[ SciTech]

Long-haul storage of fruits

ITI discovers new post-harvest technology:

by Dhaneshi YATAWARA

Dr. Shanthi Wilson - Head, Food Technology Division

Sri Lanka, blessed with a tropical climate throughout the year produces one of the best quality fruits. Though we have restricted ourselves to imported apples, grapes and oranges in the recent past, Sri Lanka boasts of a cocktail of fruits which are very high in nutritional values. Yet, tragically we seem to be unaware of the fact.

"The quality of our fruits is very good. But we need to improve on the post harvest technologies if we are to win the world market," said Dr. Shanthi Wilson of the Sri Lanka Industrial Technology Institute (ITI). Dr.Wilson heads the Food Technology unit of the ITI - a unit that brings many novel innovations into the food industry of the country. "We are passing on the technical know-how, especially to entrepreneurs in the outstations. We have conducted several workshops and seminars through the Ministry of Science and Technology at 'Vidatha' centres," Dr. Wilson added.

Extended storage

ITI's food technology division, with a dedicated team of scientists, has discovered many steps to improve the post harvest periods of the food industry. Among the products especially catering to the fruits of Sri Lanka, importantly to the export quality ones, waxes used to extend the storage life of fruits during long distance transport. Fruits tend to ripe and get damaged during transport because at the time of plucking the fruits are already matured. "Fruits, especially for the export quality ones, ripening while in transport is a problem. They need an extended time," said Dr. Ms. Ilmi Hewajulige, a senior research officer actively involved in post harvest technology research at the ITI.

New wax produced by the ITI for longer shelf life of fruits

This wax, made with locally found ingredients, helps to extend the storage life of fruits like papaya, pineapple, mangoes, bananas and even for export quality king coconuts. "This wax would retain the green colour of the matured fruit restricting the ripening process. After the treatment fruits should be transported in cool storage," Dr. Hewajulige explained.

This would encourage the fruit exporters to use sea transport where more cargo can be transported at a lesser cost. More fruits will be exported with a lesser expense to our local fruit farmers and traders resulting more profits for the businesses. "Air transport is quicker but if a businessman wants to send more it would be quite costly for him. The problem with sea transport is that it takes comparatively a longer time, depending on the destination. What we found is that if we can delay the ripening process of these fruits, it can be retained as the export quality until it reaches the destination," Dr. Wilson added.

Elaborating further Dr. Wilson added that this wax had shown excellent results with mangoes which are prone to ripening very quickly. The wax works with pineapple very well when applied to the fruit and not to the crown. According to these scientists natural wax that covers the crown is enough to protect it. With king coconuts, retaining the calyx is essential to maintain the export quality as it tends to affect the appearance of the nut. This wax prevents the calyx falling off from the nut.

Waste prawn shells

Dr. Ilmi Hewajulige Senior Researcher

In another research by Dr. Hewajulige a successful method was found to extend the storage life of papaya using prawn waste material. Dr. Hewajulige identified the antifungal activity of chitosan which is extracted from the head and shell waste of prawns against the fungi of 'Colletotrichum' species. Colletotrichum sp. is the common causative agent for post harvest diseases.

"This solution works very well for the Rathna and Red lady varieties of papaya, which are the most common varieties of papaya available in Sri Lanka. This will extend the shelf life by 14 days," she further explained. Dr. Hewajulige found this out when she was doing the experiment on the Rathna variety. When these fruits were treated with an aqueous solution of chitosan and stored at a low temperature at a pre-identified maturity stage. This treatment extended the shelf life of papaya for 14 days without any adverse effect on the flavour. Expanding her studies further, Dr. Hewajulige found that the other variety - red lady - though can not be preserved using only chitosan the storage life could be expanded using chitosan subjected to gamma radiation. Even for the Rathna variety can be extended further by extra seven days treating with this irradiated chitosan.

To expand the export market of our precious fruits to those lucrative markets in Europe and Middle East it is important to improve the post harvest management practices to meet the stringent quality standards of these countries.

Wonderful 'Lemna' to clean up dirty waters

Common duckweed plant

Mother Nature has her own wonderful phenomena. Her reactions are quite unpredictable. Revealing these secrets of hers can be filled with surprises to the human being; amidst the fact that humans do a greater injustice to the nature by polluting the surroundings.

