Fundamental Principles of High Pressure Processing - Coursework Example

Food Process Technology: High Pressure Processing Food Process Technology: High Pressure Processing Fundamental principles and theory of high pressure processing History Food processing using high pressure processing was first reported in the late 19th century in the USA parts of Western Virginia, in precisely 1899. Through the application of hydrostatic pressures, it was discovered that micro-organisms could be destroyed, helping keep food stay longer than its initial shelf life without any preservation technique. With pressures that ranged around 658 MPa applied for approximately ten minutes, food products like meat, fresh juices, fresh milk, and a diverse variety of fruits were found to have a longer shelf life. However, despite the potential that high pressure food processing showed back then, counter-results in the early 20th century and the challenges of high pressure unit manufacturing and packaging material ensured that the experiments were discontinued. The counter measures included evidence that the process destroyed some essential egg-white protein structure (Fellows, 2000). Key advanced research of the process resurfaced in the late 1980s after major changes in the forefront of manufacturing sector ensured the availability of packaging material that was a major hindrance to the research back then. Japan was at the forefront of this food process technique, and given its agility, first products to be commercialized were in the market in the early 1990s. Food products that made it into the market, processed using high pressure technique largely constituted of fruit juices and jams. These were packed in plastic packs that were flexible and tightly sealed to ensure effective preservation. Under chilled environments, these food products had a an average shelf life of 2 months, a time that was stated as being adequate to prevent any enzyme activity that would usually render the food spoilt after a short period of time under normal environments. Apart from juices and jams, other varieties of food products that made it into the commercial zone included other varieties of fruit forms such as yoghurts, salads, sauces, and jellies. Products processed using high pressure reached the US market in the mid-1990s. However, these products were merely found in the European markets even up to the start of the 21st century. One key limitation to the products’ popularity despite the effectiveness and shelf life promised by the process was the high prices of the products that were close to three or four times the prices of the unprocessed food of similar description, that is, the unpreserved food (Fellows, 2000). High Pressure Processing Theory The technique of high pressure processing is implemented when up to 1000 MPa is applied to submerged, packaged food. The liquid used ensures that the pressure distribution among the packaged food is supplied equally, spreading the high pressure to a majority of the food that destroys micro-organisms. This destruction is usually courtesy of bacterial barosensitivity during their growth log phase, a term referring to bacterial sensitivity to high pressures. With previous experiments showing that 350 MPa or 400MPa applied for 30 and 5 minutes respectively could inactivate bacteria, causing a huge percentage of reduction of the same in food, the upper limits of 1000MPa as initially declared is effective enough to guarantee any consumer of such processed food of hygienic consumption (Fellows, 2009). The effect of high pressure on bacteria has been explained scientifically through key observations. At high temperatures, the spores on bacteria are usually forced to germinate. This forced growth affects the bacteria by inactivating the germinated cells. Additional mild heating of temperatures between 55 – 60o causes the spores to get destroyed at pressures ranging within 400MPa. Diverse strains of enzymes and bacteria have been observed to harbor diverse barosensitive levels. Depending on the strains, different pressure levels and heat would be required to inactivate them. Others have been known to succumb to low pressures while some have been known to withstand high pressures of even 1000MPa. Example of hardcore enzymes are peroxidase usually found in peas and pectin in strawberry, known to withstand highs of 1200MPa. Ironically, some enzymes’ activities have been known to be heightened by high pressures due to the reactions of excreted substrates from their bodies by the growth of their cells (Tadapaneni, Banaszewski & Patazca, 2008). The application of high pressure technique n food processing has been justified by the research findings showing that only non-covalent chemical bonds could be affected by high pressures. Covalent chemical bonds, known to be the main composition of many foods, and precisely those that contribute to a food’s nutritional value, flavor, and texture, stay intact under high pressures. However, microbial contents of food, made up of non-covalent bonds are destroyed, making them inactive in food content. The non-requirement of heat in the process also ensures that no nutritional value is destroyed whatsoever. This food processing technique has been considered effective due to the uniformity of the pressure applied to food. Other food processing techniques such as convective heating, dielectric heating, microwaving, or radiant heating have been found to harbor weak points as the food sometimes is sparsely affected given the inadequate heat experienced in hidden or poorly placed areas. Application of High Pressure Processing in dairy and beverage processing industries Dairy products have been identified as some of the fastest perishable food products apart from sea food among other food products. With regard to this, an initial investigation was done on the potential benefits that high pressure processing could be applied in dairy products, and thus to some extension, other beverages. A prompt to this study was initiated by the continuous popularity that high pressure processing was gaining in the food industry, with key focus on Japan as the country where most of the food processing was conducted using this method. A variety of areas were discovered to have the potential of incorporating high pressure processing, and these included: ice cream aging, cheese ripening, milk protein hydrolysates, and modified functionality on milk proteins (Koutchma, 2014). High Pressure Processing on Cheese ripening Under normal