YOGPR 6/1/99 4:43 PM Page i YOGHURT Science and Technology © 2000 Woodhead Publishing Limited YOGPR 6/1/99 4:43 PM Page ii Related titles on food science and technology from Woodhead Publishing: General Feta and related cheeses Eds R K Robinson and A Y Tamime (respectively Reading University and Scottish Agricultural College, U.K.) Contents include: traditional methods for the manufacture of Feta cheese; industrial manufacture of Feta cheese; manufacture of Halloumi; manufacture of Egyptian, soft pickled cheeses; miscellaneous white-brined cheeses; cheeses made by direct acidification 272pp 234 ¥ 173 mm hardback 1991 Chilled foods: a comprehensive guide Eds C Dennis and M Stringer (respectively Director-General and Director of Food Science Division, Campden and Chorleywood Food Research Association) “This book lives up to its title in reviewing a major section of the food industry.” International Food Hygiene Contents include: trends in consumer tastes and preferences; market place product knowledge; legislation; refrigeration of chilled foods; temperature monitoring and measurement; processing; chilled food packaging; chilled foods microbiology; conventional and rapid analytical microbiology; microorganisms and safety in refrigerated foods; non-microbial factors affecting quality and safety; shelf-life determination and challenge testing; quality and consumer acceptability; cleaning and disinfection; hygienic design; total quality management 400pp 234 ¥ 173 mm hardback 1992 ISBN 85573 270 X Food safety and quality Instrumentation and sensors for the food industry Ed Erika Kress-Rogers (ALSTOM; formerly Leatherhead Food RA) “In this book existing and forthcoming instrumentation systems are surveyed to provide a practical guide for those involved in designing, selecting and using such systems in the food industry International experts have presented their knowledge in an applied framework to provide the most comprehensive workbook for practitioners ever written.” Food Science and Technology Abstracts Contents include: colour measurement; compositional and texture analysis; rheological measurement; analysis of water activity; ultrasound; infrared techniques; microwave measurement; laboratory instrumentation; chemical sensors, biosensors and immunosensors 740pp 234 ¥ 156 mm hardback 1993 ISBN 85573 363 For more information contact Customer Services at Woodhead Publishing Ltd, Abington Hall, Abington, Cambridge CB1 6AH, England; tel: +44 (0)1223 891358 ext.30; fax: +44 (0)1223 893694; e-mail: wp@woodhead-publishing.com Please also visit our web site: www.woodhead-publishing.com © 2000 Woodhead Publishing Limited YOGPR 6/1/99 4:43 PM Page iii YOGHURT Science and Technology Second edition A Y Tamime Scottish Agricultural College Auchincruive, Food Standards & Product Technology Department, Ayr KA6 5HW, Scotland R K Robinson University of Reading, Department of Food Science & Technology, Reading RG6 2AP, England Cambridge England © 2000 Woodhead Publishing Limited YOGPR 6/1/99 4:43 PM Page iv Published by Woodhead Publishing Limited Abington Hall, Abington Cambridge CB1 6AH England Published in North and South America by CRC Press LLC 2000 Corporate Blvd, NW Boca Raton FL 33431 USA First published 1985, Pergamon Press Ltd Second edition 1999, Woodhead Publishing Ltd and CRC Press LLC © 1999, Woodhead Publishing Ltd The authors have asserted their moral rights Conditions of sale This book contains information obtained from authentic and highly regarded sources Reprinted material is quoted with permission, and sources are indicated Reasonable efforts have been made to publish reliable data and information, but the authors and the publishers cannot assume responsibility for the validity of all materials Neither the authors nor the publishers, nor anyone else associated with this