FILTERING PIGMENTS FROM HONEY BY NANOFIBER MEMBRANE

Honey is a natural food product which has various health benefits. It can be consumed either as is or added to other foods as a sweetener. In the latter case, the pigments in honey can cause some off-color problems in the... [ view full abstract ]

Honey is a natural food product which has various health benefits. It can be consumed either as is or added to other foods as a sweetener. In the latter case, the pigments in honey can cause some off-color problems in the products. For example, when honey is added to jam or jellies as a sweetener, the brown coloring caused by heat treatment during process affect consumer acceptance adversely. In honey carotenoids and anthocyanins are present as pigments, whereas carotenoids are the largest occurring one. Due to fact honey is very sensitive to heat and other process conditions, if the pigments are needed to remove then it must be done without heat or chemical treatments. It is hypothesized that pigments may be removed from honey by using nanofiber membrane. It is predicted that the hydrophilicity of the filter medium is a crucial factor for removing pigments from honey. Electrospun nanofibers as filter membrane appear to be suitable for membrane applications, due to the easiness of modifying the surface of the medium. For instance, the surface characteristics of nanofiber membranes, such as hydrophilicity, porous structure and sizes, can be adjusted according to the filtration needs by electrospinning parameters. In this study, the objectives were two-folds. First, polyacrylonitryle (PAN) nanofibers were obtained by electrospinning. Then, PAN nanofibers used as filter membrane for removing pigments from honey. PAN nanofibers were obtained from the PAN solution in dimethylformamide (DMF) at 10% by using electrospinning. The feed rate, the applied voltage and the distance to the collector plate were 3 ml/hour, 40 kV and 25 cm, respectively. The electrospinning was conducted for 30 min. Contact angle measurements of electrospun samples were conducted. The honey was filtrated through a laboratory set-up containing electrospun PAN nanofiber membrane at 1 bar. The physicochemical properties of filtrate such as viscosity, refractive index, pH, electrical conductivity, dielectric parameters were determined. Outcomes of this study may help to separate sensitive functional ingredients such as pigments, active ingredients without getting damaged from heat or chemical treatments. The electrospun nanofiber membranes seem to have a high potential utilization in food industry in the future.