Effect of oxidoreduction potential and of gas bubbling on rheological properties and microstructure of acid skim milk gels acidified with glucono-δ-lactone

Abstract

Milk oxidoreduction potential was modified using gases during the production of a model dairy product and its effect on gel setting was studied. Acidification by glucono-delta-lactone was used to examine the physicochemistry of gelation and to avoid variations due to microorganisms sensitive to oxidoreduction potential. Four conditions of oxidoreduction potential were applied to milk: milk was gassed with air, nongassed, gassed with N(2), or gassed with N(2)H(2). The rheological properties and microstructure of these gels were determined using viscoelasticimetry, measurement of whey separation, and confocal laser scanning microscopy. It appeared that a reducing environment led to less-aggregated proteins within the matrix and consequently decreased whey separation significantly. The use of gas to modify oxidoreduction potential is a possible way to improve the quality of dairy products.

Rheological and physical properties of camel and cow milk gels enriched with phosphate and calcium during acid-induced gelation

“…3c, d). The obtained results were in agreement with the findings of Martin et al (2009) who reported that G 0 and G 00 of GDL-induced skim milk gels increased in the 0.016-1.60 Hz range.…”

Redox Potential: Monitoring and Role in Development of Aroma Compounds, Rheological Properties and Survival of Oxygen Sensitive Strains During the Manufacture of Fermented Dairy Products

“…So, for GDL-gels, the viscosity was affected by bubbling. Martin et al [20] showed that the type of gas used for bubbling has a significant influence but no clear trend can be deduced from these results in terms of the influence of an oxidizing or reducing environment.…”

“…Martin et al [20] studied the effects of Eh on model acidified skim milk gels obtained using GDL and prepared under different gaseous conditions. The milk prepared in air is an oxidizing medium; nitrogen, which is a neutral gas, can be used to remove oxygen from milk -even so the milk Eh remains oxidizing in these conditions -and hydrogen leads to a reducing Eh (below 0).…”

“…However, we do not know if these modifications are due to the impact of Eh on physicochemical phenomena, lactic acid bacteria, or both. For this purpose, Martin et al [20] wanted to determine to what extent chemical phenomena affect acid milk gelation under different Eh conditions. Glucono-δ-lactone (GDL) was used to acidify milk to avoid variations caused by microorganisms sensitive to Eh.…”

“…The milk prepared in air is an oxidizing medium; nitrogen, which is a neutral gas, can be used to remove oxygen from milk -even so the milk Eh remains oxidizing in these conditions -and hydrogen leads to a reducing Eh (below 0). Martin et al [20] focused on the effect of gas bubbling on gel structure through viscoelastic properties and measurement of whey separation (Table 1). Table 1.…”