E- ImmunoassaysE- ImmunoassaysImmuoassays are finding increasing use in the food Immuoassays are finding increasing use in the food industry for the qualitative and quantitative industry for the qualitative and quantitative analysis of food productsanalysis of food products . .

Immunoassays specific for low molecular weight Immunoassays specific for low molecular weight carbohydrates are developed by attaching the carbohydrates are developed by attaching the carbohydrate of interest to a protein, and then carbohydrate of interest to a protein, and then injecting it into an animalinjecting it into an animal . .

With time the animal develops antibodies specific With time the animal develops antibodies specific for the carbohydrate moleculefor the carbohydrate molecule..

These antibodies can then be extracted from the These antibodies can then be extracted from the animal and used as part of a test kit for animal and used as part of a test kit for determining the concentration of the specific determining the concentration of the specific carbohydrate in foodscarbohydrate in foods..

Immuoassays are extremely sensitive, specific, easy Immuoassays are extremely sensitive, specific, easy to use and rapidto use and rapid..

   Analysis of Analysis of PolysaccharidesPolysaccharides

A wide variety of polysaccharides occur in foodsA wide variety of polysaccharides occur in foods . .

Polysaccharides can be classified according toPolysaccharides can be classified according to::

11 - -Their molecular characteristics (Their molecular characteristics (e.g., e.g., type, type, number, bonding and sequence of number, bonding and sequence of monosaccharides)monosaccharides)

22 - -Physicochemical characteristics (Physicochemical characteristics (e.g., e.g., water water solubility, viscosity, surface activity)solubility, viscosity, surface activity)

33 - -Nutritional function Nutritional function ((e.g., e.g., digestible or non-digestible or non-digestible)digestible)..

IIndigestible polysaccharides form part of a ndigestible polysaccharides form part of a group of substances known as group of substances known as dietary dietary fiberfiber..

which also includes which also includes ligninlignin (which is a (which is a polymer of aromatic molecules)polymer of aromatic molecules)..

Consumption of many types of dietary fiber Consumption of many types of dietary fiber has been shown to have beneficial has been shown to have beneficial physiologically functional properties for physiologically functional properties for humans, humans, e.g., e.g., prevention of cancer, heart prevention of cancer, heart disease and diabetesdisease and diabetes..

Analysis of StarchAnalysis of StarchStarch is the most common digestible Starch is the most common digestible polysaccharide found in foodspolysaccharide found in foods..

In natural foods, such as legumes, cereals or In natural foods, such as legumes, cereals or tubers, the starch granules are usually tubers, the starch granules are usually separated from the other major separated from the other major components by drying, grinding, steeping components by drying, grinding, steeping in water, filtration and centrifugationin water, filtration and centrifugation . .

The starch granules are water-insoluble and The starch granules are water-insoluble and have a relatively high density (1500 kg/mhave a relatively high density (1500 kg/m33) ) so that they will tend to move to the so that they will tend to move to the bottom of a container during bottom of a container during centrifugationcentrifugation..

Analysis methodsAnalysis methods

Once the starch has been extracted there Once the starch has been extracted there are a number of ways to determine its are a number of ways to determine its concentrationconcentration::

11 - -Specific enzymesSpecific enzymes are added to the are added to the starch solution to breakdown the starch starch solution to breakdown the starch to glucose. The glucose concentration is to glucose. The glucose concentration is then analyzed using methods described then analyzed using methods described previously (previously (e.g., e.g., chromatography or chromatography or enzymatic methods)enzymatic methods)..

The starch concentration is calculated The starch concentration is calculated from the glucose concentrationfrom the glucose concentration . .

22 - -IodineIodine can be added to the starch solution can be added to the starch solution to form an insoluble starch-iodine to form an insoluble starch-iodine complex that can be determined complex that can be determined gravimetrically gravimetrically by collecting, drying and by collecting, drying and weighing the precipitate formedweighing the precipitate formed..

or or titrimetrically titrimetrically by determining the by determining the amount of iodine required to precipitate amount of iodine required to precipitate the starchthe starch . .

33 - -If there are no other components present If there are no other components present in the solution that would interfere with in the solution that would interfere with the analysis, then the starch the analysis, then the starch concentration could be determined using concentration could be determined using physical methodsphysical methods, , e.g., e.g., density, refractive density, refractive index or polarimetryindex or polarimetry . .

Analysis of FibersAnalysis of Fibers

Over the past twenty years or so nutritionists Over the past twenty years or so nutritionists have become aware of the importance of fiber have become aware of the importance of fiber in the dietin the diet..

Consumption of fiber helps protect against Consumption of fiber helps protect against colon cancer, cardiovascular disease and colon cancer, cardiovascular disease and constipation. Adequate intake of dietary fiber constipation. Adequate intake of dietary fiber is therefore beneficial to good healthis therefore beneficial to good health..

