Influence of Transglutaminase Crosslinking on Casein Protein Fractionation during Low Temperature Microfiltration

Abstract

Low temperature microfiltration (MF) is applied in dairy processing to achieve higher protein and microbiological quality ingredients and to support ingredient innovation; however, low temperature reduces hydrophobic interactions between casein proteins and increases the solubility of colloidal calcium phosphate, promoting reversible dissociation of micellar β-casein into the serum phase, and thus into permeate, during MF. Crosslinking of casein proteins using transglutaminase was studied as an approach to reduce the permeation of casein monomers, which typically results in reduced yield of protein in the retentate fraction. Two treatments (a) 5 °C/24 h (TA) and (b) 40 °C/90 min (TB), were applied to the feed before filtration at 5 °C, with a 0.1 µm membrane. Flux was high for TA treatment possibly due to the stabilising effect of transglutaminase on casein micelles. It is likely that formation of isopeptide bonds within and on the surface of micelles results in the micelles being less readily available for protein-protein and protein–membrane interactions, resulting in less resistance to membrane pores and flow passage, thereby conferring higher permeate flux. The results also showed that permeation of casein monomers into the permeate was significantly reduced after both enzymatic treatments as compared to control feed due to the reduced molecular mobility of soluble casein, mainly β-casein, caused by transglutaminase crosslinking.

Whey filtration: a review of products, application, and pretreatment with transglutaminase enzyme

“…59,60 The type of filtration performed after enzymatic pretreatment was identified as ultrafiltration in studies reported in the literature, 12,16,17,56 and as microfiltration in another study. 15 The choice of membrane type is related to the type of molecule to be retained.…”

“…The temperature during the enzyme action needs to be controlled, as TGase activity is higher at temperatures close to 40 °C, allowing for cross‐linking without altering the properties of the whey 12,15‐17,48,56 . As pointed out in the literature 58 using TGase at an incubation temperature of 10 °C requires approximately 10 times more enzyme to compensate for the differences in TGase activity observed at 40 °C.…”

“…11,14 Enzymatic cross-linking is sparsely documented in the scientific literature, yet studies have revealed promising results related to increased permeate flux and protein concentration. [11][12][13]15,16 This technique promotes cross-links between lysine and glutamine residues, increasing the molecule's size and facilitating its retention in the filtration membrane. Enzymatic cross-linking brings additional benefits, such as reducing membrane fouling, preventing scaling, and improving process efficiency.…”