Drying kinetics and quality aspects of bitter gourd (Momordica charantia) dried in a novel cabinet dryer

Abstract

An attempt was taken to investigate the effect of drying air temperature and slice thickness on the drying kinetics and quality of bitter gourd (Momordica charantia) dried in a novel cabinet dryer (HSTU Fruit and Vegetable Dryer). Fresh bitter gourd was sorted, cleaned, and sliced at 4 mm, 6 mm, and 8 mm thickness. All the samples were blanched in boiling water at 100°C for 3 mins. Then the slices with an initial moisture content of 96.47±0.6% were dried, spreading as a thin layer in the trays of the cabinet dryer using three drying air temperatures of 60, 70, and 80°C until the desired final moisture content (MC) of 4.66±0.4% was obtained. The results indicated that the shortest drying time (2.08 hrs) was required by the sample of 4 mm thickness, which was dried at 80°C to reduce moisture from 96.47±0.6% initial (wet basis, wb) to 4.66±0.4% final moisture (wb). The sample of 8 mm thickness dried at 60°C took the longest drying time (6.67 hrs). The higher drying rate (34.32 gm H2O/min.cm2 ) was noticed at a constant drying rate period in the case of a 6 mm thick slice at 70°C. Whereas a lower drying rate (9.29 gm H2O/min.cm2 ) was observed for drying 8 mm slices using 60°C air temperature. Even though, the effect of blanching on drying characteristics of bitter gourd was not noticed so much, the drying rate was found to be increased slightly of pretreated bitter gourd thus drying time was shorter. A comparison on colour analysis of both fresh and blanched bitter gourd showed that a 6 mm slice dried at 70°C was found better in retaining green colour than other samples. The rehydration ratio (6.63±0.62) and the percentage of water uptake (86.75±0.58) of rehydrated pretreated bitter gourd were also higher in a dried sample of 6 mm. Therefore, pretreated bitter gourd is suggested to dry quickly using 70oC in a cabinet dryer slicing at 6 mm thickness to obtain a better quality dried product.

Improvement of Hot Air Dried Bitter Gourd (Momordica charantia L.) Product Quality: Optimization of Drying and Blanching Process by Experimental Design

“…The increase in slice thickness affected drying times by requiring more time to remove moisture. The findings of this study are in accordance with findings of previous research [4,53,56]. Previous studies conducted on various crops have demonstrated that the thinner sliced products dry more quickly [4,30,57].…”

“…The findings of this study are in accordance with findings of previous research [4,53,56]. Previous studies conducted on various crops have demonstrated that the thinner sliced products dry more quickly [4,30,57]. At 60 • C and 70 • C DATs, regardless of slice thickness, the drying time decreased, while the blanching time was increased.…”

“…The longest drying experiment was performed at 60 • C DAT on unblanched bitter gourd samples with 10 mm slice thickness and terminated at 384 min. In this study, the drying time of the bitter gourd slices was unaffected by the blanching procedure, contrary to previous studies on various products subjected to different blanched processes [4,52,53]. Drying is a manner of removing the water contained in a product while maintaining regulated airflow, temperature, and humidity levels, lowering the moisture content of the food to a point that prevents microbial development that would cause the food to rot and deteriorate.…”

“…It is a well-known tropical vegetable grown across the world for both culinary and medicinal purposes due to its health-related benefits [1,2]. Bitter gourd is recognized for its nutritional and therapeutic properties and is a nutrient-and antioxidantrich vegetable regarding polysaccharides, protein, vitamins, and minerals [3,4]. The mature bitter gourd is also a rich source of iron, phosphorus, vitamin A and vitamin C, as well as β-carotene [5].…”

Moisture Sorption Behavior and Effects of Temperature, Slice Thickness, and Loading Density on Drying Kinetics of a Local Sweet Potato Cultivar Grown in Bangladesh

“…Numerous studies reported the characteristics of fruits and vegetables using low-cost cabinet drying methods. Some of the notable studies include the common foodstuff such as bitter gourd [19], carrot [20], bananas [21], and pumpkin [11]. In these studies, the authors reported that the drying conditions (drying temperature) and sample geometry (slice thickness and shape) affect the drying kinetics and quality of the dried product.…”