Pollution is totally created by the man. It is a by product of the development and industrialisation, is not at fault. The man who creates these innovations.

With such a background this article attempts to reveal a nature's way of rectifying the error which humans create by releasing heavy metals to water bodies through waste water. This contamination of water bodies by heavy metals that come from industrial waste is a severe environmental problem faced all over the globe. The normal practice is to remove these pollutants through a chemical method. "Using the chemical method may require some more steps to clean up the byproducts if any, produced as result of these chemical reactions," said Dr. (Ms) Siththy Iqbal of the Department of Chemistry of the Open University of Sri Lanka. Dr. Iqbal along with her husband, Dr. M. C. M. Iqbal and their student Ms. Meena Thayaparan conducted a research which produced a promising alternative to this conventional clean-up method.

`Lemna' species

These three researchers, with findings from the National Science Foundation's grant conducted an experiment with using the common duckweed plant or scientifically known as `Lemna' sp. "Initially we used about 12 floating and submerged aquatic plants. We restricted the study to these floating and submerged aquatic plants since we were researching on water ways," Thayaparan said. Checking 12 different floating and submerged aquatic plants the researchers came to a conclusion that `Lemna' species showed maximum absorption. It is a wonder the nature has passed on to this tiny floating aquatic plant with elliptic leaves with faintly visible veins. The researchers collected samples of selected aquatic plants naturally growing in the waterways and started growing them in a green house under similar conditions. These re-grown plants were used for tests.

This is to make sure plants do not contain heavy metals before the research.

They found `Lemna' was able to absorb the highest quality of chromium. It was evident with the results that specific plants can be used to remove specific metals from the polluted water sources. They found within four days Lemna' absorbs the maximum amount. "After that the plants need to be removed from the waterbody which we call as 'harvest' followed by a fresh community of Lemna' plants," Meena explained. According to the researchers 'Lemna' can absorb up to 50% of the chromium levels in the water sample.

Phytoremediation

This method, scientifically known as phytoremediation is a modern technology, using plant processes to remove, breakdown and make harmless (detoxify) offensive metals and other toxic substances from contaminated surroundings. Some plants have the ability to collect massive amounts of heavy metals in their tissues without showing toxic symptoms. This method has been widely practised to fix, restore and preserve polluted sites throughout the world.

Laboratory studies have confirmed that some water plants like 'Lemna' sp. (as already explained), can absorb heavy metals like chromium, cadmium, lead, mercury and nickel.

"We suggest to use this method in an artificial wetland - a manmade site like a large pond or a tank to store waste or contaminated water - and treat the water using this method," Dr. Siththy Iqbal said explaining the practical side of the story. "The harvest can be discarded in a proper manner for a hazardous waste," Meena added.

Experiments continue with these researchers as to check out the ability of chosen water plants to mop up industrial waste contaminated with these heavy metals.

According to the researchers some of these plants are also able to take up heavy metals as their non-living biomass or better known as dry matter, at times, offer a potential to be used as biofilters.

Cinnamon oil, new found preservative

A team of Greek researchers have found that cinnamon oil can be used as a preservative in certain food applications due to its antifungal activity. It is said that cinnamon oil may inhibit the growth of micro-organisms by as much as 60%.

Essential oils are known to be effective against wide spectrum of micro-organisms and leave no detectable residues. Outcome of the research may have considerable commercial significance and has a high potential for oil vapour-enrichment.

Time has come to return to natural sources of anti-fungal additives from chemical bases. The reasons for this are manifold and include general consumer preferences for natural foods, legislative changes and the isolation of antibiotic resistant pathogens.

The team tested cinnamon oil in the range of 25 and 500 ppm for its activity against certain fungi, including Colletotrichum coccodes, Rhizopus stolonifer, Botrytis cinerea, Cladosporium herbarum and Aspergillus niger. The invitro experiments showed that the anti-fungal activity was related to the concentration of the essential oil. When the 25 ppm concentration was tested, a 63% reduction in the production of the fungal spores was observed. At a concentration of 500 ppm, fungal sporulation (except for B. cinerea) was completely retarded.

