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.

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 (R 2 ) and root mean square error (RMSE) values, the Page model was obtained as the best-suited model. For this model, the R 2 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 (B 1 0.025 ± 0.002 mg/100 g, B 2 0.016 ± 0.002 mg/100 g, B 3 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 .

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The aim of the study was to develop fruit juice concentrate from Citron and its kinetic evaluation during storage at 10 ºC, 25 ºC and 40 ºC respectively, for 12th week. The effect of different temperatures on the quality of the juice concentrate was also investigated. The concentration of ascorbic acid in the juice concentrate was monitored after every week of storage. The results showed that degradation kinetics of ascorbic acid during storage was followed by the first-order kinetics. The degradation rates of ascorbic acid during storage at 10 ° C, 25 °C and 40 °C  were obtained as 2.27 ± 0.24, 2.46 ± 0.31 and 2.56 ± 0.34 1/week  respectively. The higher degradation rate was observed at 40 °C storage temperature. Temperature-dependent rate constants of ascorbic acid of citron juice concentrate was obeyed the Arrhenius relationship with higher R2 values as 0.96.  Total antioxidant degradation was also high at higher storage temperatures. The amount of total phenolic content was decreasing at the first few weeks of storage, but later period of storage it was in gradually increasing trend. The storage study demonsrated that ascorbic acid, total polyphenol and antioxidant activity were not degraded at lower temperature after 12th week.