Rheological properties of cholesterol-reduced,yolk-stabilized mayonnaise

The effects of cholesterol on droplet size distribution and rheological properties of cholesterol-reduced egg yolk-stabilized emulsions were determined. Oil-in-water emulsions were prepared by using spray-dried eggs submitted to different levels of cholesterol reduction (14–81 wt% of cholesterol removed). Cholesterol was extracted in a modified Jennings apparatus with subcritical CO₂ (9°C and 4.66·10⁶ Pa). Oscillatory and steady flow tests, as well as droplet size distribution measurements, were carried out on the cholesterol-reduced egg yolk-stabilized emulsions. The rheological parameters increased with the level of cholesterol reduction up to 40–80 wt% for emulsions having the same total amount of egg yolk. Opposite results, however, were obtined with some emulsions stabilized by a highly cholesterol-reduced (≈80 wt%) egg yolk. These results were explained by taking into account two opposite phenomena: an increase in the concentration of surface-active agents as cholesterol content decreased, and a lipoprotein structural rearrangement induced by cholesterol removal.     

Rheological properties and sensory texture of mayonnaise

Mayonnaises are viscoplastic oil‐in‐water emulsions, in which rheological properties have important influences on functional properties and the sensory quality. A set of 17 samples of both traditional and light mayonnaises were tested at 10 and 25 °C, using a rheoviscometer Rotovisco RT 10. Nonlinear relations were observed between the yield value and the apparent viscosity. The yield value was correlated with several sensory characteristics rated after manipulation with a spoon, but not in oral testing. No relations were obtained between the apparent viscosity and sensory characteristics. The yield value and the texture acceptability were related significantly to the flavour acceptability. Multivariate statistical techniques were found advantageous for improving the prediction of the texture acceptance.     

Comparison of total fat,fatty acids,cholesterol, and other sterols in mayonnaise and imitation mayonnaise

Nine brands of mayonnaise and five brands of imitation mayonnaise were purchased from supermarkets in the Washington, DC, area. The samples were analyzed for total fat, fatty acids, sterols, and moisture. Little variation in total fat and saturated fatty acid values was observed among the brands of mayonnaise. The polyunsaturated fatty acid content of mayonnaise ranged from 28.0 to 47.9 g/100 g product. The cholesterol levels were divided between two ranges, 50-55 and 75-79 mg/100 g product. In contrast, there was wide variation in the lipid composition of the different brands of imitation mayonnaise. The total fat values for these products varied from 14.3 to 50.4 g/100 g product. The cholesterol content varied between 0 and 72 mg/100 g product; the latter figure equals the cholesterol content of many of the mayonnaise samples.     

The mayonnaise industry of the United States

There is every reason to believe that the growth of the industry will continue in the future as it has done in the past, assuming that the quality of the products is as well maintained as it has been. In general, the confidence of the buyer has been gained, and there is less and less tendency to go to the trouble to make the products which can be purchased of practically equal quality and comparable price. There is much yet to be learned regarding problems of distribution along the lines brought out in this report, and in similar ways. Much educational work must be done before all the manufactures see the value of such investigations, and are ready to help themselves by helping others. The association, as representing the industry can do many of these things with the coperation of the manufactures, both members and non-members, and, now, as before, the department of Commerce is glad to assist in any way compatible with its duties and abilities     

Preliminary gas chromatographic analysis of flavor compounds in mayonnaise

The flavor compounds in fresh, 3- and 6-month-old mayonnaise at room temperature have been analyzed by a gas chromatographic method. The results indicate that as the storage time of mayonnaise increased, the flavor compounds formed from oil in mayonnaise increased. However, the concentrations of allyl isothiocyanate which is the major flavor compound of mustard, and acetic acid and ethyl acetate which are the major compounds in vinegar did not change during the 6 months’ storage at room temperature. The analytical method described has shown good reproducibility in the analysis of mayonnaise flavor compounds and can be used as an instrumental analytical method to evaluate the mayonnaise flavor quality and to complement the sensory evaluation of mayonnaise. Ohio Agricultural Research and Development Center Journal Series Article 46–82.     

