Физико-химични показатели и сензорна оценка на ранно зреещи сортове праскови и нектарини

The present study was carried out to determine some physicochemical, composition and sensory attributes of earlyripening peach varieties: “Filina” (peach), “Gergana” (nectarine), and “Ufo-4” (flat peach). Fruit weight, shape and size, as well as color and firmness were evaluated. Image analysis was used to describe properties such as length, width, thickness, etc. Skin hue ranged from 33.45±10.70 to 42.75±29.87. Dry matter (%), ash content (%), total soluble solids, pH, titratable acidity, total sugar content, and protein content were employed to characterize the studied varieties. Results showed differences in all properties of the types. Ash content varied from 0.45±0.04% to 0.96±0.12% and pH from 3.95 to 4.46. “Gergana” had the lowest total soluble solids. A trained descriptive sensory panel evaluated the peach varieties in five categories with a total of twenty-five attributes. The fruit attributes were evaluated by a 15-point ascending scale. The panellists detected differences between varieties in each of the categories (aroma, texture, taste, internal and external appearance). These results offer and highlight new data in terms of early-ripening peach variety properties.Настоящото проучване е проведено с цел определяне на някои физикохимични, химични и сензорни качества на ранно зреещи сортове праскови: „Филина“ (праскова), „Гергана“ (нектарина) и „Уфо-4“ (плоска праскова). Оценени са теглото, формата и размерът на плодовете, както и цветът, и твърдостта. За описание на свойства като дължина, ширина, дебелина и др. е използван анализ на изображения. Оттенъкът на прасковената обелка варира от 33,45±10,70 до 42,75±29,87. Сухо вещество (%), съдържание на пепел (%), общо разтворими твърди вещества, рН, титруема киселинност, общо съдържание на захар и съдържание на протеин характеризират изследваните сортове. Резултатите показват разлики във всички свойства на сортовете. Съдържанието на пепел варира от 0,45±0,04% до 0,96±0,12%, а рН от 3,95 до 4,46. Гергана има най-ниските стойности на общо разтворими твърди вещества. Обучен сензорен панел оцени сортовете праскови в пет категории с общо двадесет и пет характеристики. Характеристиките на плодовете се оценяват по 15-степенна скала, в която 15 е максималната стойност. Дегустаторите откриват разлики между сортовете във всяка от категориите (аромат, текстура, вкус, вътрешност и външен вид). Получените резултати предлагат и подчертават нови данни по отношение на свойствата на ранно зреещи прасковени сортове

Changes in Creep Behaviour and Microstructure of Model Mozzarella Cheese During Working

The effect of shear work input on the microstructure, fat particle size and creep behavior of model Mozzarella type cheeses was studied. Cheese samples were prepared in a twin screw cooker at 70 °C by mixing protein and fat phases together with different amounts of shear work input. Major changes in cheese structure were observed while working at 150 rpm and 250 rpm screw speeds. Confocal microstructures plus macroscopic observations showed systematic changes in structure with increased shear work inputs with unmixed buttery liquid observed at kg−1, typical Mozzarella type microstructures (elongated fat-serum channels) at 6–15 kJ kg−1 and homogeneously distributed, small size fat droplets at \u3e58 kJ kg−1. At very high shear work inputs, \u3e 75 kJ kg−1, striations or anisotropy in the microstructures had disappeared and small micro-cracks were evident. A 4-element Burger\u27s model was found adequate for fitting the creep data of model cheese at 70 °C but a 6-element model was required at 20 °C. As shear work input increased retarded compliance decreased and zero shear viscosity increased indicating the more elastic behavior of the cheeses with higher shear work input. Changes in the protein matrix appear to be the main reason for increased elastic behavior

Comparative study of quality characteristics of Kashkaval cheese from fresh and chilled curd

The influence of chilledcurd on Kashkavalcheese microbiological, functional, textural and sensorial characteristics was studied. It was found that salting the curd in a hot solution influenced to a greater degree the microflora reduction from the starter culture in Kashkaval cheese obtained fromfresh curd. In terms of species composition, Streptococcusssp. had a higher survival rate compared to Lactobacillusssp. During maturation, this trend changed and the number of Lactobacillusssp. increased, while that of Streptococcus ssp. remained constant and even slightly decreased in both studied samples. Melting and textural characteristics of the two studied cheese samples did not differ significantly at the end of the maturation process. The overall scores of the sensory profile were higher in the cheese obtained from fresh curd but no statistical differences (p>0.05) between separate sensory indices were established. The obtained results indicated that "Cagliata"can be successfully used as an alternative raw material for fresh curd in the production of Kashkaval cheese.publishedVersio

Effect of Shear Work Input on Steady Shear Rheology and Melt Functionality of Model Mozzarella Cheeses

Model Mozzarella cheeses with varied amounts of shear work input were prepared by working molten cheese mass at 70 °C in a twin screw cooker. Rheology and melt functionality were found to be strongly dependent on total shear work input. A non-linear increase in consistency coefficient (K from power law model) and apparent viscosity and decrease in flow behaviour index (n from power law model) were observed with increasing amounts of accumulated shear work, indicating work thickening behaviour. An exponential work thickening equation is proposed to describe this behaviour. Excessively worked cheese samples exhibited liquid exudation, poor melting and poor stretch. Nonfat cheese exhibited similar but smaller changes after excessive shear work input. We concluded that the dominant contributor to the changes in properties with increased shear work was shear induced structural changes to the protein matrix. A good correlation was found between the steady shear rheological properties and the melting properties of the cheeses

Strain Hardening and Anisotropy During Tensile Testing of Sheared Model Mozzarella Cheeses

