Flavor compounds in white bread have been analyzed by a static-headspace-type GC/MS and sensory evaluation for clarifying the effects of mixing stage and fermentation time on the intensity of flavor compounds as assessed in the crumb and sensory scores of flavor in white bread. Principal component analysis (PCA) and analysis of variance (ANOVA) were applied to the peak area of total ion chromatogram as well as sensory scores of 8 sensory descriptors for flavor intensity. Although the results of instrumental analyses showed the superiority of fermentation time over mixing energy as the governing factor of white bread flavor, the results of statistical analyses for the scores of sensory evaluation showed the superiority of mixing energy over fermentation time. The difference in the governing factor was probably due to overestimation for the effect of alcohols on the flavor quality of white bread, especially ethanol derived from the fermentation process.Keywords: flavor compounds, fermentation time, GC/MS, mixing stage, principal component analysis, sensory evaluation, static headspace method, white bread *To whom correspondence should be addressed. E-mail: maedatat@mail.ni-net.co.jp IntroductionThe bread-making process can be broadly classified into three sub-processes: mixing, fermentation, and baking. The mixing and fermentation processes play an important role in determining the qualities of white bread. Numerous studies have been carried out on the aroma and flavor of white bread-complex flavor compounds derived from raw materials and the fermentation and baking processes (Baltes et al

No abstract

Catalytic transformation of glycidol while maintaining its epoxide moiety intact is challenging because the terminal epoxide that interacts with the hydroxyl group via a hydrogen bond is labile for the ring-opening reaction. We found that a quaternary alkyl ammonium salt catalyzes the selective transformation of glycidol to glycidyl esters by transesterification of methyl esters. The developed method can be applied to the synthesis of multiglycidyl esters, which are valuable epoxy resin monomers. Mechanistic studies revealed the formation of a binding complex of glycidol and quaternary alkyl ammonium salt in a nonpolar solvent and the generation of the alkoxide anion as a catalyst through the ring-opening reaction of the epoxide. Computational studies of the reaction mechanism indicated that the alkoxide anion derived from glycidol tends to abstract the proton of another glycidol rather than work as a nucleophile, initiating the catalytic transesterification. Payne rearrangement of the deprotonated glycidol, which produces a destabilized base that promotes nonselective reactions, is energetically unfavorable due to the double hydrogen bond between the anion and diol. The minimal interaction between the quaternary alkyl ammonium cation and the epoxide moiety inhibited the random ring-opening pathway leading to polymerization.

Atomic structures on active oxidized silicon films by an ozone gas at room temperature are investigated by an atomic force microscopy. A step-terrace structure similar to that on a clean Si (001) prepared by a silicon homoepitaxy is preserved on the ozone oxidized surface. These atomically regulated structures are also discernible on the SiO2/Si interface when a 1.0-nm-thick SiO2 film oxidized by an atmospheric ozone is removed by a diluted HF etching. It is revealed that the homogeneous lateral oxide growth, i.e., layer-by-layer growth, proceeds at room temperature by an active oxidant such as ozone.

The objective of this work was to establish a three-dimensional measuring method for the size, morphology and distribution of internal structure such as ice crystals, bubbles and solids content within an ice cream sample by using a cryogenic microtome spectral imaging system (CMtSIS). The 3-D images of ice crystals, bubbles and milk solids were recognized by reconstructing the circles in 2-D images into 3-D spheres; and the Overrun by Volume (ORV) was obtained by incorporating the area of bubbles on integrated image and the volume of bubbles in the 3-D image. Keywords: Ice crystal, Bubble, Internal structure, Spectral imaging, Micro- to macro-scale, Freeze-Drying