Dietary fiber is defined as plant Dietary fiber is defined as plant polysaccharides that are indigestible by polysaccharides that are indigestible by humans. Plus lignin, the major components humans. Plus lignin, the major components of dietary fiber are cellulose, hemicellulose, of dietary fiber are cellulose, hemicellulose, pectin, and hydrocolloidspectin, and hydrocolloids..

Crude Fiber MethodCrude Fiber Method

The crude fiber method gives an The crude fiber method gives an estimate of indigestible fiber in foodsestimate of indigestible fiber in foods..

It is determined by sequential It is determined by sequential extraction of a defatted sample with extraction of a defatted sample with 1.25% H1.25% H22SOSO44 and 1.25% NaOH and 1.25% NaOH..

The insoluble residue is collected by The insoluble residue is collected by filtration, dried, weighed and ashed to filtration, dried, weighed and ashed to correct for mineral contamination of correct for mineral contamination of the fiber residuethe fiber residue..

Filth detectionFilth detectionExamination of whole foods for insect Examination of whole foods for insect and rodent contaminationand rodent contamination::

Insect tunneling and webbingInsect tunneling and webbing..

Whole larvae and adultsWhole larvae and adults..

Rodent contaminationRodent contamination::rodent excretarodent excreta..

Animal hairsAnimal hairs

Filth recovery methodsFilth recovery methods

11 - -Sedimentation in heavier than water Sedimentation in heavier than water liquidsliquids::

This procedure can be used to separate This procedure can be used to separate rodent excreta pellet fragments rodent excreta pellet fragments from cerealsfrom cereals..

In a liquid with a specific gravity near In a liquid with a specific gravity near 1.49 the pellet fragments tend to 1.49 the pellet fragments tend to settle out while much of the cereals settle out while much of the cereals floatfloat..

22 - -Sieving: in certain instances, a size Sieving: in certain instances, a size separation offers a rapid means of separation offers a rapid means of separating filth from foodseparating filth from food..

33 - -When gasoline is mixed with an When gasoline is mixed with an aqueous mixture containing aqueous mixture containing insects or insect fragments, the insects or insect fragments, the insects float up with the gasoline insects float up with the gasoline layerlayer..

FruitsFruits

The water content of fruits varies from The water content of fruits varies from 60- 90%60- 90%,,

fruits undergo a series of progressive fruits undergo a series of progressive changes from the unripe stage, to ripe changes from the unripe stage, to ripe stage, to the rotten and fermentative stage, to the rotten and fermentative stagesstages..

The ripening point of a fruit is The ripening point of a fruit is considered to be that point at which considered to be that point at which the sugar content is a maximumthe sugar content is a maximum..

In In oranges and grapefruitoranges and grapefruit, maturity , maturity is based on a minimum invert is based on a minimum invert sugar-citric acid ratio (eight to sugar-citric acid ratio (eight to one)one)..

ApplesApples are considered ripe when the are considered ripe when the last trace of starch disappearslast trace of starch disappears..

The browning of fruit flesh on The browning of fruit flesh on exposure to air is due to the exposure to air is due to the oxidation of the tannin in the fruit oxidation of the tannin in the fruit by an oxidase enzyme in the by an oxidase enzyme in the presence of the oxygen of the airpresence of the oxygen of the air..

Maturity test for oranges Maturity test for oranges and grapefruitand grapefruit

Since the colour of grapefruit and Since the colour of grapefruit and oranges is inadequate as a measure oranges is inadequate as a measure of maturity, a more objective of maturity, a more objective standard is usedstandard is used..

This is based on the ratio of total This is based on the ratio of total solids to acid present in the juice, solids to acid present in the juice, this is often termed the sugar: acid this is often termed the sugar: acid ratio as the major part of the total ratio as the major part of the total solids is sugarsolids is sugar..

ProcedureProcedure::

Determine the acidity by titration with 0.1 N Determine the acidity by titration with 0.1 N sodium hydroxide solution and express the sodium hydroxide solution and express the acidity in terms of percentage of citric acidacidity in terms of percentage of citric acid..

Determine the total solid content of the fruitsDetermine the total solid content of the fruits..

The maturity ratio is then the percentage of The maturity ratio is then the percentage of total solids divided by the percentage of total solids divided by the percentage of citric acidcitric acid . .

The minimum ratio for orange is 8: 1, and for The minimum ratio for orange is 8: 1, and for grapefruit is 7: 1grapefruit is 7: 1..

Maturity test for applesMaturity test for apples

11 - -The firmness of the fruitThe firmness of the fruit..

22 - -The starch contentThe starch content..

33 - -The soluble solidsThe soluble solids..

44 - -The development of red colourThe development of red colour . .

55 - -The colour of the seedsThe colour of the seeds..

Starch test:Starch test: As apples mature, the As apples mature, the amount of starch decreases and in amount of starch decreases and in some varieties it is negligiblesome varieties it is negligible..