publication, shall be liable for any loss, damage or liability directly or indirectly caused or alleged to be caused by this book Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage or retrieval system, without prior permission in writing from the publishers The consent of Woodhead Publishing Ltd and CRC Press LLC does not extend to copying for general distribution, for promotion, for creating new works, or for resale Specific permission must be obtained in writing from Woodhead Publishing Ltd or CRC Press LLC for such copying Trademark notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation, without intent to infringe British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging in Publication Data A catalog record for this book is available from the Library of Congress Woodhead Publishing ISBN 85573 399 CRC Press ISBN 0-8493-1785-1 CRC Press order number: WP1785 Cover design by The ColourStudio Typeset by Best-set Typesetter Ltd., Hong Kong Printed by TJ International, Cornwall, England © 2000 Woodhead Publishing Limited YOGPR 6/1/99 4:43 PM Page v Contents Preface to second edition Preface to first edition Historical background 1.1 Introduction 1.2 Evolution of the process 1.3 Diversity of fermented milks 1.4 Patterns of consumption 1.5 Methods of production and classification 1.6 References Background to manufacturing practice 2.1 Introduction 2.2 Preliminary treatment of the milk base 2.2.1 Milk as a raw material 2.2.2 Separation of cellular matter and other contaminants present in milk 2.2.3 Milk reception and storage 2.3 Standardisation of fat content in milk 2.4 Standardisation of the solids-not-fat content in milk 2.4.1 Traditional process 2.4.2 Addition of milk powder 2.4.3 Addition of buttermilk powder 2.4.4 Addition of whey powder and/or whey protein concentrates 2.4.5 Addition of casein powder 2.4.6 Concentration by vacuum evaporation (VE) 2.4.7 Concentration by membrane filtration 2.4.8 Addition of non-milk proteins 2.5 Addition of stabilisers/emulsifiers © 2000 Woodhead Publishing Limited YOGPR 6/1/99 4:43 PM Page vi 2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.5.1 General background 2.5.2 Miscellaneous properties and conditions Addition of sweetening agents 2.6.1 General introduction 2.6.2 Types of carbohydrate sweetener Addition of miscellaneous compounds 2.7.1 Penicillinase 2.7.2 Preservatives 2.7.3 Minerals, vitamins and/or fatty acids Homogenisation 2.8.1 Effects on milk constituents 2.8.2 Aspects of processing Heat treatment 2.9.1 Destruction of micro-organisms/pathogens 2.9.2 Production of stimulatory/inhibitory factors 2.9.3 Changes in the physicochemical properties of milk 2.9.4 Processing effects on the physical properties of the gel Fermentation process 2.10.1 Introduction 2.10.2 Starter organisms 2.10.3 Gel formation Cooling 2.11.1 One-phase cooling 2.11.2 Two-phase cooling Addition of fruit/flavouring/colouring ingredients 2.12.1 Fruits 2.12.2 Flavouring agents 2.12.3 Colouring matter Packaging 2.13.1 Introduction 2.13.2 Functions of packages 2.13.3 Types of packaging materials 2.13.4 Comparative studies on permeability of different yoghurt packages 2.13.5 Migration of monomers and other compounds 2.13.6 Tamper-evident packaging 2.13.7 Aluminium foil lids 2.13.8 Sterilisation of packaging materials 2.13.9 Outer or shipping container Refrigerated cold storage, transport and distribution 2.14.1 The cold store 2.14.2 During transport 2.14.3 The retail shop and the consumer Conclusion References Processing plants and equipment 3.1 Home or small-scale production © 2000 Woodhead Publishing Limited YOGPR 6/1/99 4:43 PM Page vii 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.1.1 Miscellaneous systems 3.1.2 Packaging system Medium-scale production 3.2.1 Hand operated vat 3.2.2 Multipurpose vat 3.2.3 Mini dairy 3.2.4 