The document discusses the chemistry and nutritional characteristics of several tuber crops, focusing on cassava, sweet potato, and edible aroids. It provides details on the typical nutrient profiles of tubers compared to cereals, as well as specifics on cassava and sweet potato composition, processing methods to reduce toxins, and various food and industrial uses. Cassava is shown to be high in starch and low in protein, while sweet potato contains moderate amounts of starch, protein, and sugars. Traditional processing helps remove cyanide from cassava.
fermentation an ancient food processing technologies in world,uses of fermentation includes biological enrichment of food,helps to preserve food, decrease cooking time, an ancient tradition method, science of fermentation is Zymology, beneficial bacteria inhibits bad micro organisms growth. fermented foods of africa,asia, china,babylon and pakistan
The General process involved in making alcoholic drink from sorghum. This drink is native to Africa especially, west Africa. popularly consumed in Ghana, Nigeria , Togo etc
fermentation an ancient food processing technologies in world,uses of fermentation includes biological enrichment of food,helps to preserve food, decrease cooking time, an ancient tradition method, science of fermentation is Zymology, beneficial bacteria inhibits bad micro organisms growth. fermented foods of africa,asia, china,babylon and pakistan
The General process involved in making alcoholic drink from sorghum. This drink is native to Africa especially, west Africa. popularly consumed in Ghana, Nigeria , Togo etc
Bread is the product of baking a mixture of flour, water, salt, yeast and other ingredients. The basic process involves mixing of ingredients until the flour is converted into a stiff paste or.
How bread is made step by step?
How is bread produced?
What is the process of making bread?
Where is bread produced?
bread manufacturing process flow diagram
bread manufacturing process
bread making process in factory
how bread is made in a bakery
how is bread made in factories
how is bread processed
production of bread by fermentation
process of making bread from wheat
Fermented milk products, also known as cultured dairy foods, cultured dairy products, or cultured milk products, are dairy foods that have been fermented with lactic acid bacteria.
This particular presentation describes all the fermented milk products like yoghurt, cheese etc. VIEW, SHARE, ENJOY!
INTRODUCTION:
BREAD is a dietary product obtained from the fermentation and the subsequent baking of a dough mainly made of cereal flour and water, made in many different ways and sometimes enriched with typical regional ingredients.
Ingredients of bread:
Flour is the bulking ingredient of bread, it forms the structure of the product,contains gluten which helps to form an elastic stretchy dough.
Yeast is a raising agent. Yeast produces gases to make the bread rise.
Salt is required to bring out flavour in the bread, it is used in small quantities.Too much of this ingredient will stop the yeast from growing.
Yeast needs energy to grow. Sugar provides the food for the yeast; it is needed to help the yeast grow.
Water is used to bind the flour together and helps to form the structure of the bread.
Fats or oils improve the texture of the bread, preventing it from going stale quickly.
Starter culture:
Baker's yeast is the common name for the strains of yeast commonly used as a leavening agent in baking bread and bakery products, where it converts the fermentable sugars present in the dough into carbon dioxide and ethanol. Baker's yeast is of the species Saccharomyces cerevisiae, which is the same species (but a different strain) commonly used in alcoholic fermentation which is called brewer's yeast.
Bread Making Process
Mixing has two functions: to evenly distribute the various ingredients and allow the development of a protein (gluten) network to give the best bread possible.
Once the bread is mixed it is then left to rise (ferment).
Any large gas holes that may have formed during rising are released by kneading.
Moulding the dough into desired loaf shape.
During the final rising the loaf fills with more bubbles of gas, and once this has proceeded far enough they are transferred to the oven for baking.
The loaf is then placed in a preheated oven to bake. Such a high heat will kill the yeast, thus stopping its process of rising and growth.
The whole loaf is cooled to about 35°C before slicing and wrapping can occur without damaging the loaf.
Types of Bread
1. White Bread
2. Brown Bread
3. Wholemeal bread
4. Rye bread
Apart from above there are several types like Crisp bread, Flatbread is often simple, made with flour, water, and salt.
Microbial spoilage
Molds are the primary spoilage organisms in baked goods, with Aspergillus, Penicillium, and Eurotium being the most commonly isolated genera.
