Transcription

LAB. MANUAL 5MANUAL OF METHODSOFANALYSIS OF FOODSFRUIT AND VEGETABLE PRODUCTSFOOD SAFETY AND STANDARDS AUTHORITY OF INDIAMINISTRY OF HEALTH AND FAMILY WELFAREGOVERNMENT OF INDIANEW DELHI2015

ACKNOWLEDGEMENTDeepest Sense of Gratitude and Indebtedness to all theMembers of the Panel “Method of Sampling and Analysis” andExperts, who have helped, supported knowledge and insight,have led the successful completion of Revision of manuals.Sincere Thanks to the Panel, Chairman for his valuableguidance, and encouragement and the Secretariat of thispanel who have worked hard throughoutthe tenure of revision work.Deepest Appreciation to the Chairperson, FSSAI and CEO,FSSAI for the cooperation, support and constantencouragement, without which the workwould not have seen the light of day.*******

FRUIT AND VEGETABLE PRODUCTS 2015MANUAL FOR ANALYSIS OF FRUIT AND VEGETABLE PRODUCTSTABLE OF CONTENTSS. No.TITLEPAGENO.1.0Thermally Processed Fruits and Vegetables1(Canned)2.0Thermally Processed Fruits and Vegetable Juices,10Fruit Beverages, Fruit Drink, Fruit Nectars andNon Thermally Processed Beverages (canned, Bottled etc)3.0Thermally Processed Fruit Drink, Beverages, Pulp, Juice,30Puree (Canned, Bottled Poly packed)4.0Soup Powders315.0Tamarind Pulp, Puree, Concentrate326.0Fruit Bar / Toffee347.0Fruit and Vegetable Cereal Flakes358.0Squashes, Crushes, Fruit syrups, Sherbets, Ginger Cocktail369.0Murabba3610.0Candied, Crystallised, Glazed Fruit / Vegetable, Fruit Peel3811.0Mango Chutney3812.0Tomato Ketchup, Sauce, Culinary Paste3913.0Soya bean Sauce3914.0Brewed and Synthetic Vinegar3915.0Carbonated Fruit Beverages, Drink4616.0Jam, Jelly and Marmalde4717.0Dehydrated Fruits and Vegetables4718.0Pickles5119.0Table Olives5120.0Dried Fruits and Vegetables52

FRUIT AND VEGETABLE PRODUCTS 2012MANUAL FOR ANALYSIS OF FRUIT AND VEGETABLE PRODUCTSStandards for processed fruits and vegetables are laid down in section 2.3 ofFood Safety and Standards (Food Product Standards and Food Additives) Regulations,2011 and include thermally processed fruits and vegetables, fruit and vegetable juices,soups (canned/bottled/flexibly packed), soup powders, dehydrated vegetables, fruitjam/ jelly/ marmalade/ fruit cheese, squashes, sherbets, chutneys, pickels etc. thestandards for dried fruits and nuts are given in section 2.3.47 (raisins, pistachio nutsetc.)1. THERMALLY PROCESSED FRUITS AND VEGETABLES (CANNED / BOTTLED /FLEXIBLY PACKAGED)1.1 Physical examinationNote the external condition of the can such as rusty spots, body dents, scratches,leakage around seams, condition of the ends etc. The external condition of the can isdescribed in terms such as:a) FLAT (both ends concave)b) FLIPPER (a mechanical shock producing distortion in one end or both ends)c) SPRINGER (one end is distorted while other end is flat) andd) SWELL (both ends convex)1.2 Determination of VacuumPlace the pointed end of the vaccum gauge in the middle of the top plate of thecan and press firmly to pierce the can. Note down the vaccum in millimeters of mercury(Ref: - I S I Hand book of Food Analysis (Part 1) – 1980 page 2)1.3 Fill of Container1.3.1 PrincipleThis method determines the percent total volume of a container occupied by the1

FRUIT AND VEGETABLE PRODUCTS 2012contained food. It is designed primarily for cans but can be used for wide mouth glasscontainers also1.3.2 ApparatusHead space Gauge – One can be conveniently made from a straight edgea small ruler.1.3.3 ProcedureOpen the container (use a can opener for cans and remove lid for jars) andmeasure the distance from the container top to the food using the headspace gauge.This is usually done at the center but if the food surface is uneven, then make severalmeasurements at different points and average them Pour out the food over a sieve todetermine drained weight Wash, dry and weigh the container.Fill the container with water to within 5 mm of the top (using the head spacegauge). Weigh the container and water.Next draw off water from the container until the water is at the same level asmeasured for the food. Again weigh the container and water. (Note that the watertemperature should be the same during both weighings)1.3.4 CalculationThe % fill of the container W2 –T X 100W1 - TWhereT Weight of empty containerW1 Container plus water, first weightW 2 Container plus water, second weight(Ref: - F.A.O Manuals of Food Quality Control 14 / 8 page 184)2

