Date of Award:

1987

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Nutrition and Food Sciences

Advisor/Chair:

Dr. Carl Anthon Ernstrom

Abstract

The effect of ultrafiltration, diafiltration, and preacidification of milk on the partition of specific milk components between retentate and permeate was studied. Percent retention (for any component Y) was determined as:

[ l - (%Y in soln. permeate/%Y in soln. retentate)] X 100 where %Y in soln. = [%Y/(%Y + %H 20)]

Simultaneous samples of retentate and permeate were taken at several points during each process. Percent retention of total solids, fat, total protein, rennet clottable nitrogen, lactose, total calcium, ionic calcium, sodium, phosphorous, and riboflavin was determined at each sampling point. Percent retention of β-carotene, vitamin B12, retinol, and zinc was determined at different stages of ultrafiltration only.

As UF proceeded, percent retention of total solids, total protein, total calcium, ionic calcium, sodium, phosphorous, and riboflavin increased. Percent retention of lactose was not affected and was 0-4%. Percent retention of fat, rennet clottable nitrogen, zinc, retinal, β-carotene, and vitamin B12 was 99-100%. As diafiltration proceeded, percent retention of total solids, lactose, total calcium, ionic calcium, sodium, phosphorous, and riboflavin increased. Percent retention of these nutrients was increased when compared to ultrafiltration alone.

Milks with lower pH values (resulting from preacidification) also had lower percent retention of total calcium and phosphorous than milks with normal pH values. Percent retention of sodium was lower during ultrafiltration and diafiltration of acidified milk when compared to ultrafiltration and diafiltration of normal milk. Percent retention of other nutrients was not affected by acidification.

Loss of whey proteins into permeate resulted in a lower recovery of total protein after diafiltration than ultrafiltration alone and ultrafiltration of acidified milk. These proteins were determined to be α-lactogobulin and β-lactogobulin.

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