Quality control
As a foodstuff, bread is subject to stringent government food processing regulations, including, but not limited to the percent of additives allowed, sterilization of plant equipment, and cleanliness of plant workers. In addition to adhering to these regulations, processors control the quality of their products to meet consumer expectations by installing checkpoints are various stages of the processing.
•Jam is one of the worldwide used food, it has a part in every culture, and its flavours can represent their tradition.
•Studies show that First-ever evidence of jam being used as a portion of food from the 1st century Ad. The flavours seem different based on the raw materials used but the process of making it is almost similar.
•Food research lab helps you to know the production of mixed fruit jam for the food product development industries and food development companies.
To Continue Reading : https://bit.ly/3moVfyw
Website: https://bit.ly/30CoWUC
E-mail us : info@foodresearchlab.com
Bread is the product of baking a mixture of flour, water, salt, yeast and other ingredients. The basic process involves mixing of ingredients until the flour is converted into a stiff paste or.
How bread is made step by step?
How is bread produced?
What is the process of making bread?
Where is bread produced?
bread manufacturing process flow diagram
bread manufacturing process
bread making process in factory
how bread is made in a bakery
how is bread made in factories
how is bread processed
production of bread by fermentation
process of making bread from wheat
Fermented milk products, also known as cultured dairy foods, cultured dairy products, or cultured milk products, are dairy foods that have been fermented with lactic acid bacteria.
This particular presentation describes all the fermented milk products like yoghurt, cheese etc. VIEW, SHARE, ENJOY!
INTRODUCTION:
BREAD is a dietary product obtained from the fermentation and the subsequent baking of a dough mainly made of cereal flour and water, made in many different ways and sometimes enriched with typical regional ingredients.
Ingredients of bread:
Flour is the bulking ingredient of bread, it forms the structure of the product,contains gluten which helps to form an elastic stretchy dough.
Yeast is a raising agent. Yeast produces gases to make the bread rise.
Salt is required to bring out flavour in the bread, it is used in small quantities.Too much of this ingredient will stop the yeast from growing.
Yeast needs energy to grow. Sugar provides the food for the yeast; it is needed to help the yeast grow.
Water is used to bind the flour together and helps to form the structure of the bread.
Fats or oils improve the texture of the bread, preventing it from going stale quickly.
Starter culture:
Baker's yeast is the common name for the strains of yeast commonly used as a leavening agent in baking bread and bakery products, where it converts the fermentable sugars present in the dough into carbon dioxide and ethanol. Baker's yeast is of the species Saccharomyces cerevisiae, which is the same species (but a different strain) commonly used in alcoholic fermentation which is called brewer's yeast.
Bread Making Process
Mixing has two functions: to evenly distribute the various ingredients and allow the development of a protein (gluten) network to give the best bread possible.
Once the bread is mixed it is then left to rise (ferment).
Any large gas holes that may have formed during rising are released by kneading.
Moulding the dough into desired loaf shape.
During the final rising the loaf fills with more bubbles of gas, and once this has proceeded far enough they are transferred to the oven for baking.
The loaf is then placed in a preheated oven to bake. Such a high heat will kill the yeast, thus stopping its process of rising and growth.
The whole loaf is cooled to about 35°C before slicing and wrapping can occur without damaging the loaf.
Types of Bread
1. White Bread
2. Brown Bread
3. Wholemeal bread
4. Rye bread
Apart from above there are several types like Crisp bread, Flatbread is often simple, made with flour, water, and salt.
Microbial spoilage
Molds are the primary spoilage organisms in baked goods, with Aspergillus, Penicillium, and Eurotium being the most commonly isolated genera.
Quality control
As a foodstuff, bread is subject to stringent government food processing regulations, including, but not limited to the percent of additives allowed, sterilization of plant equipment, and cleanliness of plant workers. In addition to adhering to these regulations, processors control the quality of their products to meet consumer expectations by installing checkpoints are various stages of the processing.
•Jam is one of the worldwide used food, it has a part in every culture, and its flavours can represent their tradition.
•Studies show that First-ever evidence of jam being used as a portion of food from the 1st century Ad. The flavours seem different based on the raw materials used but the process of making it is almost similar.
•Food research lab helps you to know the production of mixed fruit jam for the food product development industries and food development companies.
