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To design a food product that could be used for a North Pole expedition. This product must be easy to regenerate in an arctic environment and packaged so as to eliminate the risk of physical, microbial and chemical contamination. The food will need to be easy and light to carry as the expedition is taking place on foot and the weight of the product will be an issue. Perhaps most importantly, the food needs to be nutritious for the people embarking on the expedition as this will be the only (other than energy bars) to stock up on protein and carbohydrates.
The North Pole is arguably one of the most inhospitable environments on the planet but yet a handful of people each year set off with the goal of reaching it on foot. Most explorers set off from Cape Columbia which is the northernmost point of Canada. From here they will walk 475 miles across the frozen Arctic Ocean and will encounter dangers of all shapes and sizes, from wildlife, hidden glacier caves and frost bite. The red line on the map below shows the direct route that will be taken by the majority of people taking on the challenge.
There is an enormous amount of training required to be able to complete an expedition of this nature as once the expedition is started there is little, if any, external help available. This means that everything that is needed for the expedition must be carried on a sledge or on the person. Many factors about an expedition such as this are disheartening, such as the "negative drift" that occurs through the movement of the Arctic ice that can mean the expedition personnel may go to sleep having completed 12 miles that day only for the ice movement during the night to take 3 or 4 miles off the days total. Not only do will they be battling the negative drift during night time but they will be faced by a wind chill factor of -40Â°c 24 hours a day. All of this combined would leave even the most hardened explorer disheartened, therefore the food product that is to be designed will need to be visually appealing as well as being apetising. This will act as a morale boost as well as a meal.
The product that is being designed must be:
Easy to cook/regenerate
Easy to carry
Easy to open
Packaged in a way that will not permit physical, chemical or microbiological contamination
Not be adversely affected by freezing conditions
The people that will be attempting this expedition will be using massive amounts of energy to reach their goal for the day and will need a meal that will not only build up energy levels for the next day but also provide protein to aid in muscle repair. The product that is being designed will be a pasta based dish with chicken, carrots, peas and onion incorporated into it. The bulk of this dish will be pasta and this will be the main source of carbohydrates for the consumer. Carbohydrates require less water to digest than proteins or fats and are the most common source of energy. The chicken in this product will contain the protein that is required for muscle repair. Proteins and fats are vital building components for body tissue and cells and are also a source of energy for the body. The carrots will provide an intake of vitamin A which is an essential human nutrient and they will provide also carbohydrates. Also, the peas in this product will provide a source of vitamin C.
Potential hazards with the final product and raw ingredients
The raw ingredients that are going to be used for this product must be of a good quality. Micro-organisms that were in the product before drying or were introduced during processing can survive for extended periods. (Adams and Moss). If the raw product is of a good microbiological standard it will make it less likely that there will be microbiological failures upon final product testing. Therefore, reducing the chance of food related illness from the product. This is especially important with respect to the pathogens if they were present in hazardous numbers before drying or if time and temperature allow them to resume growth in a product that is re-hydrated before consumption (Adams and Moss)
My raw ingredients will be;
There have been a number of instances where the survival of pathogens or their toxins has caused problems in products such as chocolate, pasta and dried milk. (Adams and Moss).
The main pathogen associated with pasta is Bacillus cereus. This pathogen is a gram positive, aerobic, spore forming rod that is facultatively anaerobic. It grows over a temperature range from 8 - 55Â°c, optimally around 28-35Â°c and does not have any marked tolerance for low pH (min 5.0 - 6.0), depending on the acidulant) or water activity (min. ~0.95). (Adams and Moss). This hazard will be controlled because the final product will have an aW of around <0.60. This will inhibit the growth of B.cereus and the pathogen will spore in these adverse conditions. Once the pathogen has reached the stage of a spore it is no longer able to cause harm in that state and will only have the potential to cause harm again if the spore germinates. The spore will only germinate in favourable conditions and these conditions will not be available within the product at any stage as the aW will always stay at <0.60 and the product will be frozen.
