Effect of thiocyanate and hydrogen peroxide on the keeping quality of ovine, bovine and caprine raw milk

Abstract

The preservation of raw ovine, bovine and caprine milks by the activation of their natural lactoperoxidase (LP) systems was investigated. The LP system of the samples was activated by adding different amounts of sodium thiocyanate and sodium percarbonate to give three different concentrations of thiocyanate and hydrogen peroxide: 7, 14 and 28 mg/L and 15, 30 and 60 mg/L, respectively. Each type of raw milk, ovine, bovine and caprine, was analysed after being treated as follows: Control (C), LP inactivated (T0), LP activated with different concentrations of thiocyanate (7, 14 and 28 mg/L) and hydrogen peroxide (15, 30 and 60 mg/L) and stored at 4°C for 72 h. The results indicated that concentrations of 28 mg/L (SCN−) and 60 mg/L (H2O2) would be adequate for preserving milks of different mammals at 4°C, but we should take into consideration the international norm – 14 mg/L of SCN− and 30 mg/L of H2O2, respectively. Overall, the results have shown that, by activation of the LP system in raw milk, it was possible to store ovine, bovine and caprine milks at 4°C for several days. Changes in titratable acidity, total colony counts, psychrotrophic bacteria, coliforms, moulds and yeasts of the milk samples were followed during storage at low temperature with increasing dose. The effect of doses was greater in bovine milk than in caprine milk and finally in ovine milk.

The effect of refrigerated storage of raw milk on the physicochemical and microbiological quality of Tunisian semihard Gouda‐type cheese during ripening

“…However, lower pH values were observed for milk stored at 4 °C during 48, 72 and 96 h. This result was in agreement with previous researchers reporting a decrease in the pH value from 6.82 ± 0.06 to 6.75 ± 0.11 and 6.61 ± 0.26, after a storage time at 4 °C for 24 h, 3 and 4 days, respectively (Ruas‐Madiedo et al. 1998; Boularès et al. 2011b).…”

“…In general, the physicochemical composition of milk samples showed average values similar to those described by previous findings during the refrigeration of milk at 4 °C for different times (Ruas‐Madiedo et al. 1998; Boularès et al. 2011b).…”

“…The dairy industry has long recognised the importance of raw milk quality (Senky et al 1988;Eneroth et al 1998Eneroth et al , 2000Aaku et al 2004). The widespread use of refrigeration at farms and dairy processing plants maintains the quality of milk by reducing the growth rate of mesophilic bacteria and extends the storage time of raw milk before processing (Mankai et al 2003;Seifu et al 2003;Boularès et al 2011b). However, refrigeration favours the multiplication of psychrotrophic bacteria present as normal contaminants in raw milk and also brings about a change in the physicochemical characteristics of the milk constituents (Banks et al 1988;Silveira et al 1999;Mankai et al 2003;Mankaï et al 2005).…”

Effect of the lactoperoxidase system on proteolysis and physicochemical changes in ultra high temperature milk during storage

“…Proteolysis in UHT milk samples may be due to plasmin and/or bacterial proteinases and/or SCC elastase and catehepsin G (Bastian and Brown, 1996; Le Roux et al, 2003), which depends on the microbiological quality of milk samples. Thus, activation of LPS in refrigerated raw milk improves its hygienic quality (Boulares et al, 2011) and reduces its concentration of extracellular bacterial proteinases, compared with control raw milk.…”

Optimizing the use of Sinapis alba seed meal extracts as a source of thiocyanate (SCN−) for the lactoperoxidase system

“…The reactions inhibit growth of both Gram negative (e.g., Escherichia coli O157:H7) and Gram positive bacteria (e.g., Listeria monocytogenes), thus making the LPSys potentially useful in improving food safety (Elliot et al, 2004;El-Shenawy, Garcia, & Marth, 1990;Marshall & Reiter, 1980). Although investigators have demonstrated the effect of the LPSys in milk (Boulares, Mankai, & Hassouna, 2011;Seifu, 2007;Seifu, Buys, & Donkin, 2005), application in other food systems is limited. For example, application of the LPSys in beef cubes significantly reduced the number of microorganisms including L. monocytogenes after 7 d of incubation at 12 C (Elliot et al, 2004).…”