To Continue Reading : https://bit.ly/3moVfyw
Website: https://bit.ly/30CoWUC
E-mail us : info@foodresearchlab.com
This presentation involves with the fermented products of dairy items and their manufacturing procedures. This presentation includes production of cheese, buttermilk, yoghurt, kefir and sour cream
PROCESSING OF COCONUT MILK
Content
• Introduction of Beverage
• Introduction of Coconut
• Production
• Types of coconut
• Structure & Composition
• What is COCONUT MILK?
• Composition of Coconut Milk
• Preparation of Coconut Milk
• Instruments
• Coconut Beverages
• Packaging
The processing and uses of barley malt extract, by David CarrollKathleen Domanic
First published in FST magazine’s July 2017 issue, pages 20 - 21.See www.safst.co.za.
Bluebird Foods is the sales and distribution agent to Cereal & Malt (www.cerealandmalt.com). Except for barley malt extract, we also supply barley flour, malt flour, oat flour, oat meal and rice flour.
Sugarcane juice is the liquid extracted from pressed sugarcane. It is consumed as a beverage in many places, especially where sugarcane is commercially grown, such as Southeast Asia, the Indian Subcontinent, North Africa, and Latin America. Sugarcane juice is obtained by crushing peeled sugar cane in a mill and is one of the main precursors of rum.
We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
How to Create Map Views in the Odoo 17 ERPCeline George
The map views are useful for providing a geographical representation of data. They allow users to visualize and analyze the data in a more intuitive manner.
3. General nutrition
Widely grown and consumed as subsistence staples in
many parts of Africa, Latin America, the Pacific Islands and
Asia.
Second only in importance to cereals as source of CHO.
Provide minerals and essential vitamins.
Used by supplementing with groundnut, meat, vegetable
soups, grain legumes and fishes to compensate protein
deficiencies.
It is supplemented with the tender leaves of sweet potato,
cassava and cocoyam which are rich sources of protein,
minerals and vitamins
5. General characteristics of roots & tubers
compared with cereals (FAO, 1983)
Cereals Roots and tubers
Low moisture content, typically 10% to 15% High moisture content, typically 70% to
80%
Very low respiration rate with very low
generation of heat. Heat production is
typically 0.05 mega joule/ton/day for dry
grain
High respiration rate. Heat production is
typically 0.5 to 10 megajoules/ ton/day at
0°C to 5 to 70 megajoules/ton/day at 20ºC
Hard texture Soft texture, easily bruised
Stable, natural shelf life is several years Perishable, natural shelf life is a few days to
few months
Losses usually caused by moulds, insects
and rodents
Losses usually caused by rotting (bacteria
and fungi), senescence, sprouting and
bruising
6. CASSAVA
(Manihot esculenta C.)
Cassava, a starchy food, has high calorific value
compared to rice, wheat and maize.
A mature cassava plant has 6% leaves, 44% stems
and 50% tubers.
Cassava tubers - 55 to 60% water, 30 to 40%
carbohydrates, 1% protein and 1% mineral matter.
Major carbohydrate – starch (from 1 to 6%).
Non-reducing sugars predominate & small amounts
of glucose, fructose and maltose.
7. Protein - low with lysine and tryptophan -major amino
acids & small amounts of methionine, cystine and
cysteine.
Vitamins- vitamin C, lacks other vitamins.
Minerals – Ca & P in sufficient amounts; deficient in
other minerals.
Some products of cassava are rich in calcium and
iron and has been attributed to the absorption Ce
and Fe from water.
8. Cyanogenic glycosides in cassava
Cassava roots and leaves contain cyanides in two
different forms:
i) Glycosides; linamarin and lotaustralin.
ii) Non-glycosides; hydrogen cyanide (HCN) and
cyanohydride.
Cyanogenic glycoside HCN
linamarase
9. Great variation in toxicity between cultivars.
A distinction is usually made between "sweet"
cultivars with relatively low contents of cyanogenic
glycosides (below 50mg/kg on a fresh weight basis),
and "bitter" cultivars with high cyanogenic glycoside
content 400 mg/kg.
Highest proportion of HCN is found in the peels and
the cortex layer immediately beneath the peels
Cassava root is always peeled before being
processed or consumed.
Peeling removes the cortex and the outer periderm
layer adhering to it.