circumstances, cheese ripening takes an average of 60 days, an eternal duration if at all any dairy commercial business person would be asked given the high demand of this product. Despite the duration taken for the aging to occur, there was also limited authority for any farmer or processing plant to declare the safety of the cheese with regard to bacterial infection and infestation. This limitation caused a lot of impatience and doubt among both consumers and dairy farmers and processors with limited alternatives to turn to. To counter the challenge of long duration used for cheese ripening, an initial experiment was done where Cheddar cheese ripening was enhanced using 50MPa at 25o. This took only 3 days to complete the ripening, unlike the 60 days, or even up to 90 days that was the norm for cheese ripening. Casein, an important formation of Cheddar cheese was observed to increase with the exposure of high pressure. The production of this component was directly proportional to the increase of pressure exerted in the process (Smith & Hui, 2004). Justification of the effectiveness that high pressure processing had in cheese ripening had to be furthered by concurrent tests on other compositions of cheese matured under normal duration and that matured under pressurized environment with a little temperature boost. Everything was found to be approximately at the same level, thus justifying the process’ efficiency just as the initial process that was used for cheese ripening. This was a major breakthrough in the dairy sector as it ensured major economic gains coupled with all the initial benefits that cheese ripening came with. High Pressure Processing in milk product inactivation of micro-organisms Milk has quite a high number of nutrients associated to its composition, a reason why any food processing technique requires keen analysis before application. Without this, there are risks of diluting the nutritional value of milk. Apart from the many food processing techniques analyzed to be suitable for milk preservation, high pressure processing drew interest among researchers on its effectiveness given the initial success it yielded in fruit preservation. Eventual experiments done under various environments to subject milk to various pressures and temperatures for the purpose of ensuring a cascading result on all microorganisms showed diverse results on different organisms. Microbial inactivation was seen to occur on different organisms under different pressure and temperature levels. For instance, Escherichia coli showed an increased level of sensitivity to pressure subjected to increased temperatures while Staphylococcus aureus were observed to be more resistant to pressure. Subsequent tests carried out among other strains were carried out to study the variability of high pressure processing on milk. These assisted in the determination of the optimal environments adequate enough to inactivate micro-organisms in milk (Schaschke, 2013). Results obtained from this initial experiments allowed the application of high pressure processing in milk, ensuring a technique that would ensure milk was able to stay packed in storage under considerable environments for a much longer time compared to the initial shelf life. High pressure processing for beverages Extracted fruit juice and other beverages have always had a tendency of quick decomposition given their delicate balance of nutrition and broken down elements. With increased demand in fresh beverages other than processed juices and other beverages that contained a lot of chemicals, there was a need to incorporate an effective yet secure and reliable food processing technique for the preservation of beverages. Intense research and study eventually indicated that high pressure processing was an appropriate technique that could be used in preserving beverages. Prior to the application of high pressure processing to the preservation of beverages, most preserved beverages had a high content of chemicals that were meant to act as preservatives. These chemical preservatives tended to affect most consumers due to their various allergies and reactions to the components in these chemicals. However, the ushering in of high pressure processing in the preservation of beverages eliminated the need of chemical addition in fruit juices and other beverages by simply the application of controlled pressures before packaging. This ensured consumption of beverages that could be termed fresh, with their original texture, nutritional content, and taste. Other beverages used to suffer heat application all for the sake of preservation. This caused a lot of damage to important nutritional values to particular beverage components. With the introduction of high pressure processing, the need to heat these beverages was eliminated, ensuring that consumers wholly partook their beverages with their capacity nutritional values. The motivation to apply high pressure processing technique in beverage companies for preservation was derived from the high demand for nutritious and safe beverages. Consumers were exhausted with the consumption of useless beverages laden with a lot of chemicals that had the potential to harm the body. Equipment used for High Pressure Processing of Food Before high pressure food processing became popular as it is currently, one of the key hindrance apart from packaging that repulsed food processors was the equipment used for the entire process. Construction of most high pressure processing machines require a certain level of specialization and resources that are expensive. It was estimated in 1996 that basic juice high pressure plant cost close to 20 times that of a plate heat exchanger system of equal capacity in food processing. The main equipment composition of any high pressure processing machinery or system are: Pressure generation system Pressure vessel and a closure Temperature control device Materials handling system A basic structure of a high pressure processing equipment (Fellows, 2000). The pressure vessel that comes with a closure is made up of strong, tensile steel able to withstand a lot of pressure ranging between 400 and 600 MPa. Normally, the pressures surpass this level and it may require stronger material for the vessel. The closure is equally made of strong and similar material to the vessel, but in a flexible way to ensure quick removal. During operation, a medium for transmitting pressure is directed to the pump after all air has been removed from the vessel. This is done