Why do we analyse Preservatives in canned food?

  Every food product has a target amount of each critical component or constituents. 
This is especially important since the components we are looking at are preservatives. Preservatives ought to be kept in that limited amount that is deemed as safe. Any higher amount consumed may cause dangerous side effects. Some of these food preservatives are tested on laboratory animals and when these animals consumed the preservatives in large quantity, their body reacted in a certain way that cause a disease. Hence there is a need to analyses the safety level of canned food and its nutritional value. 


  Varying from these targets set by Food and Drugs Administration (FDA) can affect the end product’s quality and cause undesirable effects. This is why manufacturers have to do quality check on the canned food products, or the check will be done by FDA inspectors. 
This can be achieved by following good manufacturing practice regulations specified by the FDA for specific food products and by having analytical techniques that are capable of detecting . In many situations it is important to use analytical techniques that have a high sensitivity, i.e., that can reliably detect low levels of harmful material. 
  
  Food manufacturers and government laboratories routinely analyze food products to ensure that they do not exceed the safety amount of preservatives and also ensure that they do not add any harmful substances in. All these procedures ensured that the food production facility is operating correctly.


  Analyzing the quantity of preservatives in canned food is important as it is a look out for the consumers' health and safety. Consuming a large amount of preservatives can lead to various side effects mentioned in a previous post. And it is also for quality control. Hence, we used Gas Liquid Chromatography to analyse as it is high in sensitivity and produces reliable results.

Importance of Gas Liquid Chromatography

Gas Liquid chromatography (GLC) is an important technique for analytical chemists as compounds can be separated and analysed by vaporisation without decomposition. 

Although it is similar to other column chromatography techniques, there are also differences. 

from Chemtech :

Firstly, the process of separating the compounds in a mixture is carried out between a liquid stationary phase and a gas moving phase, whereas in column chromatography the stationary phase is a solid and the moving phase is a liquid. (Hence the full name of the procedure is Gas-liquid chromatography, referring to the mobile and stationary phases, respectively.) Secondly, the column through which the gas phase passes is located in an oven where the temperature of the gas can be controlled, whereas column chromatography (typically) has no such temperature control. Thirdly, the concentration of a compound in the gas phase is solely a function of the vapour pressure of the gas.

It is a simple, sensitive and effective in separating components in a mixture and in quantifying the amount of components present.  Both qualitative and quantitative analyses are both possible with GLC. 

Qualitative

We can identify unknown components in a mixture by comparing retention times with known standards. However, this is only tentative. If we stronger matching, we combine GC with mass spectrophotometry and use mass spec to identify the components. 

Quantitative

We can find the concentration of the component by using the peak areas, which is proportional to the concentration. It can be calculated by using a calibration curve, derived from a series of analytes

.

Application of GC 

Food analysis

from ars.usda.gov:

Gas chromatography (GC) is used widely in applications involving food analysis. Typical applications pertain to the quantitative and/or qualitative analysis of food composition, natural products, food additives, flavor and aroma components, a variety of transformation products, and contaminants such as pesticides, fumigants, environmental pollutants, natural toxins, veterinary drugs, and packaging materials.

Forensics

 from justchromatography:

GC is widely used by forensic scientists – from analysis of body fluids for the presence of illegal substances, to testing of fiber and blood from a crime scene, and to detect residue from explosives.

They have also found the use of GC with differential mobility spectrometry as a cheap, on location method of detection for flammable liquids used in crimes of arson. 

In conclusion, Gas chromatography is useful in helping us understand and identify unknown components, whether it is in student labs, food analysis and even in solving crimes.

Analysis Results

From this analysis, we want to determine how much of these additives are in the canned food that we are consuming often.

We did this to find out if any canned products exceed the amount that's supposed to be the limit.

This is entirely dependent on what type of canned food you are consuming as some use different additives (eg, canned meat/ canned fruits), so it is up to us to read up the labels to make sure we know what we are eating.

The order of the analytes coming out of the GC will be:

• Sodium nitrite(first)
• Potassium bisulfide
• Sorbic acid
• Dehydroacetic acid
• Monosodium Glutamate
• Aspartame
• Saccharin (last) 

The highest concentration, as it is commonly used for a lot of canned items, would be Mono sodium glutamate (MSG).There are many things we should consider, because MSG may cause harm to our bodies.

Using this analysis, we can be more aware of the things that we consume and not just blindly buy what is right in front of our eyes. We should be more selective and try to make healthier choices. It isn't always important to be frugal when safety is considered.

Sample Preparation

The type of canned food we are going to use is Canned processed meat.
After we obtain a representative sample from the canned meat, we will now prepare a lab sample.

Chemicals and Reagents
Sodium nitrite
Saccharin
Potassium bisulfide
Monosodium Glutamate
Aspartame
Sorbic acid
Dehydroacetic acid

Materials and Methods
The canned meat is homogenized with cutter and a blender and immediately stored at -20⁰C in an air tight container (to prevent deterioration and change in composition) until use.


Preparation of Standard solutions 
 Stock standard solutions of individual compounds (100 mg) were prepared by exact weighing of powder and dissolution in 100 mL of acetone as standard solution.
Multi-analyte working standard solutions were prepared by diluting the standard solution to a series of concentration ranging from 0.2 to 6.0 ug/mL for use.