10. Cyanogenic glycosides in cassava -
REMOVAL
The glycosides are hydrolysed to HCN by the
endogenous enzyme linamarase, which is present in
the human digestive tract.
All the traditional cassava processing methods
reduce or remove the toxicity by releasing HCN from
the glycosides.
Since HCN is soluble in water it can be removed by
soaking.
Boiling fresh cassava has little effect on its toxicity as
the glycoside linamarine is heat resistant and the
enzyme linamarase is inactivated at 75°C.
11. Peeling
Removal of peels reduces the cyanogenic
glycosides. This can reduce the cyanide content by
at least 50% in cassava tubers.
Grating
This process takes place after peeling. Grating also
provides a greater surface area for the
fermentation to take place.
Soaking of cassava roots normally preceeds cooking
or fermentation. It provides a larger medium for
fermentation and allows for greater extraction of the
soluble cyanide into soaking water.
12. Boiling/cooking
About 90% of free cyanide is removed within 15
minutes. Cooking destroys the enzyme linamarase at
about 72oC.
Fermentation
Some cyanidrophilic/cyanide tolerant micro-organisms,
effect breakdown of the cyanogenic glycosides.
Drying
Cassava roots contain about 61% water, coupled with the
solubility of its cyanogenic glucoside component, the
dehydration (dewatering) process results in a substantial
reduction in the content of this toxin in the pressed pulp.
13. Cassava tubers as food
Peeled and cut into pieces and boiled in water & eaten
as such or along with side dishes.
Consumed after toasting and baking.
Frying of sliced cassava is a common process in India.
The fried chips are used as snack foods.
Parboiling cassava slices is another process carried
out in Kerala. - keeping cassava slices in boiling water
for 10-15 minutes- then drying in the sun & fried and
consumed as snack food.
14. Cassava flour products
Porridge by mixing with hot water.
Preparing traditional South India dishes such as
chappathi, puttu, idly, dosa and uppuma.
Prepare bread by mixing 15% cassava with wheat
flour.
Farinha - made by cooking the cassava pulp, with
continuous stirring, on the griddle on low fire, and the
product appears granular. It has good storage life
and may be eaten dry, mixed with hot or cold water
to make a paste or gruel or mixed with other foods.
15. Sago - obtained from cassava starch in India.
Moist starch is made into globules by shaking and
the globules are surface gelatinized. Wholesome
infant and convalescence food. Eaten generally by
mixing with milk and sugar, as porridge.
Macaroni is prepared by blending cassava,
groundnut flour and wheat in the ratio of 60:15:25.
The product contains a good amount of proteins and
can be used after cooking like rice.
16. Cassava Starch and Industrial uses
Industries like textiles, food, dextrin, sweetener and
chemical industries
Starch is mainly used in textiles for sizing, which
involves coating of the warp yarn with a smooth film
of starch withstand the abrasive and flexural stresses
which the yarn is subjected to, during weaving
operations.
Advantages of cassava starch are
Lower price
Higher strength
Higher viscosity, Transparency.
17. Cassava starch is also used for finishing operations in
textile industries to give brightness to the fabrics. In
this respect cassava starch is superior to other
starches.
Paper
Increase the tearing and bursting strength of the
finished paper, improve the retention of fibres in the
wire mesh conveyor, allow higher retention of fillers in
the final product and reduce the BOD of the effluent.
Oxidized and cationic starches are preferably used.
Oxidized starch is a low viscosity product obtained by
treating the starch with sodium hypochlorite of low
concentration.
18. Cationic starch - reacting starch with reagents like
diethyl-amino ethyl chloride or glycidyl trimethyl
ammonium chloride.
Oxidized starch is used in coating operations when a
pigment coating is required for the paper.
Starch imparts sufficient fluidity to the coating.
Glyoxal is used for imparting water resistance for
coating paper used in lithograph offset printing.
Cationic starch - efficient surface sizing agent for
paper.
19. Food
As a thickener, filler, binder and stabilizer due to
desirable properties like easy and complete
gelatinization, high viscosity, high clarity, low
retrogradation tendency and neutral flavour except for
the long stringy nature of its paste.
Best suited for preparing Instant puddings, pie fillings,
icings, instant powders, etc., in the Western countries.
