Hélène J. Giroux

Encapsulation of hydrophobic aroma in whey protein nanoparticles

Aroma-loaded nanoparticles (d < 300 nm) were prepared by cross-linking denatured whey protein through pH-cycling. The effect of nanoparticulation conditions and aroma concentration on the physicochemical characteristics of nanoparticles and aroma release profile was studied. Better retention of aroma was observed when ethyl hexanoate was added before nanoparticle formation. The highest aroma retention was obtained for nanoparticles produced at pH 5.0 and 5.5 without calcium addition. These nanoparticles are characterized by a less compact and more porous internal structure allowing a higher loading of aroma. Increasing aroma concentration increased the diameter and the voluminosity of the aroma-loaded nanoparticles. The percentage of aroma retention showed an increase from 7% to 24% over the tested concentration range while the value averaged 2% for native or denatured whey protein. Encapsulation of ethyl hexanoate in whey protein nanoparticles reduced the mass transfer of aroma at the surface of the matrix and improved its retention.

Effect of flaxseed lignans added to milk or fed to cows on oxidative degradation of dairy beverages enriched with polyunsaturated fatty acids

Nutritional value is a priority in new product development. Using vegetable or marine oils, rich in polyunsaturated fatty acids, in dairy beverage formulations is an option to provide the consumers with healthier products. However, these formulations are prone to oxidation, which is responsible for rapid flavour degradation and the development of potentially toxic reaction products during storage. Flaxseed lignans, secoisolariciresinol diglucoside (SDG), and its mammalian metabolites have antioxidant activity and could be used in beverage formulations to prevent oxidation. Commercially available SDG extract was added to the formulation of dairy beverages enriched with flaxseed oil. As an alternative approach, dairy beverages were produced from milk naturally rich in SDG metabolites obtained through the alteration of cow diet. Resistance to oxidation was determined from the kinetics of hexanal and propanal production during heat and light exposure treatments. Increasing SDG concentration in dairy beverage slightly reduced redox potential but had no effect on oxygen consumption during oxidation treatments. The presence of SDG in dairy beverage significantly improved resistance to heat- and light-induced oxidation. However, purified enterolactone, a mammalian metabolite from SDG, prevented oxidation at much lower concentrations. The use of milk from dairy cow fed flaxseed meal did not improve resistance to oxidation in dairy beverage. Enterolactone concentration in milk was increased by the experimental diet but it remained too low to observe any significant effect on dairy beverage oxidation.

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

The addition of propolis to food formulations containing conjugated linoleic acid (CLA) can improve nutritional properties and stability during storage. The purpose of this study was to enrich dairy beverages with both CLA and Canadian propolis extracts and to determine the chemical characteristics of the enriched beverages, with a focus on antioxidant properties and protection against lipid oxidation. Analysis of DPPH, ORAC, color and aldehyde production along with CLA quantification was performed. Adding different propolis extracts increased the antioxidant capacity of dairy beverages enriched with CLA, while pasteurization treatment reduced the antioxidant capacity. The production of aldehydes during storage under light exposure was reduced significantly in the presence of propolis extracts. Since no nutritional loss was observed during processing and storage of dairy beverages, the main advantage of using propolis extract relates to its higher antioxidant capacity and ability to reduce off-flavors associated with aldehyde production.