Quality of Processed Cheddar Cheese as a Function of Emulsifying Salt Replaced by κ-Carrageenan

Hydrocolloids act as stabilizer and thickening agents, thus able to replace emulsifying salts. The present study was planned to use к-carrageenan in the production of processed cheddar cheese and to explore its effect on physico-chemical and textural properties of processed cheddar cheeses. Different concentration of ?-carrageenan were used with gradual decrease in salt contents along with natural cheese, fat, and water to prepare processed cheddar cheese. The prepared samples were analyzed for physico-chemical and sensory attributes at storage interval of 45 days during and after 90 days. With the increase in hydrocolloid concentration, stiffer product was obtained and meltability of the samples decreased than control. Processed cheddar cheese samples having 0.15% к-carrageenan with 2% emulsifying salt (1.34% sodium citrate and 0.66% disodium phosphates) were found more acceptable in terms of physico-chemical and sensory attributes, but all sensory attributes got fewer score with the passage of storage time.     

Influence of κ-carrageenan on the thermal gelation of salt-soluble meat proteins

Cooked ham-based model systems were prepared using salt-soluble meat protein isolate, κ-carrageenan and sodium and potassium chloride. The pH was set to 6.2 using a 50mM PIPES-buffer. An experimental mixture design was used to study the effect of carrageenan on the structure build-up of the gelled meat products. In situ gelation experiments were carried out on a controlled-stress rheometer, while a texture analyzer was used to determine the large deformation behaviour. The water holding capacity was measured by a centrifugal technique and confocal scanning laser microscopy was used to visualize the microstructure of the gelled meat products. κ-Carrageenan was found to increase the complex modulus, the gel strength and the water holding capacity, although these properties were mainly governed by the concentration of meat protein isolate.     

Formation of acrylamide at temperatures lower than 100°C: the case of prunes and a model study

Acrylamide concentrations in prune products--baby strained prunes (range = 75-265 μg kg(-1)), baby apple/prune juice (33-61 μg kg(-1)), prune juice (186-916 μg kg(-1)) and prunes (58-332 μg kg(-1))--on the Canadian market were determined. The formation of acrylamide in a simulated plum juice was also investigated under 'drying conditions' in an open vessel at temperatures <100°C for 24 h and under 'wet conditions' in a closed vessel at a temperature of 120°C for 1 h. Acrylamide was produced in a simulated plum juice under 'drying conditions' in amounts comparable with those found in prunes and prune juices. Acrylamide was not produced in simulated plum juice under 'wet conditions' in a closed vessel at temperature of 120°C for 1 h, but under the same condition an authentic prune juice doubled its acrylamide concentration. Formation of acrylamide in prune products was attributed to the presence of asparagine and sugars in the starting materials.     

Heat-induced aggregation of whey proteins in the presence of κ-casein or sodium caseinate

Aggregates were formed by heating mixtures of whey protein isolate (WPI) and pure κ-casein or sodium caseinate at pH 7 and 0.1 M NaCl. The aggregates were characterized by static and dynamic light scattering and size exclusion chromatography. After extensive heat-treatment at 80 °C for 24 h, almost all whey proteins and κ-casein formed mixed aggregates, but a large proportion of the sodium caseinate did not aggregate. At a given WPI concentration the size of the aggregates decreased with increasing κ-casein or sodium caseinate concentration, but the overall self-similar structure of the aggregates was the same. The presence of κ-casein or caseinate therefore inhibited growth of the heat-induced whey protein aggregates. The results were discussed relative to the reported chaperone-like activity of casein molecules towards heat aggregation of globular proteins.     

Whey protein aggregate formation during heating in the presence of κ-carrageenan

The effect of a negatively charged polymer, κ-carrageenan, on the aggregation behaviour of whey proteins during heating was studied. Aqueous solutions of whey protein isolate (WPI) at 0.5% were heated in the presence of κ-carrageenan (0.1%) at pH 7.0. This concentration was chosen as optimal in the detection of the intermediate aggregates during chromatographic analysis. The residual unaggregated protein, the intermediate aggregates and the soluble aggregates were all examined as a function of heating time and temperature, using size-exclusion chromatography coupled with light scattering detection. The presence of κ-carrageenan did not affect the aggregation of whey proteins heated at 75 °C; however, a change in the mechanism of aggregation seemed to occur at higher temperatures, and intermediates with higher molecular mass formed at 85 °C. At 90 °C, in the presence of κ-carrageenan, the extent of WPI aggregation was much larger, as soluble aggregates were no longer present and less residual protein was recovered in the unaggregated peak.     