20. Bread making.
Adhesive industry as carton sealing,laminated and
corrugated boards, pastes or glues etc.,
Sweetener industry. Malto – dextrins, glucose syrup,
high fructose syrup.
Ethyl alcohol from hydrolyzed starch. Fresh cassava
roots or flour by gelatinization and break down of
starch to simple sugars is known as saccharification
which can be accomplished by using saccharifying
agents like mild acids, amylase enzymes, and
substances like malt which contain amylase
enzymes.
22. Potassium is a predominant.
mineral constituents in mg/100 g are
Ca-30, Mg-24, K-373, Na-13, P-49, S-29 and Fe-0.8.
Quality judged on the basis of its sugar content which
varies from 2 to 6%
Sucrose major & minor quantities of reducing sugars.
Maltose - traces.
Tri-saccharides are also present in very small
amounts
23. Boiled tubers immediately after harvest are not quite
sweet.
During storage a part of the starch is converted into
reducing sugars and subsequently into sucrose. The
rate and extent of change in the sugar and starch
content vary with the variety, temperature and
humidity.
During storage, starch content got reduced from 19.1
to 14.1%, while the percentage of reducing sugars (as
dextrose) and sucrose increased from 0.9 to 1.7 and
1.9 to 6.1 respectively in a sample stored for five
months.
24. Biochemical changes during processing
of sweet potato
Curing, or baking - starch content is drastically reduced
with simultaneous increase in reducing sugars, total and
dextrin contents.
Starch gets degraded into dextrins and sugar.
Sweet potato - flatulence producing agent. - fermentation
of carbohydrates by colon bacteria to yield flatus gases
namely H2 and CO2,
Oligosaccharides stachyose and verbascose.
25. Starch
Varies from 15 to 28%.
Size of the starch granule varies from 10 to 25 μ; they
are polygonal in shape
Starch shows 'A' pattern in X-ray diffraction and the
properties are in between those of cassava and maize.
Amylase content is normally between 18 and 22%.
Starch forms clear stable gelatine with high holding
capacity and forms a useful ingredient of food production,
confectionery and baking industry.
26. Composition of sweet potato
Colour due to carotenoid content, especially β-carotene
& accounts for approximately 90 per cent.
Precursor of vitamin A
Content varied from 4-12 mg/ 100g
Vitamin C (20 - 30 mg/ 100 g)-major
Others in mg/ 100 g of sample are:
Thiamine 0.10
Riboflavin 0.06
Nicotinic acid 0.90.
27. Composition of sweet potato vines
4% protein
Fair source of Ca and P and
Good source of iron
100 g of vine tops with leave contain
Moisture 87.1 g
Nitrogen 0.57 g
Ether extract 0.67 g
Crude fibre 1.4 g
Calcium 81.2 mg
Phosphorus 67.3 mg
28. Industrial uses
Source of starch.
A variety of products such as edible syrups, industrial
alcohol, acetone, lactic acid, vinegar and yeast can be
prepared from the tubers.
Varieties of sweet potatoes rich in dyes - have been
made from stems.
Pectin is obtained as a by-product from the peels and
trim wastes and also from the pulp residue after starch
recovery.
Useful in laundry work where it imparts a cleaner colour,
greater smoothness and stiffness to fabrics treated.
29. Process for starch making
Washing of tubers
Grinding with lime water (pH 8.8-9.2)
Separation of starch from pulp
Treated with sodium hypochorite and cetrifuged
Dried to 12% moisture in vacuum drier
Pulverised and screened (Starch 85.37 %)
32. Chemistry of Taro
(Colocasia sp.)
Corms and cormels contain 63 to 85 % moisture, 13
to 30% carbohydrates, 1.4 to 3.0% protein, 0.16 to
0.36% fat, 0.6 to 1.18% fibre and 0.6 % ash.
Protein - rich in most of the essential amino acids,
but is rather low in histidine, lysine, isoleucine,
tryptophan and methionine.
Higher score for total essential amino-acids and
sulphur bearing amino-acids than other root crops.
33. Chemical Composition
Amylose - 3 to 43% (28%). has a chain length of 490
glucose units, while the amylopectin has 22 glucose
units per molecule.
Starch grains - very small (diameter from 1 to 5 μ with
an average of 3.3μ).
Dry matter as well as the starch content of the corms is
lower at the apex of the corm than at the base.