FRUIT AND VEGETABLE PRODUCTS 20121.4 Drained weight:1.4.1Principle:The sample is drained on a standard mesh sieve. The weight of the materialremaining on the sieve is expressed as percentage of the can contents.1.4.2 Apparatus:Sieve with square openings, 2.8 mm x 2.8 mm (No. 6 B.S.). Use a sieve of 20 cm ifthe total weight of contents is under 1.5 kg and of 30 cms if the weight is more than 1.5kg.MethodCanned fruitsand vegetableCannedtomatoes* Table for sieve sizeCapacity ofSieve DiameterMesh openingcontainera.less than202.8 X 2.81.5 kgDrainingtime min2b. l.5 kg ormore302.8 X 2.82a. less than 1.5kg2011.2 X 11.22b. l.5 kg ormore3011.2 X 11.22200.3 X 0.35Washeddrained wt.1.4.3 Procedure:Weigh the full can; open and pour the entire contents on a circular sieve; withoutshifting the product incline the sieve to facilitate drainage. In the case of products with acavity such as peach halves, invert if necessary so that the liquid can drain through thecavity but otherwise the product should not be disturbed. Drain for two minutes; weighthe drained solids and the empty can3

FRUIT AND VEGETABLE PRODUCTS 2012Drained weight% drained weight ------------------------------- x 100Net weight of contentsNet wt. of contents Gross weight – tare weight of the can.For canned tomatoes use a sieve with square openings of 11.2 mm x 11.2 mm.For products in sauce, use a sieve with square openings of 0.3 mm x 0.3 mm;Wash the contents on the sieve with water until free of adhering substances; spread onsieve and drain for 5 minutes, dry the underside of the sieve and weigh.(Ref: - F.A.O Manuals of Food Quality Control 14 / 8 page 183 / Codex AlimentariousCommission Recommended method 36 / 7 – 1970, and method 44 – 1972)1.5 Internal condition of the can:Examine the internal surface for any corrosion, pitting, scratching, defects inlacquering, leakages, discolouration, detinning etc.1.6 Determination of soluble solids1.6.1 Principle:Measurement of the refractive index of the test solution at 20 0C, using arefractometer, and use of tables correlating refractive index with soluble solids content(expressed as Sucrose), or direct reading of the soluble solids content on therefractometer.1.6.2 Apparatusa) Refractometer - indicating the refractive index by means of a scalegraduated in 0.001, in order to allow readings to be estimated to 0.0002.Refractometer - indicates the percentage by mass of Sucrose by means of ascale graduated in 0.5 %, in order to allow readings to be estimated to 0.25%. This refractometer shall be adjusted so that at 20distilled water a soluble solid (Sucrose) content of zero.40C it registers for

FRUIT AND VEGETABLE PRODUCTS 2012b) Water circulating apparatus - to maintain the temperature of the prisms ofthe refractometer constant to within 0.5 0 C in the neighbourhood of 20 0Cwhich is the reference temperature. If the temperature of circulating water isdifferent from 20 0C use temperature correction as per table on page no.c) Beaker- capacity 250 ml1.6.3 Procedure:1.6.3.1 Preparation of test solution(a)Clear liquid productsThoroughly mix the sample and use it directly for determination.(b)Semi thick products ( purees etc)Thoroughly mix the sample. Press a part of the sample through a gauge/muslincloth folded in four, rejecting the first drops of the liquid and reserving the remainderof the liquid for the determination(c)Thick products ( jams, Jellies etc)Weigh into the tared beaker to the nearest 0.01 gm, a suitable quantity (upto 40gm) of the sample and add 100 – 150 ml of distilled water. Heat the contents of thebeaker to boiling and allow to boil gently for 2- 3 minutes, stirring with a glass rod.Cool the contents and mix thoroughly. After 20 minutes weigh to the nearest 0.01gm,then filter through a fluted filter paper or a Buchner funnel into a dry vessel. Reservethe filterate for determination1.6.3.2 DeterminationAdjust the water circulation in order to operate at the required temperature andallow it to flow to bring the prisms of the refractometer to the same temperature whichshall remain constant to within 0.5 C during the determination.Put a small quantity of the test solution (2- 3 drops are sufficient ) on the fixedprism of the refractometer and immediately adjust the movable prism. Suitablyilluminate the field of view. Bring the line dividing the light and dark parts of the surfacein the field of view to the crossing of the threads and read the value of refractive index.5

