Saliva related lit

WEST VISAYAS STATE UNIVERSITY
College of Arts and Sciences
La Paz, Iloilo City

Review of Related Literature

Chapter two consist of the following, namely: 1) Salivary enzymes

2) Starch, 3) Starch digestion, 4) Kangkong (Ipomea aquatica Torsk),

5) Gabi (Colocasia esculenta), 6) Okra (Abelmoschus esculentus L.) and

7) Potato (Solanum tuberosum).

Salivary enzymes

According to Lee B. (2008) human salivary amylase, also called

ptyalin, is an enzyme produced by the salivary glands that initiates

carbohydrate digestion in the mouth and continues in the body of the

stomach after food and saliva has been swallowed. Salivary amylase

enzyme is the only enzyme in saliva capable of degrading

oligosaccharides, which are used by the oral microflora for

nutritional purposes. Because human salivary amylase can act anywhere

on the substrate, human alpha-amylase enzyme tends to be faster acting

than beta-amylase enzyme. Human alpha amylase is primarily classified

into two kinds of isoenzymes. S-type amylase comes from salivary

glands and P-type amylase from the pancreas. The company offers both

types of isoenzymes in research and bulk quantities, and it has the

capabilities to custom purify human alpha amylase in a wide variety of

buffers.

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The amount of salivary amylase differs in people of different

ethnic backgrounds. As the gene has undergone duplication during

evolution, has led to difference gene copy number. The number of gene

copies is directly related to the levels of salivary amylase.

A study by Richardson C. T., M. Feldman() states that chewing gum

increased salivary secretion to approximately the same extent as

modified sham feeding, whereas chewing on plastic tubing caused a much

smaller increased in salivary flow . Intravenous infusion of

bethanechol (50 micrograms . kg-1 . h-1) was approximately half as

potent as modified sham feeding or gum chewing in stimulating salivary

flow. Salivary response to sham feeding was completely blocked by 15

micrograms/kg intravenous atropine. Salivary secretion increased

approximately 20ml/h when a 700-ml amino acid meal was infused

directly into the stomach (P less than 0.01), whereas gastric

distension with 700 ml saline had no effect. These findings suggested

that food in the stomach or upper small intestine may activate a

reflex or release a hormone into the circulatory that arguments

salivary flow.

Moreover, Garnet J. R. () added that the most enduring

misconception has been that the drying of mouth under stress is due to

sympathetic inhibitory fibers, a view that must be eradicated, for

such fibers do not exist the inhibition is due to central influences

from higher centers acting on the salivary centers and thereby

suppressing reflex activity. Wide variations exist in the neuro-

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effector arrangements and in the cellular responses in the different

glands from different species. Myoepithelial cells are usually

contracted by both parasympathetic and sympathetic nerves. The blood

vessels also receive a dual innervation, but parasympathetic impulses

cause vasodilatation as part of secretion, whereas the sympathetic

vasoconstriction fibers are part of a more generalized vascular

control system and not a direct part of the reflex secretory

sympathetic pathway. Parasympathetic drive usually provides the main

stimulus for fluid formation by parenchymal cells, whereas sympathetic

nerves tend to increase the output of pre-formed components from

certain cells. Absence of nerve impulses causes variable atrophic and

other metabolic effects on the parenchymal cells. Evidence beginning

to accrue that certain nerve impulses may influence resynthetic

activities. Vacuolation , often found experimentally after strong

stimulation, also occurs to a variable extent in certain cells as a

normal part of reflex secretion and may therefore have an effect on

the components entering the saliva. If rupture of vacuoles occurs,

then this may contribute to the salivary amylase that is present in

the blood. Recents evidence points to the possibility that, even in a

monomorphic gland, not all of the components necessarily enter nerve-

induced saliva in “parallel” proportion.

Study shows that varying enzyme profiles exist among the various

components which make up whole saliva. It also indicates that numerous

salivary enzymes originate from oral microorganisms and that the

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enzyme activity of whole saliva is higher in individuals with

periodontal disease than in periodontally healthy subjects Nakamura

M., Jorgen S. ().