Small-scale packaging machines Large-scale production 3.3.1 Milk reception, handling and storage 3.3.2 Standardisation of fat content in milk 3.3.3 Fortification of milk solids 3.3.4 Homogenisation 3.3.5 Heat treatment 3.3.6 Fermentation/incubation of the milk 3.3.7 Cooling 3.3.8 Pumps 3.3.9 Miscellaneous fittings 3.3.10 Fruit handling and mixing units 3.3.11 Filling machines 3.3.12 Miscellaneous handling, chill cooling and refrigerated cold storage Mechanisation of yoghurt production and plant design Continuous yoghurt production 3.5.1 Background 3.5.2 The NIZO process 3.5.3 Recent developments Automation/process control 3.6.1 Levels of automation 3.6.2 Area/department 3.6.3 Area/department 3.6.4 Area/department 3.6.5 Area/department 3.6.6 Area/department 3.6.7 Area/department 3.6.8 Management information system 3.6.9 System architecture 3.6.10 System security Building design, maintenance and services 3.7.1 General background and introduction 3.7.2 Location of a dairy plant 3.7.3 Layout of a dairy plant 3.7.4 Design and construction of dairy buildings Conclusion References Plant cleaning, hygiene and effluent treatment Cleaning aspects 4.1 Primary objectives 4.2 Principles of the cleaning process © 2000 Woodhead Publishing Limited YOGAP 6/1/99 7:14 PM Page 591 °C 16.7 17.2 17.8 18.3 18.9 19.4 20.0 20.6 21.1 21.7 22.2 22.8 23.3 23.9 24.4 25.0 25.6 26.1 26.7 27.2 27.8 28.4 28.9 29.4 30.0 30.6 31.1 31.7 32.2 32.8 33.3 33.9 34.4 35.0 35.6 36.1 36.7 37.2 37.8 38.3 38.9 39.4 40.0 40.6 41.1 41.7 42.2 42.8 43.3 43.9 44.4 45.0 45.6 46.1 46.7 °F 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 143.6 145.5 147.2 149.0 150.8 152.6 154.4 156.2 158.0 159.8 161.6 163.4 165.2 167.0 168.8 170.6 172.4 174.2 176.0 177.8 179.6 181.4 183.2 185.0 186.8 188.6 190.4 192.2 194.4 195.8 197.6 199.4 210.2 203.0 204.8 206.6 208.4 210.2 212.0 213.8 215.6 217.4 219.2 221.0 222.8 224.6 226.4 228.2 230.0 231.9 233.6 235.4 237.2 239.0 240.8 °C 47.2 47.8 48.3 48.9 49.4 50.0 50.6 51.1 51.7 52.2 52.8 53.3 53.9 54.4 55.0 55.6 56.1 56.7 57.2 57.8 58.3 58.9 59.4 60.0 60.6 61.1 61.7 62.2 62.8 63.3 63.9 64.4 65.0 65.6 66.1 66.7 67.2 67.8 68.3 68.9 69.4 70.0 70.6 71.1 71.7 72.2 72.8 73.3 73.9 74.4 75.0 75.6 76.1 76.7 77.2 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 °F °C 242.6 244.4 246.2 248.0 249.8 251.6 253.4 255.2 257.0 258.8 260.6 262.4 264.2 266.0 267.8 269.6 271.4 273.2 275.0 276.8 278.6 280.4 282.2 284.0 285.8 287.6 289.4 291.4 293.0 294.8 296.6 298.4 300.2 302.0 303.8 305.6 307.4 309.2 311.0 311.8 314.6 316.4 318.2 320.0 321.8 323.6 325.4 327.2 329.0 330.8 332.6 334.4 336.2 338.2 339.8 77.8 78.3 78.9 79.4 80.0 80.6 81.1 81.7 82.2 82.8 83.3 83.9 84.4 85.0 85.6 86.1 86.7 87.2 87.8 88.3 88.9 89.4 90.0 90.6 91.1 91.7 92.2 92.8 93.3 93.9 94.4 95.0 95.6 96.1 96.7 97.2 97.8 98.3 98.9 99.4 100.0 100.6 101.1 101.7 102.2 102.8 103.3 103.9 104.4 105.0 105.6 106.1 106.7 107.2 107.8 °F 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 341.6 343.4 345.2 347.0 348.8 350.6 352.4 354.2 356.0 357.8 359.6 361.4 363.2 365.0 366.8 368.6 370.4 372.2 374.0 375.8 377.6 379.4 381.8 383.6 384.6 386.6 388.4 390.2 392.0 393.8 395.6 397.4 399.2 401.0 402.8 404.6 406.4 408.2 410.0 411.8 413.6 415.4 417.2 419.0 420.8 422.6 424.4 426.2 428.0 429.8 431.6 433.4 435.2 437.0 438.8 Continued © 2000 Woodhead Publishing Limited YOGAP 6/1/99 7:14 PM Page 592 °C 108.3 108.9 109.4 110.0 110.6 111.1 111.7 112.2 112.8 113.3 113.9 114.4 115.0 115.6 116.1 116.7 117.2 117.8 118.3 118.9 119.4 120.0 120.6 121.1 121.7 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 °F °C 440.6 442.4 444.2 446.0 447.8 449.6 451.4 453.2 455.0 456.8 458.6 460.4 464.4 464.0 465.8 467.6 469.4 471.2 473.0 474.8 476.6 478.4 480.2 482.0 483.8 122.2 122.8 123.3 123.9 124.4 125.0 125.6 126.1 126.7 127.2 127.8 128.3 128.9 129.4 130.0 130.6 131.1 131.7 