Selection of the most effective chemical cleaning procedure in the membrane clarification of pomegranate juice

Abstract

Membrane fouling is an important drawback of membrane‐based separation processes. After clarification of pomegranate juice by 0.22 µm polyvinylidene fluoride membrane, analysis of the FTIR spectra of formed‐cake showed that polyphenols are the main components of blocking materials. Various solutions including water (with 0.5, 1, and 1.5% NaOH or 0.1% hydrochloric acid), ethanol (with 77% and 96% purity), and mixture of ethanol (77%) with acetic acid (96%) with 99:01 ratio were used to clean membranes with different washing time of 10–30 min. The permeate flux recovery was calculated to determine the efficiency of cleaning protocols. The results showed that the cake layer was dominant because the blocking index was between 0 and 0.5. Overall, the ethanol 77% had the best performance among different solutions for cleaning (mainly due to its positive effects on membrane hydrophilicity) and the initial permeate fluxes of pomegranate juice and pure water did not change significantly after using this protocol. Practical applications Membrane technology is widely used in industrial juice clarification processes. The main problem with this process is the formation of fouling on the membrane surface, which minimizes its use in the fruit juice industry. This affects the lifetime of the membrane, the number of times the membrane is cleaned, the size of the membrane required, and ultimately the operation costs. In fact, cleaning costs make up 5%–20% of operating budgets, so more research is needed. The main method in regenerating a fouled membrane is its chemical cleaning, and the first step in this method is to find the best chemical detergent, which is determined according to the type of food, the type of membrane, and the nature of the deposition.

Fouling and Chemical Cleaning of Microfiltration Membranes: A Mini-Review

“…Cake layer formation is observed where each particle locates on the other deposited particles. This means that there is no room for particles to directly obstruct the membrane area [35,36]. The general effects of cake layer accumulation, adsorption, and concentration polarization cause fouling.…”

Strategies to Enhance the Membrane-Based Processing Performance for Fruit Juice Production: A Review

“…Membrane technology is more attractive and widely applied to separate solids from liquid in the food and fruit juice industry than conventional techniques, for instance, to clarify fruit juices [ 16 , 17 ]. Modern membrane techniques are extensively applied to separate solids from liquids in the fruit juice production industry [ 18 ] and employed in the food industry in the processing of different juices and beverages to produce fresh, natural products of superior quality without heat destruction or chemical by-products [ 19 ]. Membrane technology is considered an effective technique for juice clarification and concentration, offering numerous advantages over conventional separation technologies due to its unique properties, including excellent selectivity based on better separation properties, zero thermal stress of treated fluids attributable to moderate working temperatures, zero use of chemical supplements, modular and compact configuration, and minimal energy demand [ 20 ].…”