High pressure processing

hi students welcome to you GCE pachala I'm dr. a Sanghamitra assistant professor from for technology department convention here in college okay let me move on to our today's topic on high pressure processing consumers always prefer minimally processed foods with little or no chemical additives also they prefer food product which is safe to consume and retains the nutritional and sensorial characteristics for a product to be safe it should be free from chemical and biological hazards such fruit product was conventionally produced using thermal processing methods but it degrades the nutritional properties and alters the sensory properties such as color flavor and taste high pressure processing is one of the promising non-thermal techniques for food preservation that effectively inactivates the microorganisms to reduce the risk of foodborne diseases and has a very minimal effect on taste texture or nutritional characteristics on completion of this module you will be able to identify the principle behind high pressure processing on inactivation of microorganisms and commercially available high pressure processing foods first we'll look into the interaction about high pressure processing high pressure processing also called as hydrostatic pressure processing is one of the emerging methods of food preservation technique which allow the foot to retain its original qualities while extending the shelf life of the product this method uses pressure rather than the conventional method of heat to destroy the microorganisms due to the absence of heat treatment this method is a type of cold pasteurization technique in this method the product to be processed is sealed in its final package or introduced into a high-pressure vessel and subjected to a high ISO static pressure of 300 to 600 mega Pascal transmitted by water high-pressure processing is also called by other names such as hydrostatic pressure ultra high pressure processing and Pascal ization but height assigned us from West Virginia University agricultural experimental station was the first to pasteurized different food product in the late 80s he found that high-pressure could disable harmful microorganisms in foods like fruits vegetables milk and meat in the early 90s a study by WP lars and demonstrated that high pressure processing killed vegetative bacteria found in food products in most of the high pressure processing operations the process is carried out between 400 to 600 mega Pascal at room temperature depending upon the composition of the product due to the effect of high pressure the temperature of the product in the pressure chamber may rise by three to six degree Celsius for every hundred mega Pascal increase in pressure the quantity of pressure applied can be visualized when to 5000 kg elephants are balanced on and one centimeter square area will produce a force of about thousand mega Pascal or ten times the pressure greater than that at the bottom of the deepest ocean so from the given diagram you can visualize the different ranges of pressure zones on moving to the principles of high pressure processing it works on two principles such as li chatlier's principle and isostatic rule the first is Lee chatlier's principle it states that when a system at equilibrium is disturbed the system responds in a way that it tends to minimize the disturbance the applied pressure enhances the reaction leading to volume decrease for example reactions such as phase transition start gelatinization protein denaturation chemical reactions are accompanied by a decrease in volume will be enhanced by pressure isostatic rule states that the pressure is instantaneously and uniformly transferred throughout the sample under pressure whether the sample is in direct contact with the pressure medium or hermetically sealed in a flexible package that transmits ratio pressure is transmitted in a uniform and quasi instantaneous manner throughout the sample independent of the size and shape of the sample if a product contains sufficient amount of moisture pressure will not damage the sample as long as the pressure is applied uniformly in all the directions thus due to isostatic pressure the foot product is not collapsed during high pressure processing next we'll see about the packaging material suitable for high pressure processed foods the foot sample before high pressure processing must be packed the foot sample is treated together with the package and hence the produce remains safe and secure till the packers open by the consumer the foot sample can be packed using plastic bottles flexible pouches semi-rigid trays are cups with flexible lids Wakeham packing is ideal for HPP treatment rigid packaging material such as glass metal or ceramics are not used for HPP treatment oxygen impermeable an opaque packaging material or specialized use for HPP treated food to retain the original color and flavor of the food headspace is important factor to be considered during in package processing generally headspace is kept to a minimum in order to allow pressures inside to be reached more efficiently other factors needed to be considered during in package treatment or delamination and loss of seal integrity the packaging material should not leash the packaging chemicals into the sample regarding the working of industrial high-pressure processing systems there are three types they are batch continuous and semi-continuous type both liquid and solid food products which are pre-pack can be used in batch type system wellas continuous and semi continuous system can be used only for liquid food products high pressure processing system consists of pressure generation system pressure transmitting fluid pressure chamber and closure temperature control device and material handling system different pressure mediums such as silicon oil propylene glycol water ethylene glycol Casta sodium benzoate solutions were reported in literature's but water is commercially used