Question

Which one of the following membrane process can be adopted for cold sterilization of dairy fluids?

• A. Reverse osmosis
• B. Ultrafiltration
• C. Microfiltration
• D. Osmosis

Hint:

Dairy Membrane Spectrum:
MICROFILTRATION (0.1--1.4 $\mu$m) = Cold sterilization Bacteria and Spore removal (Bactocatch).
ULTRAFILTRATION = Protein concentration (Paneer/Cheese).
REVERSE OSMOSIS = Total dewatering Concentration.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Membrane separation technology in the dairy industry: cross-flow microfiltration using ceramic membranes ($0.1-1.4\ \mu ext{m}$ pore size) physically filters out $>99.99\%$ of somatic cells, vegetative bacteria, and bacterial endospores (Bactocatch process) without thermal protein denaturation.
Key Formula or Approach:
\[ \text{Membrane Separation: Microfiltration } (0.1 - 1.4\;\mu\text{m}) \implies \text{Permeate (Sterile Skim Milk)} + \text{Retentate (Bacteria \& Spores)} \]

Step 2: Detailed Explanation:
In dairy membrane processing and non-thermal preservation technologies:
1. Microfiltration (MF) (C): Utilizes asymmetric ceramic tubular membranes with uniform pore diameters of $0.1\text{ to 1.4\;\mu\text{m}$}. Because bacterial cells ($0.5 - 2.0\;\mu\text{m}$) and bacterial endospores ($1.0 - 1.5\;\mu\text{m}$) are significantly larger than the membrane pores while native micellar caseins, whey proteins, and lactose pass freely, cross-flow MF (the Alfa-Laval Bactocatch process) achieves up to a $5\text{ to 6\;\log_{10}$ reduction ($> 99.99\%$) of bacteria and spores}. This allows Cold Sterilization (Extended Shelf Life ESL milk) without thermal damage to milk flavor or whey proteins.
2. Ultrafiltration (UF): Fractionates proteins and macromolecules ($1 - 100\text{ nm}$).
3. Reverse Osmosis (RO): Concentrates total solids and minerals ($< 1\text{ nm}$).

Step 3: Final Answer:
Therefore, Microfiltration can be adopted for cold sterilization, corresponding to option (C).