Brettanomyces bruxellensis is one of the most important spoilage microorganisms in winemaking. It is harmful for wine industry because it produces volatile phenols, compounds primarily responsible ...for off-odours in wine. One of the possible solutions for preventing its growth is using new non-thermal processing technologies. The aim of this study was to investigate the application of one non-thermal processing technology, high power ultrasound and its combination with heating (thermosonication) on the inactivation of B. bruxellensis in red wine in batch systems. Various parameters, such as treatment duration (1, 2, 3, 6, 10 and 15 minutes), temperature (25, 35, 40 and 43 °C) and probe diameter (12.7 mm and 19.1 mm), were examined. The combination of high power ultrasound and heating (thermosonication) proved to be a better method compared to solely using high power ultrasound. However, the production of volatile phenols by B. bruxellensis was also reduced after high power ultrasound treatment. The optimal treatment of 3 min at 43 °C with high power sonicator at ultrasound frequency of 20 kHz with 12.7 mm diameter ultrasonic probe for complete inactivation of B. bruxellensis was determined.
Despite of the constant development of novel thermal and non-thermal technologies, knowledge on the mechanisms of microbial inactivation is still very limited. Technologies such as high pressure, ...ultraviolet light, pulsed light, ozone, power ultrasound and cold plasma (advanced oxidation processes) have shown promising results for inactivation of microorganisms. The efficacy of inactivation is greatly enhanced by combination of conventional (thermal) with non-thermal, or non-thermal with another non-thermal technique. The key advantages offered by non-thermal processes in combination with sub lethal mild temperature (<60 °C) can inactivate microorganisms synergistically. Microbial cells, when subjected to environmental stress, can be either injured or killed. In some cases, cells are believed to be inactivated, but may only be sub lethally injured leading to their recovery or, if the injury is lethal, to cell death. It is of major concern when microorganisms adapt to stress during processing. If the cells adapt to a certain stress it is associated with enhanced protection against other subsequent stresses. One of the most striking problems during inactivation of microorganisms is spores. They are the most resistant form of microbial cells and relatively difficult to inactivate by common inactivation techniques, including heat sterilization, radiation, oxidizing agents and various chemicals. Various novel non-thermal processing technologies, alone or in combination, have shown potential for vegetative cells and spores inactivation. Predictive microbiology can be used to focus on the quantitative description of the microbial behaviour in food products, for a given set of environmental conditions. This article is protected by copyright. All rights reserved.
This paper presents research of the high power ultrasound effect on rheological and foaming properties of ice cream model mixtures. Ice cream model mixtures are prepared according to specific ...recipes, and afterward undergone through different homogenization techniques: mechanical mixing, ultrasound treatment and combination of mechanical and ultrasound treatment. Specific diameter (12.7 mm) of ultrasound probe tip has been used for ultrasound treatment that lasted 5 minutes at 100 percent amplitude. Rheological parameters have been determined using rotational rheometer and expressed as flow index, consistency coefficient and apparent viscosity. From the results it can be concluded that all model mixtures have non-newtonian, dilatant type behavior. The highest viscosities have been observed for model mixtures that were homogenizes with mechanical mixing, and significantly lower values of viscosity have been observed for ultrasound treated ones. Foaming properties are expressed as percentage of increase in foam volume, foam stability index and minimal viscosity. It has been determined that ice cream model mixtures treated only with ultrasound had minimal increase in foam volume, while the highest increase in foam volume has been observed for ice cream mixture that has been treated in combination with mechanical and ultrasound treatment. Also, ice cream mixtures having higher amount of proteins in composition had shown higher foam stability. It has been determined that optimal treatment time is 10 minutes.
