GFAR blog

YAP proposal #57: Guava leaves as a natural preservative (Rojlina Manandhar, Nepal)

Guava plant

As the winter approaches, so starts the pickling season in Nepal. I have all the good memories of my mother preparing pickles with tomatoes, radish, cauliflower and spices drying, mixing and undergoing different processes in our balcony along with the great sunshine. After a month or so, it’s ready to serve with our meal.

That was the way we used to preserve our foods traditionally. Living in the city, I always see big trucks loaded with fruits and vegetables and also the waste it brings along with in the streets, finally going as garbage in landfill emitting greenhouse gases. Additionally, it takes time for the transportation of these fruits which are coming from Terai region of Nepal to different parts of the country. Food spoilage is prominent when the time duration elongates and become even harsher when you have strikes and power cut problems.

Due to lack of good refrigeration facility, the food spoilage occurs more. Food spoilage creates loss of nutritional value, texture, flavour of the food. Food spoilage in post-harvested fruits is due to physical damage, oxidation and microorganisms – bacteria, yeast and mould and people themselves.

Now at the age of 31, sadly I could not get my mother’s skills to make pickle. But certainly, I can make some difference in agricultural business through preserving these post-harvest fruits and vegetables using natural preservatives for long time. I was grown up watching my grandmother picking up guava leaves from our backyard and chewing often in toothache and also when the bowel does not work properly. Funny thing is I could not tolerate it at all. The idea pops up in my head from my childhood memories to use these traditional practices.

The extract of guava leaves possesses antioxidant and antibacterial properties, which makes it a potential natural preservative to extend shelf life of food. With my master’s degree in Molecular Medicine from Norwegian University of Science and Technology, I have the knowledge and experience to work on this idea, which will reduce food waste and maintain quality of food for longer.

The guava plant is easily available in most parts of the country and is cost effective and the process for making final product of guava leaf extract is simple and easy to replicate. So, we can transfer the technology to the farmers in the rural areas and boost their living standard.

The application of guava leaf extract might be limited as it might not be suitable for all fruits. So, we focus on only those that have outer covering that can be peeled off like banana, mango, lychees, oranges and more.

The non-edible part of guava plant (i.e. leaves) will be collected from the farm of Terai region. It is then dried in a solar dryer before it gets crushed in grinding machine for extraction. The powder of leaves is extracted in water as a solvent system under heat. After preparation of extract it is cooled, filtered, bottled and packaged for use. The product will be in sprayable form which will be a cheap innovation in natural preservative of food for rural areas.

After farmers pick up their fruits and collect them to transport to different places, the extract will be sprayed over them and will be ready for transportation. This is a very easy method of preservation especially for local farmers, food vendors and people from rural areas. And we will get the opportunity to take fresh fruits in our kitchen. Even we can simply spray the extract and preserve fruits like banana and mangoes which decay quickly. So, this method is reducing the amount of food spoilage and landing in landfill.

The total cost of this proposed project is USD 4,700. This sum of money will be used for:
Truss (USD 1500)
Solar Dryer (USD 500)
Institutional Stove (USD 500)
Grinding Machine (USD 200)
Weighing Machine (USD100)
Land Lease (USD 400/Year)
Bottling and Packaging (USD 500)
Labour Cost (USD 700)
Supervision Cost (USD 300)

As the sprayable bottle is just “press and done” formula, it will be easy to use. The success of my project depends on its local commercialization to people in rural communities, its use by farmers, fruit vendors and household and their reviews about effectiveness of the extract and reasonable costing of the spray bottle.

Finally, if this idea gets funding, it will give me opportunity to start this social entrepreneurship which will not only help local community to solve their local problems but also help me to earn and grow my business on natural preservative.

Blogpost and picture submitted by Rojlina Manandhar (Nepal) – rojlina_manandhar[at]

Illustration courtesy: Marie Barnidge-McIntyre/Pacific Horticulture Society

The content, structure and grammar is at the discretion of the author only.

This post is published as proposal #57 of “YAP” – our “Youth Agripreneur Project”.

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238 thoughts on “YAP proposal #57: Guava leaves as a natural preservative (Rojlina Manandhar, Nepal)”

  1. Great initiative…. we need to support the natural product. I didn’t know that Guava leaves have so mush of value. All the best for the project !!!

