Identification of peptides in traditional and probiotic sheep milk yoghurt with angiotensin I-converting enzyme (ACE)-inhibitory activity

Two sets of traditional Greek sheep milk yoghurt were produced: the first one (YC) using normal yoghurt culture (Lactobacillus delbrueckii subsp. bulgaricus !10.13 and Streptococcus thermophilus !10.7) and the second (PR) with the same normal culture mixed with Lactobacillus paracasei subsp. paracasei DC412. YC and PR had similar physicochemical properties and proteolysis patterns throughout storage. Both products showed similar peptide profiles by RP-HPLC but quantitative differences were observed in respect to storage time. Single-strain cultures of the microorganisms used showed similar peptide profiles for both lactobacilli, yet L. delbrueckii subsp. bulgaricus was the most proteolytic of all three microorganisms. The peptide content and the ACE-inhibitory activity of the water-soluble extracts of yoghurts, YC and PR, increased throughout storage. Major peptides were identified from yoghurt PR and from the separate cultures of L. delbrueckii subsp. bulgaricus and L. paracasei subsp. paracasei. Most of these peptides were derived from b-casein. A peptide, b-CN f114-121, with well-established ACE-inhibitory and opiate-like activity was identified in yoghurt PR. Further identified peptides were regarded as potential ACE-inhibitors according to their sequence

ACCELERATED RIPENING OF FETA CHEESE

