Raju Ahmmed
Department of Food Engineering, Dhaka University of Engineering and Technology, Gazipur, Bangladesh.
Farjana Akter Sukhi
Department of Food Technology and Engineering, Patuakhali Science and Technology University, Dumki, Patuakhali, Bangladesh
Fardana Binte Zaman
Department of Food Technology and Engineering, Patuakhali Science and Technology University, Dumki, Patuakhali, Bangladesh
Shimul Das
Department of Food Technology and Engineering, Patuakhali Science and Technology University, Dumki, Patuakhali, Bangladesh
Md. Fakhrul Hasan
Department of Horticulture, Patuakhali Science and Technology University, Dumki, Patuakhali, Bangladesh
Md. Junaeid Khan
Department of Food Engineering, Dhaka University of Engineering and Technology, Gazipur, Bangladesh.
Spinach, Processing, NaCl, KMS, Citric acid, Quality
Horticultural Laboratory, Patuakhali Science and Technology University (PSTU
Postharvest and Agro-processing
Indian spinach
Sample collection Indian spinach was collected directly from the farmers' fields of Dumki, Patuakhali at the optimum stage of maturity. Sample of matured and freshly harvested Indian spinach was carried at the Horticultural Laboratory, Patuakhali Science and Technology University (PSTU). Sample processing The sanitation of the process was ensured by personal hygiene and the use of aprons and gloves. All the utensils used were previously sanitized in 200 mgL-1 free chlorine. The sample was washed in fresh water, cut with sharp stainless-steel knives and immersed in cold water (7ºC) for 15 min. Indian spinach was cut into 3 mm thick slices having round shape using a knife. These were then immersed in cold water (7ºC) with 100 mgL-1 free chlorine at pH 7.0 for 15 min for sanitation. After completing the cleaning process, sliced samples were dipped in various postharvest treatments. Then the samples were put into polyethylene bags. Bags with 50 g sliced samples were sealed under different treatments. Treatments and experimental design Nine post-harvest treatments, including a control, were used for the present study. The treatments were T0: Control (untreated Indian spinach), T1: 1% NaCl, T2: 1.5% NaCl, T3: 2% NaCl, T4: 1.5% Citric acid, T5: 1% Citric acid, T6: 0.5% Citric acid, T7: 0 .5% KMS, T8: 1% KMS, and T9: 1.5% KMS. The experiment was laid out in the Completely Randomized Design (CRD) with 3 replications. Parameters Two physical changes: weight loss and firmness, and four chemical changes such as Total Soluble Solids (TSS), Titratable Acidity (TA), Vitamin C and pH were measured. Preparation of treatments 1% NaCl: Ten (10) g NaCl was added to 100 ml distilled water and then vortexing was done for proper mixing of solution. Thus, 1% NaCl solution was prepared. Again 1.5% and 2% NaCl were also prepared in the same way according to concentration. 1.5% Citric acid: Fifteen (15) g citric acid was added to 100 ml distilled water and then vortexing was done for proper mixing of solution. Thus, 1.5% citric acid solution was prepared. Again, 1% and 0.5% citric acids were also prepared in the same way according to concentration. 1.5% KMS: Fifteen (15) g KMS was added to 100 ml distilled water and then vortexing was done for proper mixing of solution. Thus, 1.5% KMS solution was prepared. Again, 1% and 0.5% KMS were also prepared in the same way according to concentration. Application of postharvest treatments Every sample was kept separately in a tray. Thereafter, the individual sample was treated by NaCl, KMS and citric acid of different concentrations for 5 min. After completing the treatments, all the samples were kept in air-tight polyethylene bags as per treatments of the study and then stored in refrigerator under low temperature. Data were recorded at 0, 2, 4 and 6 days after storage as per treatments. Physicochemical analysis Firmness: Firmness was measured by using the Magness-Taylorpressure testers (Model GY-802). The firmness testing machine was equipped with a 4-mm diameter cylindrical probe that was penetrated in the normal direction. The reading was taken for each sample at collar, middle and end points according to Hassan (2006). Weight loss: Weights of packages with sample slices were measured using an electronic balance (Sartorius BP 6100, R & M marketing, UK). The difference in the weight was expressed as gram of weight loss of the samples (Anthony et al., 2003). Titratable acidity: Titratable acidity of the filtered sample was measured with sodium hydroxide at 0.01N (the results for the Indian spinach was expressed in % of citric acids) (AOAC, 1995). pH: pH was determined in the triturated sample by a digital electronic pH meter. Before measurement, the pH meter was standardized with a buffer solution as described by (Ranganna, 1994). TSS: Ten (10) g sample of Indian spinach was blended with distilled water (40 ml) in a homogenizer (Black & Decker, BX 250, Hunt Valley, USA) for 2 min. The homogenate was filtered through a muslin cloth, and few drops of the filtrate were used to measure TSS using a hand-held Refractometer (BOE-32195). Vitamin C: The content of vitamin C was determined with Tillman’s reagent (2.6 dichlorophenolindophenol) titration until a slightly pink coloration was stabilized for 15 s. The results were expressed in mg of ascorbic acid per 10 g of sample (Pregnolatto and Pregnolatto, 1985). Data Analysis Statistical analyses were done using Mixed-model analyses of variance (ANOVAs). Mean values of the samples were compared using Fisher’s Least Significant Difference (LSD) test among the treatments.
J Bangladesh Agril Univ 17(1): 99–104, 2019
Journal