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Comparison Between Solar Tunnel, Solar-Cum Gas Dryer, and Open Sun Drying Methods for Drying Red Chilies

Comparison Between Solar Tunnel, Solar-Cum Gas Dryer, and Open Sun Drying Methods for Drying Red Chilies

Behari Lal Meghwar1*, Attaullah Khan1, Imran Ali Lakhiar1, Asif Ali Mirani2, Muhammad Siddique Daper1 and Muhammad Waseem Kalroo

1PARC, Arid Zone Research Centre, Umerkot, Sindh, Pakistan; 2Agricultural Engineering Division, PARC, Islamabad, Pakistan.

*Correspondence | Behari Lal Meghwar, PARC, Arid Zone Research Centre, Umerkot, Sindh, Pakistan; Email: 


Chili is an important crop and spice produced in Pakistan and globally. In Pakistan, the Umerkot district is the primary producer of chili crops. In this area, the chili is being usually dry under the open sun (T3) or traditional method; this practice has many drawbacks and leads to poor quality. A study was planned to find an alternative chili drying method for the study area. To achieve the desired goal, we considered two different drying methods, solar tunnel (T1) and solar cum gas (T2), and compared the rate of reducing the moisture over time with T3 method. The T1 and T2 methods are substitutes for the T3 drying method. Therefore, a small-scale natural convection solar tunnel dryer and solar cum gas-based drying methods were developed and tested at PARC-Arid Zone Research Center, Umerkot. This study was conducted in three different intervals during November 2022, and each interval was replicated three times. In addition, the chilies samples were collected (uniform in color and size) from the farmer’s field and brought to the experimental site. The experiment selected chili variety was Longi, and the initial weight of the all collected samples was 2000 g. The selected samples’ initial moisture content was considered to be 80%. The test results showed that T1 and T2 methods significantly reduced the moisture compared to T3 method. T1 and T2 method reduced the moisture level from 80% (w.b) to about 10-12% (w.b) in 63 and 54 hrs, respectively, compared to 81 hrs taken by T3. However, the total aflatoxin content of T1, T2, and T3 were 1.4, 3.0, and 2.7 ppb, respectively. The measured values were below the recommended values of the aflatoxin. Based on the experiment result, it was concluded that the T2 and T2 drying methods are a better alternative for open sun drying and ensure product quality. These methods are not subjected to the weather conditions like the rainy season.

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Pakistan Journal of Agricultural Research


Vol.37, Iss. 1, Pages 1-87


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