Reduced-fat Food Emulsions Stabilized By Self-Assembled Wheat Braen Nanofibrils

Intaking excessive fat may cause varieties of diseases, which is harmful to health. In recent years, reduced-fat foods are becoming more and more popular, when people pay great attention to health. In this paper, abundant wheat bran resource was selected as the source of nanofibrils; wheat bran cellulose was extracted by alkali cooking, bleaching,dialyzing, and then homogenization treatment. Fat was partially replaced by wheat bran nanofibrils at levels of 12.5%, 25%, 37.5% and 50%, which were named as RF-12.5, RF-25,RF-37.5, RF-50, respectively, using full fat mayonnaise without fat analogue as control,which was named as FF. Xanthan gum was applied to enhance the viscosity of reduced-fat samples.Particle size, brightness, chroma, wettability and microstructure characterization were performed on wheat bran nanofibrils. The results indicated that the particle size of the fat replacer was 1740nm, meeting the mouthfeel requirement as food additives. The brightness and lightness were improved, contributing to the color of the samples. Three-dimensional network structure was viewed by SEM photos; the network was compacted and strengthened by combining with xanthan gum.Reduced-fat mayonnaise samples were prepared by using wheat bran cellulose and xanthan gum as fat analogue. The physiochemical properties, texture, microstructure, color and rheological characterizations of these samples were carried out. The pH values of RF-series of reduced-fat mayonnaise samples increased slightly with storage time, while the pH value of FF mayonnaise sample began to decline after 7 days; however, the pHs of all of the reduced-fat samples maintained below the critical pH of 4.1, favoring to inhibiting the growth of microorganism. The samples of reduced-fat mayonnaise had lower caloric values and higher moisture contents at higher substitution level. The total color difference ?E of RF-37.5 against test time was the lowest, implying a satisfying physical and chemical stability. The texture parameters of the reduced samples were lower than the control; the sample of RF-37.5 showed the closest texture parameters to the FF sample among the four reduced-fat samples. The rheological analysis showed that all of reduced-fat samples behaved shear thinning, like FF counterpart. Within the range of tested shear rate, all of the reduced-fat samples exhibited lower shear viscosity than the FF control. The shear viscosities of RF-12.5 and FF were similar, and the rest samples showed little difference.Dynamic frequency sweep results showed that the viscoelasticity of RF-series of mayonnaise samples was higher than that of the FF control. The steady-state flow curves indicated that the reduced-fat samples exhibited thixotropy as the FF mayonnaise. The thixotropy of RF-37.5 mayonnaise samples was the closest to FF, and it showed the best rheological stability. All of the reduced-fat samples possessed better rheological stability.Apart from RF-50 mayonnaise samples,the reduced-fat mayonnaise samples had more superior centrifugal and thermal stability. Considering the droplet diameter variance with time, all of the reduced-fat samples changed less than FF sample; the RF-37.5 sample changed the least.In summary,RF-series of low fat mayonnaise were prepared by substituting fat with wheat bran nanofibrils and xanthan gum. The RF-37.5 sample was stored at 4? with slight droplet diameter change; it didn't undergo creaming after 4 months' storage. Therefore,it is an ideal reduced-fat mayonnaise. Derived from biomass resource, safe and nontoxic wheat bran nanofibril is a kind of promising fat analogue for high-fat foods. A novel approach to utilize agricultural waste wheat bran is suggested in this paper.