خواص فيزيكوشيميايي، عملكردي و تغذيه اي تفاله چاي و قهوه به عنوان منبعي از فيبر رژيمي

With the increasing importance of the sustainable use of plant resources an‎d the recycling of agricultural wastes, tea waste an‎d spent coffee ground—rich sources of insoluble fiber, structural polysaccharides, lignin, an‎d phenolic compounds—show great potential for application in food, pharmaceutical, an‎d biodegradable packaging industries. The aim of this study was to investigate the effect of acidic, alkaline, an‎d enzymatic extraction methods on the chemical composition an‎d physicochemical, structural, functional, thermal, an‎d rheological properties of insoluble fiber from tea an‎d coffee. The lightness index of tea an‎d coffee fiber was almost similar, obtained as 29.9 an‎d 29.8, respectively, but the redness an‎d yellowness values in tea were 6.0 an‎d 11.8, an‎d in coffee 10.8 an‎d 15.2, indicating the removal of some phenolic pigments in tea an‎d the presence of melanoidins in coffee. Examination of porosity an‎d density showed that tea an‎d coffee fiber had no significant difference in density, being 0.521 an‎d 0.534 g/cm³, respectively. Meanwhile, coffee fiber had a more wrinkled an‎d porous texture with a pore volume of 0.0043 m³/g an‎d a surface area of 9.6274 m²/g, while tea fiber had a pore volume of 0.0381 cm³/g an‎d a surface area of 6.9562 m²/g. The zeta potential of coffee fiber was -36.60 mV an‎d that of tea fiber was -46.15 mV, indicating colloidal stability an‎d better dispersibility in aqueous media. Tea fiber contained higher amounts of total phenolics an‎d cation exchange capacity, measured as 14.25 mg/g an‎d 0.605 mmol/g, while coffee fiber had higher antioxidant capacity with 88.81% free radical scavenging an‎d 47.74% α-amylase inhibition, likely due to the presence of melanoidins an‎d Maillard reaction products. The swelling an‎d water absorption capacities of tea fiber were 4.42% an‎d 5.04%, an‎d for coffee fiber 1.82% an‎d 3.58%, respectively. Although the emulsifying capacity of both fibers was similar at 53.87%, the emulsion stability of coffee fiber 99.25% was higher than that of tea fiber 96.5%. Thermal behavior analysis showed that the highest weight loss occurred in the temperature range of 200 – 400°C, with tea fiber showing 65.89% an‎d coffee fiber 77.38% weight reduction, indicating faster polysaccharide degradation in tea an‎d greater resistance due to lignin an‎d cross-linking in coffee fiber. Fourier-transform infrared spectroscopy revealed that hydrogen bonds among hydroxyl groups, glycosidic bonds, an‎d carbonyl groups are the main molecular interactions maintaining fiber structural integrity. Due to its porous structure, large surface area, colloidal stability, an‎d superior antioxidant activity, insoluble coffee fiber is a suitable option for use in functional beverages, dietary supplements, an‎d bioactive products, while tea fiber—with its high water absorption, high swelling capacity, an‎d considerable phenolic content—can improve the texture an‎d physical qualities of food an‎d hygiene products. This study showed that processing tea waste an‎d spent coffee ground can enable the production of value-added functional fibers while simultaneously helping reduce environmental pollution.

اميرحسين گلي

اسماعيل مهريار , ميلاد فتحي