  2. Nepal is an agricultural country and agriculture remains Nepal’s principal economic activity. Despite its importance agriculture sector faces several limitations and challenges when it comes to meeting the demands of its growing population. Food security and livelihood are the major issues in remote areas of Nepal where agriculture is the basic means of income. One of the key factors that is causing food insecurity and livelihood problems in remote areas is remoteness(lack of transportation and storage problem). In such case scientific projects like making preservatives from the biomass, will help communities not only to preserve the food but also help them to make livelihood by involving in the projects. I think this project is good enough to uplift local and national economy as well as will provide a valuable contribution in the scientific food research.

    1. You are right Gayatri!!! This idea will be fruitful for agricultural country like Nepal and many others.

  3. using natural preservative can save both money and health of the people.this idea could be a plus point.

  4. Has this technique been successfully used elsewhere? If so, has it been more cost effective than the other available techniques?

  5. Great thought indeed. My moral support goes to the Rojlina Manandhar… Never knew that Guava has such properties….would be really great if this mind get chance to explore more in innovative research…

  6. Great thought indeed, Did not knew that guava has this properties, This kind of innovative research has to be further promoted and should allow to think more. Good luck

  7. in a country where a part is producing “food” that can never reach the other part-facing food crisis; due to lack of preservation facility and transportation difficulty.
    using such preservatives we can equally reduce food crisis and uplift the economy of producers.

    i think this is a great project idea…. I wish you all the best

  8. Seems the idea is simple but innovative. Hopefully useful for local farmers. My questions include-how will you solve the problem caused by fungi and yeast as you wrote the guava extract is antibacterial? Perhaps you can make some formulation with other anti-fungal showing plant extracts to prepare the spray. In addition, the leafy color of guava leaf extract will certainly give some additional color to the food in which you applied. Several costumers may not prefer those additional coloration of fruit and vegetables? Any way the idea is useful to the farmer especially poor ones. Good luck.

    1. Hari dai , you caught me exactly at point. Actually it should be antmicrobial not antibacterial …and yes of course there are papers which describe the antifungal effect of guava leaves extract.

      Regarding the colour effect to the food, specially fruits with cover , i suppose it wont be a problem as the extract wont go inside the fruit and will remain in outer covering.But yes some people might not like it as well. We can work on that.

  9. Innovative and cost effective approach for food preservation, could be an exemplary work to show how the traditional knowledge can stem modern innovation

  10. Great initiative. What kinds of preservative are available in Guava? Is this technology already been used?
    If so than applying this technology in rural village help increase the livelihood of people
    Need lot more research on it.

    1. Bishnu sir !! I can not exactly say about the availability of preservative in guava. And also the application of this technology.Yes we need to do more research in it .

  11. simple, sustainable and very much applicable concept. Based on the findings from this study, other major research on this plant/fruit can be initiated.

  12. This project sounds interesting.. it will be a huge benefit to the farmers (especially of rural areas where there is no good facility of transportation), and consumers if this project will be successful. Good luck to the team.

  13. Organic without any sideeffect. Excellent findings. Is there any specific compund present in its leaves?

  14. Very innovative and interesting!! What is the active ingredient in guava leaves thats gives it its anti-oxidative properties?

  15. Nice initiative !!
    If this is a success, it is going to be quite useful for the farmers in Terai region where the fruits deteriorate quite fast due to hot and humid weather and lack of refrigeration facilities. All the best !!

  16. Has antibacterial property of guava leaves extract been tested ? Is it specific to particular bacteria? When you spray how would you determine the effective concentration?

    1. Yes, test for antibacterial property of guava leaves extract has been tested in lab…there are many research papers. The extract has been effective against pathogenic bacteria like Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and salmonella typhi.

      It is stated that ethanolic extract of guava leaves of 100mg/500ml inhibited the growth of Staphylococcus aureus in research paper. In regards to Nepal, what we aim to do is , we will take out bacterial samples from different fruits and vagetables and might get differrent bacteria .We will then do lab research for 2 to 3 months and decide the sprayable concentration.

