Study of protein complex formation during storage and gelation of UHT milk

International audienc

Study of protein complex formation during storage and gelation of UHT milk

International audienc

Estrazione dei composti fenolici di oli di oliva vergini ed effetti di ritenzione sui fenoli ossidati

L'interesse relativo agli antiossidanti naturali provenienti da matrici vegetali hanno mostrato in questi ultimi anni una tendenza all\u2019aumento. In particolare il frutto dell'oliva ed i suoi derivati rappresentano un'importante parte nella dieta Mediterranea ed \ue8 stata riconosciuta una sorgente antiossidanti fenolici naturali. Questi composti svolgono effetti chemioprotettivi sulla salute umana oltre a contribuire alle propriet\ue0 sensoriali dell'olio vergine di oliva come piccante e amaro. Inoltre, l'alta stabilit\ue0 degli oli vergini di oliva \ue8 correlata sia all'alto rapporto tra acidi grassi monoinsaturi e polinsaturi ma anche alla presenza di composti fenolici che svolgono azione antiossidante. Gli estratti idrofili dell'olio vergine di oliva contengono alcuni composti fenolici come fenoli semplici, lignani e secoiridoidi. Inoltre, per determinare il reale contenuto di fenoli dell'olio di oliva \ue8 importante disporre di un metodo analitico capace di fornire buoni recuperi in fase di estrazione. In letteratura sono riportate principalmente due tecniche per l'estrazione dei composti fenolici dall'olio vergine di oliva: estrazione su fase solida (SPE) ed estrazione liquido-liquido (LLE). Oltre ai composti fenolici, negli ultimi cinque anni, \ue8 incrementato significativamente l'interesse verso i composti fenolici ossidati in relazione alla possibilit\ue0 di risalire allo stato di freschezza/invecchiamento degli oli vergini di oliva. Lo scopo di questo lavoro \ue8 quello di valutare l'influenza di due differenti metodi di estrazione (i pi\uf9 utilizzati) nella separazione dei composti fenolici ossidati

Retention effects of oxidized polyphenols during analytical extraction of phenolic compounds of virgin olive oil

The hydrophilic extract of virgin olive oil contains several phenolic compounds such as simple phenols, lignans, and secoiridoids that have been widely studied in recent years. Interest in the hydrophilic extract has also been extended to the fraction of oxidized phenols that form during storage as a consequence of oxidative stress. The present investigation compares the two most commonly used extraction methods, namely liquid–liquid extraction and SPE, on fresh virgin olive oil and that kept at different temperatures in the presence of oxygen to promote the formation of oxidative products. The selective retention of these natural and oxidized phenolic compounds in relation to the extraction method was assessed. Quantification of eight identified phenolic molecules and 11 unknown peaks was performed by HPLC-DAD/MSD

Proteins and proteolysis in pre-term and term human milk and possible implications for infant formulae.

Understanding the differences between the protein system of human milk and bovine milk is critical in the development of infant formulae. In this study, the proteins of bovine milk and a bovine-based wheydominant infant formula were compared with those of human milk for infants born prematurely (preterm) or at full term (term). The protein distribution of infant formula differed significantly from that of either type of human milk. A proteomic comparison between pre-term and term human milk showed a reduction of levels of b-casein and as-casein and appearance of additional products, corresponding to low molecular weight hydrolysis products of the caseins, in pre-term milk. Pre-term milk samples also had higher total nitrogen concentration and plasmin activity, consistent with the proteomic data. These results suggest the operation of a physiological mechanism that may adjust enzyme and/or protein expression to modify protein digestibility, and may facilitate design of infant formulae, closer to maternal milk, particularly for premature infants

Predicting the Important Enzymes in Human Breast Milk Digestion

[Image: see text] Human milk is known to contain several proteases, but little is known about whether these enzymes are active, which proteins they cleave, and their relative contribution to milk protein digestion in vivo. This study analyzed the mass spectrometry-identified protein fragments found in pooled human milk by comparing their cleavage sites with the enzyme specificity patterns of an array of enzymes. The results indicate that several enzymes are actively taking part in the digestion of human milk proteins within the mammary gland, including plasmin and/or trypsin, elastase, cathepsin D, pepsin, chymotrypsin, a glutamyl endopeptidase-like enzyme, and proline endopeptidase. Two proteins were most affected by enzyme hydrolysis: β-casein and polymeric immunoglobulin receptor. In contrast, other highly abundant milk proteins such as α-lactalbumin and lactoferrin appear to have undergone no proteolytic cleavage. A peptide sequence containing a known antimicrobial peptide is released in breast milk by elastase and cathepsin D