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Pratiksha Shrestha

Food Technologist Asian Institute Of Technology (AIT) Alumini Travelling is my Passion

About me

Hello

I'mPratiksha Shrestha

Food Technologist and Startup Entrepreneur

Recent Master Graduate in Master in Food Engineering and Bio Process Technology (FEBT) from Asian Institute of Technology (AIT), Thailand, under full scholarship funded by Thai Government (Her Majesty Queen Scholarship for academic year 2015-2017 at AIT). Principle subjects under study were Food Engineering, Bio Process, Processing Effects, Laboratory, Post-Harvest and Bio Technology. Conducted successful and Independent thesis on Extraction of Nano-Cellulose from Banana Pseudo stem and its utilization in developing drug loaded bio-nanocomposite film.

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experience

ACADEMIC COORDINATOR

2014-2015

Academic Coordinator for Diploma Program at College of Applied Food and Dairy Technology (CAFODAT). Responsible for conducting all academic activities assigned by management.

QUALITY CONTROL OFFICER

2013-2014

QC Officer at Jagadamba Foods Pvt. Ltd. Responsible for quality test of raw materials, in plant processing and finished products compliance and rejection.

OFFICE SECRETARY

2011-2012

Office Secretary at Nepal Food Scientists and Technologist Association (NEFOSTA). Admin and Secretarial role for organization. Arrangement of programs and Seminars of organization.

RESEARCH ASSOCIATE

2010-2011

Research Associate at Water Engineering and Training Centre (WETC). Assist in laboratory test for microbiological, chemical tests and other specific case studies.

interests

LEADERSHIP INVOLVEMENT

Already served as General Assembly Speaker at AIT Student unit Thailand for academic year 2016-2017. Also serving as General Member of Nepal Food Scientist and Technology Association (NEFOSTA).

RESEARCH PROJECT

Involved and accomplished more than four independent research project and review articles published in national and international journals. Willing to involve in more such research project in future.

PROFESSIONAL NETWORK

Active user of various social network LinkedIn, Blogger, Twitter, Facebook, Skype and Instagram with more than 4000 connections in professional and social network for constructive suggestions and feedbacks.

ACADEMIC GUIDE

Worked as academic coordinator for diploma program for a year. Willing to involve as academic guide for Bachelor and Master programs of Food and Bio Process Technology.

SOCIAL VOLUNTEERING

Always yes! For any kind of social volunteering. Already volunteered and participated in more than 10 event organized for social cause and contribute to society in any form.

SOCIAL VOLUNTEERING

Always yes! For any kind of social volunteering. Already volunteered and participated in more than 10 event organized for social cause and contribute to society in any form.

20

TRAININGS AND COURSES

6

SOCIAL NETWROKS

5

JOURNALS AND ARTICLES

4

HONORS AND AWARDS

Portfolio

Practice questions Public Service Commission exams ( Food technology)

Hello friends. Below are the questions asked in PSC exams for food technology. Hope this helps to prepare you strong for the PSC exams. You can take a test by connecting to the link below and submit your response. Thank you.
Practice questions for PSC exam (food technology)

Fumigants for insects control

Many different chemicals in the name of insecticides and pesticides are used to protect our food from insects and pests in go-downs, in food industries and store house before they reach to us. Also not all the chemicals are appropriate for all kind of food commodities. Thus it is important to know the nature of chemicals used, and its toxicity. Below are the list of chemicals that are commonly used as fumigants as mentioned in FAO manual of fumigation.

Phosphine
Phosphine or hydrogen phosphide (PH3) is a low molecular weight, low boiling point compound that diffuses rapidly and penetrates deeply into materials, such as large bulks of grain or tightly packed materials. The gas is produced from formulations of metallic phosphides (usually aluminium or magnesium phosphide) that contain additional materials for regulating release of the gas. Aluminium phosphide is formulated as tablets, pellets or small sachets of powder with additional materials such as ammonium carbamate, ammonium bicarbonate, urea and paraffin to regulate release of fumigant and suppress flammability.

Toxicity
Phosphine is very toxic to all forms of animal life, hence exposure of human beings even to small amounts should be avoided. Poisoning can result from ingestion or inhalation; however, the gas is not absorbed through the skin. A concentration of 2.8 mg/l (ca 2 000 ppm in air) is lethal to humans in a very short time.

Properties of phosphine
Odour
Carbide or garlic-like odour
Chemical formula
PH3
Boiling point
-87.4°C
Freezing point
-133.5°C
Lowest explosion point
1.79% by volume in air
Solubility in water
26 cc/100 ml at 17°C (very slightly soluble)
Method of evolution as fumigant
From preparations of aluminium and magnesium phosphide
Pertinent chemical properties
Reacts with copper and precious metals.