132.2 132.8 133.3 133.9 134.4 135.0 135.6 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 °F °C 485.6 487.4 489.2 491.0 492.8 494.6 496.4 498.2 500.0 501.8 503.6 505.4 507.2 509.0 510.8 512.6 514.4 516.2 518.0 519.8 521.6 523.4 525.2 527.0 528.8 136.1 136.7 137.2 137.8 138.3 138.9 139.4 140.0 140.6 141.1 141.7 142.2 142.8 143.3 143.9 144.4 145.0 145.6 146.1 146.7 147.2 147.8 148.3 148.9 °F 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 530.6 532.4 534.2 536.0 537.8 539.6 541.4 543.2 545.0 546.8 548.6 550.4 552.2 554.0 555.8 557.6 559.4 561.2 563.0 564.8 566.6 568.4 570.2 572.0 * Find the known temperature to be converted in the “boxed” column, then read the conversion to the left for °C and/or right for °F Example: Convert the following known temperature, i.e 50 10.0 50 122.0 \ 50°C = 122.0°F or 50°F = 10.0°C © 2000 Woodhead Publishing Limited YOGAP 6/1/99 7:14 PM Page 593 Appendix III Volume units Metric (SI) (Prefixes) KiloHectoDecaDeciCentiMilliMicro- = 1000 = 100 = 10 = 0.1 = 0.01 = 0.001 = 0.000 001 Millilitres to Cubic centimetres to Cubic metres to ͭ ͭ Litres to Fluid ounces (US) to © 2000 Woodhead Publishing Limited ͭ Imperial (Imp) and US Gallon Yard Foot Inch Pint Fluid ounce Drams To convert volume gallons (Imp) gallons (US) fluid ounces (Imp) fluid ounces (US) cubic inches cubic inches cubic feet gallons (Imp) gallons (US) cubic feet cubic inches fluid ounces (Imp) fluid ounces (US) gallons (Imp) gallons (US) pints (Imp) pints (US) quarts (Imp) quarts (US) cubic inches gallons (US) litres millilitres fluid ounces (Imp) Multiply by 0.00022 0.00026 0.03520 0.03380 0.06100 61.0 ¥ 10-3 35.30000 220.00000 264.17000 0.03500 61.03000 35.19600 33.81400 0.21990 0.26420 1.75980 2.11340 0.87880 1.05670 1.80500 0.00780 0.02950 29.57000 1.04100 YOGAP 6/1/99 7:14 PM Page 594 Fluid ounces (Imp) to Pints (Imp) to Pints (US) to Quarts (Imp) to Quarts (US) to Cubic feet to Cubic inches to Fluid drams to Fluid ounces to Fluid ounces to Fluid ounces (US) to Gallons (Imp) to Gallons (US) to © 2000 Woodhead Publishing Limited ͭ ͕ ͕ ͭ ͭ ͭ ͭ ͭ gallons (Imp) millilitres fluid ounces (US) litres pints (US) litres pints (Imp) litres litres cubic inches gallons (Imp) gallons (US) litres cubic centilitres cubic feet gallons (Imp) gallons (US) litres fluid ounces (US) fluid ounces (US) drams (US) litres (Imp) litres cubic feet cubic inches litres gallons (US) millilitres cubic metres ounces (Imp) cubic feet cubic inches litres gallons (Imp) millilitres cubic metres ounces (US) 0.00630 28.41000 0.96000 0.56800 0.83270 0.47320 1.20090 1.13650 0.94600 1728.00000 6.48100 7.48100 28.32000 16.38700 0.00058 0.00360 0.00430 0.01640 0.55400 0.12500 8.00000 0.02080 0.02960 0.16000 277.30000 4.54600 1.20090 4546.00000 0.00460 160.00000 0.13370 231.30000 3.78530 0.83270 3785.00000 0.00380 128.00000 YOGAP 6/1/99 7:14 PM Page 595 Appendix IV Weight/mass units Metric (SI) Imperial Tonnes Kilograms Grams Ton Pound Ounce Grains Gram to ͭ Kilogram to ͕ Ounce to Pound to Grain to Gram/litre to ͭ ͭ ͭ ͭ Gram/millilitre to Pound/cubic foot to Pound/gallon (US) to © 2000 Woodhead Publishing Limited ͕ ͭ To convert weight Multiply by grain ounce pound ounce pound gram grain pound gram grain kilogram ounce ounce pound gram 15.4300 0.0353 0.0022 35.2700 2.2040 28.3500 437.0000 0.0625 453.6000 7000.0000 0.4500 16.0000 0.0023 0.00014 0.0648 To convert weight per volume Multiply by grain/gallon (Imp) grain/gallon (US) grain/ounce (US) pound/gallon (US) pounds/gallon (US) gram/cubic centimetre pound/gallon (US) gram/millilitre pound/cubic foot gram/litre 70.1140 58.4000 0.4600 0.0083 8.3450 0.0160 0.1337 0.1198 7.8410 119.9470 YOGAP 6/1/99 7:14 PM Page 596 Appendix V Miscellaneous units To convert to SI units Velocity cm s-1 m hour-1 ft s-1 ft hour-1 mile hour-1 Volumetric flow cm3 s-1 m3 hour-1 ft3 s-1 