quality control techniques for food safety

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Quality control techniques for food safety  Ultrasound Irradiation Cold Plasma Technology


Quality Control Techniques For Food Safety Quality Food quality is a sensory property that includes appearance, taste, nutritional value (nutrient content), health benefit (functional ingredient) or safety (chemical, physical, biological). It includes those attributes which affect consumers choice for a product. Need For Quality Food Major challenge for food industry is to maintain the food quality ; the reason being well aware consumers. For this reason food industry has to adopt certain techniques in order to meet the growing need of maintaining food quality; this is known as food quality control. The main issue which is considered while quality control process is to deteriorate the level of microbes and other contaminants in food. Techniques Ultrasound : Energy derived from sound waves Irradiation: Energy derived from ionising radiations Cold Plasma Technique: Energy derived from plasma Ultrasound What is Ultrasound? It is a form of energy generated by sound waves of frequencies that are too high to be detected by human ear, i.e. above 16 kHz. Ultrasound can propagate in gases, liquids and solids. Considered to be technologies that were developed to minimize processing and maximize quality and safety in food These applications include improvement in microbial inactivation, food preservation, manipulation of food texture and food analysis. Physics of Ultrasound The sound waves travel effectively through liquids which are comprised of closely compacted molecules Sound is transmitted as sequential sine waves whose height represents amplitude or loudness. A single full cycle is measured from peak to peak, and the number of these cycles per one second represents the frequency. The frequency is described in Hertz [Hz] which by convention is in honor of the German physicist Heinrich Hertz for his work on electromagnetic transmission. How can Ultrasound be applied in Food ? Ultrasound when propagated through a biological structure induces compressions and depressions of the particles and a high amount of energy is imparted. In food industry, the application of ultrasound can be divided based on range of frequency: low power ultrasound high power ultrasound Low Power Ultrasound: Low energy [low power, low intensity] ultrasound Principles of LPU for Food Analysis: It uses a small power level that the waves cause no physical and chemical alteration in the properties of the material through which it passes. This property is been utilized for non-invasive analysis and monitoring of various food materials during processing and storage to ensure quality and safety. Ultrasonic velocity (v) is determined by density () and elasticity (E) of the medium, according to the Newton-Laplace equation (Blitz, 1963). Newton-Laplace Equation: The Newton-Laplace equation is the starting point for the determination of isentropic properties of solution, using the speed of sound u and density (). This equation implies that the ultrasound velocity of the solid form of a material is larger than that of its liquid form. In food industry, the sensitivity of ultrasound velocity to molecular organizations and intermolecular interactions makes UVM Ultrasound Velocity Measurements suitable for determining composition, structure, and physical state of different food materials. It also helps in detection of foreign bodies and defects in processed and packaged food. Why Low Power ? Can provide information about the physiochemical properties of food materials, their composition, structure and physical state. The major advantage of this technique over other traditional techniques is that the measurement is so rapid and non-destructive. Applications of Low Power Ultrasound In Meat Technology In Fruits and Vegetables In Cereal products Ultrasonic monitoring for food freezing High Power Ultrasound: High energy [high power, high intensity] ultrasound 20 and 500 kHz Disruptive and enforce effect on the physical, mechanical, or biochemical properties of foods. These effects are promising in food processing, preservation and safety. The chemical and biochemical effects are effective tools for sterilizing equipments, preventing contamination of food processing surfaces by pathogenic bacteria and removal of bacterial biofilms. Principle of HPU Factors that affect power ultrasound are energy, intensity, pressure, velocity and temperature. Where, Pa is the acoustic pressure (a sinusoidal wave), which is dependent on time (t), frequency (f) and the maximum pressure amplitude of the wave. Pa max is related to the power input or intensity (I) of the transducer: I = Pa max/ 2v , where is the density of the medium and v is the sound velocity in the medium. Mechanical Chemical and Biological Effects: Why HPU ? Ultrasonic Inactivation of Microorganism The most common techniques currently used to inactivate microorganisms in food products are conventional thermal pasteurization and sterilization. Thermal processing does kill vegetative microorganisms and some spores; however, its effectiveness is dependent on the treatment temperature and time. The magnitude of treatment, time and process temperature is also proportional to the amount of nutrient loss, development of undesirable flavors and deterioration of functional properties of food products. High power ultrasound is known to damage or disrupt biological cell walls which will result in the destruction of living cells. Unfortunately very high intensities are needed if ultrasound alone is to be used for permanent sterilization. However, the use of ultrasound coupled with other decontamination techniques, such as pressure, heat or extremes of pH is highly applicable. Thermosonic (heat plus sonication), manosonic (pressure plus sonication), and manothermosonic (heat plus pressure plus sonication) treatments are likely the best methods to inactivate microbes, as they are more energy efficient and effective in killing microorganisms. The advantages of ultrasound over heat pasteurizationinclude: Minimizing of flavor loss, greater homogeneity and significant energy savings. The effectiveness of an ultrasound treatment is dependent on the type of bacteria being tested, amplitude of the ultrasonic waves, exposure time, volume of food being processed, the composition of food and the treatment temperature. Ultrasound in Food Industry Major Significance to Industry and Consumers Better quality and Healthy Food High Efficiency Saves Energy and Costs Food Irradiation Process involved packaged food is passed through a radiation chamber on a conveyor belt It is passed through a radiation beam, like a large flashlight, instead of coming in direct contact with the radioactive materials How does Food Irradiation Works? Food is exposed to a carefully measured amount of intense ionizing radiation. When food is irradiated, the radiation energy breaks the bonds in the DNA molecules of microorganism. Thus, the organism dies or becomes unable to reproduce. Frozen foods take larger radiation dose to kill microbes. The effectiveness of the process depends on the organisms sensitivity to irradiation. The food irradiation process uses three types of ionizing radiation sources: cobalt-60 gamma sources : most commonly used as they can deeply penetrate into food electron beam generators x-ray accelerators gamma rays Dose Effects Absorbed dose is measured as the quantity of radiation imparted per unit of mass of a specified material. The unit of absorbed dose is the gray (Gy) where 1 gray is equivalent to 1 joule per kilogram. Low doses (up to 1 kGy) inhibit sprouting in tuber, bulb and root vegetables, inhibit the growth of asparagus and mushrooms, and delay physiological processes (ripening, etc.) in fruits Medium doses (1 to 10 kGy) extend the shelf life, eliminate spoilage and pathogenic microorganisms High doses (10 to 50 kGy) can be used for industrial sterilization and decontamination of certain additives or ingredients Parasites and insect pests, which have large amounts of DNA, are rapidly killed by an extremely low dose of irradiation. It takes more irradiation to kill bacteria, because they have less DNA. Viruses are the smallest pathogens that have nucleic acid, and they are, in general, resistant to irradiation at doses approved for foods. Another useful effect: it can be used to prolong the shelf life of fruits and vegetables because it inhibits sprouting and delays ripening. IMPACT !! It has been studied that when irradiation is used as approved on foods: Disease-causing microorganisms are reduced or eliminated The nutritional value is essentially unchanged The food does not be