Comparative studies on ?acid-stable, heat-stable polypeptides? of ovine, caprine and bovine milks

Ramos, Mercedes; Sánchez, Rosa M.; Olano, Agustı́n; Sanz, J.; Martı́nez-Castro, I.

doi:10.1007/bf01027174

Cited by 10 publications

(4 citation statements)

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“…lc, d) allowed us to make a clear distinction between the degradation products arising from the different proteinases. Those soluble at pH 4-6 resulting from the action of plasmin on whole casein consisted mainly of peptides eluting before the whey proteins on RP-HPLC (peaks 5-7) which, from their electrophoretic mobility, correspond to proteose-peptone component 5 (Andrews & Alichanidis, 1983;Ramos et al 1988). The fraction soluble at pH 4-6 of the psychrotrophic enzyme digest of casein gave a very different elution pattern with many peaks eluting during the first 24 min of the chromatogram.…”

Section: Resultsmentioning

confidence: 99%

Application of reversed-phase HPLC to the study of proteolysis in UHT milk

López‐Fandiño

Olano

José

et al. 1993

Journal of Dairy Research

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Instability of UHT milk as well as the appearance of off flavours are partly attributed to the proteolytic activity of residual or reactivated heat-stable enzymes of both native and bacterial origin (Law, 1979;Mottar et al. 1979;McKellar et al. 1984; de Koning et al. 1985). Among the methods so far employed for assessing the extent of protein degradation in UHT products, PAGE has frequently been used to follow the hydrolysis of individual protein fractions and to detect the appearance of specific casein breakdown bands. This technique is insufficient to resolve low molecular mass peptides and lacks adaptability to automatic procedures.Reversed-phase HPLC (RP-HPLC) has proved to be a reliable method with high resolving power for separating peptides from casein hydrolysates (Gonzalez-Llano et al. 1990). The present paper describes the use of RP-HPLC to investigate the degree of protein breakdown during storage of UHT milk. In addition, RP-HPLC chromatograms of milk samples are compared with chromatograms of plasmin and psychrotrophic bacterial enzyme digests of casein as a contribution to knowledge of the significance of the presence of peptides in UHT milk. MATERIALS AND METHODS Milk samplesCommercial samples of directly (9) and indirectly (14) heated UHT milks were purchased from local markets. In addition, proteolysis upon storage at 20 °C was studied in two batches each of indirectly (I and II) and directl}' (III and IV) heated UHT milks supplied from commercial dairy plants. Analyses of the samples were performed (taking a fresh pack each time) at 15 d intervals for 3 months. Preparation of digestsWhole casein was prepared by precipitation from skim milk with 10% (v/v) acetic acid at pH 4-6, followed bj ? centrifugation at 4500 £ for 15 min. The casein precipitates were washed three times with distilled water adjusted to pH 4-6, and recovered by centrifugation prior to final lyophilization.

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Section: Resultsmentioning

confidence: 99%

Application of reversed-phase HPLC to the study of proteolysis in UHT milk

López‐Fandiño

Olano

José

et al. 1993

Journal of Dairy Research

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“…1. continued(e) the acid-stable, heat-stable fraction in a typical sample of ovine whey; (f) the supernatant remaining upon removal of this acid-stable, heat-stable fraction in a typical sample of ovine whey. Pearce, 1980;Ramos et al, 1988), was confirmed by the fact that they were not present in the isolated PP fraction [see Fig. l(e)].…”

Section: Identification and Quantitative Measurement Of Whey Proteinsmentioning

confidence: 90%

Effect of thermal treatment on the protein profile of whey from ovine and caprine milk throughout lactation

Pintado

Malcata

1996

International Dairy Journal

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The independent and combined effects of temperature, heating period and stirring rate on the extent of precipitation of each of the major proteins in ovine and caprine acid wheys at various stages of lactation were studied using two-level, replicated, complete factorial designs. Evaluation of the extent of precipitation was based on the quantitative results obtained by gel permeation chromatography. Statistical analyses indicated that temperature is the most important factor in the precipitation of u-lactalbumin and /I-lactoglobulin from acid whey from both ovine and caprine milks. The magnitude of the independent effects of heating time and stirring rate on the precipitation of B-lactoglobulin and a-lactalbumin from ovine whey reached local maxima as lactation elapsed, but such effects were rather small for caprine whey.

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“…Pour les fractions de laits de brebis et de chèvre, l'absence d'aminogramme dans les travaux rapportés dans ce domaine ne permet pas la comparaison avec nos résultats. Les teneurs en fractions glycoprotéiques des protéose-peptones de lait bovin (7%), ovin (11%) et caprin (11%) observées sont plus élevées que celles obtenues par Ramos et al (1988) qui sont respectivement de 4, 7,3 et 6,4%. Il Y a une variation, selon les auteurs, dans les taux de glycoprotéines exprimés pour la même fraction protéique.…”

Section: Analyses Chimiquesunclassified

Isolement et caractérisation de la fraction hydrophobe des protéose-peptones des laits bovin, ovin et caprin

Mati

Girardet

Xenakis

et al. 1991

Lait

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(Reçu le 9 octobre 1990; accepté le 15 décembre 1990) Résumé -Le protocole d'isolement des protéose-peptones, largement utilisé jusque là pour le lait de vache, a été adapté et appliqué aux laits de brebis et de chèvre. Les fractions de ces protéines contenant le composant-s sont isolées par chromatographie d'interactions hydrophobes. Les rendements d'extraction sont améliorés par optimisation .de ce protocole. Le comportement physicochimique des fractions protéiques (protéose-peptones totales et leurs fractions hydrophobes) est étudié, L'électrophorèse en gel de polyacrylamide en milieu non dissociant (PAGE native) montre une plus faible mobilité du composant-3 des laits ovin et caprin par rapport à leur homologue du lait bovin. En milieu dissociant, en présence de dodécylsulfate de sodium et du 2-mercaptoéthanol (PAGE-SDS), les profils électrophorétiques des fractions hydrophobes ont en commun 2 bandes principales correspondant à des glycoprotéines de 18 000 et 28 000 Da. Ces polypeptides sont impliqués dans les agrégats de hauts poids moléculaires mis en évidence par chromatographie de perméation sur gel (colonnes de Séphacryl S200 et Superose 12). L'électrophorèse bidimensionnelle a montré une bonne similitude entre les fractions protéiques des laits des 3 espèces, concernant leurs points isoélectriques et leurs poids moléculaires. La composition chimique (acides aminés, glucides, phosphore) a montré également des analogies entre les fractions protéose-peptones des laits provenant des espèces laitières étudiées.

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Comparative studies on ?acid-stable, heat-stable polypeptides? of ovine, caprine and bovine milks

Cited by 10 publications

References 10 publications

Application of reversed-phase HPLC to the study of proteolysis in UHT milk

Application of reversed-phase HPLC to the study of proteolysis in UHT milk

Effect of thermal treatment on the protein profile of whey from ovine and caprine milk throughout lactation

Isolement et caractérisation de la fraction hydrophobe des protéose-peptones des laits bovin, ovin et caprin

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