cm3 min-1 min-1 ft3 min-1 ft3 hour-1 gal (Imp) min-1 gal (Imp) hour-1 gal (US) min-1 gal (US) hour-1 Viscosity A Dynamic g cm-1 s-1 kg m-1 hour-1 lb ft-1 s-1 lb ft-1 hour-1 B Kinematic cm2 s-1 m2 hour-1 ft2 s-1 ft2 hour-1 Density g cm-3 °C-1 lb ft-3 °F-1 lb gal-1 (Imp) lb gal-1 (US) © 2000 Woodhead Publishing Limited Multiply by 1.0000 2.7778 3.0480 3.4667 4.4704 ¥ 10-2 m s-1 ¥ 10-4 m s-1 ¥ 10-1 m s-1 ¥ 10-5 m s-1 ¥ 10-1 m s-1 1.0000 2.7778 2.8317 1.6667 1.6667 4.7195 7.8658 7.5766 1.2628 6.3089 1.0515 ¥ 10-6 m3 s-1 ¥ 10-4 m3 s-1 ¥ 10-2 m3 s-1 ¥ 10-8 m3 s-1 ¥ 10-5 m3 s-1 ¥ 10-4 m3 s-1 ¥ 10-6 m3 s-1 ¥ 10-5 m3 s-1 ¥ 10-6 m3 s-1 ¥ 10-5 m3 s-1 ¥ 10-6 m3 s-1 1.000 ¥ 10-1 kg m-1 s-1 2.7778 ¥ 10-4 kg m-1 s-1 1.4882 kg m-1 s-1 4.1338 ¥ 10-4 kg m-1 s-1 1.0000 2.7778 9.2903 2.5806 ¥ 10-4 m2 s-1 ¥ 10-4 m2 s-1 ¥ 10-2 m2 s-1 ¥ 10-5 m2 s-1 1.0000 ¥ 103 kg m-3 1.6018 ¥ 10 kg m-3 9.9779 ¥ 10 kg m-3 1.1983 ¥ 102 kg m-3 YOGAP 6/1/99 7:14 PM Page 597 Appendix VI Work/energy and other related units Quantity Energy cal kcal Btu Horse power (hp) hour-1 metric hp hour-1 (Imp) kW hour-1 ft lb-1 Therm Thermic Calorific value (volumetric) cal cm-3 kcal m-3 Btu ft-3 Therm ft-3 Coefficient of expansion (volumetric) g cm-3 °C-1 lb ft-3 °C-1 Heat flux cal s-1 cm-2 kcal hour-1 m-2 Btu hour-1 ft-2 Heat release rate A Mass cal s-1 g-1 kcal hour-1 kg-1 Btu hour-1 lb-1 B Volumetric cal s-1 cm-3 kcal hour-1 m-3 Btu hour-1 ft-3 Heat transfer coefficient cal s-1 cm-2 °C-1 © 2000 Woodhead Publishing Limited SI factor 4.1868 J 4.1868 ¥ 103 J 1.0551 ¥ 103 J 2.6477 ¥ 106 J 2.6845 ¥ 106 J 3.6000 ¥ 106 J 1.3558 J 1.0551 ¥ 18 J 4.1855 ¥ 106 J 4.1868 4.1868 3.7260 3.7260 ¥ 106 J m-3 ¥ 103 J m-3 ¥ 104 J m-3 ¥ 109 J m-3 1.0000 ¥ 103 ¥ kg m-3 °C-1 28.8330 ¥ kg m-3 °C-1 4.1868 ¥ 104 W m-2 1.1630 W m-2 3.1546 W m-2 4.1868 ¥ 103 W kg-1 1.1630 W kg-1 6.4612 ¥ 10-1 W kg-1 4.1868 ¥ 106 W m-3 1.1630 W m-3 1.0350 ¥ 10 W m-3 4.1868 ¥ 104 W m-2 °C-1 YOGAP 6/1/99 7:14 PM Page 598 kcal hour-1 m-2 °C-1 Btu hour-1 ft-2 °F-1 Power cal s-1 kcal hour-1 Btu s-1 Btu hour-1 hp (metric) hp (Imp) ft lb s-1 Specific enthalpy cal g-1 Btu l-1 Specific heat cal g-1 °C-1 Btu lb-1 °F-1 Thermal conductivity cal s-1 cm-2 (°C cm-1) kcal hour-1 m-2 (°C cm-1) Btu hour-1 ft-2 (°F ft-1) Btu hour-1 ft-2 (°F in-1) © 2000 Woodhead Publishing Limited 1.1630 W m-2 °C-1 5.6704 W m-2 °C-1 4.1868 W 1.1630 W 1.0551 ¥ 103 W 2.9308 ¥ 10-1 W 7.3548 ¥ 102 W 7.4570 ¥ 102 W 1.3558 W 4.1868 ¥ 103 J kg-1 2.3260 ¥ 103 J kg-1 4.1868 ¥ 103 J kg-1 °K-1 2.3260 ¥ 103 J kg-1 °K-1 4.1868 ¥ 102 W m-2 1.1630 W m-2 1.7308 W m-2 1.4423 ¥ 10-1 W m-2 YOGAP 6/1/99 7:14 PM Page 599 Appendix VII Force and pressure units Quantity Force dyn kg force lb force ton force Pressure dyn cm-2 kg f m-2 standard atmosphere atmosphere or kg f cm-1 bar lb f ft-2 lb f in-1 mm mercury (Hg) inch Hg © 2000 Woodhead Publishing Limited Multiplication factor 1.0000 ¥ 10-5 N 0.9867 N 4.4482 N 9.9640 ¥ 103 N 1.0000 ¥ 10-5 N m-2 9.8067 N m-2 1.0133 ¥ 105 N m-2 9.8067 ¥ 104 N m-2 1.0000 ¥ 105 N m-2 4.7880 ¥ 10 N m-2 6.8948 ¥ 103 N m-2 1.3333 ¥ 102 N m-2 3.3866 ¥ 103 N m-2 YOGAP 6/1/99 7:14 PM Page 600 Appendix VIII Length and area units Metric (SI) Imperial Kilometre (km) Metre (m) Centimetre (cm) Millimetre (mm) Mile (mi) Yard (yd) Foot (ft) Inch (in) metre = 100 cm = 1000 mm kilometre = 1000 m metre = 39.4 in = 3.28 ft = 1.09 yd = 0.621 ¥ 10-3 mile yard = ft = 36 in mile = 1760 yd To convert length Multiply by Inches to centimetres Feet to metres Yards to metres Miles to metres Centimetres to inches Metres to feet Metres to yards Kilometres to miles 2.5400 0.3048 0.9144 1609.0000 0.3940 3.2810 1.0936 0.6213 To convert area Multiply by Square inches to square centimetres Square feet to square metres Square yards to square metres Square centimetres to square inches Square metres to square feet Square metres