Shampa Sarkar
Department of Food Processing and Preservation, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh
Debashis Kumar Dutta Roy
Department of Food Engineering and Technology, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh
Alomoni
Department of Food Processing and Preservation, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh
Md. Abu Bakkar Siddik
Institute of Nutrition and Food Science, University of Dhaka, Bangladesh
Kothika Das
Department of Food Engineering and Technology, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh
Md. Jiaur Rahman*
Department of Biochemistry (MSc Student), Memorial University of Newfoundland, St. John’s, NL, Canada
Tomato pulp, Preservatives, Storage, Nutritional quality
Department of Food Processing and Preservation, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh
Postharvest and Agro-processing
2.1. Sample Collection and Procurement of Materials A local tomato winter variety was selected for the study. Full ripened fruits were obtained from local farm, which were uniform in size and color. The fruit was washed thoroughly with water to remove unwanted entities like dust, dirt, pesticides residues and surface microflora. Two preservatives sodium benzoate (NaC6H5CO2) (Merck 6290) and potassium Metabisulphite (K2S2O5) (Merck 106357) were purchased from dealers of local market.
2.2. Pulp extraction, Pasteurization, Packaging and Storage After washing, the tomatoes were dried, blanched at 95ºC for 5 min and processed immediately for pulp extraction. Extraction was done in an electric pulper where pulp was separated from the seeds and the obtained pulp was pasteurized in a water bath at a temperature of 82°C for 30 minutes. (At this temperature it is possible to completely kill spore forming bacteria which are sensitive to acidity of apricot pulp, with no changes in physical and chemical attributes) After pasteurization chemical preservatives (SB and PMS) as per treatment separately at 0.05% and 0.1% were mixed with the pulp. The treated pulp samples were then transferred to sterilized glass bottles and stored under ambient conditions (25°C), refrigerated (4ºC) and freezing (≤-10ºC) for a period of 150 days and assessed for chemical parameters at interval of 30 days.
2.3.1. Determination of Lycopene Content Lycopene content of tomato pulp was measured by the method of Grolier et al. [9]. The sample (5-10 g) was extracted with acetone in a pestle and mortar. After that the acetone extract was kept in a separating funnel containing with 10 to 15 ml of petroleum ether and mixed gently. The colour pigment was discarded and extracted with petroleum ether and acetone and 5% Na2SO4. This process was continued until it became colorless. The color phase was transferred to a volumetric flask and measured the absorbance at 503nm by Spectrophotometer (TVT300XPH, Sweden, Perten Instrument). Lycopene content was calculated.
2.3.4. Determination of Titratable Acidity Ten grams of sample was thoroughly mixed with distilled water. The mixture was then titrated by adding 0.1N NaOH until a pH of 8.1 was attained. The volume of the sodium hydroxide, added to the solution, was multiplied by a correction factor of 0.064 to estimate titratable acidity as a percentage of citric acid monohydrate (g 100 g-1) according to the AOAC (2002).
2.3.5. Determination of Total Soluble Solid (TSS) Total soluble solids (TSS) content of all samples was determined using a digital refractometer (Model, PAL-Tea, ATAGO, Tokyo, Japan) and were expressed as degrees °Brix according to the AOAC (2002). All the readings were performed at 20 °C after filtration through hydrophilic cotton.
2.4. Statistical Analysis Each experiment was done in triplicate. The results were expressed as mean ± standard deviation and were analyzed by SPSS (version 17.0 SPSS Inc). One–way analysis of variance was performed using ANOVA procedures. Significant differences between the means were determined by Duncan's Multiple Range test. P < 0.05 was considered as a level of significance.
American Journal of Food and Nutrition, 2015, Vol. 3, No. 4, 90-100
Journal