The main pathogens associated with carrots, peas and onion would be E.coli 0157, Clostridium perfringens and Bacillus cereus. Organic vegetables are not going to be used as the risk of E.coli 0157 is higher than that of standard vegetables. This is due to the growing conditions of these vegetables and mainly the use of fertilisers that may be harbouring the pathogen. E.coli 0157 is the most pathogenic form of the bacteria E.coli. E.coli is a member of the enterobacteriaceae family and is a measophile that is catalase positive, oxidase negative, gram negative and a non sporulating rod. (Adams and Moss). The growth range of this bacteria is 7 - 50Â°c with an optimum of 37Â°c (human body temperature). This bacteria shows no marked heat resistance, with a D value at 60Â°c of the order of 0.1 min. A near neutral pH is optimal for growth but growth is possible down to pH 4.4 under otherwise optimal growing conditions. The minimum aW for growth is 0.95. (Adams and Moss). This pathogen will be controlled in my product by the cooking process that will eliminate it to a safe level through the application of heat and then the remaining bacteria will be controlled through the low aW of the product after the freeze drying process.
Clostridium perfringens is a gram positive, rod shaped, spore forming anaerobe that has a growth range of 12 - 50Â°c although its growth is very slow below 20Â°c. At its temperature optimum, 43 - 47Â°c, growth is extremely rapid with a generation time of only 7.1 min at 41Â°c. vegetative cells show no marked tolerance to acid (minimum pH 5, optimum 6.0 - 7.5) and have a minimum aW for growth of 0.95 - 0.97. (Adams and Moss). This bacteria is found in soil and dust and may be able to contaminate vegetables whilst at their growth stage. Again, the pathogen will be controlled through the low aW of the final product following the freeze drying process.
The B.cereus risk involved with the vegetables being used in this dish is already listed above as a hazard associated with the pasta. B.cereus is found in soil and dust and has the potential to cause problems with root vegetables due to the fact that the vegetables are grown in the ground and therefore may be in contact with spores of B.cereus.
Only one pre-cooked ingredient is going to be used in the meal and that is going to be pre-cooked chicken chunks. Audits would need to be carried out on the supplier of the chicken to ensure that the product is being manufactured in a way that will ensure that it is safe to eat. As this product is a ready to eat food it could be subject to a various number of pathogens due to cross contamination with raw products, staff, equipment and the environment. The chicken must be kept in sealed containers under constant temperature control until it is ready to be used. This constant temperature control will limit the growth of pathogenic bacteria.
Method of processing
All ingredients will be bought in raw except for the chicken that will be purchased already cooked. The chicken will be purchased from a reputable supplier, preferably one that deals with Military or a similar organisation that has ration packs. The chicken will be purchased in chunks and cooked rather than raw so as to reduce the risk of cross contamination in the preparation stage of processing.
The pasta shells will be bought in bulk and will be subjected to cooking which will cook the product and also cause B.cereus bacteria to spore. The carrot, peas and onions will all be pealed, chopped finely and pre washed for 4 minutes with a chlorine solution at a dilution rate of 25ppm. They must be finely chopped as the freeze drying process does not work effectively on dense products as the moisture particles will not evaporate effectively.
Following the cooking process, a rapid freezing process will follow. The product will then be blast frozen; this will allow the cooked product to be reduced to minus 18Â°c - 22Â°c. (A Dictionary of Food Hygiene). This blast freezing process will prepare the food for the first stages of the freeze drying process.
Method of preservation
The method of preservation that is going to be used to limit the growth of pathogenic micro-organisms is going to be freeze drying. Freeze drying is the evaporation of the water from a frozen food, so retaining nutrients and texture.
