Identification of small molecule flavor compounds that contribute to the somatosensory attributes of bovine milk products.

Compounds that contribute to the somatosensory flavor profile of bovine fluid milk products were investigated. Sensory descriptive analysis defined five main attributes that consisted of "mouthcoating, astringent/drying, fatty texture, dairy mouthfeel, and tingling/irritation" sensations. Utilizing multi-dimensional LC sensory guided fractionation, compounds with these attributes were selected, purified and subsequently identified by LC/MS as orotic acid, pantothenic acid, hippuric acid, and p-cresol sulfate. Quantitative analysis of the four compounds across skim milk, low fat milk and whole milk indicated the concentrations were not significantly different; however, they were significantly lower in cream. Sensory recombination milk model analysis of each compound at endogenous concentrations of fluid milk indicated all compounds were sensory active. Furthermore, using a 2-AFC sensory test, skim milk spiked at two-fold higher concentrations of the 4 compounds had a significantly "creamier, fuller body" when compared with skim milk itself (α = 0.01).

Identification of objectionable flavors in purported spontaneous oxidized flavor bovine milk.

Spontaneous oxidized flavor (SOF) has been reported over the past 5 decades as a sporadic objectionable flavor problem in bovine milk. Parameters previously reported to influence SOF development in milk have been contradictory, limiting the ability to monitor and develop mitigation strategies. The current paper investigates the causative compounds associated with milk identified as SOF milk in the Midwest dairy region of the United States. Based on GC/MS-olfactometry analysis, endo-borneol, 2-methylisoborneol, and α-terpineol were identified as the off-flavor compounds. Sensory recombination studies further confirmed the sensory contribution of these compounds to the noted off-flavor attributes in the original milk, which were described as "green," "musty," and "unclean." These compounds are known microbial-derived flavor taints, indicating oxidation was not the origin of the objectionable flavor in the milk. This noted misclassification of the milk as SOF indicates the challenge of defining flavor defects without the identification of the active compounds.

Vertical ground motion and its effects on liquefaction resistance of fully saturated sand deposits.

Soil liquefaction has been extensively investigated over the years with the aim to understand its fundamental mechanism and successfully remediate it. Despite the multi-directional nature of earthquakes, the vertical seismic component is largely neglected, as it is traditionally considered to be of much lower amplitude than the components in the horizontal plane. The 2010-2011 Canterbury earthquake sequence in New Zealand is a prime example that vertical accelerations can be of significant magnitude, with peak amplitudes well exceeding their horizontal counterparts. As research on this topic is very limited, there is an emerging need for a more thorough investigation of the vertical motion and its effect on soil liquefaction. As such, throughout this study, uni- and bidirectional finite-element analyses are carried out focusing on the influence of the input vertical motion on sand liquefaction. The effects of the frequency content of the input motion, of the depth of the deposit and of the hydraulic regime, using variable permeability, are investigated and exhaustively discussed. The results indicate that the usual assumption of linear elastic response when compressional waves propagate in a fully saturated sand deposit does not always hold true. Most importantly post-liquefaction settlements appear to be increased when the vertical component is included in the analysis.