高生物活性柠檬膳食纤维的功能特性研究

以柠檬皮渣为原料采用冷冻干燥、热风干燥两种工艺制备膳食纤维,测定所得膳食纤维的维生素C(VC)含量、黄酮含量、葡萄糖透析延迟能力、阳离子交换能力,比较两种工艺对制品生理功能指标的影响。结果表明经冷冻干燥后所得膳食纤维的VC含量为144.078mg/100g,黄酮含量为1267.574mg/100g,经热风干燥后所得膳食纤维的VC含量为66.674mg/100g,黄酮含量为1000.037mg/100g;冷冻干燥80目产品、16目产品的葡萄糖透析延迟指数分别为62.21和57.07,热风干燥80目产品、16目产品的葡萄糖透析延迟指数分别为56.01和49.46;在NaOH滴入量为0～8mL时,两种工艺所得产品的阳离子交换能力基本一致,在NaOH滴入量为8～11mL时,阳离子交换能力由高到低分别为:冷冻干燥80目产品,热风干燥80目产品,冷冻干燥16目产品,热风干燥16目产品,并且这种差异性在各处理样品间表现为显著。总体来说是冷冻干燥工艺所得膳食纤维更具有优势。     

Chemical profile, functional and antioxidant properties of tomato peel fiber

Tomato processing residue is defined as a secondary raw material that can increase its value, being considered a potential source of dietary fiber and bioactive compounds. Commercial tomato peel fiber has been analyzed to ascertain the proximate and nutritional composition (moisture, fat, protein, dietary fiber, ash, and minerals), the fractions (insoluble, IDF, and soluble, and SDF) and sugar composition of dietary fiber, functional properties (water retention capacity, WRC, swelling capacity, SWC, fat absorption capacity, FAC, glucose diffusion retardation index, GDRI, and osmotic pressure), total antioxidant activity (AA), and the content of antioxidant bioactive compounds (phenolic compounds and lycopene). To extract phenolic compounds and dietary fiber, three methods were assayed in this study: enzyme hydrolysis, maceration, and ultrasonic assistance. The content of TDF was 84.16%, and the major fraction was the IDF (71.82%), formed mainly by hemicelluloses. Tomato peel fiber retained 6.76 g of water/g as WRC, and it was significantly correlated with the IDF content. In addition, the content of IDF determined the low FAC and SWC and the GDRI at 60 min (39.22%). The main phenolic compound was rutin, followed by naringenin, rutin derivatives, and chlorogenic acid derivatives. These were better extracted using ultrasonic assistance, whereas lycopene showed mean values between 3 and 4 mg/100 g. The AA of tomato peel fiber was low, since the phenolic compounds are mainly bound to the cell wall of plant, showing a low capacity for scavenging radicals. Due to its chemical profile and functional properties, tomato peel fiber can be used as a food supplement, improving the different physical, chemical, and nutritional properties of foods. However the color and flavor of this product must be considered in its applications to avoid a negative effect on the sensory characteristic of the foods to which it is added.