Food Analysis
Food isn't always found in a packet; sometimes we are unable to figure out the nutrient contents of an edible content, whether it be a bought packaged product or a naturally grown organism. Because of this, we have tests implemented to figure out just what exactly is in the foods we eat and serve to our pets. Below are three common examples of food testing; take note that there are other, more valid tests than the ones stated below, such as a bomb calorimetre (a test that measures the Gross Energy of food - McGraw, 2015), however due to the lack of equipment at our desposal, we were unable to do more specific tests.
An Ash Test is a procedure used to measure the mineral content within a food product. Minerals are the only nutrient that are inorganic, making them impervious to burning, and the only edible content to remain after excessive burning (McClements, 2009).
This test was completed (as seen in figure 23) to test out various pet food brands in order to identify the worth of the product.
In order to begin an Ash Test, you will need:
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A chosen food product
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Bunsen burner
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Crucible (burn proof container to hold the food)
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Fire proof stabiliser (cushioned triangle seen beneath the crucible in figure )
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Heat proof mat
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Tripod
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Tongs
Ash Test
Figure 23. A Recording of Wainwrights Dry Puppy Grain Free food being burned into ash during an ash test (Morley, 2015).
To begin the Ash Test, the equipment was set out appropriately. The Bunsen burner was placed onto a heat mat, and a stabiliser was fitted with a crucible. The chosen food product was weighed (as well as the crucible) before being crushed and placed into the crucible, before being settle appropriately on top of the tripod. The Bunsen burner was then lit, and set to a temperature high enough to burn. The other nutrients found within the food would then burn (and possibly combust) until nothing but ash remained. When the ash was clear within the crucible, the Bunsen burner would be turned off and everything would be left to cool. The crucible would then be removed by the use of tongs and left on the heat proof mat to cool. When appropriately cooled, the ash-filled crucible would be reweighed.
In order to figure out the measurements of ash content (A), the weight of the crucible (C) would have to be removed from the total weight of the remaining food (T).
[ T - C = A ]
Then the original food weight before burning (B) would need the remaining weight to be removed, to end up with the ash content. The answer would need to be multiplied by 100 to announce the percentage of food that contained ash/minerals.
[ T / B = A x 100 = A% ]
The following buttons will redirect you to the results given from the tested food products:
A Proximate Test is used to identify Glucose, Starch, Protein, Fat, and Vitamin C within food products using various chemicals (see figure 24). The colours of the chemicals will alter in reaction to a substance being available within the food. The stronger the colour results, the higher content of the nutrient.
Unfortunately, this test is not accurate in regards to results, as there are no specific percentages or measurements given. It is an approximate measuring, but is useful enough to alert us of a certain nutrient being present.
To begin the Proximate Test, you will need:
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Numerous test tubes (or you can thoroughly clean them out per use)
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Test tube rack
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Food sample
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Bunsen burner
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Heat proof mat
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Tripod
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Beaker (large enough to hold several test tubes)
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Benedicts Reagant
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Iodine Solution
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Biuret
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Ethanol
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Dichlorophenolindophenol (DCPIP)
When starting the Proximate Test, the test tubes were set out along the test tube rack. The food sample was separated into five equally measured parts, and placed into each test tube.
To tests for glucose, one of the samples were added a few pippette drops of Benedicts Reagant. When added to the sample, the test tube needs to be placed within water within a beaker. The beaker should be heated upon a Bunsen burner, so the water can heat the chemical into a reaction. When Benedicts Reagant can identify glucose, it turns a reddish-orange colour.
To test for starch, one of the samples were added a few pippette drops of Iodine Solution. Unlike the previous test, this chemical needs no stimulant to react, and will simply turn a dark blue/black when starch is present.
To test for protein, one of the samples were added a few pippette drops of Biuret. No added stimulant for a reaction is not needed, and thus the presence of protein will turn the chemical purple/lilac in colour.
To test for fats, one of the samples were added a few pippette drops of Ethanol. Ethanol is highly flammable and needs to be kept away from the Bunsen burner. When added to the food, the contents should be shaken within the test tube, and poured into a seperate test tube filled with water. The shaken mixture will then create a layer above the water; the thicker the cloudy layer, the fattier the content.
To test for vitamin C, the last sample was added as few pippette drops of DCPIP. This needs no added stimulant to react. DCPIP is naturally blue in colour, but will turn pink in the slight presence of vitamin C, and will clear up to almost completely transparent when the vitamin is abundant.