Starch

Starch, common name applied to a white, granular or powdery,

odorless, tasteless, complex carbohydrate, (C6H10O5)x, abundant in the

seeds of cereal plants and in bulbs and tubers. Molecules of starch

are made of hundreds or thousands of atoms, corresponding to values of

x, as given in the formula above, that range from about 50 to many

thousands.

According to Maarel M. et al. (2001) starch-containing crops form

an important constituent of the human diet and a large proportion of

the food consumed by the world’s population originates from them.

Besides the use of the starch-containing plant parts directly as a

food source, starch is harvested and used as such or chemically or

enzymatically processed into a variety of different products such as

starch hydrolysates, glucose syrups, fructose, starch or maltodextrin

derivatives, or cyclodextrins.

Starch Digestion

According to Bryce A. (2010) Digestion begins in the mouth,

where by means of mastication the food is comminuted and mixed with

saliva. This fluid contains a ferment which converts the insoluble

starch of such foods as bread and puddings into the more soluble form

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of maltose or malt sugar. This transformation does not take place in

one stage, for there are several steps in the process, and unless the

food has been carefully cooked hardly any maltose is formed in the

mouth at all. Ptyalin, however, which is the name of the ferment, is

able to carry on its salutary work of conversion in the stomach for

something like half an hour after the food has been swallowed, or at

all events until the bland alkaline saliva has been neutralized by the

acid gastric juice. The stages in the best circumstances in the mouth

are starch, dextrin, maltose, and the process is not advanced much

further in the stomach, although any cane sugar present may be

decomposed (or inverted as it is called) by the acid of the gastric

juice and ferments contained in the swallowed food into grape sugar

(dextrose) and fruit sugar (laevulose). Moreover, After being ejected

from the stomach into the intestinal canal all carbohydrate, whether

cooked or uncooked, so far as it can be reached through its envelope

of cellulose, is attacked by the amylopsin - a ferment in the

pancreatic fluid - and converted into one of the sugars, usually

maltose. Finally this mixture of sugars, maltose, lactose, cane sugar,

and laevulose, is, by means of another ferment called invertase,

changed (in large degree at any rate) into glucose (grape sugar), the

most convenient form for absorption.

In study by Englyst H. et al. (1986) Starch digestion and

absorption is not so simple. In our study of cereals (1), we observed

that starch present in oats was completely absorbed in the small

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intestine but, in processed food such as cornflakes and white bread, a

small fraction (3-5%) had become resistant to a-amylase digestion and

this escaped breakdown in the small bowel. The present study of banana

identifies a further type of starch that resists breakdown by

mammalian a-amylase, namely raw starch present in certain types of

granules. Table 2 shows that only 23% of the starch fed were recovered

as starch in the ileostomy effluent but that in those cases where

there was substantial starch in the banana, a large increase in the

recovery of maltose, maltotriose, and dextrin occurred. In the absence

of any other likely source, this probably represents partial-

hydrolysis products of the banana starch. The products are likely to

have been formed in the ileostomy bag, where some microbial activity

occurs after the effluent has been passed. Disaccharides such as

sucrose and maltose are probably well hydrolyzed and absorbed from the

ileum (30). Taken together with the starch recovered, the maltose plus

maltotriose plus dextrins account for 69 ±9% of the starch ingested.

Vonk R. et al. (2000) added that the exogenous glucose response
13
in serum and the CO2 excretion in breath can be used to estimate

small intestinal digestion of resistant starch, which amounts to ≈50%.

Furthermore, Vista (2010) stated that when the food is ingested,

the saliva secreted by salivary glands softens the food and the tongue

masses the food as it is chewed and converts the food to bolus. The

salivary amylase present in saliva converts initiates the process of

digestion of starch to sugar in mouth.

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Amylases cleaves 1,4-glucose linkages present in insoluble starch

and converts into soluble starches (amylodextrin, achrodextrin,

erythrodextrin) which is successively converted to smaller starches

and finally to maltose. Salivary amylase does not have much time to

act on the food in the mouth. However the action of it is quick and

continues starch digestion within the bolus till it reaches the

stomach. Salivary amylase gets inactivated in the stomach as the pH in

stomach is 3.3 due to secretion gastric juice. The starch and glucose

present in the bolus provides some protection for the enzyme from the

stomach’s acid and it continues digestion of starch for a short period

of time until it is completely inactivated.

