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The aim of this research is the evaluation of the profile of peptides isolated from skim milk hydrolysates.

Five hydrolysates were prepared using a protease from Aspergillus Oryzae (AO) separately or in combination with papain (PA) in different reaction times. The hydrolysates were fractionated by size‐exclusion HPLC and the rapid method of correct fraction area (CFA) was used for quantifying the peptides and free amino acids in the chromatographic fractions. The nutritional quality of hydrolysates is directly related to their di‐ and tripeptide contents, several reports show that the amino acid provided by these peptides are more quickly and completely absorbed than those from intact protein.

The results showed a nutritional similarity of the isolated action of AO and its combinations with PA, considering the peptide patterns produced, giving rise to 16 percent of di‐ and tripetides. Increasing the reaction time of the two enzymes led to poorer peptide profiles, while no change was achieved when the reaction time of only one enzyme (AO) in the combination was enlarged. Other hydrolytic conditions could be tested in order to improve the peptide profile of skim milk hydrolysates.

The application of this study relates to the possibility of using these hydrolysates for preparing high nutritional formulation for dietetic purposes. The use of a technique allowing the fractionation of peptides according to their size as well as the use of the skim milk as protein source, instead of casein, which is very expensive in the developing countries, represents a novel approach.

Provides an evaluation of the profile of peptides isolated from skim milk hydrolysates.

This paper aims at testing several conditions using activated carbon for removing phenylalanine (Phe) from protein hydrolysates, in order to prepare dietary supplements for phenylketonurics, based on skim milk.

Six hydrolysates from skim milk were prepared, using a protease from Aspergillus oryzae (AO), isolated or in association with papain (PA). Some parameters were tested for removing Phe, such as amount of activated carbon, temperature and stirring time. The second derivative spectrophotometry was used to evaluate the efficiency of Phe removal.

The best condition for removing Phe was achieved using an activated carbon: casein ratio of 118 (in g), a stirring time of 30 min, at a temperature of 25°C, which produced 96 to 99 per cent of Phe removal. Among the hydrolytic conditions employed, the association of AO and PA (1 hour, 1 per cent and 4 hours, 2 per cent, respectively) led to the lowest absolute value for the final Phe concentration (0.060 × 10⁻⁴ mg/100 mg of protein).

Since we know, there is no formula for PKU on the market based on skim milk hydrolysed proteins. Isolated casein, the main milk protein, is the choice in most cases. This is a factor that may be taken in consideration especially in developing countries, where milk proteins are imported and, consequently, are much more expensive than skim milk.