to square yards © 2000 Woodhead Publishing Limited 6.4520 0.0929 0.8360 0.1550 10.7640 1.1970 YOGAP 6/1/99 7:14 PM Page 601 Appendix IX Pearson square and algebraic methods Pearsons square method If the raw materials (g 100 g-1) used for the manufacture of yoghurt are: skimmed milk (solidsnot-fat and water 91), skimmed milk powder (solids-not-fat 97 and water 3) and cream (fat 50), calculate the quantitites of the above raw materials required to produce a 500 l batch of yoghurt with total solids 16 and fat 1.5 in the final product Calculate first the quantities of skimmed milk and skimmed milk powder required to give the desired level of solids-not-fat 14.5 g 100 g-1 SNF in Skimmed milk 97 - 14.5 = 82.5 + 14.5 SNF in skimmed milk powder 14.5 - = 5.5 97 88.0 82.5 ¥ 500 = 468.75 litres 88 5.5 ¥ 500 The amount of skimmed milk powder = = 31.25 kg 88 required The amount of skimmed milk required = Total 500.00 litres Since the above mix contains only small quantities of fat, e.g 0.1 g 100 g-1, the balance of the required fat comes from the cream as follows: Fat present in fortified skimmed milk 0.1 Fat in cream 50 1.5 50 - 1.5 = 48.5 + 1.5 - 0.1 = 1.4 49.9 © 2000 Woodhead Publishing Limited YOGAP 6/1/99 7:14 PM Page 602 The amount of fortified skimmed milk = required The amount of cream required = 48.5 ¥ 500 = 485.97 litres 49.9 1.4 ¥ 500 = 14.03 litres 49.9 Total 500.00 litres Although the above calculation does not take into consideration the amount of solidsnot-fat present in the cream (4.5 g 100 g-1) and the starter culture inoculum (12 g 100 g-1), the accuracy is sufficient for most practical purposes However, as an additional check, the final composition of the yoghurt can be calculated as follows: Product Weight (l or kg) Weight of fat supplied (kg) Weight of solidsnot-fat supplied Skimmed milk 485.97 0.1 ¥ 485.97 = 0.49 100 ¥ 485.97 = 43.74 100 97 ¥ 31.25 = 30.31 100 Skimmed milk powder 31.25 *** Cream 14.03 50 ¥ 14.03 100 Starter culture at 3% rate of inoculation 15.00 *** Total 546.25 = 7.02 4.5 ¥ 14.03 = 0.63 100 12 ¥ 15 100 7.51 = 1.8 76.48 100 ¥ 7.51 = 1.37 546.25 76.48 ¥ 100 The % of solids - not - fat in yoghurt = = 14.00 546.25 \ the % of fat in yoghurt = Hence, the difference in the composition (g 100 g-1) is fat 0.13 and solids-not-fat 0.5, and such small margin of error is due to the fact that the cream (SNF) and the starter inoculum (SNF) are not considered If such small % of fat and SNF is compensated for, then the prepared milk base will have the desired level of fat and SNF The algebraic method This method of calculation takes into consideration all the raw materials used for the manufacture of yoghurt in order to obtain exactly the quantities required for a balanced mix, an approach which is similar to that used in the ice-cream industry (Hyde and Rothwell, 1973) For example, if the aim is to prepare a mix for yoghurt production which has the following chemical composition (g 100 g-1) (fat 1.5 and SNF 14.5) and the dairy materials used are whole milk, skimmed milk, skimmed milk powder and a liquid starter culture, the composition of the raw materials can be taken as: X = kg of whole milk (fat 3.5, SNF 8.5 and water 88.0); Y = kg of skimmed milk (fat 0.1, SNF 9.0 and water 90.0); Z = kg of skimmed milk powder (SNF 97 and water 3) If the inoculation rate (g 100 g-1) of the starter culture (SNF 12 and water 88) is 3, then in a batch of 100 units, kg of culture would be used containing (0.36 kg SNF and 2.64 kg of water) © 2000 Woodhead Publishing Limited YOGAP 6/1/99 7:14 PM Page 603 For convenience, the liquid ingredients could be measured in litres and the procedure of calculation is as follows: The source of fat is whole milk (3.5 g 100 g-1) and skimmed milk (0.1 g 100 g-1) and the level in the mix is 1.5 g 100 g-1 3.5X 0.1Y + = 1.5 100 100 (1) The