Transport properties of aqueous solutions of sodium alginate at 298.15 K

Mutual diffusion coefficients (interdiffusion coefficients) of sodium alginate in aqueous dilute solutions, at concentrations from 0.001 to 0.500 g mL⁻¹ and at 298.15 K, alone and in combination with caffeine, using an open-ended conductimetric capillary cell, have been measured. These results are discussed in the light of structural analysis conducted by means of theoretical calculations (molecular mechanics).     

Diffusion of calcium gluconate in aqueous solutions of lactose at 298.15 K

Binary mutual diffusion coefficients (interdiffusion coefficients) of calcium gluconate (C₁₂H₂₂CaO₁₄) in water at 298.15 K and at concentrations between 0.001 and 0.0500 mol dm⁻³ have been measured, using a Taylor dispersion method. These data are discussed on the basis of the Onsager-Fuoss model. Based on these data, the equivalent conductance at infinitesimal concentration of the gluconate ion in the studied solutions has been estimated. Through the same technique, ternary mutual diffusion coefficients (D₁₁, D₂₂, D₁₂ and D₂₁) for aqueous solutions containing calcium gluconate and lactose, at T = 298.15 K, and at different carrier concentrations, were also measured. These data permit us to have a better understanding of the structure of these systems and the thermodynamic behaviour of calcium gluconate in different media.     

Interaction between calcium chloride and some carbohydrates as seen by mutual diffusion at 25 °C and 37 °C

Ternary mutual diffusion coefficients measured by Taylor dispersion method (D₁₁, D₂₂, D₁₂ and D₂₁) are reported for aqueous solutions of calcium chloride (CaCl₂) and some carbohydrates (glucose, fructose and sucrose) at 25 °C and 37 °C at carrier concentrations from 0.000 to 0.100 M, for each solute, respectively.     

Interaction between copper chloride and caffeine as seen by diffusion at 25 °C and 37 °C

A Taylor dispersion method is used to measure ternary mutual diffusion coefficients (D₁₁, D₂₂, D₁₂ and D₂₁) for aqueous solutions of CuCl₂ (1) + caffeine (2) + H₂O-(3) at 25 °C and 37 °C at carrier concentrations from (0.000 to 0.020 mol dm⁻³), for each solute, respectively. The results are compared with these obtained for the binary systems, that is, CuCl₂ (1) + H₂O (2) and caffeine (1) + H₂O (2), also reported here. From these data it is possible to make conclusions about the influence of the caffeine solutes in diffusion of copper chloride.     

Prediction of the diffusion coefficients in multicomponent liquid refrigerant solutions

Immersion chilling and freezing (ICF) consist of soaking foods in a low freezing point liquid medium maintained at a low temperature that are considered secondary refrigerants. Data related to transport properties for the refrigerating media used in ICF processes are scarce, particularly for ternary and higher order systems. The objective of this work was to develop a model for the prediction of diffusion coefficients for systems of interest for ICF processes. The generalized Maxwell-Stefan equations were used in the model development. Data obtained from literature corresponding to Fick diffusion coefficients of the binary systems NaCl-H₂O and KCl-H₂O, and the ternary system NaCl-KCl-H₂O, were compared with predicted values. Results were satisfactory, errors of the main diffusion coefficients less than 13.5% being obtained. These results may be extended to the typical range of conditions of ICF, where no data are available in literature to date.     

A kinetic study of salt diffusion in potato at high temperature

The apparent diffusion coefficient of sodium chloride in potato was determined from the change in average concentration in cylindrical potato pieces with time when surrounded by salt solution of between 1 and 5% concentration. Measurements were made at temperatures in the range 50–120°C. The apparent diffusion coefficient of salt in potato is temperature dependent and follows the Arrhenius equation, with activation energies of 20–24 kJ mol^-1, decreasing with increasing concentration within the temperature range 70–120°C. The apparent diffusion coefficient increases with concentration. Below 60°C the Fickian diffusion equation did not predict the experimental results accurately because of changes in the dimensions and structure of the potato caused by osmosis.     

