Abstract: The present invention relates to an opioid peptide represented by general formula TyrGlyGly-X1-X2-X3-X4, wherein: X1 is represented by Thr or Glu; X1 is represented by Gly or Thr or Ala; X3 is represented by Ala or Val or Gly or Glu; and X4 is represented by His or Gln or Thr or SEQ ID NO:1, or HisTyr or GlnTyr or ThrTyr. The invention also relates to pharmaceutical and food compositions comprising the peptide and to the use of the same for analgesic purposes, and/or for providing a feeling of satiety to a subject.

Abstract: The purpose of the present invention is to evaluate the quality of feed for ruminants and consequently, avoid the transmission of TSEs through the detection of animal proteins in these foods. This purpose is embodied in the form of a method for detecting proteins of animal origin in complex mixtures comprising the stages of: (i) extraction of the proteic matter in high concentration from a sample of the initial complex mixture in a manner as to substantially remove all interferents; (ii) preparation of the matrix-analyte in a manner as to maintain low levels of impurities and an adequate matrix-analyte molar rate; (iii) analysis of the material obtained in the prior stage by MALDI-TOF mass spectrometry; (iv) optionally, fractionation of the samples or isolation of the components by RP-HPLC and identification of the components by means of automatic sequencing of the N-terminal region and sequencing of its peptidic fragments by liquid chromatography coupled to mass spectrometry (LC/MS/MS).