###### Abstract
The advent of those novel advancements in UF is owing to the bigger challenges in managing the trade-off between productivity and selectivity. In general, interests in advancing UF in protein separation are steadily increasing, as shown in Figure 1. It is obvious that published research studies in UF for peptide separation (see the inset) are always lower than UF for protein separation due to the setbacks of UF to achieve high selectivity of small peptide fractions, regardless of their higher productivity. In terms of research focus, presented in Figure 1b, the top four burgeoning preferences are in the area of membrane modifications (26%), charged-membrane UF (15%), EDUF, (15%), and dynamic UF (15%). Membrane modifications and dynamic UF are sought to tackle the issue of fouling with the best scale-up possibilities. Meanwhile, EDUF and charged-membrane UF are thriving, which can be attributed to the fact that proteins or peptides with similar size, primarily those which have lower molecular weight (the most valuable owing to their dominant bioactivity), are the most difficult to separate by traditional processes and need cutting-edge developments. There are several reviews related to protein separation by filtration and UF in particular, such as thorough membrane-based protein separation [19,20], UF application in food industries [21] and in general applications [22], alfalfa leaf protein recovery by filtration [23], whey protein separation and purifications by membrane processes [18,24,25], recovery of protein from fish meal wastewater by ultrafiltration [26], recovery of antihypertensive peptides by membrane-based production [27], pore blocking in ultrafiltration [28], fouling in MF and UF [29,30], effect of ultrasonic on membrane filtration [31], specific review on EDUF [32], and dynamic filtration [33]. There are no comprehensive reviews, however, covering definitive accounts of protein separation and purification by specific means of UF. In this paper, the main theme of our objective is hence to present recent advancements in UF membrane processes, from charged-membrane UF, EUF, EDUF, EDBM, ultrasonic-assisted UF, dynamic UF, and HPTFF to UF integration. Following them, the number of strategies in controlling fouling and concentration polarization are presented from the aspect of mem brane modifications to tailoring operation conditions: concentration, pH, ionic strength, transmembrane pressure (TMP), and temperature. Ultimately, the potentials of using UF as primary setup or complementary protocols to select the most potent bioactive peptides are described in brief in the final section. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Source** & **Hydrolysis Enzyme(s)** & **Protocols** & **Bioactivity** & \multicolumn{2}{c}{**Target Compound (s)**} & **Remarks** & **Ref** \\ \hline _Grateloupia_ & & \multicolumn{2}{c}{Preindustrial} & & & & \\ _turturturu_ & - & \multicolumn{2}{c}{(Polyteresulfone (PES)} & & & & \\ (Macroalgae) & & & & & & \\  & & & & & & \\  & & & & & & \\  & & & & & & \\ \hline _Enteromorpha_ & \multicolumn{2}{c}{QuixStandTM} & & & & & \\ _clathrata_ & \multicolumn{2}{c}{Alcalase} & \multicolumn{2}{c}{Benchtop System} & & & & \\ (Macroalgae) & & & & & & \\  & & & & & & \\ \hline \multirow{4}{*}{Pigeon pea} & \multirow{4}{*}{Flavourzyme} & \multirow{4}{*}{ \begin{tabular}{c} Sequential UF \\ pancretain, \\ Alcalase, or \\ Pancreatic \\ \end{tabular}  } & \multirow{4}{*}{ \begin{tabular}{c} -Antioxidant \\ American 8400 \\ (1, 3, 5,10 kDa) \\ \end{tabular}  } & \multirow{4}{*}{ \begin{tabular}{c} Peptides < \\ (inhibitor lipid \\ peroxidation) \\ \end{tabular}  } & \multirow{4}{*}{ \begin{tabular}{c} Yield: 36.97\% (<1 kDa from \\ 1 kDa \\ 5 kPa \\ \end{tabular}  } \\  & & & & & \\  & & & & & \\ \hline \multirow{4}{*}{Soy protein} & \multirow{4}{*}{Flavourzyme} & \multirow{4}{*}{ \begin{tabular}{c} Sequential UF \\ (30, 10, 1, \\ 0.3 kDa) \\ \end{tabular}  } & \multirow{4}{*}{ \begin{tabular}{c} -Lipolysis \\ stimulator \\ \end{tabular}  } & \multirow{4}{*}{\