700. Factors influencing the activity of cheese starters. The role of milk peroxidase

Abstract

1. Certain starter cultures have been found to be inhibited in the presence of milk peroxidase.2. A high correlation has been established between the inactivation of milk peroxidase and of the inhibitory action by use of critical values of any of the following: temperature, pH, concentration of either sodium azide or hydrogen peroxide.3. The inhibitory action can be overcome by the addition of certain reducing substances such as cysteine and sodium hydrosulphite.4. The inhibitory action is exhibited by the corresponding separated milk and whey.5. It is suggested that this inhibition may be due to the formation of a specific inhibitory oxidation product having a quinonoid structure.6. The addition of 1–2% of pasteurized milk or whey to autoclaved milk caused total inhibition, whereas such additions to milk heated to 190° F. showed no such effect. This is attributed to the presence of SH groups in the latter milk capable of reducing the oxidation product.7. It is suggested that the inhibition due to peroxidase is identical with that ascribed to lactenin 2, and that the inhibition described in our previous paper as due to ‘agglutinin’ is identical with that ascribed to lactenin 1.

Inhibiting factors produced by lactic acid bacteria. 1. Oxygen metabolites and catabolism end-products

“…Lactoperoxidase can tolerate an acidity equivalent to pH 3 in vitro (Wright, 1958) and resists human gastric juice (Gothefors and Marklund, 1975). It is relatively heatstable, since it is only partially inactivated by a short pasteurization at 74°C (Wright and Tramer, 1958), after which there subsists enough residual activity for the LPS to remain effective.…”

“…It is relatively heatstable, since it is only partially inactivated by a short pasteurization at 74°C (Wright and Tramer, 1958), after which there subsists enough residual activity for the LPS to remain effective.…”

Les levains lactiques mésophiles. Une revue

“…Il détermine une croissance plus rapide du levain en raison de la dégradation partielle des protéines du lait, qui est source d'acide aminés et de peptides. En outre, les inhibiteurs naturels du lait cru, connus sous le nom générique de lacténines, sont inactivés [1,20,76]. Parmi les lacténines, on distingue les agglutinines qui entraînent une agglutination des souches sensibles, suivie d'un dépôt au fond de la cuve d'un sédiment plus ou moins important constitué par des amas de bactéries agglutinées et de caséine coagulée; cette sédimentation s'accompagne d'un développement irrégu-lier du levain lactique et retarde l'acidification (Emmons et al, [16]).…”

A polyol mixture or molasses treated beet pulp in the silage based diet of dairy cows: II. The effect on the lactoperoxidase and thiocyanate content of milk and the udder health

“…No reason for these fluctuations could be found. It is evident that a certain LP activity is needed in milk in order to activate the inhibitory system, since milk is known to contain factors which weaken the inhibitory system such as catalase and reducing compounds (Wright andTramer 1958, Björck 1977). …”