Agata Marzec

Structure influence on mechanical and acoustic properties of freeze‐dried gels obtained with the use of hydrocolloids

The influence of the structure formed by the type of hydrocolloids (low-methoxyl pectin, the mixture of xanthan gum, and locust bean gum, and mixture of xanthan gum, and guar gum) and the aeration time (3, 5, 7, and 9 min) on textural properties of freeze-dried gels were investigated. The hardest texture generating the strongest acoustic emission was obtained by freeze-dried pectin gel, characterised by the lowest porosity and the largest pore diameter. Aeration time significantly affected mechanical and acoustic properties of the pectin gel lyophilisate. No effect of gel aeration time on tested characteristics of samples with mixture of hydrocolloids was observed. Strong positive correlations between acoustic energy as well as the maximum force and work and negative ones between porosity and pore diameter indicate that greater resilience and stronger acoustic emission of freeze-dried gels was caused by the reduction of porosity and the increase in the pore size of the material.nnnPRACTICAL APPLICATIONSnThe research is expected to show the phenomenon of structure formation when preparing and freeze-drying gels and explain the influence of the process parameters (time of aeration, the type of hydrocolloids) on the formation of the internal structure and physical properties of a dried product, especially mechanical and acoustic properties. This achievement will contribute to the development of the science of food and human nutrition, especially within the context of the popular research on aerated diet products. The expected result will be the ability to develop a new technology for producing food with a delicate texture, using the phenomenon of sublimation. As a result, designing changes in the structure of freeze-dried fruit gels with a delicate structure will be possible due to the choice of ingredients and aeration parameters in order to develop innovative food characterised by favorable nutritional, health and functional properties, which will be attractive for the consumers.

Functional Properties and Oxidative Stability of Flaxseed Oil Microencapsulated by Spray Drying Using Legume Proteins in Combination with Soluble Fiber or Trehalose

The objective of this study was to evaluate the potential of double wall material combinations, using legume protein (soy protein isolate and pea protein isolate) in combination with wheat dextrin soluble fiber or trehalose, as alternative materials for microencapsulation of flaxseed oil by spray drying. The obtained preparations, with oil content of 35%, were fine and difficult flowing powders, regardless of their composition. The 1% addition of silica to the powders significantly reduced their cohesiveness and improved their flowability. The efficiency of microencapsulation, calculated based on oil fat content, ranged from 62 to 98% and was higher in the powders with trehalose and in the powders containing soy protein. Effective protection against oxidation of microencapsulated oil was achieved in the protein-trehalose matrix, especially in the case of the vacuum-packed powders with pea protein during storage at refrigeration temperature. Replacing trehalose with soluble fiber enabled formation of powders less susceptible to caking under conditions of increased humidity, but it resulted in decreased microencapsulation efficiency. The combination of pea protein/carbohydrate resulted in the formation of microcapsules with porous structure, especially in the system with soluble fiber. With time, the structure of the primary emulsions and those reconstituted from powders containing pea protein changed from liquid to greasy and paste-like.

Extruded bread classification on the basis of acoustic emission signal with application of artificial neural networks

Abstract The presented work covers the problem of developing a method of extruded bread classification with the application of artificial neural networks. Extruded flat graham, corn, and rye breads differening in water activity were used. The breads were subjected to the compression test with simultaneous registration of acoustic signal. The amplitude-time records were analyzed both in time and frequency domains. Acoustic emission signal parameters: single energy, counts, amplitude, and duration acoustic emission were determined for the breads in four water activities: initial (0.362 for rye, 0.377 for corn, and 0.371 for graham bread), 0.432, 0.529, and 0.648. For classification and the clustering process, radial basis function, and self-organizing maps (Kohonen network) were used. Artificial neural networks were examined with respect to their ability to classify or to cluster samples according to the bread type, water activity value, and both of them. The best examination results were achieved by the radial basis function network in classification according to water activity (88%), while the self-organizing maps network yielded 81% during bread type clustering.

Comparative analysis of structure and strength of vitelline membrane and physical parameters of yolk of ostrich, emu, and greater rhea eggs

Abstract In this study, we analyzed selected morphological traits of eggs, as well as structure, strength, and protein composition of the vitelline membrane (VM) of ostrich, emu, and greater rhea eggs. Ninety eggs (30 for species) were analyzed for the following parameters: egg weight, yolk weight, yolk ratio, and yolk index. In addition, pH value, water activity, consistency index, and flow behavior index were determined. The strength of VM was measured using the TA.HDPlus Texture Analyzer. Micrograph images were taken via a scanning electron microscope. Polyacrylamide gel electrophoresis was conducted under denaturing conditions. Ostrich eggs were characterized by the highest egg and yolk weight compared with those of emu and greater rhea eggs, whereas emu eggs had the highest yolk ratio compared with those of ostrich and greater rhea eggs (P > 0.05). Yolk content differed among the species in terms of water activity; it was found to be higher in emu eggs than in ostrich and greater rhea eggs (P > 0.05). Based on flow curves, yolks of the ratites were classified as pseudoplastic non‐Newtonian fluids. The consistency index was significantly higher in yolks of ostrich and emu than that of greater rhea eggs, whereas the VM of yolks of greater rhea eggs was the most resistant (had the highest breaking force = 26.4 g). All species differed significantly regarding the structure of VM, the outer layer (OL) in particular, which was found to constitute fibers of various thicknesses that were differently arranged. Fibers of the OL of the VM of emu, whose fibers were the least differentiated but formed the most compact network, were the most diverse in characterization. An electropherogram of the VM of ostrich revealed 11 primary protein bands: 6 for the OL and 5 for the inner layer (IL), that of emu revealed 9 bands: 5 for the OL and 4 for the IL, and that of greater rhea revealed 10 bands: 6 for the OL and 4 for the IL.

Dried strawberries as a high nutritional value fruit snack

The purpose of this study was to determine the possibility of using a chokeberry juice concentrate as a component of osmotic solution and convection-microwave-vacuum drying applying to obtain dried pro-health-promoting strawberries. The research material was Honeoye strawberries, which were dehydrated in sucrose and sucrose with chokeberry juice concentrate addition, and then subjected to microwave-convection-vacuum or freeze-drying. Analyses were conducted to determine the influence of the applied processes on vitamin C content, total polyphenols, antioxidant activity, and sensory properties in dried fruit. Study results confirmed the possibility of using a chokeberry juice concentrate as a component of the osmotic solution, especially with regard to polyphenolics content and antioxidant activity. In addition, convection-microwave-vacuum drying was shown to be a promising technology for the production of dried strawberries, with high pro-health potential and acceptable sensory qualities.

Application of the support sensory system and principal component analysis to compare meat of chickens of two genotypes

ABSTRACT Sensory quality of roasted breast muscles of two genotypes of chickens kept for 9 weeks of life in an outdoor or indoor system was tested by Quantitative Descriptive Analysis (QDA). After roasting in a convective-steam oven, 72 individual pectoral muscles of cocks (36 from each genetic group, 18 from outdoor and 18 from indoor system) were subjected to the sensory evaluation. There was a significant effect of genotype on fat odor (fatty flavor, P = 0.007), color (P = 0.007), and texture parameters: juiciness (P = 0.046) and greasy feel (P = 0.027). The rearing system had a significant effect only on meat juiciness (P = 0.015). Significant genotype × rearing system interactions were found for juiciness (P = 0.015) and different taste (P = 0.05). Principal component analysis showed distinct differences in the sensory traits of roasted breast muscle of two chicken genotypes produced in different rearing systems.