*Sample preparation is very important as inadequate preparation can cause matrix contamination.

Sample preparation
5g of homogenized canned meat samples were neutralised with 10% sodium hydroxide or 10% hydrochloride in a 100-mL beaker. 

This neutral solution was transferred to 500-mL round-bottomed flask containing 15mL of 15% tartaric acid, 60g sodium chloride and one drop of silicon resin. 

The solution was then diluted with water to the volume of 200mL and steam-distilled at a rate of 10mL/min. 50mL of distillate was transferred to the separation funnel, acidified with 10% sulphuric acid, saturated with sodium chloride, and extracted with 100mL (2x) of diethyl ether. The combined diethyl ether layer was washed with 30mL of saturated sodium chloride solution, added with anhydrous sodium sulphate to make free the solution of water, and then filtered through a filter. The residue was then added with acetone to a volume of 5mL for GC determination.

Recovery test
30g of extracted canned meat was spiked with 250ug of each preservative and mixed well.

The analysis was carried out carried out in triplicate and the sample blank unspiked with standards was also performed.

GC conditions
· Flame Ionisation detector
· Carrier gas flow rate: 30mL/min
· Temperature of detector: 250⁰C
· Temperature of injection port: 250⁰C
· Column: capillary support-coated open tubular 

   0.53mm x 30m, 0.5um film thickness
· Injection volume: 1uL

· Oven temperature: 105⁰C for 7min, raised to 160⁰C at 10⁰C/min, then kept at 160⁰C for 2.5min

*Before running the analysis, ensure that there is no gas leak. 

Optimize the chromatographic conditions for the best separations.

And we'll be using auto sampler for this analysis...

That's all for now! Hope i didn't leave out anything. :) 


Citation
Journal of Food and Drug Analysis, Vol. 9, No. 4, 2001, Pages 215-219 

Some Additives that are found in canned food

These are some of the additives found in canned food. We have included their uses and also their known side effects.

• Monosodium Glutamate (MSG) - it enhances flavour.

It is linked to headaches, tightness in the chest, and a burning sensation in the forearms and back of the head.
It caused negative side effect on people who are suffering from asthma.

• Aspartame-it is a low calories sweetener.
  It caused migraine and headaches in people who are allergic to aspartame. 

MSG and Aspartame are excitotoxins that can lead to neurological damage and they interfere with the release of insulin and leptin, which are hormones intricately involved with satiety and fat storage. They also cause an increase in fasting blood glucose levels.

• Potassium bisulfide- Known as an antioxidant preservative, potassium bisulfite has some antioxidant capabilities, meaning it can fight inflammation-causing free radicals in the body, it is an anti-caking, firming and glazing agent that is added to wine to reduce wine browning and promote clarity.
  However it should not be used to preserve raw fruits and vegetable.
  Potassium bisulfite can be used on fruits intended for dehydration or canning. :)
  It can cause allergic reactions like tongue swelling, rashes etc. Sodium nitrite - It is used to make smoked fish and in meat-curing preparations. It preserve by preventing botulism and is a colour fixative.
• Sorbic Acid - extend shelf life
  Anti microbial, used to inhibit the growth of most moulds, yeasts and other bacteria.
                                      

• Saccharin - An artificial sweetener
Saccharin has been linked to cancer in laboratory animals.
However the real risk to humans remains a matter of controversy.
• • Sodium nitrite - It is used to make smoked fish and in meat-curing preparations. It preserve by preventing botulism and is a colour fixative. 
It can combine with chemicals in stomach to form nitrosamine which is a highly carcinogenic substance. 
• Dehydroacetic acid - used to reduce pickle bloating as preservatives in straweberry and squash. It is mostly used as fungicide and bactericide.

Information are retrieved from the following sites:

http://edition.cnn.com/HEALTH/indepth.food/additives/table.html


http://www.livestrong.com/article/312215-potassium-bisulfite-as-a-food-preservative/


http://www.bbc.co.uk/health/physical_health/conditions/food_additives.shtml


http://www.foodconsumer.org/newsite/2/Diabetes/diet_foods_0702120700.html




Thank You :)

Analytical Methods

We have narrowed down to two analytical method that we want to use to analyse the possible contaminants in the canned/preserved foods.

It will be either High performance liquid chromatography (HPLC) or gas chromatography. (GC)However, we are leaning more towards Gas chromatography.

What is HPLC?

from ksu.edu.com

High Performance Liquid Chromatography (HPLC) is an analytical process utilizing special instruments designed to separate, quantify and analyze components of a chemical mixture.

What is GC?

from Wake Forest website

Gas Chromatography (GC) is used to separate volatile components of a mixture.  A small amount of the sample to be analyzed is drawn up into a syringe. 

Safety Assessment of Additives

Experimental studies have been done to test the carcinogenicity of a few common additives used. Most additives are concluded to be safe for consumption, but however in small quantity. Consumption of additives in large amount may lead to many undesirable consequences like possible liver damage,  possible negative effects on child development, pose higher risk of heart disease, behavior change like Attention deficit hyperactivity disorder (ADHD), Oppositional Defiant Disorder (ODD), and Obsessive Compulsive Disorder (OCD).