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Freshness is an important index of egg quality. In this study, a synchronous fluorescence spectral technique was employed to determine the freshness of an intact egg. Synchronous fluorescence spectra of intact eggs were acquired using a fluorescence spectrometer supported by a laboratory fluorescence acquisition device and egg freshness (Haugh Unit) was obtained using destructive methods. Eggs feature fluorescence signals were mainly concentrated in two regions: A (excitation wavelength of 290 nm over the emission wavelength range of 320-380 nm) and B (excitation wavelength range of 380-570 nm over the emission wavelength range of 610-735 nm). The two regions were selected as regions of interest, which include 2581 Excitation-Emission (Ex-Em) wavelengths; stepwise discrimination analysis was performed on the 2581 Ex-Em wavelengths to choose optimal Ex-Em wavelength combinations. A Multiple Linear Regression (MLR) prediction model was built using fluorescence signals based on the optimal Ex-Em wavelength combinations. The results revealed that the freshness of an egg could be accurately predicted with Rp2 of 0.8879 and a root mean square error estimated by validation (SEP) of 6.2896. This work demonstrates that the synchronous fluorescence spectral technique has high potential for nondestructive sensing of egg freshness.

Freshness is an important index of egg quality. In this study, a synchronous fluorescence spectral technique was employed to determine the freshness of an intact egg. Synchronous fluorescence spectra of intact eggs were acquired using a fluorescence spectrometer supported by a laboratory fluorescence acquisition device and egg freshness (Haugh Unit) was obtained using destructive methods. Eggs feature fluorescence signals were mainly concentrated in two regions: A (excitation wavelength of 290 nm over the emission wavelength range of 320-380 nm) and B (excitation wavelength range of 380-570 nm over the emission wavelength range of 610-735 nm). The two regions were selected as regions of interest, which include 2581 Excitation-Emission (Ex-Em) wavelengths; stepwise discrimination analysis was performed on the 2581 Ex-Em wavelengths to choose optimal Ex-Em wavelength combinations. A Multiple Linear Regression (MLR) prediction model was built using fluorescence signals based on the optimal Ex-Em wavelength combinations. The results revealed that the freshness of an egg could be accurately predicted with Rp2 of 0.8879 and a root mean square error estimated by validation (SEP) of 6.2896. This work demonstrates that the synchronous fluorescence spectral technique has high potential for nondestructive sensing of egg freshness.

Background - Streptococcus suis is a zoonotic pathogen that infects pigs and can occasionally cause serious infections in humans. S. suis infections occur sporadically in human Europe and North America, but a recent major outbreak has been described in China with high levels of mortality. The mechanisms of S. suis pathogenesis in humans and pigs are poorly understood. Methodology/Principal Findings - The sequencing of whole genomes of S. suis isolates provides opportunities to investigate the genetic basis of infection. Here we describe whole genome sequences of three S. suis strains from the same lineage: one from European pigs, and two from human cases from China and Vietnam. Comparative genomic analysis was used to investigate the variability of these strains. S. suis is phylogenetically distinct from other Streptococcus species for which genome sequences are currently available. Accordingly, ~40% of the ~2 Mb genome is unique in comparison to other Streptococcus species. Finer genomic comparisons within the species showed a high level of sequence conservation; virtually all of the genome is common to the S. suis strains. The only exceptions are three ~90 kb regions, present in the two isolates from humans, composed of integrative conjugative elements and transposons. Carried in these regions are coding sequences associated with drug resistance. In addition, small-scale sequence variation has generated pseudogenes in putative virulence and colonization factors. Conclusions/Significance - The genomic inventories of genetically related S. suis strains, isolated from distinct hosts and diseases, exhibit high levels of conservation. However, the genomes provide evidence that horizontal gene transfer has contributed to the evolution of drug resistance.