Influence of high intensity ultrasound with different probe diameter on the degree of homogenization (variance) and physical properties of cow milk

The main goal of this research is to analyze the influence of ultrasonic probe diameters (7 and 10 mm) of high-intensity ultrasound with constant frequency (30 kHz) on the degree of homogenization (variance) of cow milk. Influence of different probe diameters on the physical properties of cow milk was also tested. Changes in temperature, pH and density were measured under the following operational conditions of the ultrasonic device: amplitude, A = 20, 60,100%; and applied cycle, c = 0.6, 0.8, 1, with various treatment duration, t = 2, 6, 10, 15 min. Obtained results are processed in the “Statistica 8” software. Microscopic images of fat globules were edited in Image J software, while size of fat globules was represented with Log-normal distribution. Statistical analysis was conducted and influence of probe diameters on physical properties was expressed over p-value (p < 0.05) and β- standardized coefficient analyses of variance (ANOVA). Applications of different probe diameter have significant influence on all physical properties and variance. With increase of the amplitude and time, significant influence on variance (degree of homogenization) is observed.Keywords: Ultrasound, homogenization, cow milk, physical propertie

Textural properties of infra red dried apple slices as affected by high power ultrasound pre-treatment

Drying is a process frequently used in food industry, often based on the use of conventional methods using heat exchange by conduction or convection. This kind of method may lead to quality loss in structure, texture and  sensory characteristics of final products. Consequently, the need for research of new drying methods arises.  One of such methods is power ultrasound aided drying. The aim of this work was to investigate the impact of  high power ultrasound pre-treatment on drying rate and textural properties of the infra red dried apple slices.  Ultrasound device working at a frequency of 24 kHz with a power capacity of 200 W was used for ultrasound  pre-treatment. The amplitudes used for ultrasonic pre-treatment were 50 and 100%. The results showed that  the use of different amplitudes of ultrasound reduces the time of drying and allows elimination of more water  from the apple slices. Usage of 50 and 100% of ultrasonic amplitude in great extent shortened the duration of  drying (up to 40%). The results showed that hardness of samples gradually increases (50% amplitude –  97.260 N; 100% of amplitude – 217.90 N) with increase of ultrasound intensity. As a result, hardness of  untreated apple slices (41.037N) was significantly lower (p < 0.05).Key words: High power ultrasound, amplitude, drying, apple

Reducing Fat Globules Particle-Size in Goat Milk: Ultrasound and High Hydrostatic Pressures Approach

Innovative and eco-friendly food technologies in practical usage today like Ultrasound (US) and High Hydrostatic Pressures (HHP) are feasible to adequately maintain various food properties while processed, such as texture, sensorial and organoleptic characteristics, and microbiological issues as well. Benchmarked attribute of the mentioned approach lies in the ability of US and HHP to control and withhold both temperature and treatment duration. While temperature could be controlled within room ambient, treatment time is mostly below 30 minutes. US and HHP treatment were performed as separate treatments in order to obtain better homogenization. Goat milk was exposed to ultrasonic propagation up to 100 W of nominal power and high pressures up to 600 MPa. Maximum treatment time was 9 minutes. Ultrasonic homogenization indicates enhanced homogeneity of fat globules while high pressure process parameters have a significant influence on the observed mean particle diameter (fat globules). Improved stability and quality of emulsions (goat milk) was obtained by both applied processes. Statistical analysis indicated the influence of process parameters on fat globule size distribution between 0.3 – 4 μm and variance lower than 0.6

Influence of refrigeration and ageing time on textural characteristics of fresh meat

Research of the textural characteristics of pork, beef and baby beef meat samples was conducted. Hardness and adhesivity of the meat was measured immediately after slaughtering, then after 24, 48 and 72 hours. Half of the samples were kept at room temperature, while the other half were refrigerated at 4 C. The results showed that the hardness and adhesivity suddenly dropped during the first 24 hours (up to 345 N, or 41.7 %). After next 48 hours of storage, the values of measured textural properties showed a slight decrease (only additional 15.6 %). The refrigerated samples retained their textural properties a lot better (31 % decrease in hardness during first 24 h, additional 7.4 % in the next 48 hours) than the non-refrigerated ones. In correlation with consumer and industry experience with the texture of cooked or fried meat, refrigeration is a better choice after 48 hours, while after that period, meat at room temperature, is too soft for further processing

