2 Abstract Purpose of Project
Purpose of Project:
Microbial spoilage of food is a leading cause of food wastage. This leads to economic losses by the average household. Most modern food preservation techniques make use of chemicals which can have potential negative effects. For centuries, many cultures around the world have used and touted herbs and spices as antiseptics. This knowledge prompted this project:: i.e. to create a packaging to help prolong the shelf life of food by upcycling waste paper infused with antimicrobial spice/s.
A variety of spices (cinnamon, cloves, cardamom, salt, turmeric, mustard, fenugreek, cumin), were tested for their antimicrobial properties against Escherichia coli using the disc diffusion method. The spice showing the most antimicrobial activity was incorporated into homemade recycled paper and tested for antimicrobial activity using the disc diffusion method. The “spicy paper” was then packaged together with bread and observed for signs of microbial spoilage.
The results showed that cloves possessed the most antimicrobial properties, and when infused in the “spicy paper” it inhibited microbial growth. Bread packaged with the “spicy paper” did not show any growth of bread mould when compared to bread that was not packaged with “spicy paper”.
Spices can be used in creating alternative food packaging. There are a wide range of spices and herbs yet to be tested, that can be incorporated into packaging. By using recycled paper this project can be viewed as a potential for the upcycling of waste paper to help prolong the shelf life of fresh foods.
Food is wasted at almost every point of the food manufacturing chain. However, in households the five main reasons why food is wasted are: food spoilage, over-buying, date label confusion, over preparing and poor planning. For example, in the United States of America about two-thirds of food waste at home is due to food not being used before it goes bad. Food spoilage at home occurs due to improper storage, lack of visibility in refrigerators, partially used ingredients and misjudged food needs. (1)
Due to growing health concerns and clean green living, consumers are showing an increase in the demand for natural, renewable and biodegradable resources. In order to survive food producers are meeting the demands of consumers’ increased needs for good quality processed foods, especially with respect to making food last longer without decreasing the taste, flavours, appearance and nutritional properties. (2)
Chemical preservatives are able to satisfy these needs, i.e. prolong shelf life, retaining as much of the natural flavours and appearances as well as nutritional value. However chemical preservatives are not always healthy and could cause potential health risks. (3) . To overcome this problem active packaging technologies have been developed. This is a packaging that incorporates antioxidants and antimicrobial components that preserves the food inside it. (2)
For centuries different cultures around the world had identified the effectiveness of using spices to make their food last longer and for medicinal purposes. (4)
This project aims to do the same in a cheaper and biodegradable way so that less privileged people can enjoy those same benefits at a cheaper price.
By extending the shelf-life of fresh foods, of which the poorer communities have less of, there is less chance that the small amounts of fresh foods they have, might get contaminated by microbial growth due to the lack of refrigeration etc. Additionally using spices is a healthier alternative to chemical preservatives. This project also makes use of recycled paper which helps reduce the amount of plastic that is used in those poor communities because they have little to no recycling systems and it can contribute its small part in helping the environment.
To determine if the shelf life of perishable foods can be extended by using a spice infused recycled paper packaging as a preservative.
Using the spice infused paper will inhibit microbial growth and extend the shelf life of fresh foods.
6.1 Effectiveness of spices at inhibiting microbial growth was determined using the Kirby Bauer disc diffusion method. (5)
Nutrient agar plates were swabbed with Escherichia coli. Sterile paper discs were moistened with sterile water, then dipped in the powdered spices (cinnamon, cloves, cardamom, salt, turmeric, mustard, fenugreek, cumin)
The spice coated paper discs were placed, using forceps, onto the inoculated agar plates, sealed with parafilm, and incubated at room temperature for 36 hours.
After 36 hours the plates were examined for bacterial growth and zones of inhibition (clearing/ no growth) around the discs. The presence of zones of inhibition around the discs indicated the effectiveness of the spice at inhibiting the bacteria.
The larger the zone of inhibition, measured using a ruler, the greater the power of inhibition of the spice.
6.2 Incorporating the spice which showed the greatest inhibitory power into a homemade recycled paper. (6)
Scrap-paper was shredded into small relatively equal sized pieces.
The shreds were soaked in warm water for approximately 3 hours.
The soaked paper shreds were then blended with the selected spice in a food processor until a smooth pulp.
The pulp was spread into a thin container with drainage holes to dry.
The dry spice infused paper was then stored in a clean container in preparation for the next phase of testing
6.3 Testing the effectiveness of spice infused paper, “spicy paper” at inhibiting microbial growth using the Kirby Bauer disc diffusion method. (5)
The spice-infused paper was tested using the disc diffusion method, whereby discs of the paper were placed on E. coli inoculated agar plates, incubated for 36 hours, and then viewed for zones of inhibition.