source of SNF (g 100 g-1) is whole milk (8.5), skimmed milk (9) and skimmed milk powder (97), and the level in the mix is 14.5; however, the amount of SNF (0.36 kg) which originates from the starter culture must be deducted, i.e 8.5X 9Y 97Z + + = 1.45 - 0.36 = 14.14 100 100 100 (2) The source of water (g 100 g-1) is whole milk (88.0), skimmed milk (90.9), skimmed milk powder (3.0) and the weight of the water from the starter culture; therefore, the formula becomes: Amount of water present in the mix is equal to: 100 - (wt of fat + wt of SNF + wt of water from the starter culture) 100 - (1.5 + 14.5 + 2.64) = 81.36 88 X 90.9Y 3Z + + = 81.36 100 100 100 (3) Multiply equations (1), (2) and (3) by their denominator, i.e 100 3.5X + 0.1Y = 150 (4) 8.5X + 9Y + 97Z = 1414 (5) 88X + 90.9Y + 3Z = 8136 (6) Calculate the value of X from equation (4) X= 150 - 0.1Y 3.5 (7) Substitute the value of X (7) in equation (5) and (6) 8.5 88 (150 - 0.1Y ) 3.5 (150 - 0.1Y ) 3.5 + 9Y + 97Y = 1414 (8) + 90.9Y + 3Z = 8136 (9) Multiply equation (8) by its denominator, i.e 3.5 8.5 (150 - 0.1Y ) + 31.5Y + 339.5Z = 4949 1275 - 0.85Y + 31.5Y + 339.5Z = 4949 31.5Y - 0.85Y + 339.5Z = 4949 - 1275 30.65Y + 339.5Z = 3674 (10) Multiply equation (9) by its denominator, i.e 3.5 88(150 - 0.1Y ) + 318.15Y + 10.5Z = 28 476 13 200 - 8.8Y + 318.15Y + 10.5Z = 28 476 318.15Y - 8.8Y + 10.5Z = 28 476 - 13 200 309.35Y + 10.5Z = 15 276 © 2000 Woodhead Publishing Limited (11) YOGAP 6/1/99 7:14 PM Page 604 Divide the value (Z) in equation (10) by the value (Z) in equation (11) in order to calculate the multiplication factor by which the value (Y ) can be calculated 339.5Z = 32.33 10.5Z Multiply equation (11) by the factor 32.33 10 001.29Y + 339.47Z = 493 873.08 (12) Subtract equation (10) from equation (12) 10 001.29Y + 339.47Z = 493 873.08 30.65Y + 339.5Z = 3674 9970.64Y + zero = 490 199.08 (The value of Z in equations (10) and (12) is approximately equal) 490 199.08 9970.64 = 49.16 kg or l of skimmed milk required \Y = Substitute the value of Y in equation (10) to calculate the value of Z 49.16(30.65) + 339.5Z = 3674 1506.75 + 339.5Z = 3674 339.5Z = 3674 - 1506.75 = 2167.25 2167.25 339.5 = 6.38 kg of skimmed milk powder required \Z = Substitute the value of Y in equation (7) to calculate the value of X 150 - 0.1(49.16) 3.5 150 - 4.916 = 3.5 145.08 = 3.5 = 41.45 kg or l of whole milk required X= Therefore add the weights of the raw materials required: whole milk skimmed milk skimmed milk powder starter culture 41.45 49.16 6.38 3.00 Total 99.99 The above total should amount to exactly 100, but the slight discrepancy is due to various approximations made in the above calculations; however, a second check from the above weights of raw materials can be made to confirm the chemical composition of the final yoghurt: © 2000 Woodhead Publishing Limited YOGAP 6/1/99 7:14 PM Page 605 Product Weight in kg Weight of fat supplied Weight of SNF supplied Whole milk 41.45 3.5 ¥ 41.45 = 1.45 100 8.5 ¥ 41.45 = 3.52 100 Skimmed milk 49.16 0.1 ¥ 49.16 = 0.05 100 ¥ 49.16 100 97 ¥ 6.38 100 ¥ 12 100 Skimmed milk powder 6.38 *** Starter culture 3.00 *** 99.99 1.5 = 4.42 = 6.19 = 0.36 14.48 The above example could be applied to calculate exactly the weight of any dairy raw material which could be used for the manufacture of yoghurt (see Chapter 2) and since the quantity or unit of a 100 is used, it can be easily converted to a much larger volume of production Reference hyde, k.a and rothwell, j (1973) In Ice Cream, Churchill Livingstone, London © 2000 Woodhead Publishing Limited [...]