At present these researchers are mainly focusing on the mechanisms underlying the impacts of essential oil volatiles on disease development with a major contribution to limiting the spread of the pathogen by lowering the spore load in the storage/transit atmospheres as well as the use of essential oil as an alternative food preservative.n

(Source : ITI Bulletin vol.3)

New egg substitute

An American company introduced a new substitute which can replace up to almost 100 percent of eggs used in baked goods. These ingredients could appeal to manufacturers who want to reduce the cost or even add extra fibre into their products. It will help them to reduce the costs eliminates one of the most common food allergens, creating possibilities for better vegan baking.

The product is marketed as a blend of sugarcane fibre, xanthan gumand guar gum which can replace up to 100 percent of egg yolk and white in baked foods such as muffins and cakes while maintaining the desirable texture and appearance of the company. It is used at 20 percent of the weight of the egg removed, by adding it to water to make up the remaining 80 percent of egg weight.

Though egg prices have increased in the past year as a result of increased cost of grain, they are important in providing the structure and texture.n

(Source : ITI Bulletin vol.3)

ViduJaya from February 18 - 22

Celebrating the Golden Jubilee of the Sri J'pura University:

The University of Sri Jayewardenepura will conduct 'ViduJaya' a five-day exhibition from February 18 till February 22 celebrating its Golden Jubilee.

Parallel to the exhibition, a series of lectures will be conducted specially targeting the Advanced Level students featuring renowned academics in the respective fields.

This lecture series will also be focusing on giving students an introduction to the new A/L syllabus. Following lecture series will be conducted from 19 - 23 February (except on February 22) as two lecture sessions daily from 1.00 p.m. to 2.30 p.m. and from 3.00 p.m. to 4.30 p.m. at the Chemistry Lecture Hall 1 (C1).

February 19: For Biology,

Prof. H. G. Nandadasa from the Department of Botany, Dr. Hiran Amarasekara - Head, Dept. of Forestry and Environment Science Mr. C.M.R Anthony - Director, the National Institute of Education

February 20: For Physics,

Dr. S. D. Rosa - Senior Lecturer from the University of Colombo

February 21: For Combined Mathematics,

Senior Lecturers G.I.K. Silva and K.K.W.A. Sarath Kumara

February 23: For Chemistry,

Prof. S.P. Deraniyagala and Dr. Sudantha Liyanage

More lectures and educating sessions will also be conducted during the exhibition period especially on subjects related to improving rubber, food, and agriculture related industries.

Discussions on preserving the environment, forestry management and many other timely topics are scheduled to be conducted by renowned lecturers and experts in the field.

Chitosan

With the findings from the Industrial Technology Institute to extend the storage life of papaya using papaya, it would be interesting to know something more about usages of chitosan. Chitosan is produced commercially by deacetylation of chitin, which is the structural element in the exoskeleton of crustaceans (crabs, shrimp, etc.).

Given its low potential for toxicity and its abundance in the natural environment, chitosan is not expected to harm people, pets, wildlife, or the environment when used according to label directions.

Chitosan is a linear polysaccharide composed of randomly distributed â-(1-4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). It has a number of commercial and possible biomedical uses. In agriculture, chitosan is used primarily as a plant growth enhancer, and as a substance that boosts the ability of plants to defend against fungal infections. It is approved for use outdoors and indoors on many plants grown commercially and by consumers.

Chitosan can also be used as a part of a water filtration process. Chitosan causes the fine sediment particles to bind together and is subsequently removed with the sediment during sand filtration. Chitosan also removes phosphorus, heavy minerals, and oils from the water. Chitosan is an important additive in the filtration process. Chitosan, in combination with bentonite, gelatin, silica gel, isinglass or other fining agents is used to clarify wine, mead, and beer. Added late in the brewing process, chitosan improves flocculation, and removes yeast cells, fruit particles, and other detritus that cause hazy wine. Chitosan combined with colloidal silica is becoming a popular fining agent for white wines, because chitosan does not require acidic tannins (found primarily in red wines) to flocculate with.

Chitosan has been used to precipitate caseins from bovine milk and cheese making.

Chitosan is hypoallergenic, and has natural anti-bacterial properties, further supporting its use in field bandages.

Chitosan is also famous in the world as a `fat attractor': It is supposed to have the capability of attracting fat from the digestive system and expelling it from the body so that users can, it is claimed, lose weight without eating less. However, some scientific research suggests that these claims are likely without substance. (Source : Internet)