THE ACCELARATED RIPENING OF FETA CHEESE WAS ACHIEVED BY THE ADDITION TO THE CHEESEMILK A) NEUTRAL PROTEINASE FROM B. SUBTILIS, B) ACID PROTEINASE FROM ASP. ORYZAE AND C) CULTURES FROM LB. BULGARICUS AND STR. THERMOPHILUS WITH INCREASED NUMBER OF CELLS WHOSE ABILITY OF ACID PRODUCTION FROM LACTOSE WAS REDUCED BY HEATING AT 63 C. THE RIPENING OF CHEESES WAS EVALUATED UP TO 8 MONTHS BY DETERMINING THE PH, MOISTURE, FAT, ACID DEGREE VALUE, BRINE CONCENTRATION, TOTAL N, NON PROTEIN N AND N OF AMINO ACIDS, DIACETYL, ACETALDEHYDE AND FREE FATTY ACIDS. POLYACRYLAMIDE GEL ELECTROPHORESIS (PAGE) OF CHEESE SAMPLES WAS USED TO COMPARE THE EXTENT OF DEGRADATION OF CASEIN FRACTIONS IN TREATED AND UNTREATED CHEESES DURING RIPENING. MICROFLORA EVALUATION DURING RIPENING WAS ALSO STUDIED. ORGANOLEPTIC ASSEMENT SHOWED THAT THE TREATED CHEESES DEVELOPED TYPICAL FLAVOUR, BODY AND TEXTURE IN HALF THE TIME (40 DAYS) COMPARED TO THE UNTREATED CHEESES (80 DAYS). ALSO THE QUALITY OF TREATED CHEESES DID NOT DETERIORATE FOR AT LEAST 8 MONTHS. IT WAS FOUND THAT THE ADDITION OF PROTEOLYTIC ENZYMES IN THE CHEESEMILK MAY INCREASE THE AMOUNT OF SMALL PEPTIDES AND AMINOACIDS BY UP TO 400% OF THE NORMAL LEVEL IN 40-DAY OLD CHEESES. ANY INCREASE, THOUGH, OF THESE SUBSTANCES BEYOND 175% OF THE NORMAL, IMPARTED BITTER FLAVOUR TO THE CHEESE. IT WAS ALSO FOUNDTHAT THE ADDITION OF SMALL QUANTITIES OF LIPASE TO THE CHEESEMILK WAS NECESSARY SO THAT THE CHEESES OF HIGH PROTEOLYSIS OBTAIN A TYPICAL AND BALANCED FLAVOUR. A DISADVANTAGE OF ACCELARATED RIPENING OF FETA CHEESE, WITH THE ADDITION OF PROTEINASES IN CHEESE MILK, IS THE REDUCED YIELD OF CHEESES (ABOUT 3,16% WITH PROTEINASE FROM B. SUBTILIS AND 2,63% FROM ASP. ORYZAE).