Effect of glucose on the stability of fresh mutton during storage at ambient temperature (25 ± 2 °C)

The feasibility of using d-glucose to extend the shelf life of fresh mutton at 25 ± 2 °C was investigated. Aqueous solutions of 5% d-glucose (w/v) containing 1000 ppm potassium sorbate, when applied on acidulant-treated mutton, are able to inhibit spoilage by delaying proteolytic activity, as seen by significantly lower (P < 0.01) levels of biogenic amines until 4 days of storage. Though there was no significant change in standard plate count during storage, as compared with a 1 day control, Enterobacteria were significantly (P < 0.01) inhibited. Cadaverine, the marker for threshold level of spoilage, was absent up to 4 days. Measurement of glucose retention revealed that 0.25% (0.25 g/100 g mutton) was still available at the end of 4 days, when no spoilage had set in, though there was a slight fermented odour. Thus, the investigation shows that, surface treatment with glucose helps to extend the shelf life of fresh mutton up to 3 days at 25 ± 2 °C.     

Shelf life of meat from lambs given essential oil-free rosemary extract containing carnosic acid plus carnosol at 200 or 400 mg kg

The use of dietary rosemary extract (DRE) at low doses is proposed as a nutritional strategy to improve meat preservation. Lamb diet was supplemented with 0, 200 or 400 mg DRE (containing carnosic acid and carnosol at 1:1 w:w) per kg feed during the fattening stage. Meat quality was evaluated in lamb fillets packed under protective atmosphere and kept in retail conditions for up to 14 days. The effects of diet and storage time were determined on different physical–chemical (L*a*b* color, pH, TBARS, protein oxidation and volatiles from lipid oxidation), microbial (total viable and psychrophilic bacteria, Enterobacteriaceae, molds and yeasts) and sensory (appearance and odor) characteristics of the meat. The antioxidant and antimicrobial effects of DRE on meat were demonstrated. DRE delayed lean and fat discoloration, lipid oxidation, odor deterioration and microbial spoilage, extending the shelf life time of fillets from around 9 to 13 days. Both DRE doses provided similar shelf life extension.     

Green tea – A potential preservative for extending the shelf life of fresh mutton at ambient temperature (25 ± 2 °C)

This investigation was taken up to evaluate the feasibility of using green tea (GT) to extend the shelf life of fresh mutton, at ambient storage conditions (25 ± 2 °C and 85 ± 5% RH). The ethanolic extract of GT (GTE) was found to significantly inhibit (P < 0.01) spoilage microflora, including certain pathogens of acidulant treated mutton (pH 3.8) for up to 4 days. Application of GTE did not cause any deleterious change in sensorial and physical quality and the mutton was acceptable for up to 4 days. While the control samples showed initial signs of spoilage between 20 and 24 h and registered an increase in free fatty acids (FFA) from 1.24 g to 4.1 g/100 g lipid and biogenic amine index (BAI) from 0.27 mg to 4.63 mg/100 g mutton, at the end of two days of storage, the GTE treated sample showed FFA levels of 1.5 g/100 g lipid and BAI of 0.25 mg/100 g mutton at the end of the 4 days. GTE treatment could be effectively used to extend the shelf life of fresh mutton for up to 4 days in Indian climatic conditions, since it significantly (P < 0.01) inhibits the formation of these lipolytic and proteolytic degradation products, which are responsible for sensorial spoilage.     

Assessment of beef production from Brahman × Thai native and Charolais × Thai native crossbred bulls slaughtered at different weights. II: Meat quality

The objective was to assess meat quality of Brahman × Thai native (BRA) and Charolais × Thai native (CHA) crossbred bulls. In total 34 BRA and 34 CHA under practical farm conditions were randomly assigned for slaughter at 500, 550 and 600 kg live weight, respectively. Longissimus dorsi muscle was taken for meat quality and sensory evaluations. CHA meat had higher intramuscular fat, exhibited higher marbling scores and relatively better colour than BRA meat. Although muscle fiber area was similar for both genotypes, shear force values were higher for CHA meat. Water holding capacity was better for CHA meat shown by lower 7-day ageing, thawing and grilling losses. However, the sensory evaluation ratings were similar for both genotypes. Increasing slaughter weight from 500 kg up to 600 kg had no significant effect on meat quality. In conclusion, meat quality of CHA was superior to BRA.     