until an optimal or desired pressure level is achieved. The pumping is usually categorized into two: either direct or indirect compression (Feeherr, Doona & Dunne, 2007). The temperature control device is used to regulate the amount of heat applied on products during the process. The heat is usually supplied to the vessel by a heating or cooling medium that is usually placed in a container surrounding the pressure vessel. Usually, the container is such that it can maintain a constant temperature usually required in high pressure processing. However, in case of a special need to change the temperature time and again, an environment is usually created by the container medium, usually with the help of an internal heat exchanger, to make this simpler. The pressure generation system is fundamental in the production of enough pressure required for the entire high pressure processing. This system usually requires tremendous energy sources to facilitate for the high demand in pressure. It is always fitted with good material to equip it with the capacity to withstand any pressure produced, and avoid any leakages or disasters in case of any mishaps. The materials handling system is comprised of various compartments to hold various materials, including the processed food. This system requires material best suited to withstand deterioration from various food components and other basic things like rust and weight. This system’s cleanliness also needs to be maintained to avoid any contamination during the food processing period. Comparison of High Pressure Processing with Conventional Processing Techniques There are many other alternative processing techniques that could replace high pressure processing. These include convective heating, pasteurization, dielectric heating, microwaving, or radiant heating. However, compared to high pressure processing, there are many advantages that could not be experienced in the alternative conventional processing techniques. These are discussed as below. Advantages of High Pressure Processing over Conventional Processing Techniques The entire characteristics of the fresh product before processing always remain almost intact. These include texture, taste, and nutritional value, all characters that retain a food’s quality. Most other conventional processing techniques, especially those that incorporate heating and the addition of other chemical components exhaust a great deal of the product’s components. High pressure processing gives surety of food safety given its immense capabilities of destroying a wide range of pathogens. This is due to its capability during processing to inactivate microorganisms equally by spreading the pressure to every food particle. In other conventional processing techniques, there is usually sparse distribution of the processing medium, giving a chance to other medium to still thrive, causing a danger to the consumers (Clark, Jung & Lamsal, 2014). The advantage to extend shelf life more than other conventional techniques is a plus that many consumers value. This is because of the assured length of time that a food can be guaranteed in custody. There is also less risk of the consumption of expired food. With high pressure processing, there is usually minimal or no need at all of any chemical preservatives. This reduces the chance of contaminated foods or various allergic reactions by diverse consumers usually experienced from various chemical compositions of food that is apart from the food’s nutritional composition. The process is also environmentally friendly and hygienic given its basic requirement of only an energy source and water. Most of the conventional techniques require excessive energy and dangerous chemicals that endanger the ecosystem. For instance, the disposal of chemical remnants of these other techniques may endanger animals and plants, and worse, human beings that may interact with them unknowingly. Disadvantages of High Pressure Processing over Conventional Processing Techniques Despite its numerous advantages, high pressure processing also has some disadvantages as compared to other conventional processing techniques. The high dependence on the exposure and multiplication of spores of inactivation of bacteria has suffered a setback as research has determined that some spores are resistant. This leaves the doubt of the foods prepared under this method of being completely safe for consumption. Barosensitivity measures varied among the various bacteria makes it a challenge to determine the pressure to be exerted on different foods to ensure inactiveness of the bacteria. As a result, foods could still retain some level of bacteria, leaving the consumer with a high chance of disease of poisoning with regard to the consumption of bacteria-infected food (Rastogi & Raghavarao, 2007). Food that has been processed using high pressure processing requires a certain level of temperature to ensure that the inactive bacteria do not get activated. This could be a challenge as some consumers could lack equipment such as refrigerators to keep such food. The installation of the equipment used for high pressure processing is exorbitantly high, thus requires a considerable amount of capital before equipping a plant with the equipment for the processing. References Clark, S., Jung, S., & Lamsal, B. (2014). Food Processing: Principles and Applications (2nd ed.). New Jersey: Wiley. Feeherr, F., Doona, C., & Dunne, P. C. (2007). High Pressure Processing of Foods. New Jersey: Wiley-Blackwell. Fellows, P. (2000). Food Processing Technology Principles and Practice (2nd ed.). London: Oxford Brookes University Fellows, P. (2009). Food Processing Technology: Principles and Practice (Woodhead Publishing in Food Science, Technology and Nutrition (3rd ed.). Cambridge: Woodhead Publishing Koutchma, T. (2014). Adapting High Hydrostatic Pressure for Food Processing Operations. New York: Academic Press. Rastogi, N. K. & Raghavarao, K. S. M. S. (2007). Opportunities and Challenges in High Pressure Processing of Foods. Mysore: Central Food Technological Research Institute. Schaschke, C. J. (2013). Developments in High-Pressure Food Processing (Food Science and Technology). New York: Nova Science Publishers, Inc. Smith, J. S., & Hui, H. Y. (2004). Food Processing: Principles and Applications. New Jersey: Wiley-Blackwell. Tadapaneni, R. K., Banaszewski, K. & Patazca, E. (2008). Composition and Antioxidant Capacity of Strawberry-Based Beverages. Bedford Park, IL: Center for Nutrition Research. Read More