Modelling the transport of lactic acid, sodium chloride and reducing sugars in carrot slices submerged in brines - Part II. Multivariate approach

In this paper following a methodology of (nested) increasing model complexity, it was found that the apparent diffusivities and the partition coefficients associated with the transport of lactic acid and sodium chloride from the brine into carrot slices submerged therein can be modelled as functions of temperature using Arrhenius-type relationships and as exponential functions of the initial concentrations of either solute in the brine. The apparent diffusivities in the free liquid phase, in the case of transport of reducing sugars from the carrots to the brine, are assumed to vary with time as a consequence of the bursting of the carrot cells following first-order kinetics on both the concentration of intact cells and dead cells. In this case, and following a similar methodology, the apparent diffusivity in the free liquid phase, the pseudo-firstorder rate constant for cell bursting, and the partition coefficients are well modelled when they are all assumed to follow temperature dependencies given by Arrhenius-type relationships; the dependencies on the initial concentration of salt in the brine were found not to be statistically significant. The underlying assumptions of normal distribution and constant variance were checked using plots of residuals, whereas the decision on the acceptable complexity of the nested models was taken based on the values of the F-distribution. The analysis developed is relevant for practical purposes because the multivariate models obtained in the form of correlations are simple functions of easily measured operating variables

Modelling the transport of lactic acid, sodium chloride and reducing sugars in carrot slices submerged in brines - Part I. Univariate approach

The transport phenomena pertaining to the independent diffusion of lactic acid and sodium chloride from a brine into carrot slices submerged therein, and of reducing sugars in the opposite direction, were experimentally studied at various temperatures and initial concentrations of salt and acid in the brine. The data sets obtained at each combination of temperature and initial concentration of the brine were independently fit to three analytical models derived from just principles on three alternative mechanisms postulated for the time-variation of the diffusivity. Incremental sum of squares analyses have shown that the diffusion of acid and salt into the carrots is well described by a constant diffusivity, whereas the diffusion of reducing sugars out of the carrots is well described by a diffusivity undergoing a sigmoidal variation with time. This sigmoidal variation may be explained by the assumption that the bursting of the carrot cells is simultaneously proportional to the fraction of intact cells and the fraction of burst cells of the carrot material. The analysis developed is relevant because it allows an approximate prediction of the rates of acid and salt intake, as well as the release rates of reducing sugars, pertaining to bried carrot slices, the basic processes that occur during manufacture of lactic acid carrot pickles

Optimizing a lactic fermentation of sliced carrots

Response surface methods were utilized in the statistical optimization of several quality factors pertaining to the preservation of carrot slices using a brine containing lactic acid produced by in situ fermentation. These factors were the concentrations of salt, acid, and reducing sugars, and the texture of the carrot material, and the pH, concentrations of acid, reducing sugars, and biomass (at two different times) of the brine. the processing variables considered were the temperature, the salt concentration of the brine, and the ratio of volumes of brine to the carrot material. the starting (corner and center) factorial design has indicated that, within the experimental range of practical interest, a linear model failed to provide a good fit to the experimental data; hence, this design was complemented with an axial design. Checks of the residuals and estimates of third-order parameters have indicated that no apparent reason existed to question the statistical adequacy of the quadratic empiric model. the loci of the optima (and the characterization of such optima) were then obtained for this model, and the general directions for the variation of the values of the processing parameters were presented. This study has indicated that temperature may be manipulated to give rise to any desired increase or decrease of the quality factor chosen, a conclusion that may be relevant in attempts to industrially improve carrot preservation processes based on lactic acid fermentation

Firmness of carrot slices submerged in brines: experimental data and mathematical model

The firmness of carrot slices was measured at various temperatures for several concentrations of brines in sodium chloride and lactic acid. A model assuming that textural decay is due to irreversible, pseudo first-order enzyme-catalyzed degradation of the carrot cell wall polysaccharides in the presence of two alternative paths for first order enzyme deactivation was fitted to the aforementioned data sets. The physicochemical and statistical significance of the model and fits were evaluated and discussed. The model is useful for predictions of the textural decay based on reasonable physicochemical considerations in a wide range of brine specifications with practical interest

De novo CLTC variants are associated with a variable phenotype from mild to severe intellectual disability, microcephaly, hypoplasia of the corpus callosum, and epilepsy

Purpose To delineate the genotype-phenotype correlation in individuals with likely pathogenic variants in the CLTC gene. Methods We describe 13 individuals with de novo CLTC variants. Causality of variants was determined by using the tolerance landscape of CLTC and computer-assisted molecular modeling where applicable. Phenotypic abnormalities observed in the individuals identified with missense and in-frame variants were compared with those with nonsense or frameshift variants in CLTC. Results All de novo variants were judged to be causal. Combining our data with that of 14 previously reported affected individuals (n = 27), all had intellectual disability (ID), ranging from mild to moderate/severe, with or without additional neurologic, behavioral, craniofacial, ophthalmologic, and gastrointestinal features. Microcephaly, hypoplasia of the corpus callosum, and epilepsy were more frequently observed in individuals with missense and in-frame variants than in those with nonsense and frameshift variants. However, this difference was not significant. Conclusions The wide phenotypic variability associated with likely pathogenic CLTC variants seems to be associated with allelic heterogeneity. The detailed clinical characterization of a larger cohort of individuals with pathogenic CLTC variants is warranted to support the hypothesis that missense and in-frame variants exert a dominant-negative effect, whereas the nonsense and frameshift variants would result in haploinsufficiency.6 month embargo; published online: 28 November 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]