Thermal expansion coefficient and specific heat capacity from sound velocity measurements in tomato paste from 0.1 up to 350 MPa and as a function of temperature

The thermodynamic properties of food as a function of pressure and temperature are essential for modeling high-pressure processes. Sound velocity measurements in liquids at high pressure conditions are particularly interesting because they allow for deriving other properties such as the specific heat capacity or thermal expansion coefficient which are difficult to measure. By other means, in this work, the sound velocity was measured in tomato paste at high pressures with a purposed designed acoustic cell. The measurements were made in a wide range of pressures and temperatures from 0.1 to 350 MPa and from 0 to 50 °C, respectively. The sound velocity was directly measured with an accuracy of 0.1% using the transmission technique with piezoelectrics operating at 2 MHz. Thereafter, the isentropic compressibility coefficient of tomato paste was calculated from experimental data. Specific heat capacity and thermal expansion coefficient were also obtained through a software algorithm.     

Assessment of beef production from Brahman × Thai native and Charolais × Thai native crossbred bulls slaughtered at different weights. I: Growth performance and carcass quality

Effects of genotype and slaughter weight on growth performance and carcass quality of Brahman × Thai native (BRA) and Charolais × Thai native (CHA) crossbred bulls were studied. Thirty-four BRA and 34 CHA bulls raised under practical fattening beef farm conditions were randomly selected and slaughtered at 500, 550 and 600 kg live weight, respectively. Parameters of growth performance, carcass quality and commercial prime cuts were determined. Results showed that growth performance and carcass quality of CHA was better, since they showed higher weight gain, better body muscle score, higher carcass weight high dressing percentage, higher carcass muscle, less carcass fat and bone plus connective tissue proportions, better carcass classifications, greater loin eye area and higher commercial prime cut percentage. Slaughter weights up to 600 kg resulted in increased carcass weight, loin eye area and percentage of commercial prime cuts and can therefore be recommended.     

Rehydration kinetics at 5 and 15 °C of dry salted meat

The surface of meat products during intermittent drying is successively subjected to dehydration and rehydration processes. The aim of this paper was to study the rehydration kinetics at two temperatures (5 and 15 °C) of salted ground pork, (2% or 4% NaCl) dried to different water contents, (10%, 20% and 35%) using Peleg and Weibull’s models. Surface structure of dried samples was analyzed with electron microscopy and related to rehydration kinetics. The equilibrium water content decreased with temperature and increased with NaCl, but was not affected by the initial water content. The rehydration rate at the beginning decreased with water content and was significantly higher at 5 °C than at 15 °C, but it was not significantly affected by NaCl content. However, the equilibrium water decreased with temperature and tended to increase with NaCl content, but was not affected by the initial water content. High level of dehydration resulted in a more damaged and porous meat matrix. This microstructure may contribute to accelerating the rehydration process.     

Effect of micronisation temperature (130 and 170 °C) on functional properties of cowpea flour

Functional properties of cowpea flour from seeds micronised at two different surface temperatures (130 and 170 °C) were studied. Micronisation (130 and 170 °C) significantly (P ? 0.05) increased the water absorption capacity and least gelation concentration of the flour. The treatment significantly (P ? 0.05) reduced the water solubility and swelling indices, gel strength and foaming capacity of the flour. The changes in cowpea flour functional properties, such as the loss of foaming capacity in flours from micronised (130 and 170 °C) seeds, were associated with significant (P ? 0.05) increase in the surface hydrophobicity and cross-linking of the cowpea protein. SDS–PAGE of the protein-rich fractions revealed changes in the protein subunit profile which included the formation of disulphide bonds and possibly Maillard cross-links. The flour from M-170 °C seeds was significantly (P ? 0.05) darker than was the flour from unmicronised and M-130 °C seeds.     

Moisture sorption isotherms of sorghum malt at 40 and 50 °C

The desorption and adsorption equilibrium moisture isotherms of sorghum malt at the temperatures of 40 and 50 °C, over the water activity range of 0.1-0.9, were determined using the static gravimetric method. A non-linear regression programme was used to fit five moisture sorption isotherm models [Modified Henderson, Modified Chung-Pfost, Modified Guggenheim-Anderson-de Boer (GAB), Modified Halsey and Modified Oswin] to the experimental data. The models were compared using the standard error of estimate, mean relative percentage deviation, fraction explained variation and residual plots.The Modified Chung-Pfost model was found to be the best for predicting the desorption equilibrium moisture content, while the adsorption equilibrium moisture content was best predicted by the Modified Oswin model. The desorption and adsorption water activities were found to be best fitted by the Modified Oswin model.The moisture sorption isotherms were sigmoidal in shape and showed a marked effect of temperature. The span of the moisture sorption hysteresis loop formed, decreased with increase in temperature, while the size increased with increase in temperature.     