The Working Principle and Use of High Pressures in the Food Industry

Primjena visokog tlaka kao nove netoplinske metode obrade namirnica u prehrambenoj industriji nalazi sve veću primjenu u svim fazama proizvodnje. Ova nova tehnologija doživljava svoj najveći tehnološki napredak tijekom devedesetih godina prošlog stoljeća. Glavna prednost obrade visokim tlakom u odnosu na konvencionalne metode obrade je u kraćem vremenu obrade koja se u većini slučajeva kreće u vremenskom intervalu od nekoliko sekundi do 30 minuta. Obrada čvrste ili tekuće namirnice s ambalažnim materijalom ili bez njega provodi se pri temperaturama koje su u rasponu 5 - 90 °C, pri tlakovima 50 - 1000 MPa. Tlakovi se jednoliko prenose po cijelom obujmu namirnice neovisno o njezinim dimenzijama i obliku. Sve navedene veličine procesa zajednički pridonose očuvanju karakteristika obrađenog proizvoda u smislu minimalnih promjena teksturnih, senzorskih, organoleptičkih i nutritivnih svojstava. Cilj ovoga rada je prikazati princip rada uređaja visokog tlaka i njegov učinak na široki spektar operacija u modernoj prehrambenoj industriji.High pressure in the food industry, as a new non-thermal method, is applied in many phases of food processing. This new non-thermal technology was developed in the 1990s. The main advantages of high-pressure processing are in the short time of processing which is between a few seconds and 30 minutes. Processing of solid or liquid food products with or without packaging happens in the temperature interval 5 – 90 °C, and pressures 50 – 1000 MPa. The driving pressure is distributed uniformly through the whole product independently of its quantity and shape. These processing characteristics combined with improved food microbiological safety, less energy expenditure, low concentration of waste products and longer shelf life make high-pressure processing a very promising novel food technology. Combined with lower cost of treatment (but unfortunately higher initial cost of equipment) compared to traditional processing technologies, it is also economically profitable. The main purpose of such treated food products are in preservation of sensory, nutritive and textural properties. As the temperature increase is very low, there are no significant changes in sensory properties, in contrast to conventional thermal processing (sterilization, pasteurization). However, with the combination of heating or cooling and high pressure, modification of existing and creation of new food products is possible. Today, high pressure is used for the treatment of meat products (inactivation of microorganisms), freezing and defrosting of foodstuffs, production of fruit juices (pasteurization), processing of oysters, modification of milk characteristics (foaming) etc. The main purpose of this work is to present the working principle and application of high pressure in the food industry

Comparison of Conventional and Ultrasound-assisted Extraction Techniques on Mass Fraction of Phenolic Compounds from Sage (Salvia officinalis L.)

An innovative ultrasound-assisted extraction (UAE) is the rapid non-thermal extraction technique, which in comparison to conventional extraction (CE), offers high reproducibility in a short time with simplified manipulation, reduced solvent consumption and lower energy. Optimization of ultrasonic conditions was conducted for devices with nominal output power of 100 and 400 W, including the influence of geometrical parameters of probes regarding ultrasound-assisted extraction. The results showed that the optimal parameters for extraction of total phenols and rosmarinic acid as a dominant compound in sage extracts were as follows: solvent: 30 % ethanol, extraction duration of 11 minutes, and ultrasonic device output power of 400 W. The antioxidant capacity of the obtained extract correlated with the concentration of total phenols and flavonoids, and among individual phenols the rosmarinic acid contributed the most to the antioxidant capacity. The achieved results and statistical analysis (p ≤ 0.05) have shown how UAE resulted in shorter extraction time, and increased extraction capacity of phenolic compounds by using solvents with a less amount of organic phase