The following buttons will redirect you to the results given from the tested food products:
Proximate Test
Figure 24. A sicentist setting out the beginnings of a Proximate test (WiseGEEK, 2015).
Dry Test
A Dry Test is used to measure the amount of dry matter found within a food. The percentage of dry matter found will be able to measure out the moisture content also.
For example, a food product containing 20% dry matter will have 80% moisture content.
In order to begin the Dry test, you will need:
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A food sample
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Heat proof dish
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Moisture oven
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Tongs/heat proof gloves
To figure out the dry matter content of a food sample, the food sample first needs to be measured. It should only be maximum 3 grams in order for a quicker result. When weighed, the food is put into the dish and placed into an oven (see figure 25) that has been preheated to 110 degrees celcius before inserting the food. The food should then be left to dehydrate for 30-45 minutes.
After being dehydrated, the food dish should be removed (with tongs orheat proof gloves; it will be very hot) and left to cool. When cool enough to touch comfortably, the result should be reweighed.
In order to figure out the measurements of dry content (C), the weight of the dish (D) would have to be removed from the total weight of the remaining food (T).
[ T - D = C ]
The total original weight (H) needs to be removed from the new weight (T), to end up with the moisture content. The answer would need to be multiplied by 100 to announce the percentage of food that contained water.
[ H - T = C x 100 = C% ]
The opposite of the percentage will be equivalent to the percentage of dry matter content.
For Example:
If Dry Matter = 40%
Moisture Content = 60%
The following buttons will redirect you to the results given from the tested food products:
Figure 25. A Moisture Oven, used to dehydrate products (USDA, 2015).
Food Sources Review
I chose four examples of pet foods to analyse through Ash Testing, Priximate Testing, and Dry Testing, and gathered the results to compare to the information given on the packet ingredients. This way, we can compare and identify if the company brands are accurate at stating what we are feeding to our pets.
The first chosen food is called 'Wainwright's Dry Puppy Grain Free' (see figure 26), a popular food brand known for avoiding using any cereal grains within their ingredients. It has been stated that the food is used for all dog breeds from time of weaning to 18 months.
Figure 26. A Packet of Wainwright's Dry Puppy Grain Free Dog Food (Jackson, 2015)
Figure 27. The results of an Ash Test on the chosen dog food (Morley, 2015).
The first test was the Ash Test. The complete food had been measured to 1.1g before being placed within the crucible and burned into ash (see figure 27). When only ash remained and the specimen had cooled, it was reweighed to 0.2g. By following the previous formula shown above, we can see that:
[ 0.2 / 1.1 = 0.1818 x 100 = 18.18% ]
This shows that Wainwright's Dry Puppy Grain Free food contains an average of 18% of ash content. Surprisingly, this is double the nutrition content labelled on the package, which reads to be 9% Crude Ash.
The next text that was carried out was the Proximate Test. With this, 5 samples of food were taken and seperated into different test tubes, before being tested with the appropriate chemicals. The results are shown in the table below beside a comparison of the labelled ingredients on the packaging:
The results show that the ingredients labelled on the packet are not as accurate as they claim. The packet reveals that there should be a high level of protein, because young animals need protein in order for their bodies to grow, however the test proved that only low traces of protein were found.
Not only this, but there was proven to be high content of fat as well; much higher than stated on the llabelling. Fatty build up in domestic animals is a common problem, especially when the animal is owned for companionship and doesn't receive the necessary excercise to use their energy. This can be considered negative and uan unwanted trait within puppy food, especially since bones are still goriwng and excess weight can strain the still growing body.
Whilst there was a reasonable amount of Vitamin C found within the diet, carbohydrates were also at a reasonable level; not high enough to cause any unwanted energy spurts that occur with young puppies.
Figure 28. The results of a Dry Matter Test on the chosen dog food (Morley, 2015).
The final test was the Dry Test. The complete food had been measured to 3.8g before being placed within the oven and evaporated of liquid content for 45 minutes (see figure 28). When removed and left to cool, it was reweighed to 3.7g. By following the previous formula shown above, we can see that:
[ 3.8 - 3.7 = 0.1 x 100 = 10% ]
This shows that Wainwright's Dry Puppy Grain Free food contains an average of 10% of water content. This means there there is 90% dry matter content.
Being a dry food diet, water must be available at all times for the pet. Some animals, especially younger animals, can struggle to eat solid food, so adding moisture to food content can be beneficial towards them eating their food.