as the pressure medium a pump is connected to the pressure chamber to pressurize the water hydrostatic pressure is applied to the foot pack through its pressure medium that is water the pad and sealed food product or immersed in the pressure medium in a pressure chamber which is completely sealed the pressure applied varies between 300 to 600 mega Pascal at ambient temperature for most of the commercial applications products or health for three to five minutes at 600 mega Pascal once the desired pressure limit is reached the pump is stopped and the valves are closed and the pressure can be maintained without further energy input after the desired holding period the pressure chamber is depressurized pressure transmitting fluid is released and the foot pack can be removed in activation of microorganism is one of the main objective for the application of high pressure processing of foods let us discuss about the effect of high pressure on microbial inactivation the application of pressure alters the permeability of cell membrane and disturbs the physico-chemical balance of t-cell the leakage of intercellular constituents through the damaged cell membrane leads to cell death after HPP treatment and this treatment also inhibits DNA replication and gene expression enzymes compared to proteins nucleic acids are more resistant to pressure induced denaturation even at pressure of about thousand mega Pascal the structure of nucleic acid can remain intact but the enzymes are affected by high pressure hence the mechanism of DNA replication and transcription and translation into proteins are inhibited the innovation of protein synthesis is also caused by dissociation of ribosomes and the pressure HPP treatment inhibits the growth of microbes and food but the sensitivity of microorganisms to the pressure varies between species and strain of same species gram-positive bacteria are more resistant to pressure than gram-negative bacteria yeast and molds bacterial spores are highly resistant to high hydrostatic pressures also the sensitivity to pressure varies based on the stage of growth cycle of microorganism for example cells and exponential phase are more sensitive to cells at log or stationary phase of growth the application of high pressure leads to changes in cell morphology induces biochemical reactions denaturation of protein and key enzyme and disruption of genetic mechanisms the extent of inactivation of microbes depend on type and number of microorganisms magnitude and duration of treatments temperature and composition of foods daddy shows that ready to eat meat treated at 600 mega Pascal pressure at 20 degree Celsius for 180 seconds showed no changes in censorial quality but showed a four log reduction and Listeria monocytogenes in inoculated product also the HPP treatment extended the shelf-life of refrigerated samples most type of East are inactivated when exposed to 300 to 400 mega Pascal at 25 degrees C within a few minutes whereas East spose need high pressure for inactivation similarly Pseudomonas fluorescens and Listeria that completely inactivated in meat products processed at pressures more than 280 200 and 400 mega Pascal's respectively at 20 degree Celsius but after a storage period of three to nine days at three degree Celsius Pseudomonas species were observed in the treated sample the reason maybe the organisms were not completely inactivated but stressed during the processing in such cases high pressure processing can be coupled with other processing methods such as moderate thermal treatment of 50 degree Celsius during high pressure processing treatment of food it has few effect on chemical composition of foods also for example the temperature of water increases approximately 3 degree Celsius per 100 mega Pascal the increase in temperature is higher in case of food rich in fat content and the effect of HPP on low molecular weight component is minimal this can be seen in case of vitamins pigments and flavor which remains relatively unchanged during HPP treatment compared to the thermal treatment during his VP treatment of minced beef pink color of meat treated at 200 to 350 mega Pascal turned to gray brown at 400 to 500 mega Pascal this discoloration is due to global denaturation heme displacement or release or oxidation of ferrous myoglobin to ferric myoglobin at 100 mega Pascal regarding the effect of HPP on quality of food color in food products such as meat pressure-induced denaturation results and changes in the physical functionalities and changes in color of the product compared to the raw meat product the color degradation can be partly reduced by packing the meat under way come with an oxygen scavenger however the color of cook meat is not largely affected in case of HBP treatment of green vegetables the color of the product showed an intense green color after treatment this might be due to disruption of cell which resulted in leakage of chlorophyll into the intercellular spaces yielding a more intense bright green color on the vegetable surface such changes of color from green to olive green was observed in case of HPP treated green beans during HPP treatment of fruit products such as mango pulp grape juice no significant color change was observed after treatment but it was reported that anthocyanin pigments in HPP treated strawberries black currants were not stable during storage this might be due to incomplete inactivation of enzymes during HPP treatment but we got to the effect of HPP on quality of food texture this treatment results in little or no permanent change in texture of food product which are devoid of air pockets however shrinkage can occur due to the distortion and the product with air voids and this treatment improved the textural properties of foods like melting of cheese generation of Christian and formers of fridge tables mother and uniform textured gels are obtained an HP induced fish gels than the gels produced by heat treatment also the first gels