Formation of nanotubes and gels at a broad pH range upon partial hydrolysis of bovine α-lactalbumin

The influence of pH (from 7.5 to 4.0) on the hydrolysis and self-assembly process of nanotubes formed from partially hydrolysed bovine α-lactalbumin was studied. The results showed that the pH had no influence on the products resulting from hydrolysis, but a decrease in pH dramatically reduced the hydrolysis rate. In contrast, the self-assembly process was favoured by decreased pH due to the reduced electrostatic repulsion between the fragments making up the nanotubes. Initially, upon adding a protease, a rapid change in conformation was indicated by circular dichroism spectroscopy. Subsequently no further change was observed. Due to slower hydrolysis and faster self-assembly at pH 6.5 and 4.0, the main building fragments were integrated quickly into nanotubes, and hence avoided further hydrolysis. Self-assembly of protease-induced α-lactalbumin nanotubes can thus be extended over a broad range of pH values. These findings might be useful for future applications in both food and pharmaceutical industries.     

Emulsion formulation optimization and characterization of spray-dried κ-carrageenan microparticles for the encapsulation of CoQ10

The present study is aimed to prepare κ-carrageenan microparticles for the encapsulation of model drug, coenzyme Q10 (CoQ10). A face-centered central composite design was employed to study the effects of three different formulation variables (κ-carrageenan, emulsifier, and oil). The powder yield was found inversely affected by the κ-carrageenan and oil concentration. The encapsulation efficiency was maximized in the region of the middle level κ-carrageenan concentration, the high level emulsifier concentration, and the low level oil concentration. The emulsifier concentration was the most influential variable on the particle size of powder. The optimal formulation was reported as 0.91% (w/v) κ-carrageenan concentration, 0.64% (w/v) emulsifier, and 1.0% (w/w) oil. Both differential scanning colorimeter and X-ray diffraction analyses proved that incorporation of CoQ10 into κ- carrageenan microcapsules resulted in amorphous powder with significantly (p<0.05) higher water solubility compared to pure CoQ10 and physical mixture in the crystalline form.     

Formation of β-cyclodextrin inclusion enhances the stability and aqueous solubility of natural borneol

The aims of this study were to optimize the preparation conditions of natural borneol/β-cyclodextrin (NB/β-CD) inclusion complex by ultrasound method, and to investigate its improvement of stability and solubility. The complex was characterized by different various spectroscopic techniques including Fourier transform infrared spectroscopy, X-ray diffractometry, and differential scanning calorimetry. The results demonstrate that NB could be efficiently loaded into β-CD to form an inclusion complex by ultrasound method at a molar ratio of 1 : 1 and mass ratio of 1 : 6. The complex exhibited different physicochemical characteristics from that of free NB. Typically, formation of β-CD inclusion significantly enhanced the stability and aqueous solubility of NB. PRACTICAL APPLICATION: Natural borneol (NB) has the potential to be widely used in the fields of medical and functional food, due to its specificity. However, the disadvantages of unstability in the preparation and storage process due to its easy sublimation and the low water solubility limit its application. This research provides an effective way to improve the solubility and stability of NB by preparing NB/β-CD inclusion complex. Furthermore, theoretical basis is also provided for the application development of NB.     

Study of the functionality of selected hydrocolloids and their blends with κ-carrageenan on storage quality of vanilla ice cream

In the present paper, the functionality of hydrocolloids related to the rheological, physical and sensory characteristics of ice cream mixes and frozen ice cream was studied. Carboxylmethylcellulose, guar gum, sodium alginate and xanthan gum were used as primary stabilizing agents, whereas κ-carrageenan as secondary. The hydrocolloid concentrations were 0.1 and 0.2% and the primary to secondary ratio was 9:1. The ice cream samples were stored under quiescent frozen conditions. Samples were taken after 4, 8 and 16 weeks of storage and examined for the functionality of the stabilizing systems.The addition of hydrocolloids significantly reinforced the shear thinning behavior, particularly in the case of sodium alginate, xanthan gum, and κ-carrageenan which was attributed to gelation phenomena. Sodium alginate attained the better stabilizing effect improving textural quality and acceptance of ice creams even after 16 weeks of storage, whereas the presence of κ-carrageenan found to be a crucial factor for the cryoprotection. Xanthan gum was also evaluated as an effective stabilizing agent, indicating that gelling hydrocolloids may remarkably amend ice cream shelf life.Moreover, principal components and cluster analysis of instrumental and sensory data furnished important information for the correlation of objective and sensory properties and discrimination of stabilizing systems based on quality criteria.     

Does smearing inoculum reflect the bacterial composition of the smear at the end of the ripening of a French soft, red-smear cheese?