      Thank you for such logical question.

    1. There have been use of many solvents like water, methanol, ethyl alochol. Alcoholic solvents are much preferred than aqueous solvents for extraction.

  17. Great initiative and very pragmatic approach to preserve food indeed. Wish you all the best!

  18. Great idea. I feel so bad for the farmers in road inaccessible places, whose agri products are trashed, due to lack of transportation. Ahh especially those delicious golden apples from high altitude! I am excited to see this implemented so that the greater population can reap the benefits of our own agri- products, mitigating our heavy reliance on imports.

    1. Ya we are helpless for those poor people. If we could do this in real this would be a great achievement for us and specially for farmers.

  19. How much amount of guava leaves will be needed to preserve around 1 truck of banana?

    1. This is really tricky and very practical question. Even i wonder. As for banana, it is the most quickly decaying fruit. More brainstorming is yet to be done for the calculation for a truck of banana.

      Thank you for your sensible query.

  20. This idea is unique and it will be beneficial to local farmers….this technology is cost effective too….all the best Rojlina…

  21. Very innovative and interesting project using natural preservative. Wish you all the best!

  22. Great initiative. And good luck!

    I was also wondering if you extract the antioxidant before drying the leaves, will that have similar effect? But, I know drying leaves for extraction is pretty common method.

    You stated that this extract cannot be used for all types of fruit, why do you say that? I thought since the extract that you are going to use is from leaves, it can be used for fruits without outer covering (like apples) as it might broaden the application of this method!
    Pardon my naive questions! 🙂

    1. Thats another interesting question. As normally we dry the leaves or plants for plant based research. For extraction purpose also,for higher surface area we dry leaves and grind it. Actually , i have not used fresh leaves for plant research. For example guava fruit is seasonal and leaves of the plant do fall after drying . And for this kind of research we need to collect many plant leaves and it is not possible to store them fresh as there might be contamination problem. So usually, leaves are dried and stored.

      And regarding antioxidant effect before and after drying the result might be different for guava leaves.

      Regarding the limitation in use of extract in fruit and vegetables, it might not be palatable. Regarding fruits with covering, we just pill it off and eat the main fruit like banana, mango, litchi, etc. But the fruits like apple, we will consume it directly and we are not sure about the taste with leaf extract and many people might not prefer. And same goes to vegetables .

      Indeed its a common question and it will be really nice if the application is wider.

      Hope you will get to eat your apple soon after preserving for long time as well 🙂

      1. Yes Roslina, the crude extract might give off-flavour limiting its use to the pillable fruits only; but inevitable for rural poor farmers. However if you could extract the active ingredients and refine properly to get rid of off-flavours, the product could definitely have wider application and impact. Good luck.

  23. I think this is very good initiative. We still chew guava leaves when we have bowel problem. I know capability of Rojilina, she is very hard-working and creative. Hope you will be funded

  24. Great initiative!! Innovation like this is much needed for Nepal. The purposed natural preservative product will definitely be valuable resource for the country which lacks refrigerated transportation facilities. Good luck.

  25. Pretty neat idea of using natural products instead of chemicals to use as preservatives.

  26. I think this is a wonderful idea. WIth so many changes occuring to the global environment right now, with mostly unforseen concequences, it is really smart to propose a natural alternative for food preservation.

  27. A very innovative way environment friendly way of food conservation….with antioxidant phytochemicals in supplements 🙂 good luck.

  28. Good Idea and A good approach to replace chemical preservatives. Must be intiated and supported.Good Luck

  29. Certainly, YOU can make some difference in agricultural business through preserving these post-harvest fruits and vegetables using natural preservatives for long time 🙂

  30. A good way to use locally and naturally available materials in Nepal. This project could also be of significance at a national level in long term if it works. Out of curiosity though, has any pilot been conducted on this?

  31. Guava leaves, because of its presence of antimicrobial and antioxidant compounds, have the potential to become an efficient natural preservative. One of the thing I remember is a characteristic pungent smell from guava leaf which also act as a natural repellent to many pests.This is an elegant idea to begin with and go further once its effectiveness is proven in a pilot scale. I hope the proposed project gets the start up funding from this organization.

