Milk is an important component of a balanced diet and contains numerous valuable constituents. Considerable acclaimed health benefits of milk are related to its proteins, not only for their nutritive value but also for their biological properties. Scientific evidence suggests that anticarcinogenic activities, antihypertensive properties, immune system modulation, and other metabolic features of milk, are affiliated with its proteins (intact proteins or its derivatives). In this article, the main health-related aspects of milk proteins, such as anticarcinogenic, immunomodulatory, antimicrobial, anticariogenic, antihypertensive, and hypocholesterolemic effects are reviewed. Collectively, the findings indicate the effectiveness of milk proteins on reduction of risk factors for cancer, cardiovascular diseases and overall improvement of health aspects.

The most widespread method applied for standardization of milk protein in cheese production is ultrafiltration. In the current study, pasteurized, unhomogenized whole milk was ultrafiltered with APV ultrafiltration system, 51 spiral wound, polysulfone membrane with 20000 Da molecular weight cut off (DDS, Nakskov, Denmark) at 50oC, such that the pressure difference between the two sides of membranes was not more than 3.6 bar. Permeate that was collected, contained (w/w%) 0.01 % proteins. The protein was isolated from crystalline TCA to the concentration of 12.5% (w/v), and then characterized by discontinuous SDS-PAGE (10-20% acryleamide). The products of proteolysis contained a-lactalbumin (49.95±2.25 %), b- lactoglubolin (22.30±2.3%) and casein proteolysis products (30±4%) and (96.68±1.725), (99.18±0.46) and (98.39±1.005) % were rejected by ultrafiltration membrane, respectively. Casein micelles were rejected completely (100%), therefore, they couldn’t penetrate to permeate from retentate. Incomplete rejection of casein and penetration of casein into permeate indicates the leakage of retentate in to permeate.

In this study the bacterial growth inhibitory activity of peptide fragments produced from goat’s milk whey proteins by enzymatic hydrolysis using trypsin, ficin and a combination of both was investigated. Goat’s milk whey proteins were isolated and subjected to enzymatic hydrolysis and peptides were purified by ultrafiltration followed by reverse-phase high-performance liquid chromatography (RP-HPLC). Growth inhibitory activities of hydrolysates ranged from 4.67% to 87.46% for E.coli and 3.03% to 98.63% for B.cereus. Among all peptide fragments, permeate containing 3kDa peptides produced by trypsin showed maximum inhibition against Gram positive and Gram negativebac bacteria. This fraction was further purified by HPLC. Fourteen peptide fractions were collected and evaluated for their growth inhibitory activities. Two fractions showed the highest growth inhibitory activities with MIC50’s of 383±8 mg/ml and 492±10 mg/ml against E.coli and B.cereus, respectively. Taken together, the results of this study indicated that it is possible to produce novel antibacterial peptide by enzymatic hydrolysis of goat’s milk whey proteins which can potentially replace synthetic food preservatives in food industries.