FABRICATION AND OPTIMIZATION OF ELECTROSPUN POLYACRYLONITRILE (PAN) NANOFIBER MEMBRANES AS FILTRATION MEDIA FOR APPLE JUICE

• Main Author: SAWITRI (NIM : 20214013), ASTI
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/21292
• Institution: Institut Teknologi Bandung

Clarification of juice is one aspect in the process of packaging juice industry. Juice is a nutritious drink that is widely consumed and is good for health. A kind of juices with high consumption in the world is apple juice. Polysaccharides, proteins, tannins, metal, and microorganisms that are contained in apple juice can cause turbidity in the juice. In addition, there are components of total phenols such as flavonoids, anthocyanins, catechin, and chalcones, and they are as a major factor causing browning of juice. The browning and turbidity do not change its taste, but its appearance becomes unattractive. Membrane filtration method is potential alternative for juice purification at industrial scale. The purpose of apple juice purification is to get high turbidity reduction. But in the process, the reduction of high turbidity results in too high reduction of chemical composition (total phenols). Although total phenols is a cause for browning of apple juice, but it is also as one of the contributors of antioxidants in apple juice. Therefore, this research made filtration media capable of reducing turbidity as high as possible, but maintaining total phenols as high as possible. Nanofibers membrane is one of potential filtration media for apple juice. One technique that is used in nanofibers synthesis is electrospinning. In this research, it has been successfully manufactured nanofibers membrane filtration media based on polyacrylonitrile (PAN) solution. Fabrication of PAN nanofibers membranes was done by varying solution parameters to produce different fiber diameters, and variation of processing time to get nanofiber membranes with different thicknesses. Morphology of the obtained PAN fibers were smooth without beads. The average fiber diameters obtained from the PAN solution concentrations of 6, 9, 12, and 14 wt.% were (341 ± 70), (534 ± 91), (1,274 ± 419) and (2,107 ± 762) nm, respectively, for the membrane thicknesses of (0.123±0.034), (0.127±0.037), (0.129±0.019), and (0.129±0.022) mm, respectively. Fabrication of membranes with thickness variation was performed on nanofiber membranes with a diameter of (534 ± 91) nm in which the thicknesses were 0.127, 0.176, and 0.222 mm. In this study, the efficiency of the PAN nanofiber membranes as filtration media for apple juice was analyzed by using two parameters, namely the selectivity of the membrane towards turbidity and total phenol content, as well as membrane flux. It has been found that, for membranes with the same thickness, the highest reduction of turbidity was given by the membrane with the smallest fiber diameter ((341 ± 70) nm), which is 89%, and its reduction of total phenols was 61% with initial and final fluxes of 552.97 and 107.86 L/m2.hours, respectively. Moreover, for membranes with the same fiber diameter, the highest turbidity reduction was given by the membrane with the thickest (0.222 mm), which is 98%, and the reduction of total phenols was 30% with flux of 135 L/m2.hours. Therefore, the PAN nanofiber membranes are potential as filtration media for apple juice because effectively reducing turbidity, but effectively maintaining its total phenols when compared to the Nylon-6 nanofiber membranes as reported by Fuenmayor (2014) with the reduction of total phenols up to 70%.