Adsorption of Naringin in Natsudaidai (Citrus natsudaidai Hayata) Juice with Polyvinylpyrrolidone, Nylon-66 and High porous Polymer

Abstract

Adsorption of naringin in nats udaidai juice with polyvinylpyrrolidone (PVP), nylon-66 and high porous polymer (HPP) was studied. With addition ratio of 5%, nylon-66 adsorbed more than 74% of the naringin content in juice, PVP about 65% and HPP about 59%. When juice was treated with nylon-66 and PVP, the adsorption of naringin reached a maximum value after 1 hr and was constant thereafter. Adsorption of naringin increased with the increasing ratio of adsorbent to juice. However, the adsorbed weight of naringin per unit weight of adsorbent decreased with the increasing ratio of adsorbent to juice. Adsorption of naringin with nylon-66 was at a maximum between pH 2 and 4. With PVP, maximum adsorption occurred between pH 3 and 5. And with HPP, maximum adsorptiono ccurred between pH 5 and 7. Because the solubility of naringin increases with increasing temperature, adsorption is supposed to decrease with increasing juice temperature. This was true with nylon-66 and PVP. However, adsorption of naringin with HPP was found to increase at higher juice temperature. When juice was treated with PVP or nylon-66, adsorption of naringin decreased with increasing sugar concentration, and HPP showed no adsorption in fivefold concentrate. When juice was treated with PVP or nylon-66, other juice components beside naringin were adsorbed. For example, the reduced ascorbic acid content decreased notably. However, HPP, gave the least influence on the adsorption of other juice components besides naringin.