ProcedureProcedure : :

11 - -Dip slices of apple into a solution of Dip slices of apple into a solution of iodine in potassium iodide for 1 iodine in potassium iodide for 1 minuteminute . .

22 - -Use the depth of the blue staining as Use the depth of the blue staining as an index of the amount of starch an index of the amount of starch presentpresent..

Soluble solids:Soluble solids: As apples mature, As apples mature, the soluble solids content the soluble solids content increasesincreases..

Colour of seeds:Colour of seeds: As apples mature, As apples mature, the seeds turn brown to black in the seeds turn brown to black in colourcolour..

Frozen fruits and fruit Frozen fruits and fruit productsproducts

Frozen fruits are made by freezing a properly Frozen fruits are made by freezing a properly prepared fruit ingredient or mixture of fruit prepared fruit ingredient or mixture of fruit ingredients specified in fill of containeringredients specified in fill of container..

May be added an optional May be added an optional sweetening sweetening ingredientingredient::

Sugar, any mixture of sugar with dextrose or Sugar, any mixture of sugar with dextrose or corn syrupcorn syrup..

An optional liquid An optional liquid packing mediumpacking medium::

Heavy syrup, medium syrup, light syrup, corn Heavy syrup, medium syrup, light syrup, corn syrupsyrup..

Vegetable ProductsVegetable Products

The analysis of these products The analysis of these products includes the estimation of includes the estimation of moisture, ash, metallic moisture, ash, metallic

constituents, sugars, acidsconstituents, sugars, acids,,……..

Maturity in frozen Maturity in frozen vegetablesvegetables

This method depends upon the This method depends upon the determination of the specific determination of the specific gravity of the sample by means gravity of the sample by means of the difference in weight in air of the difference in weight in air and in a liquid of known specific and in a liquid of known specific gravitygravity..

Canned PeasCanned Peas

Prepared fromPrepared from::

A variety of A variety of Pisum sativumPisum sativum. .

WaterWater

Optional ingredient: salt, sugar, Optional ingredient: salt, sugar, dextrose, spice, flavoring, dextrose, spice, flavoring, adjusting pH to 8adjusting pH to 8..

Quality:Quality: the standard quality for the standard quality for canned peas iscanned peas is::

11 - -Not more than 4% by count of the peas in the Not more than 4% by count of the peas in the container are spotted or discolouredcontainer are spotted or discoloured..

22 - -Normally coloured, not artificially colouredNormally coloured, not artificially coloured..

33 - -Weight of pea pods and other harmless Weight of pea pods and other harmless extraneous vegetable material is not more extraneous vegetable material is not more than 0.5- 1% of the drained weight of peas in than 0.5- 1% of the drained weight of peas in the containerthe container..

4- Weight of pieces of peas is not more than 10%.4- Weight of pieces of peas is not more than 10%.

5- The alcohol insoluble solids is not more than 5- The alcohol insoluble solids is not more than 23.5%.23.5%.

Spices, Flavors and Spices, Flavors and CondimentsCondiments

Spices are aromatic vegetable Spices are aromatic vegetable substances used for the substances used for the seasoning of foodseasoning of food..

Some of the determinations of Some of the determinations of spices includes; moisture, ash, spices includes; moisture, ash, nitrogen, heavy metals, reducing nitrogen, heavy metals, reducing sugars and starchsugars and starch..

Volatile and non-volatile extractVolatile and non-volatile extract::Extract 2 g of the sample in continuous extractor Extract 2 g of the sample in continuous extractor for 20 hours with anhydrous etherfor 20 hours with anhydrous ether..

Evaporate the ether to a small volumeEvaporate the ether to a small volume..

Transfer to a small weighed beakerTransfer to a small weighed beaker..

Evaporate at room temperature, allow to stand Evaporate at room temperature, allow to stand over sulphuric acid for 18 hours in a over sulphuric acid for 18 hours in a desiccatordesiccator..

Weigh and calculate the gain in weight as Weigh and calculate the gain in weight as percentage of total ether extractpercentage of total ether extract..

Heat the extract gradually and then at 110Heat the extract gradually and then at 110oo C until C until successive weighings show no losssuccessive weighings show no loss..

The difference in weight equals the volatile ether The difference in weight equals the volatile ether extract while the residue is the non-volatile extract while the residue is the non-volatile ether extractether extract..

Alcohol extractAlcohol extract::

Shake 2 g of the sample in a 100 ml Shake 2 g of the sample in a 100 ml volumetric flask with 95% alcohol volumetric flask with 95% alcohol for 8 hrsfor 8 hrs..

Filter and evaporate 50 ml of the Filter and evaporate 50 ml of the filtrate to dryness in a dishfiltrate to dryness in a dish..

Dry at 100Dry at 100oo C, the residue is the C, the residue is the alcohol extractalcohol extract..