Η ΕΠΙΤΑΧΥΝΣΗ ΤΗΣ ΩΡΙΜΑΣΗΣ ΤΟΥ ΤΥΡΙΟΥ ΦΕΤΑ ΕΠΙΤΕΥΧΘΗΚΕ ΜΕ ΤΗΝ ΠΡΟΣΘΗΚΗ ΣΤΟ ΓΑΛΑ ΤΥΡΟΚΟΜΗΣΕΩΣ: Α) ΟΥΔΕΤΕΡΗΣ ΠΡΩΤΕΙΝΑΣΗΣ ΑΠΟ B. SUBTILIS, Β) ΟΞΙΝΗΣ ΠΡΩΤΕΙΝΑΣΗΣ ΑΠΟ ASP. ORYZAE ΚΑΙ Γ) ΚΑΛΛΙΕΡΓΕΙΩΝ LB. BULGARICUS ΚΑΙ STR. THERMOPHILUS ME ΑΥΞΗΜΕΝΟ ΑΡΙΘΜΟ ΚΥΤΤΑΡΩΝ, ΤΩΝ ΟΠΟΙΩΝ Η ΔΥΝΑΤΟΤΗΤΑ ΠΑΡΑΓΩΓΗΣ ΟΞΕΟΣ ΑΠΟ ΤΗ ΛΑΚΤΟΖΗ ΜΕΙΩΘΗΚΕ ΜΕ ΘΕΡΜΑΝΣΗ ΣΤΟΥΣ 63 C. Η ΩΡΙΜΑΣΗ ΤΩΝ ΤΥΡΙΩΝ ΠΑΡΑΚΟΛΟΥΘΗΘΗΚΕ ΓΙΑ 8 ΜΗΝΕΣΜΕ ΤΟΝ ΠΡΟΣΔΙΟΡΙΣΜΟ ΤΟΥ ΡΗ, ΥΓΡΑΣΙΑΣ, ΛΙΠΟΥΣ, ΟΞΥΤΗΤΑΣ ΛΙΠΟΥΣ, ΣΥΝΤΕΛΕΣΤΗ ΑΛΑΤΟΣ, ΟΛΙΚΟΥ Ν, ΜΗ ΚΑΖΕΙΝΙΚΟΥ Ν, ΜΗ ΠΡΩΤΕΙΝΙΚΟΥ Ν ΚΑΙ ΑΖΩΤΟΥ ΑΜΙΝΟΞΕΩΝ, ΔΙΑΚΕΤΥΛΙΟΥ, ΑΚΕΤΑΛΔΕΥΔΗΣ ΚΑΙ ΕΛΕΥΘΕΡΩΝ ΛΙΠΑΡΩΝ ΟΞΕΩΝ. Ο ΤΡΟΠΟΣ ΠΡΩΤΕΟΛΥΣΗΣ ΔΙΕΡΕΥΝΗΘΗΚΕΜΕ ΗΛΕΚΤΡΟΦΟΡΗΣΗ ΔΙΑΛΥΜΑΤΩΝ ΤΩΝ ΤΥΡΙΩΝ ΣΕ ΠΗΚΤΗ ΠΟΛΥΑΚΡΥΛΑΜΙΔΙΟΥ. ΕΠΙΣΗΣ ΠΑΡΑΚΟΛΟΥΘΗΘΗΚΕ Η ΕΞΕΛΙΞΗ ΤΗΣ ΜΙΚΡΟΧΛΩΡΙΔΑΣ ΤΩΝ ΤΥΡΙΩΝ. ΟΙ ΟΡΓΑΝΟΛΗΠΤΙΚΕΣ ΔΟΚΙΜΕΣ ΕΔΕΙΞΑΝ ΟΤΙ ΤΑ ΠΕΙΡΑΜΑΤΙΚΑ ΤΥΡΙΑ ΑΠΟΚΤΟΥΣΑΝ ΓΕΥΣΗ, ΟΣΜΗ, ΔΟΜΗ ΚΑΙ ΥΦΗ ΣΤΟ ΜΙΣΟ ΧΡΟΝΟ (40 ΜΕΡΕΣ) ΑΠΟ ΟΤΙ Ο ΜΑΡΤΥΡΑΣ (80 ΜΕΡΕΣ). ΕΠΙΣΗΣ ΟΤΙ Η ΠΟΙΟΤΗΤΑ ΤΩΝ ΤΥΡΙΩΝ ΔΕΝ ΥΠΟΒΑΘΜΙΖΟΤΑΝ ΤΟΥΛΑΧΙΣΤΟ ΜΕΧΡΙ ΤΟΥΣ 8 ΜΗΝΕΣ. ΒΡΕΘΗΚΕ ΟΤΙ ΜΕ ΤΗΝ ΠΡΟΣΘΗΚΗ ΤΩΝ ΠΡΩΤΕΟΛΥΤΙΚΩΝ ΕΝΖΥΜΩΝ ΕΙΝΑΙ ΔΥΝΑΤΗ Η ΑΥΞΗΣΗ ΤΩΝ ΜΙΚΡΩΝ ΠΕΠΤΙΔΙΩΝ ΚΑΙ ΤΩΝ ΑΜΙΝΟΞΕΩΝ ΜΕΧΡΙ 40% ΣΕ ΣΥΓΚΡΙΣΗ ΜΕ ΤΟ ΜΑΡΤΥΡΑ ΣΕ ΤΥΡΙΑ ΗΛΙΚΙΑΣ 40 ΗΜΕΡΩΝ. ΑΛΛΑ ΟΠΟΙΑΔΗΠΟΤΕ ΑΥΞΗΣΗ ΤΩΝ ΑΖΩΤΟΥΧΩΝ ΑΥΤΩΝ ΚΛΑΣΜΑΤΩΝ ΠΑΝΩ ΑΠΟ 175% ΕΙΧΕ ΩΣ ΑΠΟΤΕΛΕΣΜΑ ΤΗΝ ΕΜΦΑΝΙΣΗ ΠΙΚΡΗΣ ΓΕΥΣΗΣ. ΕΠΙΣΗΣ ΒΡΕΘΗΚΕ ΟΤΙ ΓΙΑ ΝΑ ΑΠΟΚΤΗΣΟΥΝ ΤΑ ΤΥΡΙΑ ΜΕ ΑΥΞΗΜΕΝΗ ΠΡΩΤΕΟΛΥΣΗ ΤΥΠΙΚΗ ΚΑΙ ΙΣΟΡΡΟΠΗΜΕΝΗ ΓΕΥΣΗ ΗΤΑΝ ΑΠΑΡΑΙΤΗΤΗ Η ΠΡΟΣΘΗΚΗ ΣΤΟ ΓΑΛΑ ΤΥΡΟΚΟΜΗΣΕΩΣ ΜΙΚΡΩΝ ΠΟΣΟΤΗΤΩΝ ΠΑΡΑΣΚΕΥΑΣΜΑΤΟΣ ΛΙΠΑΣΗΣ. ΜΕΙΟΝΕΚΤΗΜΑ ΤΗΣ ΕΠΙΤΑΧΥΝΣΗΣ ΤΗΣ ΩΡΙΜΑΣΕΩΣ ΜΕ ΤΗΝ ΠΡΟΣΘΗΚΗ ΠΡΩΤΕΙΝΑΣΩΝ ΕΙΝΑΙ ΟΤΙ Η ΑΠΟΔΟΣΗ ΣΤΟ ΤΥΡΙ ΗΤΑΝ ΜΕΙΩΜΕΝΗ (ΚΑΤΑ 3,16% ΜΕ ΠΡΩΤΕΙΝΑΣΗ ΤΟΥ B. SUBTILIS ΚΑΙ ΚΑΤΑ 2,63% ΜΕ ΠΡΩΤΕΙΝΑΣΗ ΤΟΥ ASP. ORYZAE) ΣΕ ΣΥΓΚΡΙΣΗ ΜΕ ΤΟ ΜΑΡΤΥΡΑ