reading the color and flavor of the original product during the pressure holding stage of the treatment the firmness of pure pineapple Kara paper either decreased or recovered gradually when treated at 100 mega Pascal and 200 mega Pascal the reason for the increase to formless is due to the activity of pectin methyl ester ace during the high-pressure treatment d esterified pectin forms a gel network with divalent ions resulting in increased hardness when cherry tomatoes were treated up to pressure of 400 mega Pascal it showed a increased textual damage whereas at pressures above 400 mega Pascal a less damage was observed in the sample and the product resembled more like the untreated samples along with the extension of shelf-life HPP treatment readings a sensorial properties of majority of wood product HP treated sausages were preferred on the basis of appearance and taste compared to the thermally treated sausages similarly in case of HPP treated fish filleted the taste was not altered after treatment but the pressures above 300 mega Pascal's produced a product with opacity similar to that of light coke product white grape juice was treated under pressure of 400 to 500 mega Pascal and the color and sensory characteristics were investigated the pressure-treated juice samples remind more stable and retain the sensorial characteristic than the control juice during 16 days of storage HPP treatment of food products provides shelf-life similar to that of the thermal pasteurization this technique kills the vegetative bacteria the product requires refrigerated storage if the product is not acetic HPP treatment of food extends the shelf life by two or three times compared to the non pasteurized counterpart and improves the food safety in order to have a processed product with minimal changes in flavor color and texture HPP is better option with extended shelf-life shelf life of HPP treated products can be established based on microbiological and sensory testing hvp treated ham and poke on storage at 4 to 6 degree Celsius extended the shelf-life of product up to 8 weeks and also the product showed a good microbiological and sensory quality the HPP treated fruit juice lasts for about 30 to 45 days than the Rogers which lost normally for 3 to 5 days the major advantage of treated Jews are safer product that the retail stores can keep the product on their shell for much longer time without going into a waste let us now move on to the commercial status of HPP treated foods Japan is the first country to offer hvp treated food products HPP treated products are also available in other international markets in Spain France USA and these food products such as fruit juices smoothies jams jellies fruit purees soups sauces ready to eat meat products fish yogurt and salad dressing or commercialized the foreign drug administration and US Department of Agriculture have approved the use of high pressure processing as a post packaging pasteurization technique applicable for pasteurizing low acid food products and shelf-stable high acid food product along with the corresponding guidelines and regulations HPP treatment has both its advantages and limitations let us see one by one regarding the advantages of HPP this treatment can be used for both solids and liquids with or without packaging this technique is suitable for product with high moisture content and this treatment process raw product without significantly altering their flavor texture or appearance and this method is environment friendly and facilitates the package to withstand a change in volume up to 15 percent followed by a return to its original shape without losing the seal integrity or barrier properties hvp treatment inactivate spoilage causing microorganisms in activates enzymes and reduces the potential for foodborne illness this method promotes the ripening of cheese minimizes oxidative browning and extend the shelf life for food samples it does not alters the shape of food because the pressure is applied evenly from all sides this method retains the freshness texture flavor color and appearance of the food product and it is highly effective against mold bacteria and virus hvp treatment of meat reduces the usage of salt under the limitations of high pressure processing there are a few points to be considered HPP treatment is not suitable for products with encapsulated yeah such as bread mushrooms and marshmallows the capital cost of HBP set up for a commercial scale is very high compared to the conventional thermal methods the HPP equipment requires high precision in construction and the handling of equipment and the process is little complex a high level of maintenance is required and foam packaging is not suitable for HPP treated either because it is too compressed we have now come to the end of this module let me summarize the points HPP treatment is also called as hydrostatic pressure processing with pressure of 300 to 600 mega Pascal which is used for food products high pressure processing works on two principles such as Lee Chatelier principle and isostatic rule Wakeham packing is more ideal for hvp treatment religious packaging materials are not suitable for high pressure processing treatment at high pressures the permeability of cell membrane get alters and disturbs the physical chemical balance of the cell which inactivates the vegetative microorganisms the pressure sensitivity of microbes varies based on type species strain stage of growth cycle of microorganisms industrial high pressure processing systems are of Bosch type continuous type and semi continuous type HPP treatment will increase the temperature of foods through adiabatic heating approximately three degree Celsius per 100 mega Pascal hope you have got an understanding of what high pressure processing is thank you for your patient hearing happy learning thank you

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Length: 22min 42sec (1362 seconds)

Published: Tue May 22 2018