    1. It would be really nice and encouraging if we get this funding and utilise the natural components from the extract against natural processes which makes our food deteriorate and of less quality.

  32. I read this project with great interest. I am impressed by the idea of project.I believe that this is an interesting research question that need to tested. If it comes true that will have wider applications in terms of many factors such as its availability at local level, health benefits and most importantly it is natural. This project represents the perfect example of “Think locally act globally” .
    Apart from research project, I would like to draw the attention of global community towards this fact that
    “Only 24% of STEM (sceince, technology, Engineering, mathematics) professionals are women, and out of those women only 0.02-0.04% are from Nepal”. By supporting women in science from developing countries like Nepal , we will have impact not only on economy but also inspire many women from developing countries to join these streams.

    I pray people living in Nepal who are tirelessly working hard to come out from the earthquake post effects. It is such an inspiring to read such a scientific question they are raising even at this time difficult time.

    Deepak upreti

    1. Thank you Deepak for nice information. We need more women researchers around the globe.

      Thank you for your support as well. Hope this women from Nepal will get the fund 🙂

  33. Amazing initiative!! This is such a smart idea, never knew guava leaves had so much value and potential. Wish you all the very best in this project.

  34. Innovative idea of using local resources locally and if the idea goes to action the success depends on how effective results are made with such preservatives..all the best !

  35. This is a great thought and shouldn’t be that challenging, using locally abundant resource (guava leaves) for the longevity of harvested fruits, which ultimately benefits social health and economic condition of agricultural countries like Nepal ( I should say throughout the world).

  36. Perfect research and great initiative on natural preservative. Absolutely invaluable tips to improve for the better quality of life.

  37. Never knew about such odea before, hope this will br useful for the nepalese agriculture in the future!

  38. Good Idea. Replacement of Chemical preservative. As Nepal is Agricultural country It is a good initiative. Goodluck

  39. Going natural is laudable all by itself, on top of that replacing chemical preservatives, which are generally toxic to life and environment, is a great contribution to humanity as well as to nature as a whole-of which we are a part.. ….. If nature wins the race humanity will win automatically………
    My best wishes for this endeavour.

    1. Thank you . The chemical preservatives are causing different health hazards to human and people are now more consciuos about it. Many people are now preferring organic . So , its high time to think about natural alternatives.

  40. Preserving food naturally can go a long way; not only as a boost to local business in an agricultural country like Nepal, but also as a health benefit (less chemical usage means less carcinogenic products). I believe, this project can definitely bring some new changes in food industry.

  41. Idea is good. It will be a better to do more research on this issue. Good luck for that

  42. It sounds great. I am very happy that you are using your experience and knowledge in this specific area which is very innovative and applied research. Good Luck!!

  43. It sounds great. I am very happy that you are using your skills and knowledge in this specific area which is innovative and applied research. Good luck!!

  44. Guava is considered as one of the most common fruits successfully grown all over Nepal in both tropical and subtropical climates. Especially, for countries like Nepal where around two-thirds of people rely on agriculture for their livelihood and Nepalese farmer which sole source of income comes from selling different types of seasonal fruits and vegetables grown in their farm. Fruits and vegetable spoilage is a major issue they are facing these days. As people are facing power outage all the time; this has even limited people to store these fruits and vegetables in cold room or refrigerators. This is a brilliant idea which will undoubtedly help farmers, vendors, consumers who can not afford refrigerator and other commercial preservatives available in the market. Good Luck Rojlina !

  45. The idea of natural preservative which is organic and without less side effects seems interesting to me. Wish you all the best for this research project. Good luck!

  46. The adorable innovative idea that have potentiality to revolutionized the organic way of agriculture…Best of Luck Rojlina!!!!!!

  47. The adorable innovative idea that can be revolutionized the organic way of agriculture with natural preservation system…..

  48. This is a great initiative specially for our country. I really like this idea. Given a platform, I think it’s application will have a great impact in the agriculture. I wish you good luck 🙂

  49. (Not sure my last comment got published typing it again)
    Its a good initiative. I am sure finding science behind the beneficial properties is included in your plan. As one of the comments above suggested, a small scale exploration could be ideal in my opinion. 1000s of ethnobotanical practices in Nepal need scientific exploration by well trained scientists like yourselves.
    Best wishes

  50. The idea of developing natural preservative which is organic and without less side effects seems interesting to me. Wish you all the best. Good luck!