Methyl bromide
Methyl bromide was widely adopted for plant quarantine purposes because many plants, vegetables and some fruits were found to be tolerant to concentrations effective against the insects concerned. More recently it has been used extensively as an industrial fumigant for stored products, mills, warehouses, ships and railway cars. For this purpose it has now largely replaced hydrogen cyanide.
Methyl bromide is an effective and versatile fumigant. The most important of these is its ability to penetrate quickly and deeply into sorptive materials at normal atmospheric pressure. Also, at the end of a treatment, the vapours dissipate rapidly and make possible the safe handling of bulk commodities. Another important property is the fact that many living plants are tolerant to this gas in insecticidal treatments. Methyl bromide is nonflammable and nonexplosive under ordinary circumstances and may be used without special precautions against fire.
Because methyl bromide has a comparatively low boiling point and is not greatly sorbed by many materials, it may be used for low temperature treatments that are not practicable with many other fumigants.

Toxicity
Methyl bromide is not as toxic to most insect species as are some other commonly used fumigants, such as HCN, acrylonitrile and ethylene dibromide. The effect of methyl bromide on humans and other mammals appears to vary according to the intensity of exposure. At concentrations not immediately fatal, this chemical produces neurological symptoms.


properties of hydrogen cyanide
Odour
Nil at low concentrations;
strong musty or sickly sweet at high concentrations
Chemical formula
CH3Br
Boiling point
3.6°C (38.5°F)
Freezing point
-93°C
Molecular weight
94.95
Flammability limits in air
Nonflammable (see next page)
Solubility in water
1.34 g/100 ml at 25°C
Pertinent chemical properties
Powerful solvent of organic materials, especially natural rubber. When pure, noncorrosive to metals. Liquid reacts with aluminium (see text)
Method of evolution as fumigant
From steel cylinders under naturalor added pressure. Also dispensed from 1 lb cans or 20 ml glass ampoules
Commercial purity
99.4%






















Hydrogen cyanide (HCN)
Hydrogen cyanide was one of the first fumigants to be used extensively under modern conditions. The use of HCN has been declining in recent years, but it is still important in certain fields of application. HCN is very soluble in water. The solution of HCN in water is a dilute acid and this acid render food materials unpalatable and possibly hazardous for human consumption and unappealing for marketing. 

Toxicity
HCN is one of the most toxic of insect fumigants. HCN is a powerful, quick acting poison. In humans and other warm-blooded animals it induces asphyxiation by inhibiting the respiratory enzymes and renders tissues unable to absorb oxygen from the blood in the normal manner.

properties of hydrogen cyanide
Alternative name : hydrocyanic acid; abbreviation used : HCN
Odour
Suggestive of almonds
Chemical formula
HCN
Boiling point
26°C
Freezing point
-14°C
Molecular weight
27.03
Flammability limits in air
6 to 41% by volume
Solubility in water
Infinite at all temperatures
Pertinent chemical properties
Weak acid. Relatively noncorrosive. When stored as a liquid without chemical stabilizer may decompose and explode in the container.
Method of evolution as fumigant
Discharge from steel cylinder with aid of compressed air. By evaporation of liquid absorbed in porous material, such as card board discs or diatomaceous earth. By action of moisture in air on calcium cyanide, or of sulphuric acid on sodium cyanide
Commercial purity
96 to 99%


Ethylene dibromide
Although EDB is a fumigant of considerable utility, it has a high boiling point and is sorbed by many materials, into which it does not penetrate well. It is thus more limited in usefulness than some of the more volatile fumigants. It has, however, found extensive use in soil fumigation, a subject outside the scope of this manual.

Toxicity
Ethylene dibromide is more toxic to human beings than methyl bromide. It is a severe skin irritant and can be absorbed through the skin as well as the respiratory tract.

properties of ethylene dibromide
Alternative names : 1, 2-dibromoethane, ethylene bromide
Abbreviation used in this manual : EDB
Odour
Like chloroform
Chemical formula
CH2Br.CH2Br
Boiling point
131.6°C
Freezing point
10 C
Molecular weight
187.88
Flammability limits in air
Nonflammable
Solubility in water
0.431 g/100 ml at 30°C
Pertinent chemical properties
Stable
Method of evolution as fumigant
By evaporation of liquid, often in mixture with other fumigants


Ethylene oxide
As an insecticide, the principal use of ethylene oxide (ETO) has been for fumigation of bulk grain in recirculating systems and in the vacuum fumigation of packaged foods and tobacco. In recent years, ETO has been used extensively for the cold sterilization of medical supplies and instruments, for preventing spoilage in foodstuffs and spices and also for controlling diseases in honeycombs and equipment from honeybee colonies.