Figure 29. A Packet of Purina ONE Senior 7+ - Chicken & Whole Grains Cat Food (ZooPlus, 2013)
The next chosen food product is called 'Purina ONE Senior 7+ - Chicken & Whole Grains' (see figure 29), another once again popular food brand for pets. The packaging takes notice to having no added colourants and being for geriatric cats above the age of 7 years.
The first test was the Ash Test. The complete food had been measured to 1.1g before being placed within the crucible and burned into ash (see figure 30). When only ash remained and the specimen had cooled, it was reweighed to 0.2g. By following the previous formula shown above, we can see that:
[ 0.2 / 1.1 = 0.1818 x 100 = 18.18% ]
This shows that Purina ONE Senior 7+ food contains an average of 18% of ash content. This is much more than what is stated to be found within the packaging, which claims to contain 6.8% Crude Ash.
The next text that was carried out was the Proximate Test. With this, 5 samples of food were taken and seperated into different test tubes, before being tested with the appropriate chemicals. The results are shown in the table below beside a comparison of the labelled ingredients on the packaging:
Figure 30. The results of an Ash Test on the chosen cat food (Morley, 2015).
The results show that Purina ONE Senior 7+ food also have inaccurate labelling, as there is very little protein and much higher fat content. With senior cats, not as much energy is needed, so the extra fat content not only provides uneccesary energy stores, but also encourages weight gain in elderly animals, which can be detrimental to their health.
Not only this, but cats require an amino acid known as Taurine, which is essential for their health. Whilst its can't be proven that Taurine isn't in the dry food, the protein content is low, meaning that there is a risk of not having enough supplements to maintain their health.
Vitamin C content is unusually high, however it can be argued that there is a high content of nutrients in order to help prevent ailments that occur from older age.
The final test was the Dry Test. The complete food had been measured to 3.6g before being placed within the oven and evaporated of liquid content for 45 minutes (see figure 31). When removed and left to cool, it was reweighed yet remained at 3.6g. By following the previous formula shown above, we can see that:
[ 3.6 - 3.6 = 0 x 100 = 0% ]
This shows that Purina ONE Senior 7+ food contains no water content. This means there there is 100% dry matter content.
Being a dry food diet with no water content available, it is essential that the diet is to be accompanied with fresh water at all times. Some animals, including geriatric animals, can struggle to eat solid food, so adding moisture to food content can be beneficial towards them eating their food.
Figure 31. The results of a Dry Matter Test on the chosen cat food (Morley, 2015).
The next chosen food are Mealworms. Unlike the previous meals, these are not able to be considered an entire meal, but used more as part of a diet. This is called a Straight meal; meaning it is incomplete and doesn't contain all of the necessary nutrients needed to maintain the health of a body. A variety of species eat mealworms, including reptiles, birds, meerkats and hedgehogs.
The first test was the Ash Test. The straight food had been measured to 0.5g before being placed within the crucible and burned into ash (see figure 32). When only ash remained and the specimen had cooled, it was reweighed to 0.1g. By following the previous formula shown above, we can see that:
[ 0.1 / 0.5 = 0.2 x 100 = 20% ]
This shows that mealworms have an average of 20% of ash content. This shows that mealworms hold a lot of minerals and are a very healthy portion of a diet.
The next text that was carried out was the Proximate Test. With this, 5 samples of food were taken and seperated into different test tubes, before being tested with the appropriate chemicals. The results are shown in the table below beside a comparison of the labelled ingredients on the packaging:
Figure 32. The results of an Ash Test on mealworms (Morley, 2015).
The results show that mealworms are very high in protein content. This would make them useful for animals that are still developing in growth, such as younger animals.
Although they provide small amounts of fat, no carbohydrates or vitamin C could be traced within the test. Being a straight food, it is incomplete in the essential nutrients and should always be used as an addition to a meal, and not a meal by itself.
Figure 31. The results of a Dry Matter Test on mealworms (Morley, 2015).
The final test was the Dry Test. The straight food had been measured to 3.2g before being placed within the oven and evaporated of liquid content for 45 minutes (see figure 31). When removed and left to cool, it was reweighed yet remained at 2.9g. By following the previous formula shown above, we can see that:
[ 3.2 - 2.9 = 0.3 x 100 = 30% ]
This shows that mealworms contain 30% water content. This means there there is 70% dry matter content.
Although water can be found within mealworms, it is essential that any diet is to be accompanied with fresh water at all times. Small traces of water content within food is often not enough for a body to sustain itself.