Membrane Processing Technology in the Food Industry: Food Processing, Wastewater Treatment, and Effects on Physical, Microbiological, Organoleptic, and Nutritional Properties of Foods

Abstract

Membrane processing technology (MPT) is increasingly used nowadays in a wide range of applications (demineralization, desalination, stabilization, separation, deacidification, reduction of microbial load, purification, etc.) in food industries. The most frequently applied techniques are electrodialysis (ED), reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), and microfiltration (MF). Several membrane characteristics, such as pore size, flow properties, and the applied hydraulic pressure mainly determine membranes' potential uses. In this review paper the basic membrane techniques, their potential applications in a large number of fields and products towards the food industry, the main advantages and disadvantages of these methods, fouling phenomena as well as their effects on the organoleptic, qualitative, and nutritional value of foods are synoptically described. Some representative examples of traditional and modern membrane applications both in tabular and figural form are also provided.

How physico-chemical and surface properties of cation-exchange membrane affect membrane scaling and electroconvective vortices: Influence on performance of electrodialysis with pulsed electric field

“…When taking L D = 2 nm and δ = 50 μm, for the bulk concentration of Mg 2+ (about 0.02 mol/L), one can find that in the SCR the concentration of Mg 2+ should be about 8 × 10 −7 mol/L. Assuming that the concentration of OH − ions is of the same order, the product of c Mg 2+(c OH −) 2 is about 5 × 10 −19 (mol/L) 3 . This value is much lower than the solubility product constant, K s , of Mg(OH) 2 (the minimum value related to the brucite crystal form is about 5 × 10 −12 (mol/L) 3 ).…”

“…12), c OH −/c Mg 2+ becomes as high as about 0.5 in the center of the diffusion layer (a rather high degree of concentration polarization and water splitting rate were used in the calculations), then c OH − decreases to reach the value 10 −7 , which is imposed by the bulk (feed) solution. The evaluation of the product c Mg 2+(c OH −) 2 in the center of the diffusion layer for the above conditions gives 5 × 10 −8 (mol/L) 3 that is higher than the maximum solubility product constant of Mg(OH) 2 relating to the amorphous form, 1.6 × 10 −9 (mol/L) 3 . Thus, within the suggested conditions one can expect that the formation of precipitation will mainly occur at a certain distance from the CEM depleted interface.…”

“…However, the value of K s for Ca(OH) 2 , portlandite, is rather high, 4.35 to 8 × 10 −6 (mol/L) 3 [47,48], hence, one can expect its precipitation only if the concentration of OH − ions is high, and that of Mg 2+ is low. The precipitation of portlandite is more expected on the concentration side of CEM where a highly alkaline solution is presented, if the transfer of Mg 2+ ions across the membrane is hampered what was described above for the case of CMX-SB-1.…”

“…10a) was unexpected. According to the portlandite K s = 4.35 to 8 × 10 − 6 (mol/L) 3 [47,48] it is supposed to precipitate at least in comparison with Mg(OH) 2 in brucite crystal form (K s = 4.4 to 8.8 × 10 −12 (mol/L) 3 ), Mg(OH) 2 in amorphous form (K s = 1.25 × 10 −11 (mol/L) 3 to 1.6 × 10 −9 (mol/L) 3 Table 3 Membrane thickness (mm) and ΔThickness (difference between thickness after ED and initial value) (mm) for CMX-SB-1 and CMX-SB-2 under different PEF conditions.…”

“…Electrodialytic (ED) processes are more and more involved in the modern agri-food industrial market [1][2][3]. However, scientists have to solve the problems of concentration polarization phenomena (CP) and fouling formation to make ED more attractive and to increase its applications on complex systems such as food.…”