percentage of AUA content (Azad et al., 2014). Proximate analysis Moisture and total ash content were determined using Fischer and Ranganna’s method respectively. Fiber, residual fat and crude protein were determined by Fritted Glass Crucible (AOAC 978.10), Hexane Extraction (AOAC 2003.06) and Automated Kjeldahl method (AOAC 976.05) respectively. Measurement of elementary analysis The minerals were determined using Atomic Absorption Spectrophotometric method (AOAC, 968.08). The minerals Ca, Mg, Fe and Zn. were measured with GBC 908 Atomic Absorption spectrophotometer. P was determined by the ammonium molybdate method (Shimadzu ultraviolet -visible spectrophotometer 1601 PC). K and Na were analyzed using a Corning 410 Flame Photometer. Microbiological analysis Enumeration of Total Aerobic Plate Count (Maturin and Peeler, 1998), Total Fungal Count (Tournas et al. 1998), Escherichia coli (Hitchins et al. 1998), Salmonella, (Andrews and Hammack, 1998) and Staphylococcus aureus (Bennett and Lancette, 1998) were carried out following Bacteriological Analytical Manual (1998). Total Plate Count was enumerated by Pour Plate Method on melted nutrient agar/ plate count agar. Enumeration of fungas was carried out by spread plate technique on potato dextrose agar (PDA) media. Enumeration of Pseudomonas aeruginosa and Staphylococcus aureus were carried out by selective method where Baired- Parker ager medium and cetrimide agar plates were used for Staphylococcus aureus and Pseudomonas aeruginosa respectively. Escherichia coli count was carried out by three-tube most probable number (MPN) method. Lactose broth and eosin methylene blue (EMB) agar were used for E. coli. Salmonella count was carried out using Enrichment method where Lactose broth, selenite broth and bismuth sulphite agar were used. Total Plate Count of Escherichia coli, Staphylococcus aureus and Fungas were enumerated on plate count agar. Incubation temperature and time were 37ºC and 24h. Suspected pathogens were biochemically confirmed. Statistical analysis Descriptive statistics of parameters of yield%, Eq.wt., MeO%, AUA%, DE% and Protein% were computed at first. In order to test the equality of different extraction conditions, one way analysis of variance (ANOVA) test was used. Since parameters varies significantly (p<0.05) in different extraction conditions, Duncan Multiple Rank Test (DMRT) of Post Hoc was performed. SPSS of its version 17.0 was used for data analysis.
Bangladesh J. Sci. Ind. Res. 52(3), 229-238, 2017
Journal