Effects of membrane process applications on product quality at black mulberry juice and concentrate production

In this study, as an alternative to traditional thermal evaporation, osmotic distillation, membrane distillation and integrated membrane processes in which both systems were performed were investigated for the concentration of black mulberry juice. In this context, the effects of concentration by different membrane systems and thermal evaporation were compared in terms of pH, total acidity, total phenolics, hydroxymethyl furfural (HMF), anthocyanins, anthocyanin degradation products, antioxidant capacity, sugar and colour. The effects of ultrafiltration instead of traditional fining for juice clarification and different storage conditions of black mulberry juice samples on some product characteristics were also investigated. When conventional thermal evaporation and membrane systems for the concentration of black mulberry juice were compared, application of membrane systems found to be much more advantageous especially for total monomeric anthocyanin, polymeric colour ratio, antioxidant capacity and HMF levels. The total anthocyanin content in samples concentrated by thermal evaporation is approximately 50% lower than the samples concentrated by membrane systems while the polymeric colour ratio is about 2.5 times higher. No HMF formation was detected in samples concentrated by membrane systems. There was no significant difference between the membrane concentration methods. It has been determined that ultrafiltration can be applied successfully for the clarification in the production of black mulberry juice, and the pore size of ultrafiltration membrane used has an effective on the product characteristics. At the point of examining the changes in some physicochemical properties of the black mulberry juice under different storage conditions, it has been determined that temperature is a very important factor, and it is beneficial to keep the storage temperature low in terms of quality characteristics of the product.