Toxicity
Despite a general impression to the contrary, ETO must be regarded as poisonous to humans by inhalation, although it is not as lethal in comparatively low concentrations as some other fumigants. The acute toxic effects of ETO in humans and animals include acute respiratory and eye irritation, skin sensitization, vomiting and diarrhoea.

properties of ethylene oxide
Alternative names: 1, 2-epcxyethane, oxlrane
Abbreviation used in this manual : ETO
Odour
Irritating, mustard-like. May be hard to detect in low concentrations
Chemical formula
(CH2)2O
Boiling point
10.7°C
Freezing point
-111.3°C
Molecular weight
44.05
Flammability limits in air
3 to 80% by volume
Solubility in water
Infinite at 0°C
Pertinent chemical properties
Highly reactive and flammable; relatively noncorrosive
Method of evolution as fumigant
By discharge by natural pressure from gas cylinders. Owing to high flammability, usually mixed 1 : 9 with carbon dioxide.
Commercial purity
99.5%


Carbon disulphide
Carbon disulphide (CS2) was one of the first fumigants employed on a large scale. Its tendency to burn or explode presents a hazard. Carbon disulphide penetrates well and is still the only fumigant used in certain parts of the world.

Toxicity
Judged on the basis of lethal dosages, CS2 ranks rather low among the insect fumigants because relatively large dosages by weight are required. Carbon disulphide is toxic to humans.

properties of carbon disulphide 
Alternative name : carbon bisulphide
Abbreviation used in this manual: CS2
Odour
Sweetish when pure; impurities, such as hydrogen sulphide, give characteristic unpleasant odours
Chemical formula
CS2
Boiling point
46.3°C
Freezing point
-111 C
Molecular weight
76.13
Flammability limits in air
1.25 to 44% by volume
Solubility in water
0.22 g/100 ml at 22°C
Pertinent chemical properties
Flash point about 20°C and ignites spontaneously about 100°C
Method of evolution as fumigant
By evaporation of liquid; now used more often in nonflammable mixtures
Commercial purity
99.99%


Sulphuryl fluoride
Sulphuryl fluoride has been developed as an effective fumigant for controlling dry wood termites. This gas has outstanding dispersion and penetrating qualities which permit it to infiltrate termite tunnels and crevices and destroy the insects.

Toxicity
Its mammalian toxicity by inhalation, is about equal to that of methyl bromide.

properties of sulphuryl fluoride 
Odour
None
Chemical formula
SO2F2
Boiling point
-55.2°C
Melting point
-120°C
Molecular weight
102.06
Specific gravity

gas (air = 1)
2.88
liquid (water at 4°C = 1)
1.342 at 4°C
Latent heat of vaporization
79.5 BTU/lb at -55.2°C
Flammability limits in air
Nonflammable
Solubility in water
0.075 g/100 g at 25°C
Pertinent chemical properties
Noncorrosive, relatively unreactive and harmless to wide variety of household materials
Method of evolution as fumigant
From steel cylinders under natural pressure
Commercial purity
99%


Chloropicrin
Chloropicrin is a powerful tear gas; it is one of the most toxic to insects of the fumigants commonly used today. It is sometimes added in small proportions to other fumigants, e.g., hydrogen cyanide and methyl bromide, to serve as a warning agent. Although the tear gas effect of Chloropicrin is helpful in preventing persons from staying in dangerous concentrations during the fumigation process, it is also a handicap because fumigated commodities are unpleasant to handle for some time after fumigation. Chloropicrin is corrosive to metals and care should be taken to protect metal surfaces and equipment during treatment.

Toxicity
Chloropicrin is toxic to nematodes and certain fungi and it has found wide application as a soil fumigant. In humans, a concentration of 2.4 g/m³ can cause death. Concentration ss low as 1 ppm of Chloropicrin in air produces an intense smarting pain in the eyes, and the immediate reaction of any person is to leave the vicinity in haste.

properties of chloropicrin 
Alternative names: trichloronitromethane, nitrochloroform Strongly irritating tear gas
Chemical formula
CCl3 NO2
Boiling point
112°C
Freezing point
-64°C
Molecular weight
164.39
Specific gravity

gas (air = 1)
5.676
liquid (water at 4°C = 1)
1.651 at 20°C
Flammability limits in air
Nonflammable
Solubility in water
0.227 g/100 ml at 0°C
Pertinent chemical properties
Nonflammable; relatively inert; corrosive in presence of moisture
Method of evolution as fumigant
By evaporation of liquid from pure compound or mixed with carbon tetrachltride. Sometimes dispersed as aerosol with methyl chloride as carrier.
Commercial purity
99%


Fumigant mixtures
Fumigants are sometimes marketed in mixtures with other compounds.There are a number of practical reasons for combining fumigants, the more important being. The most important is to reduce risk of flammability and provide different patterns of diffusion.
Source: http://www.fao.org/docrep/X5042E/x5042E08.htm#Methyl bromide  

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PRATIKSHA SHRESTHA
+977-1-6226783
Kathmandu, Nepal

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