The effect of sodium chloride content and temperature on pork meat isotherms

The knowledge of sorption isotherms is essential for understanding the drying process. Throughout the dry cured meat process, changes occur in the NaCl content and temperature on the surface of meat products. The aim of this study was to obtain the desorption isotherms from raw and salted meat at different air temperatures and NaCl content. The desorption characteristics were studied in the relative humidity range of 11.2 to 94.5 % at storage temperatures of 5, 13 and 26°C and at 0, 8, 20 and 30% (dm) of added salt (NaCl). The salted meat samples isotherms at 26°C shows a breaking point between water activities (a(w)) of 0.70 and 0.75. At a(w) lower than 0.70, NaCl content and temperature have only a slight effect on water content equilibrium. At a(w) above 0.75, water content equilibrium increased with the increase in NaCl content and the decrease in temperature. A significant NaCl*Temp interaction was detected at a(W) 0.903 and 0.946.     

Effect of sodium chloride replacement on some characteristics of fermented sausages

The reduction of added NaCl in fermented meat products has been proposed to decrease the amount of sodium in the diet. The effect of substituting NaCl by KCl, potassium lactate (K-lactate) or glycine (0-40%) in some sensory, microbiological and physicochemical characteristics of fermented sausages was evaluated. The sensory effects of substituting NaCl by mixtures of glycine and KCl or glycine and K-lactate was also evaluated. The partial substitution of NaCl by KCl, K-lactate and glycine had little effect on microbiological stability. However, flavour and/or textural defects were detected by sensory analysis with substitution levels of 40% by KCl, 30% with K-lactate and 20% with glycine. The partial substitution (above 40%) of NaCl with different mixtures of KCl/glycine and K-lactate/glycine showed important flavour and textural defects which did not permit an increase in the level of substitution compared to those obtained with the individual components.     

Kernel lot distribution assessment (KeLDA): a study on the distribution of GMO in large soybean shipments

The reliability of analytical testing is strongly affected by sampling uncertainty. Sampling is always a source of error and the aim of “good” sampling practice is to minimize this error. Generally the distribution of genetically modified (GM) material within lots is assumed to be random in order to use binomial distribution to make inferences. This assumption was never verified in practice and no experimental data investigating the distribution of genetically modified organisms (GMOs) exist. The objectives of the KeLDA project were: (1) to assess the distribution of GM material in soybean lots (2) to estimate the amount of variability of distribution patterns among lots. The GM content of 15 soybean lots imported into the EU was estimated (using real-time PCR methodology) analyzing 100 increment samples systematically sampled from each lot at predetermined time intervals during the whole period of off-loading. The distribution of GM material was inferred by the one-dimensional (temporal) distribution of contaminated increments. All the lots display significant spatial structuring, indicating that randomness cannot be assumed a priori. The evidence that the distribution of GM material is heterogeneous highlights the need to develop sampling protocols based on statistical models free of distribution requirements.     

Revisiting the correlation between proteins' thermoresistance and organisms' thermophilicity

The possibility to rationally design protein mutants that remain structured and active at high temperatures strongly depends on a better understanding of the mechanisms of protein thermostability. Studies devoted to this issue often rely on the living temperature (T(env)) of the host organism rather than on the melting temperature (T(m)) of the analyzed protein. To investigate the scale of this approximation, we probed the relationship between T(m) and T(env) on a dataset of 127 proteins, and found a much weaker correlation than previously expected: the correlation coefficient is equal to 0.59 and the regression line is T(m) approximately 42.9 degrees C + 0.62T(env). To illustrate the effect of using T(env) rather than T(m) to analyze protein thermoresistance, we derive statistical distance potentials, describing Glu-Arg and Asp-Arg salt bridges, from protein structure sets with high or low T(m) or T(env). The results show that the more favorable nature of salt bridges, relative to other interactions, at high temperatures is more clear-cut when defining thermoresistance in terms of T(m). The T(env)-based sets nevertheless remain informative.     