6.4 Testing the effectiveness of spice infused paper, “spicy paper” at inhibiting microbial growth on fresh food.
The final stage of the experiment was to evaluate the effectiveness of the “spicy paper” on common food. Three slices of brown bread were incubated in plastic containers at room temperature to observe for the growth of bread mould. The first container served as the control and contained a slice of bread with no spice paper included, the second slice of bread was incubated with a piece of the lower concentration clove-infused paper, and the third container contained a slice of bread with a piece of the higher concentration clove-infused spice paper.
Dependant: Rate of spoilage of food, microbial growth on agar.
Independent: Spices and spice paper
Control: Fresh food, plain paper and time
6.6 Data analysis:
Observational study whereby results were noted by the presence or absence of microbial growth on media and food.?
7.1 Spice Testing Results
Inhibition Zone: 28mm Inhibition Zone: 9mm
Inhibition Zone: 0mm Inhibition Zone: 0mm
Inhibition Zone: 0mm Inhibition Zone: 0mm
Inhibition Zone: 0mm Control
Results of the spice tests to find the best performing spice.
Each agar plate with the spice coated paper disc from phase 1 of the experiment was inspected after the 36 hour incubation period to find the plate with the largest or widest inhibition zone. The inhibition zone is an area around the paper that shows inhibited micro-organism growth and hence indicates the spice has prevented growth.
The result of phase 1 indicated that cloves produced the widest inhibition zone (28mm) and hence exhibited the greatest antimicrobial action. Cinnamon also proved to be a promising spice for future consideration, with an inhibition zone of 9mm.
From traditional folk-lore it was expected that turmeric should produce a good result as well, however there was no antimicrobial action observed in phase 1 of experimentation.
7.2 Results from testing the spice infused paper
Two concentrations of the spice infused paper was made. Samples of the spice infused paper were added to agar plates to undergo the diffusion tests to evaluate if the spice paper exhibits the same properties as the spice did on its own.
Lower Concentration- No Inhibition zone
Size of Clear Zone: 0 Higher Concentration – Large Inhibition zone
Size of Clear Zone: 13mm
The higher concentration paper showed a wide zone of inhibition (13mm) indicating that the “spicy paper” was showing the desired effect.
7.3 Results from testing the “spicy paper” effect on food
By day 7 the control started to show signs of bread mould on the slice of bread. By day 12 neither container with the spice-infused paper had developed any bread mould on the bread.
Of all the different spices that were tested to determine the spice with the best antimicrobial properties, cloves (Syzygium aromaticum) displayed the best results.
According to research cinnamon, and mustard also display as strong an effect as cloves. (4) In this research project cinnamon was the only other spice that confirmed this. Mustard however didn’t, and this could be due the fact that store bought powdered mustard was used, whilst the clove and cinnamon powders were obtained by grinding the whole spices prior to testing. The mustard powder could have lost its effect due the addition of other ingredients in manufacturing.
Cloves are used as a spice to add flavour to food. Clove essential oil is extracted from the buds, leaves and trunk. Clove essential oil is also used as an antiseptic in oral infections. For this experiment dry clove buds were used. Further research conducted to understand why cloves displayed the observed properties, highlighted that a compound called eugenol is the main bioactive compound in cloves. This is what gives cloves its distinctive smell, flavour and anti-microbial properties. Roughly, 89% of clove essential oil is eugenol. (7)
To harness the antimicrobial properties of the cloves, a recycled homemade paper was made. The method was modified in the blending and drying processes (method: step 2). The first batch of spice paper showed little to no inhibition against the bacteria, so a second batch containing a higher concentration of cloves was made. This batch showed a clear zone of 13 mm. The spice paper was then used to line containers. A control with no paper was also used. Each container had a slice of moistened bread inside. After a period of incubation the control grew mould whilst the spice paper lined containers did not.
The paper was not as pliable as was hoped. This could be due the addition of the dried clove powder. Future experimentation could be explored using clove oil instead of powder.
Additionally there are many other spices that could also be explored for similar properties.
It was also observed that a distinct clove scent was present in the paper and in the container with the food. The odour persisted throughout the experiment. This could potentially impart a taste to the food which may not be desirable to the user. Perhaps use of such ‘spicy paper’ should possibly be limited to foods such a fresh fruit and vegetables that will need to be peeled and cooked prior to eating.
Spices can be used in creating alternative food packaging. There are a wide range of spices and herbs yet to be tested and that can be incorporated into packaging. By using recycled paper this project can be viewed as a potential for the upcycling of waste paper to help with prolonging the shelf life of fresh foods.