D Parvin
Department of Crop Botany, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur 1706
JU Ahmed
Department of Crop Botany, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur 1706
MM Hossain
Department of Horticulture, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur 1706
M Mohi-Ud-Din
Department of Crop Botany, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur 1706
Evaporative cooler, Earthen chamber, Bamboo chamber, Reducing sugar, Sucrose, Potato
Department of Crop Botany, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Salna, Gazipur
Postharvest and Agro-processing
The research was carried out in the Department of Crop Botany, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Salna, Gazipur. Seed potatoes of three processing varieties viz. Asterix (BARI Alu-25), Courage (BARI Alu-29) and Lady Rosseta (BARI Alu-28) were collected from Bangladesh Agricultural Development Corporation (BADC) and Tuber Crops Research Center (TCRC) of Bangladesh Agricultural Research Institute (BARI) and then cultivated at the field laboratory of the Department of Crop Botany (Block 14) by following standard cultivation and management practices for potato prescribed by BADC and TCRC, BARI. After harvesting, potatoes were subjected to curing for 10 days and sent to the different storage conditions. Potato tubers were stored in 3 conditions: a low cost earthen chamber with evaporative cooler (EC), bamboo chamber (BC) [as recommended by TCRC, BARI] and refrigerator (RF). BC was made by bamboo and bamboo sheets and its size was 5ft×4ft×3ft (L×W×H). The size of EC was 5ft×4ft×3ft (L×W×H) and it was made by clay soil. Three holes were made on earthen wall among those two for ventilation purpose and one was used for the entrance of airflow with vapor by evaporative cooler (Model- WRA-S99, Walton, Bangladesh). An electricity power supply was connected to the evaporative cooler as well as narrow tube was jointed to the cooler for continuous water supply. A giant refrigerator (Model- ER- 202F, General Electronics. Japan) was used as the refrigerated storage. A thermo-hygrometer was kept inside each chamber as well as in the external environment. Data were collected at the day before storage and then 1-month interval basis up to 3 months on dry matter (%), weight loss (%), shrinkage (%), glucose, fructose, reducing sugar, sucrose, and total soluble sugar and starch contents. After the termination of 90 days storage, sensory evaluation of chips prepared from stored potatoes was conducted. Dry matter content (%), weight loss (%) and shrinkage (%) were determined as the procedures described by Abano et al. (2011). Energy content of potato tubers was calculated according to Bradbury (1986) by using the equation E = - 17.38M + 1699, where, E = Energy in kJ per unit weight (100 gm) and M = Moisture content (%). Cooling efficiency was determined according to Abano et al. (2011) using the maximum and minimum temperatures of external environment and the maximum temperature inside storage. Sugar content of potato flesh was extracted by following the procedure of Xue (1985) with slight modification. Briefly, 0.5 g of fresh potato flesh was extracted thrice with 5 ml of 80% (v/v) ethanol at 80°C for 30 min and the extracts were centrifuged at 5000 rpm for 10 min with a refrigerated centrifuge (Model- BCBHR-201, Bio LAB, Canada). The supernatants were combined in a 50 ml beaker and placed in a water bath at 80-85°C until the volume is reduced to about 1 ml. The sugar extract was transferred to a 10 ml volumetric flask by 3-4 wash with distilled water and used for assaying total soluble sugars, reducing sugar, sucrose, glucose and fructose contents. Glucose content was estimated spectro- photometrically by glucose enzymatic assay kit (Linear Chemical, Spain) following the procedure attached with the kit pack. Fructose and sucrose content of potato flesh was measured by the anthrone colorimetric method following the procedure of Kang et al. (2009). Reducing sugar content was measured by DNS colorimetric method following the procedure of Miller (1959) with some modifications. Total soluble sugar was calculated by the summation of glucose, fructose and sucrose contents as done by the Adu-Kwarteng et al. (2014). A series of standard solution was made for glucose, fructose, sucrose and reducing sugar to prepare standard curves for the quantification of the sugar components. Starch content was extracted following the procedure described by Kang et al. (2009). Then 1 ml of aliquot was mixed with 1 ml of distilled water and 5 ml of anthrone reagent, and boiled for 15 min. After cooling for 10 min in the dark, the absorbance was read at 620 nm using spectrophotometer. A series of standard solution was made using starch for the preparation of standard curve. After the termination of 90 days’ storage, potato chips were produced according to Kita et al. (2014) with slight modification. After washing potatoes were cut into slices of 2 ±0.1 mm thickness with a potato slicer, washed in cold saline water (NaCl @ of 20 g/L) and superficially dried by paper towels. The chips were deep fried about 3 min in refined rice bran oil heated to 180°C. After discharging of the oil and cooling, chips were taken for sensory evaluation. Sensory evaluation was performed by an untrained panel (n=10, 21- 30 yrs, 4 males and 6 females) who were the regular consumer of potato chips. Samples were randomly coded before being served to the panel. Five sensory quality parameters (color, texture, taste, crispiness and the overall acceptability) were individually evaluated based on a 9-point hedonic scale (1: dislike extremely and 9: like extremely) as described by Meilgaard et al. (2007). Statistical analysis was performed using Statistix 10 data analysis software. Monthly data collected throughout the storage duration were averaged and subjected to two-way analysis of variance for mean comparison, and significant differences were calculated according to Tukey’s HSD test. Data were reported as mean ± standard error (SE). Differences at p≤ 0.05 were considered to be statistically significant. Periodical data were presented in the graphs as the mean ± SE of 3 varieties with 3 replications for each storage conditions.
Ann. Bangladesh Agric. (2019) 23(2) : 61-78
Journal