  51. This is a simple, yet very important process/technique. I would like to know more about the chemical properties of guava leaves. We can chat when we meet. Wish you all the best.

    1. The guava leaves are antioxidative and antibacterial in nature because of phenolic content in it.

      Sure we can meet and chat on it.

  52. Looks like a promising and innovative project. This can be a cost effective and practical approach especially for local farmers and vendors to address the problem of food spoilage. Wish you all the best!!!

  53. Its intriguing to find out how conventional approaches still hold so much of practical scientific values. This is a good example representing that. I would very much like to see this idea taking shape in future and would like to wish the author best wishes.

    I was curious to know how strongly this project is based on. Have you already tried this on a small scale, probably in a laboratory setting? If so, by what percentage or factor did you see the shelf life of fruits increase with the application of guava leaf extract? Which fruits did you try this on? It would add a lot of credibility if you could include some tangible numbers to relate in this idea. Nevertheless, I wish you all the best.

    1. I have not tried this in laboratory setting , but of course in my home. It certainly needs optimized protocol in laboratory setting for better result. If the project gets funding, the fund will be used to make optimised protocol for different vegetables and fruits found inside our country. And we do have research lab working on natural products where we can perform lab works.

  54. Interesting idea! Great initiation towards boosting agricultural business. “A Feasible and Relevant Research Area” that needs to be explored. Hope this will be funded, Goodluck Rojlina!!!

  55. Good initiational approach toward the exploration of indigenous phytochemical, such idea will definitely layout probability for the intellectual candidate to glorify their academic excellence into practical work, which indeed is a gracious need for developing country. I wish best of luck may this endeavor carry on for long time.

  56. Very good use of traditional technique to bring solution to present day problem. I hope you all the best.

  57. The project looks promising.
    Hope to see such good initiative more in the future.
    All the best Rojlina…

  58. The project can contribute a lot for horticulture areas where preservation of fruits identified as a big issue. Certainly, It will help to resolve the issues mentioned by Rojlina. I am quite sure at the end of the project a herbal natural preservative will be in Nepal which can be domesticate worldwide for commercial purpose.

    My suggestion:

    1) You have to do little more about the biodiversity of Guava plants (at variety level) as In Nepal we do have different verities.
    2) The plants grow in different geographical region and different varieties may have different preservative potential. Please focus on our own local varieties. It will help you to select best variety for your work.

    Good luck!

  59. I have wonderful childhood memories linked up with guava too. It is exciting to know that guava leaves can be used as a natural preservative.
    I thank you for the brilliant proposal, and wish you good luck for the project. Would like to see people using preservatives extracted from guava leaves to preserve food in days to come– not just in Nepal but worldwide.

  60. Great project ! Very interesting as well as relevant for our community!
    Good luck and best wishes!

  61. Really an innovative and an actual application of the knowledge of ethnobotany for the benefit of the farmers and the overall upgrade of the developing countries..

  62. Great idea Rojlina. There are lots of flavonoids and polyphenols found in plants such as Luteolin, Tangeritin, Resorcinol etc. It would be great if you could identify all the exact active compounds present in guava leaves extract that provides antioxidant and antimicrobial properties using HPLC or other similar techniques. Chemically synthesizing such compounds would not only be cheaper but also sustainable since we do not have to use plant leaves any more. I guess it is beyond the scope of your project right now but something to think about in future. I wish you very best..

  63. Good work Rojlina. The project makes use of whats readily available and the perceived outcomes of the project have got economic and social potential- certainly the way to go! All the best.

  64. Really interested to know the detailed process. As I am having my own guava farm. Pls tell me what more products can be done from guava.

  65. Very innovative. This project could be a very beneficial, especially for country like ours. Great work, I support this proposal.

  66. What are the laboratory Instruments you gonna use for this research ? Please Illustrate..Can u please broaden the rough protocol you gonna follow ?

  67. Storing grains like rice and whtat with guva leaves heps their preservation – it is my my observation.

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