Influence of Dissolved Gases and Heat Treatments on the Oxidative Degradation of Polyunsaturated Fatty Acids Enriched Dairy Beverage

Abstract

The combined effect of dissolved gas composition and heat treatment on the oxidative degradation of a dairy beverage enriched with 2% linseed oil was studied. The dairy beverage was saturated with air, nitrogen, or a nitrogen/hydrogen mixture (4% hydrogen) before pasteurization or sterilization. Saturation with either nitrogen or a nitrogen/hydrogen mixture decreased the dissolved oxygen concentration in dairy beverages (Delta = 7.7 ppm), and the presence of hydrogen significantly reduced the redox potential (Delta = 287 mV). Heat treatments also reduced the oxygen content and redox potential, sterilization being more effective than pasteurization. Both pasteurization and sterilization induced the oxidative degradation of the beverages. On average, the propanal concentration increased by a factor of 2.3 after pasteurization and by a factor of 6.2 after sterilization. However, during storage, sterilized beverages resisted light-induced oxidation better than unheated or pasteurized beverages. Furthermore, saturation with nitrogen or a nitrogen/hydrogen mixture significantly reduced oxidative degradation and provided some protection against color changes during storage.

Use of oregano extract and oregano essential oil as antioxidants in functional dairy beverage formulations

“…Rapid oxygen depletion was observed during the first 3 days of storage at 50 C or of exposure to light. Similar results were obtained previously (Giroux, Acteau, et al, 2008;Giroux, St-Amant, et al, 2008). Fig.…”

“…In a previous study (Giroux, Acteau, et al, 2008;Giroux, St-Amant, et al, 2008), storage in the dark at 4 C (i.e. no light or heat) of dairy beverages similar to those used in the present experiment resulted in no change in dissolved oxygen concentration as a function of time.…”

“…Low-heat skim milk powder (35.3 g/100 g protein; Agropur, Granby, QC, Canada) was dispersed in deionized water to a protein concentration of 3.5 g/100 g and supplemented with Fe (as FeSO 4 ) at a level of 0.001 g/100 g as described by Giroux, Acteau, Sabik, and Britten (2008). Sodium azide (0.02 g/100 g) was used as a microbial growth inhibitor.…”

Use of propolis extracts as antioxidant in dairy beverages enriched with conjugated linoleic acid

“…Milk protein concentrate (MPC) was dispersed in Millipore water to a final protein concentration of 3.5 % (w/w) and supplemented with Fe at a rate of 0.001 % (w/w) using FeSO 4 × 7H 2 O [14]. NaN 3 was added at a rate of 0.02 % (w/w) to prevent microbial growth.…”

Oxidation of Frying Oils during Intermittent Usage

“…This decrease in oxygen uptake could account for the protective effect of PDMS in frying oils. Giroux et al 16 studied the combined effect of dissolved gas composition and heat treatment on the oxidative degradation of a dairy beverage enriched with 2 linseed oil. Saturation with either nitrogen or a nitrogen/hydrogen mixture decreased the dissolved oxygen content in dairy beverages, and the presence of hydrogen significantly reduced the redox potential.…”