Ultrasonication is the application of high intensity sound waves at frequencies between 16 kHz and 100MHz. Diagnostic ultrasound involves low‐amplitude propagation, which is concerned with the effect ...of the medium on the wave. The different applications of ultrasound in the food industry include ultrasound and microbial inactivation, ultrasound in filtration, ultrasound‐assisted extraction and ultrasound in enhancing fermentation. Ultrasound has been shown to serve as a technique that can be used in many traditional food processing operations and processes, and innovative applications and designs of equipment are available. However, there are some disadvantages of using this technology as the production of free radicals is possible that can damage the product. Using ultrasound in a proper way by selecting appropriate amplitude, power, intensity, temperature, pressure and time is crucial to obtain the desired product.
High power ultrasound (HPU) represents a non-thermal processing method that has been rapidly researched and used in the last 10 years. The application of power ultrasound offers the opportunity to ...modify and improve some technologically important compounds which are often used in food products. One of them is starch. The aim of this research was to examine the effect of the high power ultrasound of 24 kHz frequency on rheological and some physical properties of corn starch. Various ultrasound treatments were used; an ultrasound probe set with different intensities (34, 55, 73 W cm−2) and treatment times (15 and 30 min) and ultrasound bath of 2 W cm−2 intensity and treatment times (15 and 30 min). Rheological parameters, turbidity and swelling power of corn starch suspensions were determined for native and ultrasonically treated corn starch suspensions. Differential scanning calorimetry was used in order to examine the pasting properties of corn starch. The results have shown that the ultrasound treatment of corn starch distorts the crystalline region in starch granules. The results of differential scanning calorimetry measurements have shown a decrease in enthalpy of gelatinization. A significant decrease in consistency coefficient (k) has also been observed. The consistency coefficient decreases stepwise jointly with the increasing ultrasound power. The increase in the swelling power is associated with water absorption capacity and corn starch granules solubility, respectively.
Many novel and innovative techniques are nowadays researched and explored in order to replace or improve classical, thermal processing technologies. One of newer technique is technique of minimal ...food processing, under what we assume ultrasound processing. Ultrasound technology can be very useful for minimal food processing because transmission of acoustic energy through product is fast and complete, which allows reduction in total processing time, and therefore lower energy consumption. Industrial processing is growing more and more waste products, and in desire of preservation of global recourses and energy efficiency, several ways of active compounds extraction techniques are now explored. The goal is to implement novel extraction techniques in food and pharmaceutical industry as well in medicine. Ultrasound assisted extraction of bioactive compounds offers increase in yield, and reduction or total avoiding of solvent usage. Increase in temperature of treatment is controlled and restricted, thereby preserving extracted bioactive compounds. In this paper, several methods of ultrasound assisted extraction of bioactive compounds from plant materials are shown. Ultrasound can improve classic mechanisms of extraction, and thereby offer novel possibilities of commercial extraction of desired compounds. Application of sonochemistry (ultrasound chemistry) is providing better yield in desired compounds and reduction in treatment time.
Microwave extraction of bioactive compounds Monika Blekić; F. Chemat; Anet Režek Jambrak
Croatian journal of food science and technology,
01/2011, Volume:
3, Issue:
1
Journal Article
Peer reviewed
Open access
Microwave extraction presents novel extraction and treatment method for food processing. In paper, several examples of microwave extraction of bioactive compounds are presented. Also, novel ...innovative equipment for microwave extraction and hydrodiffusion with gravitation is presented. Advantage of using novel equipment for microwave extraction is shown, and it include, shorter treatment time, less usage or without any solvent use. Novel method is compared to standard extraction methods. Some positive and negative aspects of microwave heating can be observed, and also its influence on development of oxidation in sunflower oil subjected to microwave heating. Also, use of microwaves for the extraction of essential oils is shown. One can also see the advantages of solvent-free microwave extraction of essential oil from aromatic herbs in comparison with the standard extraction, and determination of antioxidant components in rice bran oil extracted by microwave-assisted method. Comparison of microwave and ultrasound extraction, as well as positive and negative aspects of the combination of microwaves and ultrasound is described.
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