The microbial community composition and dynamics during the production of a French soft, red-smear cheese were investigated. The colonization efficiency of the smearing inoculum was followed, and the parts played by the inoculum used and the resident microflora were tentatively estimated. Single-strand conformation polymorphism analysis (SSCP) was applied to 2 productions of a soft, red-smear cheese produced by the same dairy plant at 4-mo intervals. Microbial composition of the different cheese samples analyzed was found to be reproducible from one production to another. However, the composition of the surface flora of both cheeses at the end of the ripening did not reflect the composition of the smearing inoculum used, qualitatively as well as quantitatively. These results were confirmed by those obtained when assessing the microbial composition of the culturable flora by the spread plate technique. The inoculum used by the industry had low resiliency potentialities against colonization of cheeses by resident organisms. Therefore, fitness and colonization potential of smearing inocula should be carefully assessed by the industry before use. The use of Arthrobacter strains as part of the smearing inoculum should be evaluated.     

Surface viscosity of glycosylated derivatives of beta-lactoglobulin at the air—water interface

Surface viscosities of beta-lactoglobulin (βLG) and glycosylated derivatives of βLG were determined at the air—water interface using a rotational viscometer. The surface viscosity of 0.1% solutions increased rapidly during the first few minutes and then decreased slightly. Surface viscosity and rate of development of surface viscosity were maximum near the isoelectric point of βLG. Glycosylation of βLG decreased its rate of development and maximum surface viscosity. Apparently, surface viscosity was affected by decreased electrostatic repulsions and increased hydrophilic interactions, protein conformational stability and the interfacial concentration of βLG. The shearing action of the viscometer probably contributed to surface viscosity by increasing the rate of protein adsorption and desorption and increasing the entanglement of proteins at the air—water interface. This study increases our understanding of the protein structure—function relationships in foams and emulsions.     

Kinematic Viscosity of Aqueous Solutions of Ethanol and Glucose in the Range of Temperatures from 20 to 45°C

The purpose of this investigation was to determine, using a capillary viscosimeter, kinematic viscosity data of aqueous solutions of ethanol and glucose, at several temperatures (from 20 up to 45ºC) and concentrations. Glucose solubility strongly depended on ethanol concentration allowing the kinematic viscosity study (from 5% up to 45% w/w ethanol concentration with variable glucose concentrations as a function of its solubility). Kinematic viscosity modelling with solution concentration and temperature simultaneously, based on previous models for respective binary systems, was successfully carried out. The estimated values by this model give low average deviations (2.62%) from the experimental data. Glucose solubility (at 25ºC) in alcohol solutions and index of refraction (at 20ºC) of ternary solutions were also determined and empirical models are proposed in order to evaluate both physical properties with high (R² > 0.993 and >?0.991, respectively) accuracy.     

Effect of glucono-δ-lactone and κ-carrageenan combined with high pressure treatment on the physico-chemical properties of restructured pork

In this study, response surface methodology (RSM) was used to evaluate the combined effects of NaCl, glucono-δ-lactone (GdL), and κ-carrageenan concentration (0.25%, 0.5%, and 0.75%) on the binding properties of restructured pork under hydrostatic pressure. All the generated RSM models showed no lack-of-fit and significance at the 0.001 level. The addition of both NaCl and GdL had a significant effect on color. A significant decrease in pH was shown when the GdL level increased, and subsequently led to a decrease in WHC. However, increasing the GdL level increased the binding strength. Therefore, the results indicate that a reduction in the NaCl level during meat restructuring, under pressure treatment, can be achieved by using GdL; and even a low GdL concentration allows for palatable binding properties in meat restructuring when κ-carrageenan is added.     

Formation of discrete molecular size domains of melanoidins depending on the involvement of several α-dicarbonyl compounds: Part 2

The correlation of several α-dicarbonyl compounds with the melanoidin formation and their molecular size distribution was investigated. The results point out that α-dicarbonyl compounds, which were formed during the Maillard reaction, are not only the most important intermediates but also the direct precursors for carbohydrate-based melanoidins. Discrete molecular size domains are detected by size exclusion chromatography (SEC-DAD/RI), which were formed depending on the involvement of several α-dicarbonyls by thermal treatment of sucrose Maillard reaction solutions. By investigating sucrose Maillard reaction solutions spiked with methylglyoxal and 3-deoxyhexosulose carried on with direct melanoidin formation in aqueous solutions with α-dicarbonyls, molecular size domains of melanoidins could be connected for the first time with the reaction of several involved α-dicarbonyl compounds. High molecular size domains formed on the basis of methylglyoxal, whereas 3-deoxyhexosulose and d-glucosone promote lower molecular size domains. Concerning colour measurement methylglyoxal shows the highest browning activity followed by 3-deoxyhexosulose and d-glucosone. The reactivity of α-dicarbonyls and a correlated colour formation increase with rising alkaline pH-value. At a pH 5 the degradation and colour formation of α-dicarbonyl compounds is suppressed. The results provide new knowledge about colour formation in sucrose solutions. First part with the title, “Influence of α-dicarbonyl compounds to the molecular weight distribution of melanoidins in sucrose solutions: Part 1” was accepted in EFRT in January 2006. DOI: 10.1007/s00217-006-0277-1.     

