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Synchrotron radiation circular dichroism (SRCD) and Fourier transform infrared (FTIR) spectroscopy were used to examine the conformation evolution of micellar casein (MC) powder during storage and to determine whether the spectral changes could be related to their solubility evolution.; Results: A loss in intensity of SRCD spectra as a function of storage time has been observed. Quantification of secondary structures revealed losses of α-helix content during storage. Moreover, a redshift of the amide I band in the FTIR spectrum was demonstrated during the storage and was interpreted as a rearrangement of the secondary structure of the protein, which is in line with the SRCD results. The qualitative results obtained by FTIR clearly support the quantitative evolution of the secondary structure obtained by the analysis of SRCD spectra. Principal component analysis (PCA) of FTIR spectra permits a good separation of samples according to the storage time. PCA shows that the evolution of secondary structures and solubility loss are closely linked.; Conclusion: With the quantitative data provided by SRCD spectra, it was established that, whatever the storage conditions, a unique curve exists between loss of α-helix content and loss in solubility, showing that loss of α-helix content is a marker of solubility loss for the MC powders studied. © 2017 Society of Chemical Industry.; © 2017 Society of Chemical Industry.

The effect of I199V polymorphism at the PRKAG3 gene on carcass and meat quality of commercial pigs was studied independently from PRKAG3 200Q or RYR1 “n” allele, known to decrease meat quality, i.e., animals were genotyped for RYR1 R615C, PRKAG3 I199V and R200Q substitutions, and only pigs without 200Q and “n” were retained for the analysis of carcass and meat quality traits (n = 274). Genotype frequencies were 12.0, 57.7 and 30.3% for I/I, I/V and V/V, respectively. The I199V polymorphism affected significantly fat thickness and drip loss and tended to affect ultimate pH. Interestingly, I/V were the fattest and significantly different from V/V, with I/I pigs being intermediate. The ultimate pH of I/I was higher than the one of I/V or V/V pigs. Regarding drip loss, significant difference was detected between I/I and V/V pigs. The heterozygous I/V pigs were intermediate with differences to I/I or V/V tending toward significance. PRACTICAL APPLICATIONS Our results provide new evidence about the significant effect of second polymorphism on the PRKAG3 gene (I199V) on carcass and meat quality. Because of low frequencies of I/I genotype in the majority of modern pig breeds, the available literature data for genotype I/I are scarce. Our results confirm a beneficial impact of 199I allele for pork quality, but indicate possible adverse impact for carcass leanness. It would be worthwhile rechecking the interesting position of heterozygous I/V pigs, which turned out to be the fattest. We expect the results to be useful for breeders in search of the compromise between carcass and meat quality.