... engineering and design and this technology has been covered by Mr J Bird and Mr I Chester who represent two of the foremost equipment manufacturers in the world We would like to acknowledge their assistance and that of all the companies who provided us with technical information and illustrations Last but not least, we are grateful to Mrs A Peacock (SAC) for her patience in typing the manuscript, and Mrs... rise to a product which is insipid and stale and, Table 1.1 Selection of yoghurt and yoghurt-like products that have been identified in the Middle East and elsewhere Traditional name Country Jugurt/eyran/ayran Busa Kissel mleka/naja/yaourt Urgotnic Leban/laban or laban rayeb Turkey Turkestan Balkans Balkan mountains Lebanon and some Arab countries Egypt and Sudan Iran and Afghanistan Iraq India Armenia... process has become more rational, mainly due to various discoveries and/ or improvements in such disciplines as: • microbiology and enzymology • physics and engineering • chemistry and biochemistry Yet by today’s standards of industrial technology, the process of yoghurt making is still a complex process which combines both art and science together The micro-organisms of the yoghurt starter cultures... Appendix VI Work/energy and other related units Appendix VII Force and pressure units Appendix VIII Length and area units Appendix IX Pearson square method and algebraic methods © 2000 Woodhead Publishing Limited YOGPR 6/1/99 4:43 PM Page xiii This book is dedicated to our families © 2000 Woodhead Publishing Limited YOGPR 6/1/99 4:43 PM Page xiv Preface to second edition When the first edition of this book... Canadian Medical Association Journal, 26, 341 tamime, a.y and deeth, h.c (1980) Journal of Food Protection, 43, 939 tamime, a.y and marshall, v.m (1997) In Microbiology and Biochemistry of Cheese and Fermented Milk, 2nd Edition, Edited by Law, B Chapman & Hall, London, pp 57–152 tokita, f., hosono, a., takahashi, f., ishida, t and otani, h (1982) Dairy Science Abstracts, 44, 728 © 2000 Woodhead Publishing... animals (i.e cow, sheep, goat, buffalo and camel), and it is most likely that the transition occurred at different times in different parts of the world.Archaeological evidence shows that some civilisations (e.g the Sumarians and Babylonians in Mesopotania, the Pharoes in north-east Africa and the Indians in Asia) were well advanced in agricultural and husbandry methods, and in the production of fermented... Since the ash and lactose contents in bulk milk vary little, figures of 0.75 and 4.5 g 100 g-1, respectively, are taken as an annual averages The data were obtained between April 1993 and March 1994, before these schemes were revoked on 31 October 1994 England & Wales Milk Marketing Board (E&WMMB), Scottish Milk Marketing Board (SMMB), North of Scotland Milk Marketing Board (NSMMB), Aberdeen & District... different physical properties (Reinheimer et al., 1990; Gassen and Frank, 1991; Srinivas et al., 1997; Prabba and Shankar, 1997) In warm countries milk tends to deteriorate faster due to methods of production and handling A handbook has been published by the International Dairy Federation (IDF, 1990) that addresses this topic in detail and the measures that are used to minimise the bacterial spoilage... development of acid and flavour Their classification, behaviour and characteristics are discussed in detail in Chapter 7 However, in order to understand the principles of yoghurt making, it will be useful to describe separately the various stages of manufacture and their consequent effects on the quality of yoghurt The technology of the process, that is, the equipment required for small and large scale... protein, lactose and minerals (ash) A detailed breakdown of these components is shown in Fig 2.2 Inevitably, the chemical composition of fresh milk varies from day to day within any particular breed depending on such factors as stage of lactation and age of the cow, milk intervals, season of the year and environmental temperature, breed of cows and breeding policy, efficiency and intervals between milking,