Formation of amorphous sugar in the syrup film – a key factor in modelling of industrial sugar drying

A mathematical model of the steady-state sugar drying operation in a cross-flow rotating drum dryer is proposed. Although the model is based on the classic two-film concept of simultaneous heat and mass transfer, it also allows for the formation and growth of a thin layer of amorphous sugar due to local supersaturation of the sugar syrup. The formation of amorphous sugar is a result of the competition between crystallization and drying kinetics. The onset of amorphization is assumed to occur when the system moves from the metastable zone to the labile zone on the sucrose–water phase diagram. The rate of sucrose amorphization is controlled by the conditions prevailing on the metastability limit. Diffusivity of water through the amorphous sugar, the only adjustable parameter of the proposed model, has been determined by fitting sugar moisture data from an industrial Louvre-type dryer. The layer of amorphous sugar plays a critical role during the falling-rate period of drying. Generally, models ignoring its presence tend to overestimate the moisture removal rate. The presented model predicts a dramatic decline of the evaporation rate once the amorphous sugar begins to form which is observed in the industrial practice. The effect of key operating parameters such as air flow rate, hot air temperature, and crystal size on the dryer performance is also discussed.     

Disappearance of intermolecular beta-sheets upon adsorption of beta-lactoglobulin aggregates at the oil–water interfaces of emulsions

Native proteins usually undergo structural modification upon adsorption at interface. Heat treatments are commonly applied at the industrial scale and lead to aggregation of proteins. We characterized nanometric aggregates of β-lactoglobulin by infrared spectroscopy in solutions, in hexadecane oil-in-water emulsions and at the air–water interface at low and high (0.1 M) ionic strengths and at pH 7. In solutions, on the contrary to native β-lactoglobulin, all aggregates prepared with or without salt possessed intermolecular β-sheets evidenced by two strong absorption bands at 1614 cm⁻¹ and 1682 cm⁻¹. In emulsions, at low ionic strength, they lose their intermolecular β-sheets once they are adsorbed at the oil–water interface. At high ionic strength, most of aggregates are localized at the interfaces where they lose their intermolecular β-sheets in direct contact with the surface and only partially when they are farther from the interface. The loss of intermolecular β-sheets was similarly observed at the air–liquid interface.     

Selective effect of the product type and the packaging conditions on the species of lactic acid bacteria dominating the spoilage microbial association of cooked meats at 4°C

The product type was shown to strongly affect the growth rate and the composition of the spoilage lactic flora during refrigerated (4°C) storage of cooked, cured meats, sharing their processing plant environment, day of production and film packaging conditions. Growth of lactic acid bacteria (LAB) under vacuum was more prolific on the product in the order: ham>turkey breast fillet>smoked pork loin>pariza>mortadella>bacon, and ham>frankfurters, manufactured in two industrial meat plants A and B, respectively. The Lactobacillus sakei/curvatus group prevailed in all products, except the non-smoked, boiled whole-meats, i.e. cooked ham and turkey breast fillet, where Leuconostoc mesenteroides subsp.mesenteroides predominated. Lactobacillus sakei was by far the most prevalent species in smoked whole-meats, i.e. pork loin and bacon. Emulsion sausages, i.e. pariza, mortadella and frankfurters, contained a more diverse lactic flora.Leuconostoc carnosum and Lc. citreum occurred in boiled, whole-meats and emulsion sausages, respectively.Weissella viridescens was isolated from smoked meat products only. A very good correlation between the LAB growth and types and important intrinsic factors, such as the product pH, moisture, salt (brine) concentration and cooking method could be observed. When ham and frankfurters from plant B were stored in air, yeasts and mainly Brochothrix thermosphacta became important members of the spoilage association. Growth of LAB was faster in air. The presence of oxygen resulted in a replacement ofLc. mesenteroides subsp. mesenteroides by other Leuconostoc spp. in ham, and in a shift of the spoilage flora from homo- to heterofermentative LAB species in frankfurters.