Drying of pineapple slices combined with different pre-treatments was done to reduce various adverse changes by adding satisfactory value. Process optimization was done by dipping the pineapple slices in four different solutions (1% trehalose, 2% NaCl, 10% sucrose, and 10% fructose) before drying. The effects of different pre-treatments and drying temperatures of 50, 55, and 60 °C with a constant 30% relative humidity (RH) were optimized based on the quality attributes, drying time and microbial load of dried pineapple slices. The optimal drying temperature was 55 °C using 1% trehalose pre-treatments based on the physical and biochemical properties. The reconstituted dried pineapples implied at this condition, contributed to the better structure preservation as indicated by the lower shrinkage (0.21) and the higher Coefficient of Rehydration (0.941), and rehydration ratio (6.840). On the other hand, the retention of color, vitamin C, B vitamins, and antioxidant activity of the samples were decreased by increasing drying time and temperatures. The highest Total Phenolic Content (121.02 mg GAE/100g), Total Flavonoid Content (8.72 mg QE/100g), and DPPH radical scavenging activity (7.22 EC50 g/100g) were found at 60 °C drying temperature with 10% fructose pretreatment's samples. The lowest drying time required was 7.64 h using 2% NaCl pre-treatment at 60 °C, considering the time required to reach 20% moisture content in the dried product at 30% RH. Based on the reported results, it is concluded that 1% trehalose at 50 °C can be used to develop high quality pineapple snacks, which maintained the maximum desired physicochemical and nutritious properties. This study could play an essential role in meeting the emerging demand of developing good quality nutritious dried pineapple snacks.

Taikor (Garcinia pedunculata Roxb.) is an underutilized, however nutritious fruit, typically found in Bangladesh and northeast parts of India. Taikor slices (1 ± 0.25 cm thickness) were pretreated for 10 min in 10% sucrose, 10% fructose, and 2% brine solution. Three different temperatures, such as 45, 50, and 55 °C were used to perform the drying operation at 30% constant relative humidity (RH). The thin-layer dehydration characteristics of taikor slices were analyzed using the Newtonian, Page, and Henderson and Pabi’s model. The changes in pH, total acidity, color, β-carotene, vitamin C, B vitamins, antioxidant activity, and microbial load calculation were done to compare the comprehensive quality of untreated and pre-treated dried taikor. After assessing the coefficient of determination (R²) and root mean square error (RMSE) values, the Page model was obtained as the best-suited model. For this model, the R² and RMSE values were found to be approximately 1 and below 0.1094, respectively. Among the pretreatments, sucrose helped retain quality characteristics like ascorbic acid (115.25 ± 0.19 mg/100 g), antioxidant activity (33.25 ± 0.07%) more in the dried samples. The brine pretreated sample had minimum microbial growth. Fructose pretreated taikor samples dried at 45 °C exhibited maximum value of B vitamins (B₁ 0.025 ± 0.002 mg/100 g, B₂ 0.016 ± 0.002 mg/100 g, B₃ 0.011 ± 0.001 mg/100 g), total phenolic content (15.78 ± 0.15 mg GAE/100 g), total flavonoid content (11.11 ± 0.08 mg QE/100 g). Overall, fructose pretreated sample dried at 55 °C was found to be the best method for preserving the maximum physical and chemical quality of dried Garcinia pedunculata.

This research work aimed to optimize the fermentation time, temperature, and relative humidity of the black tea produced from Bangladesh Tea 2 (BT-2) variety by observing their quality parameters. Total theaflavin (TF), thearubigin (TR), the ratio of TF: TR, total liquor color (TLC), high polymeric substances (HPS), and total phenolic content (TPC) were evaluated for quality measurements of BT-2 black tea. Response Surface Methodology (RSM) with Box-Behnken design (BBD) was applied to optimize fermentation time, temperature, and relative humidity as well as evaluate the effects of optimized conditions on the quality of made tea. The results obtained from the response surface optimization affirmed that under the optimum conditions of time (80.14 min), temperature (28.76 °C), and relative humidity (92.30%), the model showed the value of TF (0.69%), TR (5.57%), HPS (8.61%), TLC (3.05%), and TPC (7.95 GAE g/100g tea). Moreover, the optimized model found that the TF:TR value was 1:9.13, which is close to black tea's optimum quality. The values observed in experiments were highly congruent with the predicted value by the regression model. The Analysis of Variance (ANOVA) test revealed that the model was significant for TF, TR, HPS, TLC, TPC, and TF:TR values of prepared BT-2 black tea at different levels (p < 0.001 to p < 0.01). The composite desirability of the model was 0.93, which suggests that the developed model could be utilized effectively to maintain the quality parameters of BT-2 black tea during fermentation.

This study was undertaken to estimate the antioxidant activity and total tannin content of Moringa olifera Lam. (Moringa) leaves and find a suitable extraction condition for maximum yield. Two types of solvent and three different extraction times and temperatures were experimented for extraction. Moringa leaves were oven-dried and powdered to determine the antioxidant activity in terms of total phenolic content (TPC), ferric reducing antioxidant power (FRAP), and DPPH radical scavenging activity and total tannin content. The maximum TPC value noted in methanol extract, and it ranges from 6.46 ± 0.34 g to 3.91±0.19 g gallic acid equivalent (GAE)/100g dry sample (DM). The FRAP values varied from 211.6 ± 3.75 to 344.13 ± 3.26 mg ascorbic acid equivalent (AAE)/100g DM and 166.67 ± 2.90 to 224.93 ± 1.94 mg AAE/100g DM, for methanol and ethanol extract, respectively. The DPPH radical scavenging activity ranged from 46.32 ± 1.07 to 58.09 ± 0.92% for methanol extract and 56.76 ± 1.48% to 69.72 ± 1.15% for ethanol extract. The total tannin content varied from 6.84 ± 0.05 to 10.22 ± 1.11 mg GAE/100 g dry sample and 6.77 ± 0.08 to 9.23 ± 0.51 mg GAE/ 100g DMfor methanol and ethanol extract, respectively. The highest antioxidant yield for methanol and ethanol extract of Moringa leaves differed for various conditions. Overall, Moringa leaves showed excellent antioxidant properties that can be commercially and domestically used.