The aim of this study is to evaluate the potential of tight ultrafiltration for the concentration of bioactive compounds in watermelon juice and also analyze the effectiveness of frozen storage for storing the juice concentrate. The concentration of the juice was performed at two different temperatures of 30 ± 2°C and 23 ± 2°C and at pressures of 2 and 3 bar for concentration factors of 1.5, 2, and 3. Total phenolic content in the concentrate was determined in terms of gallic acid and flavonoid concentration was analyzed in terms of rutin equivalent. Lycopene was determined spectrophotometrically using the hexane extraction method. The ultrafiltration (UF) process was successful in retaining a high percentage of bioactive compounds in the watermelon juice concentrate. Flavonoids showed the highest levels of concentration among the four important bioactive compounds. The ultrafiltration experimental set of T = 23 ± 2°C, P = 3 bar and volumetric concentration factor = 1.5 was found to be most feasible. Frozen storage at −18°C was successful in retaining a high percentage of bioactives in the concentrate after 1 month although vitamin C loss was on the higher side. Lycopene was highly preserved in the concentrate juice after frozen storage with retention of 93%.

中文翻译：

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严格的超滤和冷冻储存对浓缩西瓜汁中生物活性化合物的有效性的见解

这项研究的目的是评估紧密超滤对西瓜汁中生物活性化合物的浓度的潜力，并分析冷冻储存对浓缩果汁的有效性。在30±2°C和23±2°C的两个不同温度以及2和3 bar的压力下对果汁的浓缩进行浓缩，浓缩因子分别为1.5、2和3。确定了浓缩物中总酚含量没食子酸和类黄酮的含量按芦丁当量进行分析。使用己烷萃取法分光光度法测定番茄红素。超滤（UF）工艺成功地在西瓜汁浓缩物中保留了高百分比的生物活性化合物。黄酮类化合物在四种重要的生物活性化合物中浓度最高。超滤实验装置发现T = 23±2°C，P = 3 bar，体积浓缩系数= 1.5。尽管维生素C的损失偏高，但在−18°C下冷冻保存成功地保留了浓缩物中高百分比的生物活性物质。冷冻保存后，番茄红素在浓缩汁中高度保存，保留率达93％。