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Acid whey neutralization affects properties of harvested whey protein.

Acid whey is a byproduct of cottage cheese production and contains usable protein. Previous work has established that the organic acids in cottage cheese whey are not eliminated by ultrafiltration, and the resulting acidic whey protein concentrate or isolate has limited applications.

A proposed solution to this problem is to neutralize the acid whey prior to filtration. However, the effects of neutralization on protein flavor and functionality have not been examined. So, scientists at Cornell University evaluated the flavor and functionality of cottage cheese whey following neutralization before or after ultrafiltration (UF) to liquid WPC 80.

Essentially, the scientists found that acid whey neutralization, undertaken before or after UF, impacts the flavor, heat stability and foamability of harvested whey protein.

First, acid-set cottage cheese and Cheddar wheys were manufactured, pasteurized and fat-separated. The researchers acidified Cheddar whey with lactic acid to a pH of 4.60. Cottage and acidified Cheddar whey were then either neutralized to pH 6.35 using ammonium hydroxide before (NBUF) or after (NAUF) ultrafiltration to WPC 80.

The scientists concentrated additional cottage and acidified Cheddar wheys to WPC 80, without using neutralization, as the controls. Sensory properties, volatile compounds, heat stability, solubility and foaming properties were evaluated on the liquid WPC 80 at a 10% solids content. The entire experiment was replicated in triplicate.

Both cottage and acidified Cheddar WPC 80 NBUF samples had lower intensities of cardboard flavor and higher sweet aromatic flavors. This was concurrent with lower levels of lipid oxidation volatiles, compared to the NAUF WPC 80 samples.

Neutralization decreased the heat stability of both cottage and acidified Cheddar WPC 80. Protein solubility was generally unaffected by neutralization, but turbidity was lower in the WPC 80 NBUF samples compared to the control acidic WPC 80 or WPC 80 NAUF samples. Acidic cottage and Cheddar WPC 80 had higher foam stability than their neutralized counterparts.

Neutralization before filtration optimized flavor and also resulted in decreased turbidity compared to whey neutralized after UF. Acidic cottage WPC 80 displayed greater heat stability, but had more off-flavor and a distinct sour taste.

Further information. David Barbano, Department of Food Science, Cornell University, 289 Stocking Hall, Ithaca, NY 14853; phone: 607-255-4122; email: dmb37@cornell.edu.

Please Note: Illustration(s) are not available due to copyright restrictions.

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Publication:Emerging Food R&D Report
Date:Oct 1, 2018
Words:378
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