Moisture diffusivity in the lean tissue of dry-cured ham at different process times

The aim of this study was to determine the effective moisture diffusivity coefficient (D(e)) during dry-cured ham processing in two muscles, an internal one (Biceps femoris, BF) and an external one (Semimembranosus, SM), at different temperatures. Two adjacent samples, which included both SM and BF muscles, were selected after salting (PS), after resting (PR), after 4 months of drying (D1) and at the end of the process (D2). One was used to determine the initial profiles of moisture and NaCl/moisture and the other to determine D(e) at different temperatures (1 and 5°C in PS; 5 and 12°C in PR; 12, 19 and 26°C in D1; 19 and 33°C in D2). D(e) was higher in the muscle with the higher moisture content (BF) except in PS and PR, where a gradient of NaCl/moisture ratio was observed in SM muscle. There was a positive effect of temperature on D(e), but it decreased during processing of the dry-cured ham. A simple diffusive model, with a unique and constant moisture diffusivity coefficient or with a coefficient depending only on temperature, does not explain the whole drying process correctly. The effects of moisture content and the gradient of NaCl/moisture ratio on D(e) have to be considered.     

The effect of high pressure and residual oxygen on the color stability of minced cured restructured ham at different levels of drying,pH, and NaCl

Color stability of minced cured restructured ham was studied by considering the effects of high pressure (HP) (600 MPa, 13 °C, 5 min), raw meat pH₂₄ (low, normal, high), salt content (15, 30 g/kg), drying (20%, 50% weight loss), and residual oxygen level (0.02%–0.30%). Raw hams were selected by pH₂₄ in Semimembranosus, mixed with additives, frozen, sliced, and dried by the Quick-Dry-Slice® (QDS) process followed by HP treatment or not (control). Packaging and storage simulated industrial packaging: modified atmosphere containing 80% N₂, 20% CO₂, and residual O₂ in one of three intervals: < 0.1%, 0.1%–0.2%, or 0.2%–0.3%, and retail storage conditions: chill storage, 12 h light, 12 h darkness. HP improved the stability of the redness of 20% QDS hams, while the stabilizing effect on 50% QDS hams was smaller, concluding that water has the dominating role. Raw meat pH₂₄, salt content, and residual oxygen level had varying effects on the stability of the red color.     

NIR technology for on-line determination of superficial a(w) and moisture content during the drying process of fermented sausages

Three different NIR equipment were evaluated based on their ability to predict superficial water activity (a(w)) and moisture content in two types of fermented sausages (with and without moulds on surface), using partial least squares (PLS) regression models. The instruments differed mainly in wavelength range, resolution and measurement configuration. The most accurate equipment was used in a new experiment to achieve robust models in sausages with different salt contents and submitted to different drying conditions. The models developed showed determination coefficients (R(2)(P)) values of 0.990, 0.910 and 0.984, and RMSEP values of 1.560%, 0.220% and 0.007% for moisture, salt and a(w) respectively. It was demonstrated that NIR spectroscopy could be a suitable non-destructive method for on-line monitoring and control of the drying process in fermented sausages.     

Diversity of the heterotrophic microbial populations for distinguishing natural mineral waters