Crucial contribution of membrane lipids’ unsaturation to acquisition of chilling-tolerance in peach fruit stored at 0 °С

Peach fruits (Prunus persica L.) were less prone to chilling injury (CI) when stored at 0 °С than at 5 °С for 30 days. In order to make known the mechanism involved, the relationship between CI and membrane lipid unsaturation was investigated in this study. The results demonstrated that peach fruit stored at 0 °С manifested higher membrane lipid fluidity and higher membrane lipid unsaturation than at 5 °С. In addition, a higher omega-3 fatty acid desaturase gene (FAD) mRNA level and a higher level of linolenic acid (C18:3) were found when peach fruits were stored at 0 °С. The findings indicated that the higher membrane lipid unsaturation in peach fruit stored at 0 °С was beneficial in maintaining membrane lipid fluidity and enhancing tolerance of peach fruit to low temperature stress, and the C18:3 level could be regulated by omega-3 FAD.     

Chemical and biochemical changes of hybrid catfish fillet stored at 4 °C and its gel properties

Chemical and biochemical changes of aquacultured hybrid catfish fillet (Clarias macrocephalus × Clarias gariepinus) and its gel-forming ability as affected by age and sex of fish along with storage time were investigated. Fillets were stored at 4 °C for 0, 3, 6, 9, 12 and 15 days. There was no significant effect of sex and age of fish as well as storage time on fat, moisture and ash contents (P > 0.05). The total protein, water soluble protein, and salt soluble protein contents of the fillets significantly decreased with storage time (P < 0.05). On the other hand, pH, total volatile base nitrogen (TVB-N) and autolytic degradation products (ADP) increased as storage time continued (P < 0.05). Decreases in Ca²⁺-ATPase activity and gel properties were observed as storage time increased. However, there was no significant effect of either sex or age of fish on textural properties of gel (P > 0.05). Hybrid catfish fillet stored at 4 °C should be processed within 6 days.     

Characterization of aroma changes in human milk during storage at −19 °C

Breastfeeding is believed to impart major beneficial effects on babies, due to various human-specific components. Compatibility of family and profession, however, often necessitates the pumping of breast milk and its storage under diverse conditions, either in a refrigerator, freezer or for brief periods at room temperature. The present study investigates the formation of a characteristic fish-like and metallic off-odour during the conventional storage of human milk that does not develop during cow milk storage, and elucidates the molecular factors for these specific aroma changes. Odorants in fresh and stored human milk containing the specific fishy-metallic off-odour were characterized by means of gas chromatography–olfactometry and identified based on their mass spectrometric data and specific chromatographic and sensory characteristics.     

Extraction of ginger rhizome: kinetic studies with dichloromethane, ethanol, 2-propanol and an acetone—water mixture

The kinetics of extraction of [6]-gingerol from ground Jamaican ginger rhizome have been determined at 30°C in dichloromethane, ethanol, isopropanol and an 80% (v/v) acetone + 20% (v/v) water mixture. The extractions all proceeded in three stages: an initial 'washing' stage, a fast stage and a subsequent much slower stage. The rate of extraction of hexahydrocurcumin in ethanol was found to follow a simpler pattern. From the first order plots, the diffusion coefficients of the extracted solubles within the ginger particles were calculated. They varied inversely with the 0.6 power of the solvent viscosity, which explained why the rates of [6]-gingerol extraction decreased in the sequence: acetone < acetone + water < dichloromethane < ethanol < isopropanol. These results show that solvents of low viscosity should be chosen to attain fast extraction rates. The diffusion coefficient of [6]-gingerol was also measured at 30°C in pure acetone, ethanol and isopropanol. The values in these bulk solvents were 13–20 times greater than the diffusion coefficients of [6]-gingerol within the ginger particles for the fast stage and over 900–1800 times greater than those for the slow stage. These hindrance factors quantify the effect of the ginger matrix environment on internal diffusion.     

Effect of muscle and intensity of finishing diet on meat quality of foals slaughtered at 15 months

The effect of muscle and intensity of finishing diet on meat quality of foals slaughtered at 15 months was study. For this work, a total of twenty one foals and six muscles: longissimus dorsi (LD), semimembranosus (SM), semitendinosus (ST), biceps femoris (BF), triceps brachii (TB) and Psoas major & minor (PM) from two different intensities of finishing diet (1.5 vs. 3 kg/day) were analysed.