The freeze-drying process was developed during World War II as a method of preserving blood plasma for battlefield emergencies without requiring refrigeration or damaging the organic nature of the plasma. The technology was applied to consumer food products after the end of the war. Coffee was one of the first freeze-dried products to be marketed on a large scale. Today, many fruits, vegetables, meats, eggs, and food flavourings are freeze-dried. (http://www.answers.com/topic/freeze-dried-food)
This process will reduce the water activity (aW) of a product as the freezing process will turn liquid water into a solid, therefore limiting the aW of the product. "Microbial growth does not occur below an aW of 0.6. This applies to a number of food products but the fact microbial spoilage is not possible given proper storage conditions, does not mean that they do not pose any microbiological problems" (Adams and Moss). Freeze drying will be an effective method of processing as the low temperature and reduction of water activity will prevent growth, providing that the packaging is adequate for the conditions of storage that are required. (Adams and Moss) Products that have undergone freeze drying must stayed frozen for the duration of their life, until they are re-generated. I have chosen freeze drying as opposed to dehydration as the quality will not be affected as much as it would be if the food had been dehydrated.
The process of freeze drying is;
Small pieces of quick-frozen food are placed under vacuum and are then heated gently.
Ice crystals in the food turn directly into water vapour without first melting. This effect is called sublimination.
The food remains more or less the same size and after processing has a brittle and sponge-like character.
During dehydration water enters faster and more completely than with dehydrated products
The final quality is quite close to that of what the fresh item.
The main disadvantages to this process are that it is expensive to do and also the final product may become damaged if roughly handled. Also, this process will not destroy all bacteria and toxins. However, this product will have a very long shelf life (approx 6 months) providing the packaging stays in tact. (A dictionary of food hygiene). Large amounts of water also need to be used for the regeneration of this product. This may prove to be an issue if this process was being used for food that would be consumed as part of a space programme but for the conditions that are found in the Arctic it is not a problem as water and ice are the main two resources that are almost guaranteed not run out during the expedition.
The freeze drying process subjects products too low temperature and the reduction of water activity to prevent growth (Adams and Moss).
As the food is being freeze dried the product is already extremely light as around 98% of the water content of that food has been evaporated. The weight of this product will be approximately three quarters of the weight of a traditional wet pack and will also be easy to carry. Freeze dried foods must be sealed in airtight packaging to prevent them from absorbing moisture from the air.
This product is going to be packaged in a laminated foil pouch. Foil pouches are made from multilayer laminations and use adhesive to bind the laminated layers together. The adhesives used in this packaging must be food safe as there could be a potential risk of chemical contamination of the food should the adhesives not be food grade. This method of packaging will keep the prevent moisture income from the surrounding environment and will allow the food to have an extended life of up to 6 months or more.
The foil pouch will need to be fairly rigid so as to allow the product to have hot water added to it and then be consumed from the pouch. The primary purpose of the laminated layers within the pouch are to prevent the product absorbing moisture from the surrounding environment. However, the laminated layers will also reduce the heat transfer of the hot water through to the outer wall of the packaging that the consumer will be holding.
Other options for packaging could be plastic or metal cans. This method of packaging would be just as effective at keeping the product free from contamination but would prove more difficult and awkward to store and carry than the method of packaging I have chosen.
This will be an extended shelf life product and will have a life of 6 months (approx). This product will be required to be kept in its packaging until it is ready to be regenerated. The product itself will have immediate temperature control purely because of the environment that it is going to carried in. With temperatures in the Arctic reaching minus 40Â° the product will more than likely stay frozen for the duration of its life.
Method of regeneration & stability following regeneration
This product will be regenerated by adding hot water to the freeze dried food whilst inside its packaging.
The stability of the product once regenerated is dependent on the conditions of storage. In the production stage of creating this food it would be necessary to carry out sampling to discover the life of the product once it has been regenerated. In the case of an emergency the pouch may be re-sealed and the product would be safe for a period of 2-3days (pending results of end product testing at the production stage). Although, best practice would be to dispose of any food waste and not reseal any pouches. Once pouches are open, there is greater potential for microbial and physical contaminants to affect the food and this could have fatal consequences in this scenario due to the lack of immediate medical support.
The product designed in this study will offer a nutritional and appetising food for use in Arctic conditions with a life of up to 6 months. Storage will not be an issue with this product as the conditions the product will be used in are the coldest on the planet. The ease of regeneration will also aid users as water will be in abundance in the environment and explorers will have means of heating that water, therefore, they have food.