Most of the non-starchy nutrients of the corms are
concentrated in the outer peel.
Starch similar to cassava and gelatinization temperature
of 68 to 75OC; easily digested. Human digestibility of
raw starch was reported to be 97%.
34. Fatty acids - linoleic 42%, palmitic 25.6%, oleic 22%,
linolenic 8%, stearic 1.6% and myristic acid 0.1%.
Poor source of vitamin C, but carotene content is
equivalent to that of cabbage and twice that of potato,
Ca, P and Fe - adequate. rich in potassium.
Mucilage -negligible quantity of protein and is made of
galactose and arabinose in the ratio 6:1. The mucilage
often creates problems in extraction of starch, but is
used in sizing of paper and in pills.
Contain anthocyanins, alkaloids and sterols. The sterols
present are cholesterol, campesterol, stigmasterol and
b-sitosterol- involved in preventing fungal attack.
35. Taro Leaves and petioles
Used as vegetable.
Source of vitamins A and C
23% protein
Rich in calcium, phosphorus,
iron, vitamin C, thiamine,
riboflavin and niacin.
Fresh taro leaf lamina contains
80% of moisture while the
petiole has 94% of moisture.
36. Uses of Taro
Petioles - preparation of soup.
Young taro leaves - vegetable -boiled or covered with
coconut creams, wrapped in banana or bread fruit
leaves and cooked on hot stones.
Problems - presence of acrid principles- cause a
burning, itching sensation in the mouth, throat and on
the skin also.
Selection of varieties and proper cooking solve this
problem.
Taro cormels and leaves - fed to household stocks
such as goats & as animal feed is limited due to the
principles
37. Use of taro as animal feed some degree of processing
for neutralization of acridity, addition of supplements
and improving storability are necessary.
Taro corms are rich in starch which can be utilized in
various industries for preparation of high fructose
syrups and alcohol.
Small particle size of taro starch and the efficiency with
which colour can be added to the particles make the
taro starch suitable for cosmetic dusting preparations
such as face powders and other cosmetic powder.
Taro mucilage which swells in water and becomes
highly hydrated may be used as emulsifying, thickening
and smoothening agent for creams suspensions and
other colloidal food preparations.
38. Tannia
(Xanthosoma sp.)
Corms contain 17 - 26% carbohydrate, 1.3 - 3.7% protein,
0.2 - 0.4% fat, 0.6 -1.9% fibre and 0.6 - 1.3% ash.
Starch 17 - 35% (20%). larger in size as compared to that
of taro and hence the digestibility is poorer.
Pastes less viscous than cassava and yam starches and
the gelatins are similar in strength to maize starch gel.
Young leaves - rich in vitamin A and C but cooking led to
a loss of about 30 per cent in ascorbic acid
Tubers and petioles contain calcium oxalate and the
oxalate contents are higher than that of Colocasia sp.
39. Uses of Xanthosoma (Tannia)
Dried tubers may be ground to produce flour, which is
considered to be as palatable as cassava flour, but more
nutritious.
Tannias are more nutritious than taro, but because their
starch grains are large (average diameter 17 to 20
microns) they are not so easily digested.
Young leaves of many cultivars are used but care is
required in their preparation as calcium oxalate raphides
are present.
40. Alocasia
(giant taro)
Giant taros are used as food in India.
Tuber is peeled and eaten as vegetable after thorough cooking
usually as curries and stews.
Corms and leaf juice are used for medicinal purposes in India. In
Brazil, used as pig feed.
Acid juice of A. macrorrhiza and A. denudate are Poisonous.
Boiled petiole exudate acts as a mild laxative and also as
stimulants to the skin for removing fever blotches.
41. Elephant foot yam
(Amorphophallus carnpanulatus)
Tuber has Carbohydrate -18.0%, Protein 1 - 5% and fat
- 2%.
Higher fat and vitamin A than other aroids
Starch 4-12%.
Sufficient quantity of glucomannan, a hemicellulose
made up of glucose and mannose unit.
Glucomannan has been found to reduce the serum and
cholesterol levels in rats and is an ingredient in various
ayurvedic medicines.
Leaves has 2 to 3% protein, 3% carbohydrate and 4 to
7% crude fibre.
42.