We studied the tensile fracture properties of model Mozzarella cheeses with varying amounts of shear work input (3.3–73.7 kJ/kg). After manufacture, cheeses were elongated by manual rolling at 65°C followed by tensile testing at 21°C on dumbbell-shaped samples cut both parallel and perpendicular to the rolling direction. Strain hardening parameters were estimated from stress–strain curves using 3 different methods. Fracture stress and strain for longitudinal samples did not vary significantly with shear work input up to 26.3 kJ/kg and then decreased dramatically at 58.2 kJ/kg. Longitudinal samples with shear work input \u3c30 kJ/kg demonstrated significant strain hardening by all 3 estimation methods. At shear work inputs \u3c30 kJ/kg, strong anisotropy was observed in both fracture stress and strain. After a shear work input of 58.2 kJ/kg, anisotropy and strain hardening were absent. Perpendicular samples did not show strain hardening at any level of shear work input. Although the distortion of the fat drops in the cheese structure associated with the elongation could account for some of the anisotropy observed, the presence of anisotropy in the elongated nonfat samples reflected that shear work and rolling also aligned the protein structure

Tensile Testing to Quantitate the Anisotropy and Strain Hardening of Mozzarella Cheese

We explored anisotropy of mozzarella cheese: its presence is debated in the literature. Tensile testing proved a good method because the location and mode of failure were clear. Mozzarella cheese cut direct from the block showed no significant anisotropy, though confocal microscopy showed good structure alignment at a microscale. Deliberately elongated mozzarella cheese showed strong anisotropy with tensile strength in the elongation or fibre direction ∼3.5× that perpendicular to the fibres. Temperature of elongation had a marked impact on anisotropy with maximum anisotropy after elongation at 70 °C. We suggest the disagreement on anisotropy in the literature is related to the method of packing the mozzarella cheese into a block after the stretching stage of manufacture. Tensile stress/strain curves in the fibre direction showed marked strain hardening with modulus just before fracture ∼2.1× that of the initial sample, but no strain hardening was found perpendicular to the fibre direction

Meat Analogues from Pea Protein: Effect of Different Oat Protein Concentrates and Post Treatment on Selected Technological Properties of High-Moisture Extrudates

The effect of using oat protein concentrates from different sources on the techno/functional properties of pea protein high-moisture extrudates (HME) have been investigated. The oat protein fractions were commercially produced by wet milling (OP) or produced by dry fractionation (OA) in our pilot plant facilities. The texture cutting force of HME was significantly increased by the inclusion of OP and had higher anisotropy, while addition of OA did not influence the texture. Addition of both oat sources to the pea mixture led to higher water and oil binding ability on both initial dry ingredients and extrudates. The color of the meat analogues was significantly affected by the type of oat added. CLSM image analysis of the extrudates showed that the type of oat used influenced fiber alignment and apparent porosity of the protein network. Post-extrusion treatment with water at 80 ◦C/20 min of the extrudates significantly reduced the cutting strength of the meat analogues and significantly caused a shift toward a lighter color. The reduction of texture strength of extrudates with OP rendered it similar to cooked chicken samples, while extrudates with OA showed a more resilient fiber strength to the hot water treatmentpublishedVersio

Utilization of Industrial Rosa damascena Mill. By-products and Cocoa Pod Husks as Natural Preservatives in Muffins

Cocoa Pod Husks (CPH) and by-product from supercritical CO2 extracted Rosa damascena Mill. (RDCO2) were used as biopreservatives in muffins. Both by-products were rich source of polyphenols: 28.3 ± 0.6 mg/g Dry Weight (DW) and 17.9 ± 0.7 mg/g DW RDCO2 and CPH, respectively, and exhibited potent antioxidant capacity: 449.1 ± 8.5 µmol Trolox Equivalents (TE)/g DW (by ORAC method) and 58.9 ± 2.1 µmol Gallic Acid Equivalents (GAE)/g DW (by HORAC method) for the RDCO2, and 373.8 ± 9.0 µmol TE/g DW (by ORAC) and 36.8 ± 3.8 µmol GAE/g DW (by HORAC) for the CPH. RDCO2 extracts successfully inhibited development of several important pathogenic and saprophytic microorganisms causing microbial spoilage of food systems. The control muffins were good for consumption up to the 17th day, while the products supplemented with RDCO2 and CPH: until 20th day of storage at 22 ± 0.5 °C. The amount of dietary fibers in muffins supplemented with both by-products increased 3 times (8.57 ± 0.12 %) compared to control (2.91 ± 0.12 %) and the polyphenolic compounds increased 2.5 times (from 50.0 ± 0.3 for the control to 185.9 ± 0.6 mg/g DW). For the first time by-product of supercritical CO2 extraction of Rosa damascena Mill. was characterized and used as natural and cheap biopreservative

Measurement Techniques for Steady Shear Viscosity of Mozzarella-Type Cheeses at High Shear Rates and High Temperature

While measuring steady shear viscosity of Mozzarella-type cheeses in a rotational rheometer at 70 °C, three main difficulties were encountered; wall slip, structural failure during measurement and viscoelastic time dependent effects. Serrated plates were the most successful surface modification at eliminating wall slip. However, even with serrated plates shear banding occurred at higher shear rates. Because of the viscoelastic nature of the cheeses, a time dependent viscous response occurred at shear rates \u3c1 \u3es−1, requiring longer times to attain steady shear conditions. Prolonged continuous shearing altered the structure of the molten cheeses. The effects of structural change were greatly reduced by minimising the total accumulated strain exerted on the sample during flow curve determination. These techniques enabled successful measurement of steady shear viscosity of molten Mozzarella-type cheeses at 70 °C at shear rates up to 250 s−1