Analysis of neutral volatiles of mayonnaise by direct gas chromatography and mass spectrometry

Simple procedures have been developed for analyzing neutral volatiles from mayonnaise by direct gas chromatography and combined direct gas chromatography-mass spectrometry. For gas Chromatographic analysis, a glass liner containing glass wool coated with alkali in the lower quarter and plain glass wool in the remaining space is placed in the heated inlet of a gas Chromatograph, and mayonnaise and water are injected onto the plain packing. Neutral volatiles eluted from the mayonnaise by the combined action of water, carrier gas, and heat collect on the cool column of the gas Chromatograph, but acetic acid is trapped by the alkaline glass wool and thus does not interfere with the analysis. After removal of the liner with the spent sample, the temperature of the column oven is programmed to resolve the volatiles. For mass spectrometric analysis, neutral volatiles are passed directly from a Chromatograph inlet to a second inlet liner containing a porous polymer that traps most organic compounds but has low affinity for water. These neutral organic volatiles are desorbed from the porous polymer in the inlet of a Chromatograph interfaced with a mass spectrometer for analysis. This procedure allows components resolved by the gas Chromatograph to be identified by mass spectrometry without interference from either water or acetic acid. A total of 21 neutral volatile compounds was identified in mayonnaise. Presented at the AOCS Meeting, Chicago, September 1976.     

Oxidative stability of mayonnaise containing structured lipids produced from sunflower oil and caprylic acid

Mayonnaise based on enzymatically produced specific structured lipid (SL) from sunflower oil and caprylic acid was compared with mayonnaise based on traditional sunflower oil (SO) or chemically randomized lipid (RL) with respect to their oxidative stability, sensory and rheological properties. Furthermore, the potential antioxidative effect of adding lactoferrin, propyl gallate or EDTA to the mayonnaise with SL was also investigated. Mayonnaise based on SL oxidized faster than mayonnaise based on RL or SO. The reduced oxidative stability in the SL mayonnaise could not be ascribed to a single factor, but was most likely influenced by the structure of the lipid, the lower tocopherol content and the higher initial levels of lipid hydroperoxides and secondary volatile oxidation compounds in the SL itself compared with the RL and traditional sunflower oil employed. EDTA was a strong antioxidant, while propyl gallate and lactoferrin did not exert any antioxidative effect in the SL mayonnaise.     

Textural,rheological and sensorial properties of mayonnaise fortified with Asian sea bass bio-calcium

Asian sea bass bio-calcium (ASBC) can be fortified in low calcium food product such as mayonnaise. To ensure the smoothness of fortified products, the particle size and fishy compounds of ASBC must be reduced. Ultrasonicated ASBC (U-ASBC) was applied for different times (5–15 min) in the presence of hexane. ASBC and U-ASBC had mean particle size (D₄₃) of 21.87 ± 19.54 and 7.83 ± 7.10 μm, respectively. U-ASBC had lowered volatile compounds. Mayonnaise fortified with ASBC had the augmented firmness, consistency and cohesiveness with increasing ASBC levels (0%–10%) (p < 0.05). ASBC raised lightness (L*) and total color difference (ΔE*), but decreased a* and b*-values of mayonnaise in a dose dependent manner (p < 0.05). Higher G′, G″, viscosity and shear stress value were observed in mayonnaise sample added with ASBC. However, lower acceptability was attained when mayonnaise was added with ASBC at level higher than 2.5% due to fishy odor and grittiness perceived by panelists. The lower droplet size with higher zeta potential of mayonnaise added with ASBC or U-ASBC was related with the lower creaming index. Mayonnaise added with 7.5% U-ASBC (M-UBC-7.5) had higher viscosity with lower creaming and thermal creaming index (p < 0.05) than control and that containing 2.5% ASBC (M-BC-2.5). Denser and smaller droplet sizes were observed for M-BC-2.5 and M-UBC-7.5 than control. Lowest moisture, fat and carbohydrate contents were attained for M-UBC-7.5 with the higher protein, ash and calcium content (p < 0.05). Fortification of mayonnaise with ASBC at 2.5% or U-ASBC at 7.5% increased calcium content by 54 or 174 times, respectively, without sensorial changes.     

英国肥料管理、科研与技术推广带来的启示

通过2007年底对英国肥料管理与科研推广情况的考察,分析了英国肥料生产和施用、肥料政策和管理、肥料科研与技术推广的现状,并结合我国实际情况,对我国肥料业的发展提出了建议,为进一步提高我国肥料管理水平,进行更有效的肥料技术推广提供了依据。