New opportunities from the isolation and utilization of whey proteins.

Management of dairy whey has often involved implementation of the most economical disposal methods, including discharge into waterways and onto fields or simple processing into low value commodity powders. These methods have been, and continue to be, restricted by environmental regulations and the cyclical variations in price associated with commodity products. In any modern regimen for whey management, the focus must therefore be on maximizing the value of available whey solids through greater and more varied utilization of the whey components. The whey protein constituents offer tremendous opportunities. Although whey represents a rich source of proteins with diverse food properties for nutritional, biological, and functional applications, commercial exploitation of these proteins has not been widespread because of a restricted applications base, a lack of viable industrial technologies for protein fractionation, and inconsistency in product quality. These shortcomings are being addressed through the development of novel and commercially relevant whey processing technologies, the preparation of new whey protein fractions, and the exploitation of the properties of these fractions in food and in nontraditional applications. Examples include the following developments: 1) whey proteins as physiologically functional food ingredients, 2) alpha-lactalbumin and beta-lactoglobulin as nutritional and specialized physically functional food ingredients, and 3) minor protein components as specialized food ingredients and an important biotechnological reagents. Specific examples include the isolation and utilization of lactoferrin and the replacement of fetal bovine serum in tissue cell culture applications with a growth factor extract isolated from whey.

Distribution of free amino acids in streptozotocin-induced diabetic pregnant rats, their placentae and fetuses.

Amino acid levels in the non-pregnant streptozotocin (STZ)-induced diabetic rat have been shown to be abnormal. Our preliminary studies showed that placental transport, fetal serum levels and tissue uptake of the non-metabolizable amino acid alpha-amino isobutyric acid (AIB) were decreased in STZ-diabetic pregnant rats. In the present experiments, amino acid concentrations were measured in maternal (MS) and fetal (FS) sera and placentae (PL) by high performance liquid chromatography (HPLC) after triple extraction in 80% ethanol. Control (C), STZ-diabetic (D) and insulin-treated diabetic (DI) animals were studied at 22 days gestation. Pregnant diabetic rats had low serum levels of Gln, Lys, and Ser and insulin treatment corrected Gln and Ser but not Lys levels. Branched-chain amino acids did not show the large elevation characteristic of the non-pregnant diabetic rat. Placental levels of Tau, Gln, HPr, Thr and Lys were depressed in the diabetic animals and insulin treatment only partially improved these amino acid profiles. Placental amino acid levels did not always reflect maternal serum levels. Serum levels of most amino acids were lower in the fetus of the diabetic rat than in the fetus of the control rat. The notable exception was Ala which was higher in the fetuses of the diabetic animals. Insulin treatment of the mother did not correct many of the fetal amino acid levels even though maternal and fetal serum glucose levels at the time of autopsy were normal. The ability to maintain normal serum levels of many amino acids is impaired in the fetus of the diabetic rat.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of streptozotocin-induced diabetes in pregnant rats on placental transport and tissue uptake of alpha-amino-isobutyric acid.

Placental transport and tissue uptake of amino acids were studied in streptozotocin (STZ)-induced diabetic rats by using the non-metabolizable amino acid [U-14C]-alpha-amino-isobutyric acid (AIB). Fifteen minutes prior to autopsy, animals of each group, control (C), diabetic (D), diabetic-insulin treated (DI) and diabetic-T4 followed by 3-5-Dimethyl-3'-isopropyl-L-thyronine (DIMIT) treated (DTD), received an injection of the [U-14C]-AIB SC. Disintegrations per minute (DPM) were measured in serum and tissues subsequent to autopsy. There were no differences in maternal serum DPM/ml among groups. Fetal serum DPM, however, were lower in D and DTD groups than in the C group. The whole fetal tissue homogenate radioactivity was lower in the D, DTD, and DI groups than in the C group. In general, more AIB was taken up by fetal tissues of C than D animals. Maternal liver AIB uptake was reduced in D, DI, and DTD from C animals and net placental transport of AIB was less in D and DTD than C animals. Fetal liver protein concentrations were depressed in D and DTD animals from C and DI, but fetal brain protein concentrations showed no significant differences. Furthermore, the lower organ and fetal body weights of the D and DTD groups compared with the C and DI groups support the proposal that fetal anabolism is impaired. Maternal and fetal serum T4 concentrations were lower in D and DTD than in C and DI animals. Insulin therapy improved serum T4 levels in both mother and fetuses. It did not, however, correct all other measured parameters.(ABSTRACT TRUNCATED AT 250 WORDS)