Enhancing osmo-dehydration process of sliced okra with non-ionizing radiation for quality improvement

Fresh okra is highly perishable due to its susceptibility to microbial contamination, and traditional preservation methods often degrade its heat-sensitive nutrients. To enhance preservation, this research investigates the osmo-dehydration process of sliced okra with non-ionizing radiation for quality improvement. Okra samples were sliced to 5 mm and 8 mm, osmo-dehydrated in a 4:1 sample-to-solution ratio of 55% sucrose at 27 °C for 2–4 h, and then exposed to LED ultraviolet radiation at intensities of 4.35, 8.7, and 13.06 Mlux. Microstructural changes were assessed using scanning electron microscopy (SEM) to examine cellular structure and the effects of treatments on cell compactness, which may limit microbial growth and moisture retention. Additionally, microbial, textural, and nutritional qualities—including moisture, vitamin C, folate, and fiber—were analyzed using standard methods. Factorial Multilevel Categorical design was used to identify optimal parameters. Results showed that thinner slices exposed to longer ODT and higher radiation intensity developed more compact cellular structures, likely restricting microbial growth by limiting nutrient and moisture access. In 5 mm slices, extended ODT significantly reduced microbial counts and moisture levels compared to controls (p < 0.05), likely due to more effective dehydration, which lowers water activity critical for microbial survival. These conditions also improved moisture content (79.5% in 8 mm slices vs. 85.3% in controls) and enhanced textural properties like hardness and cohesiveness. The optimal conditions—2 h of ODT, 5 mm ST, and 4.35 Mlux—resulted in a total plate count (TPC) of 3.66 log CFU/g, a yeast and mold count (YMC) of 3.03 log CFU/g, and a coliform count (CC) of 2.78 log CFU/g. The residual moisture content was effectively reduced to 69.91%, contributing to improved shelf life by limiting microbial activity. Despite the dehydration process, nutrient retention was substantial, with folate content preserved at 46.23 µg/g and fiber content at 6.35%. This combined process of osmo-dehydration and non-ionizing radiation has significant applications for large-scale okra preservation by enhancing microbial safety and nutrient retention, offering a sustainable and efficient alternative to traditional drying methods.