Optimum conditions for action salivary amylase is pH at 5.6–6.9,

temperature - 37 °C, and certain anions and activators like chloride,

bromide, and iodide.

Kangkong (Ipomoea aquatic Forsk.)

Kangkong is found throughout the Philippines in stagnant streams,

fresh-water swamps, and pools. It was perhaps introduced. It is also

found throughout the tropics of the Old World and is extensively

cultivated in southern China.

This is a smooth, widely spreading vine, with the stems trailing

on mud or floating on the stagnant pools. The leaves are oblong-ovate

and 7 to 14 centimeters long, with a pointed tip, and a heart-shaped

or arrow-shaped base, on long petioles, the margins being entire or

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angular, and sublobed. The peduncles are erect, 2.5 to 5 centimeters

long, usually having 1 to 2 flowers, and borne in the axils of the

leaves. The sepals are green, oblong, and 8 millimeters long. The

corolla is narrowly bell-shaped, about 5 centimeters long, and

purplish; the limb is nearly white or pale pink purple inside. The

capsules are smooth and ovoid, and about 1 centimeter long.

The young leaves and stems are boiled and eaten as a leafy

vegetable. The young stems are also used as an ingredient in native

pickles (achara). “Kangkong,” according to Marañon, is an excellent

source of iron and good source of calcium. Hermano and Sepulveda says

that it is a good source of vitamins B and G, and an excellent source

of vitamin C. the leaves are also eaten by “gurami” fish, and by pigs.

Read records that the plant contains protein 1.6 per cent, fat 0.2 per

cent, and vitamins C3 and B2.

Guerrero states that the tops are mildly laxative in the

Philippines. Dr. F. Garcia declares that “kangkung,” particularly the

purplish kind, contains an insulinlike principle, and can be used as a

cure for diabetes melitus.

Kirtikar and Basu report that in Burma the juice is employed as

an emetic in cases of arsenical or opium poisoning. The latex, when

dried, is nearly equal to scammony in purgative efficiency. Menaut

says that the Cambodians use it as a poultice in cases of fever with

delirium, and apply the buds to ringworm.

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Gabi (Colocasia esculenta)

According to McEwan R. (2010) Colocasia esculenta is a tuber

commonly known by several common names, such as Amadumbe (South

Africa), Taro (Pacific islands) or Cocoyam (West Africa). It is a

traditional food crop widely grown in the subtropical parts of South

Africa. The tuber could be consumed as a good source of starch and the

locally developed cultivars are commonly used as staple food in the

KwaZulu-Natal (KZN) province of South Africa. Nutritional evaluation

of the tubers showed storage of biologically active substances that

have anti-nutritional properties (that is, they reduce the

availability of nutrients to animals and humans).

Okra (Abelmoschus esculentus L.)

Okra’s potential food, nutritional security, pods contain high

amounts of dietary fiber and they are often dried, stored, and

consumed as soup/souse much like a staple food. Half a cup of the

cooked pods (fresh) provides about 10% of the recommended levels of

vitamin B6, folic acid and vitamins A and C. The seed (usually

consumed with pods) protein is distinct from both cereals and legumes

Kumar S et al. (2010).

Potato (Solanum tuberosum)

A potato plant is a leafy vegetable. It has a thick, uneven

shaped plant stem (tuber) that grows underground. This eatable tuber

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is also called a potato. Potatoes have a thin skin that is usually

red, yellow, or brown. Inside the potato is pale flesh.

Potatoes are an important food source. They are the most widely

cultivated vegetable in the world. An average-sized potato weighing

between 6 and 8 ounces contains less than 100 calories. Potatoes

consist of about 80 percent water, 20 percent solid matter, and have a

high nutritional value. Starch makes up about 85 percent of this solid

mass and the rest is protein. Potatoes also provide vitamins including

niacin, riboflavin, thiamin, and vitamin C. They also contain minerals

such as calcium, iron, magnesium, phosphorus, potassium, sodium, and

sulfur.

Potatoes were originally cultivated in South America, probably in

Bolivia, Chile, and Peru. More than 400 years ago, the Inca Indians in

those countries grew potatoes in their mountain valleys. They made a

light floury mixture that they used to bake a potato-type bread. The

word potato comes from the Haitian name, batata, for sweet potato.

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