Homogenization Pressure and Temperature Affect Protein Partitioning and Oxidative Stability of Emulsions

The oxidative stability of 10 % fish oil-in-water emulsions was investigated for emulsions prepared under different homogenization conditions. Homogenization was conducted at two different pressures (5 or 22.5 MPa), and at two different temperatures (22 and 72 °C). Milk proteins were used as the emulsifier. Hence, emulsions were prepared with either a combination of α-lactalbumin and β-lactoglobulin or with a combination of sodium caseinate and β-lactoglobulin. Results showed that an increase in pressure increased the oxidative stability of emulsions with caseinate and β-lactoglobulin, whereas it decreased the oxidative stability of emulsions with α-lactalbumin and β-lactoglobulin. For both types of emulsions the partitioning of proteins between the interface and the aqueous phase appeared to be important for the oxidative stability. The effect of pre-heating the aqueous phase with the milk proteins prior to homogenization did not have any clear effect on lipid oxidation in either of the two types of emulsions. (Résumé d'auteur

Extraction of cocoa butter by supercritical carbon dioxide: optimization of operating conditions and effect of particle size.

The optimum operating conditions for the extraction of cocoa butter from cocoa liquor using supercritical carbon dioxide and the effect of sample particle size on cocoa butter extraction under optimized operating conditions were investigated. The optimization was conducted at 10–45 MPa and 35–75C, with extraction times of 1–12 h by response surface methodology. The effect of particle size was studied using cocoa liquor, ground cocoa nibs and crushed cocoa nibs with particle sizes of approximately 74 µm, 0.85–1 mm and 4–6 mm, respectively. The yield was analyzed for total fat content by gravimetric method and triacylglycerol (TAG) profile by high-performance liquid chromatography. The results showed higher yield of cocoa butter with higher values of pressure, temperature and extraction time. The optimum conditions for cocoa butter extraction were 45 MPa, 75C and 12 h. The smaller particle size produced a higher yield of cocoa butter. 1,3-Dipalmitoyl-2-oleoyl-glycerol (POP), 1-palmitoyl-2-oleoyl-3-stearoyl-glycerol (POS) and 1,3-distearoyl-2-oleoyl-glycerol (SOS) were the major TAGs present in the extracted cocoa butter, with POS being the highest (>30%) for all treatments studied

Oxidative Stability of Polyunsaturated Edible Oils Mixed With Microcrystalline Cellulose

The oxidative stability of mixtures of edible oils containing polyunsaturated fatty acids (PUFA) and microcrystalline cellulose (MCC) was investigated. The mixtures studied consisted of oils of either camelina (CAM), cod liver (CLO), or salmon (SO) mixed with either colloidal or powdered MCC. A 50:50 (w/w) ratio of oil:MCC resulted in an applicable mixture containing high levels of PUFA edible oil and dietary fiber. The oxidative stability of the formulated mixtures and the pure oils was investigated over a period of 28 days. The peroxide value (PV) was assessed as a parameter for primary oxidation products and dynamic headspace gas chromatography mass spectrometry (GC/MS) was used to analyze secondary volatile organic compounds (VOC). CAM and the respective mixtures were oxidatively stable at both 4 and 22 °C during the storage period. The marine oils and the respective mixtures were stable at 4 °C. At 22 °C, an increase in hydroperoxides was found, but no increase in VOC was detected during the time-frame investigated. At 42 °C, prominent increases in PV and VOC were found for all oils and mixtures. Hexanal, a common marker for the degradation of n-6 fatty acids, propanal and 2,4-heptadienal (E,E), common indicators for the degradation of n-3 fatty acids, were among the volatiles detected in the headspace of oils and mixtures. This study showed that a mixture containing a 50:50 ratio of oil:MCC can be obtained by a low-tech procedure that does not induce oxidation when stored at low temperatures during a period of 1 month