FRUIT AND VEGETABLE PRODUCTS 2012Determine percent sugar from the tableIf the determination has been carried out at a temperature other than 20 C 0.50C the following corrections are required(a) For the scale indicating refractive index apply the formula(b) For the scale indicating percentage by mass or Sucrose correct the result accordingto the table 11.6.3.3Calculation(a) Refractometer with refractive index scaleRead from table 2 the percentage mass of sucrose corresponding to the value ofrefractive index corrected for temperature if necessary. In the case of liquid or semithick products the soluble solid content is equal to the number found. If thedetermination has been carried out on a diluted sample the soluble solid content isequal toWhere,P x m1m0P is the percentage by mass of soluble solids in the diluted solution m0 is the mass, ingm of the sample before dilution m 1 is the mass in gm of the sample after dilutionTake the result as the arithmetic mean of two determinations. Express the resultto one decimal place6

FRUIT AND VEGETABLE PRODUCTS 2012(b) Refractometer with sugar scaleIn the case of liquid or semi thick products the soluble solid content, as a percentageby mass of the sucrose is equal to the value read, corrected for temperature ifnecessary. If the determination has been made on a diluted solution calculate thesoluble solids as shown aboveTake the result as the arithmetic mean of two determinations.(Ref: - I.S 13815: 1993 / I.S.O 2173: 1978 Fruit and Vegetable Products Determinationof Soluble solid Content - Refractometer method)7

FRUIT AND VEGETABLE PRODUCTS 20121.7 Determination of Sodium Chloride (salt content) in brine:1.7.1Principle:8

FRUIT AND VEGETABLE PRODUCTS 2012Direct titration of NaCl in brine with standard silver nitrate solution based on theMohr method is adequate for routine analysis.1.7.2Reagents:i) 5% (w/w) aqueous potassium chromate solution.ii) 0.1N aqueous silver nitrate solution.iii) N Sodium Hydroxide1.7.3 Procedure:Take 5 to 10 gm of liquid portion from the drained weight determination. If it isacidic, neutralize it with standard Sodium Hydroxide using phenopthlein as indicator.Add 1 ml of 5% aqueous potassium chromate solution and titrate with 0.1N AgNO3solution to produce red-brown end point.Titre value x Normality of AgNO3 x 58.4 x 100NaCl % --------------Weight of the sample x 1000(Ref: - I S I Handbook of Food Analysis (Part VIII) – 1984 page 5)1.8 Metallic contaminants:Follow procedures given in the Manual of Methods of Analysis - Metals1.9 Pesticide residues:Follow procedures given in the Manual on Pesticide residues.1.10 Microbiological examination:Follow procedures given in the relevant Manual.9

FRUIT AND VEGETABLE PRODUCTS 20122.0 Thermally processed fruit and vegetable juices fruit beverages / fruit drinksand fruit nectars (canned / bottled) / flexibly/ aseptically packaged andnon-thermally processed fruit beverages / drinks.2.1Total Solids(a) Insoluble matter absent (applicable to jellies and syrups also)Digest pure quartz sand that passes No 40 but not No 60 sieve with HCl, washacid free, dry and ignite. Preserve in stoppered bottle. Place 26- 30 gm sand and a shortstirring rod in the dish about 55 mm in diameter and 40 mm deep, fitted with cover. Drythe dish thoroughly cool in a dessicator and weigh immediately. Add enough sample toyield about 1 gm dry matter and mix thoroughly with sand. Heat on steam bath 15 – 20minutes, stirring at 2 – 3 minutes interval or until mass becomes too stiff to manipulatereadily.Dry at less than 700C under pressure of about 50 mm Hg in vaccum ovenpassing a current of dry air (dried over CaSO4 or P2O5). Make trial weighings at 2 hoursinterval after 18 hrs until change in weight is equal to 2 mg.Calculation: % Total Solids (W3-W1) X100(W2-W1)(b) Insoluble matter present (applicable to jams, marmalades and preservesalso)Accurately weigh into a large flat bottomed dish sufficient sample that will give2- 3 gm dry matter. If necessary to secure thin layer of material, add few ml waterand mix thoroughly. Dry at 700C under pressure less than 100 mm Hg untilconsecutive weighing’s made at 2 hr intervals vary less than 3mg.(Ref: - A.O.A.C 17th edition, 2000, Official method 920.151 Solids (Total) in Fruitsand Fruit Products).10

FRUIT AND VEGETABLE PRODUCTS 20122.2 Total soluble solids:Follow method given in Clause1.6 above2.3 Determination of pH Value: pH is the measurement of H ion activity; It measures active acidity. pH may bedetermined by measuring the electrode potential between glass and referenceelectrodes; pH meter is standardised using standard pH buffers.Use homogenized sample for the determination of pH.Preparation of sample for pH measurement:LiquidsImmerse the standardized electrode tip into the solution and stir the samplegently by means of a rod or "flea" to give a constant pH value.Non-homogeneous productsIf it is useful to know the pH of different components of the sample or differencesbetween the pH at several points of the test