Effect of different drying methods on the drying characteristics of Kachri and physical properties of Kachari (Cucumis callosus)

Introduction

The arid and semi-arid regions of Rajasthan are home to unique horticultural resources that sustain rural diets under harsh agro-climatic conditions. Among them, kachari (Cucumis callosus), also known as wild melon or small gourd, is a hardy cucurbit adapted to sandy soils, high temperature, and minimal irrigation. Traditionally, it has been valued for its culinary applications in chutneys, pickles, spice blends, and as a natural tenderizer in meat dishes (Patel and Panwar, 2022) [5] . Despite its adaptability and cultural significance, kachari remains underutilized and under-researched outside its native region. Nutritionally, kachari is a good source of carbohydrates, dietary fiber, vitamin C, calcium, and iron, along with bioactive compounds such as polyphenols and carotenoids (Samadia et al., 2024) [7] . These properties highlight its potential as a functional food. However, the fruit's high moisture content and short harvesting season render it highly perishable, leading to substantial post-harvest losses therefore preservation through drying is essential to extend its shelf life and improve usability. Drying reduces water activity, thereby inhibiting microbial growth and enzymatic reactions (Meena et al., 2016) [3] . The choice of drying method directly influences the sensory qualities, rehydration characteristics, and consumer acceptability of the final product. Traditional methods like sun and shade drying are widely used due to their simplicity and cost-effectiveness, while modern approaches such as oven drying provide controlled conditions but may compromise quality due to thermal stress. Although extensive research has been conducted on drying effects in related cucurbits such as pumpkin, bottle gourd, and bitter gourd, systematic studies on Cucumis callosus are limited. Thus, this study aimed to evaluate the effect of sun drying, shade drying, and oven drying (with and without peel) on the drying characteristics, physical properties, sensory acceptability, and short-term storage stability of kachari powder.

Materials and Methods

Procurement of Raw Material

Fresh, mature kachari fruits were procured from local markets of Bikaner district, Rajasthan. Uniform fruits free from visible defects were selected for the study.

Preparation of Samples

The fruits were washed thoroughly under running potable water, blotted dry, and divided into peeled and unpeeled groups. They were sliced into uniform pieces (5-8 mm thickness) to ensure consistency in drying. Drying was considered complete when slices became brittle and reached constant weight.

Drying Methods

Grinding and Storage

The dried slices were ground into powder using an electric grinder (Costa et al., 2009) and stored in HDPE pouches at room temperature (25±2 °C) preserving its nutritional and medicinal properties ((Verma, 2024) [8] .

Sensory Evaluation

Ten semi-trained panelists evaluated colour, aroma, texture, and overall acceptability using a six-point hedonic scale (0 = dislike extremely, 6 = like extremely). The most acceptable powder was further assessed for shelf-life over 30 days at 0, 15, and 30-day intervals.

Physical Properties of Powder

Physical quality parameters were determined to evaluate the functional suitability of the powders. Yield (%): Calculated as the weight of powder obtained from 1 kg of fresh fruit. (Negi, 2003) [4] Yield (%) = Weight of product Weight of raw material × 100

Hydration Capacity (%): Determined by soaking 1 g of powder in 10 mL distilled water overnight at room temperature (Bishnoi and Khetarpal, 1993) [1] . Excess water was filtered, and the weight gain was measured.

Final weight (g)-Initial weight (g) Initial weight (g)

×100

Swelling Index (mL/g): Measured by recording volume increase after adding 1 g of powder to 10 mL water in a graduated cylinder and allowing to stand for 1-2 hours (Bishnoi and Khetarpal, 1993) [1] .

Statistical Analysis

All experiments were conducted in triplicates. Observations for sensory scores and physical properties were expressed as mean±standard deviation (SD). Arithmetic mean and SD were calculated using standard formulae (Gupta, 2000). Analysis of variance (ANOVA) was applied to determine significant differences (p≤0.05) among treatments.

Results and Discussion

Sensory Evaluation

Sun drying without peel secured the highest sensory scores for colour (5.6), aroma (5.5), texture (5.4), and overall acceptability (5.6; "liked very much"). Shade drying with peel also performed well (overall acceptability 5.4). Oven drying, particularly with peel, was the least acceptable (overall acceptability 4.1).

High scores for sun drying may be attributed to natural retention of pigments and volatiles under moderate conditions. Oven drying likely caused browning and loss of aroma compounds due to higher heat exposure.

Physical properties

kachari powder (Mean ±SD) Yield (%) 12±0.17 Hydration capacity (%) 6.5±0.05 Swelling index (ml/g) 5.6±0.57

 Yield: Highest in oven drying (12.4%), followed by shade drying (11.7%), and lowest in sun drying (11.1%).  Hydration capacity: Maximum in sun drying without peel (6.5%), indicating better reconstitution.  Swelling index: Highest in sun drying without peel (5.6 mL/g), confirming superior water absorption ability.

Shelf-Life Study

Sun-dried powder without peel retained high acceptability over 30 days, with overall scores declining slightly from 5.6 (day 0) to 5.4 (day 30). Aroma showed the greatest decline, while colour and texture remained largely stable. The powder showed no visible spoilage, confirming HDPE packaging as suitable for short-term storage.

Comparative Discussion

Findings confirm that moderate drying (sun/shade) preserves sensory and functional qualities better than oven drying. while oven drying offers time efficiency, it compromises consumer acceptability, limiting its suitability for kachari powder production.

Conclusion

The study demonstrated that drying method significantly influences the sensory and physical properties of kachari powder. Sun drying without peel was identified as the most suitable technique, producing powders with superior colour, aroma, texture, hydration capacity, and swelling index, while maintaining stability during 30 days of storage These findings highlight the potential for sun-dried kachari powder as a value-added product in chutneys, pickles, spice blends, and traditional recipes. Promoting its commercial production could enhance utilization of this underexploited arid fruit, reduce post-harvest losses, and provide new livelihood opportunities in arid regions.

References

1. Bishnoi S, Khetarpaul N. Variability in physicochemical properties and nutrient composition of different pea cultivars. Food Chemistry. 1993;47(4):371-373.
2. Gupta SP. Statistical Methods. 31st rev ed. Sultan Chand and Sons; 2000.
3. Meena SR, Singh RS, Sharma BD, Singh D. Most favourite traditional cucurbitaceous vegetables and their utilization pattern in Thar Desert of western Rajasthan, India. Indian Journal of Traditional Knowledge. 2016;15(3):385-394.
4. Negi A. Development and incorporation of fruit powder for value addition of cereal-based food products [doctoral dissertation]. Hisar: CCS Haryana Agricultural University; 2003.
5. Patel MR, Panwar NL. Drying kinetics, quality assessment and socio-environmental evaluation of solar-dried Cucumis callosus. Energy Nexus. 2022;7:100065.
6. Ramyashree S. Development of process for value-added products of kachari (Cucumis callosus) [doctoral dissertation]. Maharana Pratap University of Agriculture and Technology; 2023.
7. Samadia DK, Haldhar SM, Ram H, Verma AK, Gurjar PS. Kachari melon diversity and varietal development in arid climates. Journal of Agricultural Ecology. 2024;18:14-27.
8. Verma D. Utilization of hill lemon peel for preparation of candy using different sweeteners [doctoral dissertation]. Dr. Yashwant Singh Parmar University of Horticulture and Forestry; 2024.