43. Acridity in aroids
Alocasia and Amorphophallus exhibit higher percentage
compared to Colocasia and Xanthosoma.
On chewing the corm, a stinging effect is felt on the lips
and tongue, increase in salivation occurs and the
stinging effect extends to the throat and it is
accompanied by hearing impairment and headache.
Strong correlation between the presence raphides and
acridity has been noted and various theories have been
put forward to explain acridity.
Raphides are crystals of calcium oxalate which may be
of various shapes.
44. Some of the theories suggested include:
Forceful ejection of raphides from the idioblast cell into
the mouth and throat,
Irritation caused by toxins associated with raphides
and
Mechanical irritation caused by the raphide crystals.
45. Chemical theory of acridity
Cooking or alcohol treatment does not usually affect the
raphide structure, but reduces acridity. A very acrid
chemical, the glucoside of 3,4-diglycosiliobenzaldehyde
has been identified from Colocasia antiquorum.
Protein theory - certain proteolytic enzyme is released
which causes the release of kinins and / or histamins
leading to irritation. Some proteolytic enzymes in taro
have been found and named as `taroin‘ - deactivated on
boiling for 30 minutes
All parts acrid including leaf blade, petioles, stems, etc.
Mature leaves are found to be more acrid. Though
cooking is not completely effective in removing acridity, it
is the only easy method to reduce it.
46. Chemistry of yam (Dioscorea sps)
Yam is the common name for some plant species in the
genus Dioscorea (family Dioscoreaceae) that form edible
tubers.
These are perennial herbaceous vines cultivated for the
consumption of their starchy tubers in Africa, Asia, Latin
America, the Caribbean and Oceania.
There are many cultivars of yam.
Yam contain mucilageous substances- extraction of
starch is difficult.
47. Chemistry of yam (Dioscorea sps)
Nutritional value per 100 g
Energy 494 kJ (118 kcal)
Carbohydrates 27.9 g
Sugars 0.5 g
Dietary fiber 4.1 g
Fat 0.17 g
Protein 1.5 g
Trace metals
Calcium 17 mg
Iron 0.54 mg
Magnesium 21 mg
Manganese 0.397 mg
Phosphorus 55 mg
Potassium 816 mg
Zinc 0.24 mg
Vitamins
Vitamin A equiv. 7 μg
Thiamine (B1) 0.112 mg
Riboflavin (B2) 0.032 mg
Niacin (B3) 0.552 mg
Pantothenic acid (B5) 0.314 mg
Vitamin B6 0.293 mg
Folate (B9) 23 μg
Vitamin C 17.1 mg
Vitamin E 0.35 mg
Vitamin K 2.3 μg
48. Yams contain toxic and pharmaceutically active
constituents. These include alkaloids, tannins and
steroidal sapogenins.
D.alata – dioscorin alkaloid, which is toxic.
Tannins are found in dark red fleshed varieties
D.alata.
Saponins sapogenins- most important compound.
Three sapogenins isolated from Dioscorea species
are diosgenin, botogenin and kryptogenin.
Yam sapogenins used in production of steroid drugs
and diosgenin is most used.
Phytochemicals
49. Enzymes
Polyphenol oxidase, phosphatase, phosphorylase, etc.
Ezymes phosphorylase and phosphatase were found in
D. alata, D. esculenta and D. rotundata, while amylase
occurred only in D. esculenta stored at 22°C for five
weeks.
A high molecular weight amylase inhibitor has been
isolated from mature tubers of D. alata. Quite stable to
heat and activate against human pancreatic and pig
pancreatic amylases. But had no action on fungal or
bacterial amylases.
Glycoprotein contain 64% carbohydrates and the
monosaccharide present are glucose, mannose and
galactose in the ratio 5.5 : 3.8 : 1.0.
50. References
Vincent Lebot. Tropical Root and Tuber Crops: Cassava, Sweet Potato,
Yams and Aroids
EDIBLE AROIDS Post-harvest Operations. http://www.fao.org /fileadmin/
ser_upload/inpho/docs/Post_Harvest_Compendium_-_Edible_aroids.pdf
http://www.fao.org/docrep/x5415e/x5415e01.htm
http://www.itmonline.org/arts/dioscorea.htm
http://en.wikipedia.org/wiki/Yam_%28vegetable%29