Microfiltration retentate co-product from whey protein isolate production - Composition, processing, applications and potential for value addition

Background

Microfiltration retentate (MFR), also called whey protein phospholipid concentrate, is a co-product of whey protein isolate (WPI) production derived through microfiltration (MF) of whey or whey protein concentrate. Microbiological quality and protein denaturation/aggregation in the MFR stream present challenges in valorizing the stream for utilization in specialized nutritional products. As a result, MFR is underutilized, with its current applications largely limited to commodity applications in the animal feed industry as a milk replacer and in confectionery, for example. On the other hand, the production of MFR is increasing year on year due to the increase in demand for WPI with its current production representing 14–18% of the total whey processed worldwide.

Scope and approach

In this review, we discuss MFR processing options, composition, current applications, future perspectives, and potential valorization strategies and challenges. Our approach includes a comprehensive literature review of recent studies and advancements in MFR processing. We systematically selected and analyzed peer-reviewed articles, industry websites, and reports to provide a holistic view of the current state and future directions of MFR technology.

Key findings and conclusions

The gross chemical composition of MFR is highly variable, with typical values of fat, protein, lactose, and ash ranging from 11 to 38%, 50–70%, 1–11%, and 2–4%, respectively. The protein constituents in MFR include β-lactoglobulin, α-lactalbumin, bovine serum albumin, lactoferrin, immunoglobulins, and caseino-macropeptide. Additionally, MFR is enriched with milk fat globule membrane-associated proteins such as butyrophilin, mucin 1, xanthine oxidase, and phospholipids like sphingomyelin and phosphatidylcholine. Significant research gaps exist in understanding the microbiology, bioactivity, and bioavailability of MFR components, which are crucial for supporting its valorization. Despite these gaps, there is great potential for utilizing MFR in the food industry, neonatal nutrition, and pharmaceutical applications. This potential provides opportunities to develop targeted, novel value-added ingredients from the MFR stream.