In the recent years the consumption of natural mineral waters has risen all over the world, becoming a usual alternative for tap water and other beverages. Natural mineral waters are complex environments containing a high diversity of autochthonous microbiota. The identification and characterization of this indigenous microbiota may help to detect changes occurring in the different steps of the bottling process and take preventive measures before the bottled water arrives to the consumer. The aims of this study were to describe the bacterial heterotrophic populations in natural mineral waters with a cultivation-dependent method and determine whether their autochthonous microbiota were specific enough to be clearly distinguished from that of other natural mineral waters with a phenotypic-based method. For this purpose, water from three independent Spanish springs was sampled in two seasons (winter and summer) and heterotrophic aerobic bacterial strains were isolated at two temperatures (22 ± 2°C and 36 ± 2°C) on R2A agar. Isolates were phenotyped biochemically with Php-48 plates (Bactus AB, Sweden), and the indexes of diversity and similarity between populations were calculated. The 16S rRNA gene of the most representative strains of each biochemical cluster was sequenced for its identification. Finally, a ten-fold cross-validation method was assayed for the identification of the origin of a natural mineral water when phenotyping a set of isolates. High levels of diversity were found at all sites. One of the sources was found to present less diversity due to a confirmed contamination with Pseudomonas aeruginosa. The study of the similarities showed that growing temperatures and seasons caused significant differences in structures and composition at the sources. In addition, several bacterial species were isolated and identified, some of them rarely isolated in natural mineral waters, revealing the complexity and lack of knowledge of these ecosystems. Consequently, the applied phenotypic methodology was found to be feasible for differential identification of microbiota in these environments. Moreover, the experimental model assayed was strong enough to identify the origin of a natural mineral water. It may thus be possible to confirm that the evaluation of diversity of heterotrophic aerobic bacterial populations could be applied to identify bottled water sources.     

Fuzzy Control System in Drying Process of Fermented Sausages

Abstract

Fermented sausages are dried in artificial driers, where the air relative humidity (RH) and temperature (T) are controlled. On the basis of product evaluation, an expert manually readjusts the RH set points in a staggered form. The main drawbacks of this control system are the discontinuity of the product evaluation and the cost of the experts' training. This study proposes a system to readjust the set points of RH based on the theory of fuzzy sets. Two fuzzy control systems were applied to the drying process of fermented sausages in an industrial drier at constant temperature. They used different on-line instrumental measurements related to the expert evaluation as input variables. Results show that fuzzy control can improve the manual control system and it helps quality assurance during the drying process. It reduces the risk of crust development, one of the most serious problems in fermented sausages.     

Nutritional and sensory qualities of raw meat and cooked brine‐injected turkey breast as affected by dietary enrichment with docosahexaenoic acid (DHA) and vitamin E

BACKGROUND: This aim of this study was to evaluate the effects of feeding turkeys with docosahexaenoic acid (DHA) and vitamin E on the fatty acid profile, proteolytic enzyme activities and oxidative status of raw breast meat and cooked brine‐injected breast meat. Four treatments were investigated: T1, basal diet (control); T2, basal diet plus 15 g kg^?1 DHA; T3, basal diet plus 100 mg kg^?1 vitamin E; T4, basal diet plus 5.4 g kg^?1 DHA plus 100 mg kg^?1 vitamin E. A sensory analysis of cooked brine‐injected breasts was conducted in order to assess the sensory characteristics of these products and relate them to the expected nutritional benefits. RESULTS: Among the four treatments tested, no differences were observed in enzyme activities. No activities of cathepsin B, cathepsins B + L and catalase were detected in cooked brine‐injected breast meat. Glutathione peroxidase activity was reduced and superoxide dismutase activity was similar to that measured in raw meat. The diets supplemented with DHA increased eicosapentaenoic acid and DHA levels in comparison with the control in both raw and cooked products. The increase in n‐3 polyunsaturated fatty acids (PUFAs) led to a reduction in n‐6/n‐3 PUFA ratio to values between 1.01 ± 0.11 and 2.94 ± 0.47. In cooked brine‐injected breast, treatment with 15 g kg^?1 DHA (T2) induced a considerable fishy flavour, while treatment with 5.4 g kg^?1 DHA plus 100 mg kg^?1 vitamin E (T4) induced a slight fishy flavour. However, fishy odour in T4 did not differ significantly from that of the control. CONCLUSION: By feeding turkeys with 5.4 g kg^?1 pure DHA plus 100 mg kg^?1 vitamin E, the nutritional quality is improved through the introduction of a natural antioxidant and the reduction in n‐6/n‐3 PUFA ratio. With this treatment the sensory characteristics were similar to those of control samples, except for the fishy flavour, which could probably be masked by modifying the technological process. Copyright © 2008 Society of Chemical Industry