Antioxidative ability of native and thermized sour whey in oxidation‐catalysed model systems†

Antioxidative properties of sour (cottage) were evaluated with (thermized) and without (native) heat treatment (80°C for 30 min). A model system comprising a Tween 20 stabilized peanut oil in phosphate buffer (pH 7.0) emulsion containing lipid oxidation catalysts, FeCl ₃, H₂O₂ and ascorbate was used. Native sour whey powder (SWP) was significantly better than thermized whey in terms of limiting the formation of thiobarbituric acid‐reactive substances and peroxide value. Antioxidative ability was best at pH 3.0 and decreased with increasing pH. SWP (20%, w/v) was significantly better than all commonly used antioxidants tested after 96 h of incubation at 40°C.     

Shelf life of whole milk processed by pulsed electric fields in combination with PEF-generated heat

Application of pulsed electric fields (PEF) in combination with mild thermal treatment was studied to extend the shelf life of whole milk. Five pulses with peak electric field strength of 35 kV/cm and pulse width of around 2.3 μs were applied to milk at 65 °C and sustained for less than 10 s. Shelf life of the milk was extended by a minimum of 24 days. A synergistic interaction between PEF and mild thermal treatment was found. Neither the severe PEF treatment applied at lower temperatures, nor the mild thermal treatment equivalent, including longer treatment times than used in this study, could significantly extend the shelf life of milk. However, the combination of both PEF and mild temperature extended milk's shelf life adequately. The use of a thermal regeneration system improved the energy efficiency of the studied preservation process making it highly competitive with pasteurization.     

Effects of milk high pressure homogenization on biogenic amine accumulation during ripening of ovine and bovine Italian cheeses

The aim of this work was to evaluate the biogenic amine (BA) content during the ripening of both bovine and ovine cheeses obtained using milk subjected to a homogenization treatment at 100 MPa before cheese-making. The data obtained were compared with those from cheeses produced by the same milks without any treatment or thermized. The results showed that both microbial ecology and BA concentrations of cheeses during ripening were significantly influenced by the type of milk used for cheese-making and by the treatment applied to the raw materials. In particular, the microbial counts found in Caciotta indicated that the high pressure homogenization (HPH) of milk significantly reduced the presence of the yeasts, Micrococcaceae and lactobacilli at the end of ripening. On the other hand, the HPH treatment of milk favoured the proliferation of yeasts in ovine cheese. Moreover, the ovine cheeses were characterized by a remarkably higher accumulation of BA than bovine cheeses. However, the HPH treatment of milk was able to drastically reduce the biogenic amine concentrations in both cheese typologies at the end of ripening.     

Functional attributes of native and thermized sour and sweet whey†

The functional attributes of sour (cottage) and sweet (Edam and Cheddar) whey powders and the effect of thermization (80°C/30 min) were investigated. Solubility of sour whey was significantly lower and oil‐holding capacity was higher than that of sweet whey samples. Thermization significantly enhanced thermostability (TS) of all powders, though solubility and emulsifying and foaming properties were depressed. Enhancement of TS was best demonstrated at acidic pH values of 3.0 and 4.5, where TS increased by 57 and 53%, 181 and 167%, and 31 and 48%, for cottage, Edam, and Cheddar, respectively. Thermization may be used to manufacture pasteurization and retort stable whey powders.