The demand for sustainable and eco-friendly extraction methods for bioactive compounds from natural sources has increased significantly in recent years. In this study, we investigated the effectiveness of the microwave pretreated ultrasound-assisted extraction (MPUAE) process for the extraction of antioxidants (TPC, DPPH, and FRAP) from papaya pulp and peel. The optimized variables for the MPUAE process were determined using the Box-Behnken design tool of response surface methodology. Our results showed that the optimized variables for pulp and peel were 675.76 and 669.70 W microwave power, 150 s of irradiation time, 30 °C ultrasound temperature, and 19.70 and 16.46 min of ultrasonic extraction time, respectively. Moreover, the MPUAE process was found to be more energy-efficient and environmentally friendly compared to the conventional ultrasound-associated extraction (UAE) technique. The MPUAE process emitted less CO₂ to the environment and had a shorter extraction time, resulting in a more sustainable and cost-effective extraction process. Our study suggests that the MPUAE process has the potential to be a promising and eco-friendly alternative for the industrial extraction of bioactive compounds from papaya and other natural sources.

Soil acidity is one of the major soil-degradation events throughout the world, and the long-term application of nitrogenous fertilizers is thought to be a main cause of soil acidity. In the present experiment, we collected soil and tea (Camellia sinensis L.) leaf samples from five representative tea gardens in Bangladesh and evaluated soil nutrient pools and biochemical properties of tea leaves. The results showed that there was a negative relationship between soil pH and the amount of applied nitrogenous fertilizers. Moreover, continuous application of traditional fertilizers over twenty-five years promoted not only the deficiency of phosphorus (P) and mineral-based cations, such as potassium (K⁺), calcium (Ca²⁺), and magnesium (Mg²⁺), but also increased manganese (Mn²⁺) and aluminum (Al³⁺) toxicity in soils, which suppressed the yield and quality of tea. Crucially, tea leaf production remained almost similar (average 1079.77 kg ha⁻¹) from 1995 to 2015, while the application doses of urea, TSP, and MoP increased by 24.69%, 18.92%, and 16.67%, respectively, in garden soils. However, the pH value of soil declined up to 24% from 1992 to 2020 in the tested gardens. Consequently, the availability of K⁺, P, Ca²⁺, and Mg²⁺ decreased by 56%, 25%, 55%, and 49%, respectively, in those tea garden soils. In addition, the quality of tea leaves was severely affected, as evident by the reduced levels of total flavonoids, polyphenols, soluble solids, vitamin C, vitamin B1, and vitamin B2. Moreover, free-radical scavenging activity (DPPH), caffeine, and tannin concentration were increased in tea leaves, which indicated that tea plants were potentially being stressed. Therefore, we study concluded that long-term application of traditional nitrogenous fertilizers can be an important regulator of lowering garden soil pH, which reduces native soil nutrient pools and thereby the yield and quality of tea leaves.

The present study aimed to analyze and establish an effective combination of ultrasound and immersion pretreatment processes for drying Taikor (Garcinia pendunculata Roxb.) fruits. Taikorslices were first immersed in 10 % sucrose, fructose, and glucose solution. Then, the immersed slices were treated in an ultrasonic bath at 30 °C for 10, 20, and 30 min. Drying operations were carried out at 50, 60, and 70 °C, with a fixed relative humidity of 30 %. The Page, Newton, Henderson and Pabis, and Weibull distribution models were fitted to the obtained drying data to determine the best kinetic model that effectively describes the drying properties ofTaikor. After drying operations, changes in quality parameters, e.g., β-carotene, vitamin C, B vitamins, color, antioxidant activities, and microbial loads, were measured to obtain the best drying temperature and the most effective pretreatment combination with minimum loss of nutrients of the sample. Among different kinetic models, both Page and Weibull distribution models showed the best R² values of 0.9867 and 0.9366, respectively. The chemical properties were preserved to the greatest extent possible by drying at 50 °C with glucose pretreatment. The color parameters were better preserved by fructose pretreatment. Sonication time also had profound effect on the quality parameters of dried Taikor slices. However, higher temperature drying required a shorter time for drying and exhibited better performance in microbial load reduction. This study's findings will help to establish an effective drying condition forGarcinia pedunculatafruits.

This research was conducted to assess the drying kinetics and product quality during osmotic dehydration and air drying of coconut cuts. The coconuts were osmotically pretreated by different concentration of sugar solution (40 °Brix, 50 °Brix, and 60 °Brix) and temperature of osmotic solution (35°C, 45°C and 55°C) were maintained. The proportion of fruit to solution was maintained 1:4 (w/v) and pretreatment process length was 3 hours. Higher osmotic solution temperature at 55°C with low concentration 40 °Brix resulted in a huge reduction of antioxidant activity, vitamin C, polyphenol, and color contents while higher osmotic solution concentration at 50 °Brix with lower temperature 35°C held more. The present investigation likewise exhibited that moisture loss and solute gain rate extended with the increasing of osmotic solution temperature and concentration. The outcomes demonstrated that drying regime was typically in the falling rate period. We used regression analysis to the experimental drying data to fit three thin layer drying models. The most appropriate model(s) was selected using correlation coefficient (R²) and root mean square error (RMSE). The page model showed a better fit of the experimental drying data (as compared to other models) on the basis that R²> 0.9997 and RMSE < 0.0011. These data represent a good contribution to further investigation on the mass transfer kinetics and also demonstrated that fruits could be preserved with higher nutrient applying osmotic dehydration technique.