Global production, processing and utilization of lentil: A review

doi:10.1016/S2095-3119(17)61793-3

摘要/Abstract

Abstract: Lentil is a highly nutritious legume with an ample quantity of carbohydrates and good amount of proteins, minerals, vitamins, phytochemicals and fibres. Although it has been used as staple food since ancient times, its usage has been limited in developed countries, especially due to the lower protein digestibility, presence of anti-nutritional factors, flatulence and poor cooking qualities. Processing of lentils including dehulling and splitting and isolation of major fractions, e.g., proteins and starches are some of the strategies that can be adopted to add value and increase consumption of these legumes. This review paper intends to provide detailed overview of lentil’s global production, nutritional composition and processing methods of lentil. Methods of isolation/characterization of lentil protein and starch and their subsequent application in foods are also presented.

Key words: lentil , production , cooking quality , anti-nutritional factors , processing , protein , starch

. [J]. Journal of Integrative Agriculture, 2017, 16(12): 2898-2913.

Matina Joshi, Yakindra Timilsena, Benu Adhikari. Global production, processing and utilization of lentil: A review[J]. Journal of Integrative Agriculture, 2017, 16(12): 2898-2913.

参考文献

Abu-Ghannam N. 1998. Modeling textural changes during the hydration process of red beans. Journal of Food Engineering, 28, 341–351.

Adsule R N, Kadam S S, Leung H K. 1989. Lentil. In: Salunkhe D K, Kadam S S, eds., Handbook of World Food Legumes: Nutritional Chemistry, Processing Technology, and Utilization. vol. II. CRC Press, Florida, USA. pp. 133–152.

Aguilera J M, Rademacher B. 2004. Protein gels. In: Yuda R Y, ed., Proteins in Food Processing. Woodhead Publishing, New York, USA. pp. 468–482.

Alexander W. 2015. Lentil trading and marketing: Australian grain exports. [2017-04-07]. https://grdc.com.au/Research-and-Development/GRDC-Update-Papers/2015/08/Lentil-trading-and-marketing

Alsohaimy S A, Sitohy M Z, El-Masry R A. 2007. Isolation and partial characterization of chickpea, lupine and lentil seed proteins. World Journal of Agricultural Sciences, 3, 123–129.

Asif M, Rooney L W, Ali R, Riaz M N. 2013. Application and opportunities of pulses in food system: A review. Critical Reviews in Food Science and Nutrition, 53, 1168–1179.

Atwell W A, Hood L F, Lineback D R, Varriano-Marston E, Zobel H F. 1988. The terminology and methodology associated with basic starch phenomena. Cereal Foods World, 33, 306.

Baines D, Seal R. 2012. Natural Food Additives, Ingredients And Flavourings. Elsevier, UK.

Bamdad F, Dokhani S, Keramat J. 2009. Functional assessment and subunit constitution of lentil (Lens culinaris) proteins during germination. International Journal of Agriculture Biology, 11, 690–694.

Batra V I P, Vasishta R, Dhindsa K S. 1986. Effect of heat and germination on trypsin inhibitor activity in lentil and pigeon pea. Journal of Food Science and Technology, 23, 260–263.

Bello-Pérez L A, Paredes-López O. 1995. Effects of solutes on retrogradation of stored starches and amylopectins: a calorimetric study. Starch-Stärke, 47, 83–86.

BeMiller J N. 2011. Pasting, paste, and gel properties of starch-hydrocolloid combinations. Carbohydrate Polymers, 86, 386–423.

Bhatty B S, Slinkard A E. 1979. Composition, starch properties and protein quality of lentils. Journal of Institute of Science and Technology Alimentarius, 12, 88–92.

Bhatty R S. 1984. Relationship between physical and chemical characters and cooking quality in lentil. Journal of Agricultural and Food Chemistry, 32, 1161–1166.

Bhatty R S. 1986. Protein subunits and amino acid composition of wild lentil. Phytochemistry, 25 , 641–644.

Bhatty R S. 1995. Comparisons of good and poor cooking lentils. Journal of the Science of Food and Agriculture, 68, 489–496.

Bhatty R S, Christison G I. 1984. Composition and nutritional quality of pea (Pisumsativum L.), faba bean (Vicia faba L. spp. minor) and lentils (Lens culinaris Medik.) meals, protein concentrates and isolates. Journal of Institute of Science and Technology Alimentarius, 12, 88–92.

Bhatty T S, Slinkard A E, Sosulski F W. 1976. Chemical composition and protein characteristics of lentils. Canadian Journal of Plant Science, 56, 787–794.

Biliaderis C G, Grant D R, Vose J R. 1979. Molecular weight distribution of legume starches by gel chromatography. Cereal Chemistry, 56, 475–480.

Bogracheva T Y, Wang Y L, Wang T L, Hedley C L. 2002. Structural studies of starches with different water contents. Biopolymers, 64, 268–281.

Bora P S. 2002. Functional properties of native and succinylated lentil (Lens culinaris) globulins. Food Chemistry, 77, 171–176.

Boye J, Zare F, Pletch A. 2010. Pulse proteins: Processing, characterization, functional properties and applications in food and feed. Food Research International, 43, 414–431.

Cai R, McCurdy A, Baik B K. 2002. Textural property of 6 legume curds in relation to their protein constituents. Journal of Food Science, 67, 1725–1730.

Cameron R E, Donald A M. 1992. A small-angle X-ray scattering study of the annealing and gelatinization of starch. Polymer, 33, 2628–2635.

Carman K. 1996. Some physical properties of lentil seeds. Journal of Agricultural Engineering Research, 63, 87–92.

Cepeda E, Villaran M C, Aranguiz N. 1998. Functional properties of Faba bean (Vicia faba) protein flour dried by spray drying and freeze drying. Journal of Food Engineering, 36, 303–310.

Chakraborty P, Sosulski F, Bose A. 1979. Ultracentrifugation of salt soluble proteins in ten legume species. Journal of the Science of the Food and Agriculture, 30, 766–771.

Cheftel J C, Cuq J L, Lorient D. 1985. Amino acids, peptides and proteins. In: Fennema O, ed., Food Chemistry. Marcel Dekker, New York. pp. 245–369.

Chung H J, Liu Q, Hoover R, Warkentin T D, Vanderberg B. 2008. In vitro starch digestibility, expected glycaemic index, and thermal and pasting properties of flours from pea, lentil and chickpea cultivars. Food Chemistry, 111, 316–321.

Creighton T E. 1978. Possible implications of many proline residues for the kinetics of protein unfolding and refolding. Journal of Molecular Biology, 125, 401–406.

Damodaran S. 1994. Structure-function relationship of food proteins. In: Hettiarachchy N S, Ziegler G R, eds., Protein Functionality in Food Systems. Marcel Dekker, New York.pp.1–37.

Damodaran S. 1996. Functional properties. In: Nakai S, Modler H W, eds., Food Proteins: Properties and Characterization. VCH Publishers, New York. pp. 167–233.

Damodaran S. 1997. Protein-Stabilized Foams and Emulsions. Food Science and Technology, Marcel Dekker, New York.pp. 57–110.

Danielson C E. 1950. An electrophoretic investigation of vicilin and legumin from seeds of peas. Acta Chemica Scandinavica, 4, 762–771.

Davis K R. 1981. Effect of processing on composition and Tetrahymena relative nutritive value on green and yellow peas, lentils and white pea beans. Cereal Chemistry, 58, 454–460.

Deshpande S S, Bal S. 2001. Effect of soaking time and temperature on textural properties of soybean. Journal of Texture Studies, 32, 343–347.

Deshpande S S, Cheryan M. 1986. Microstructure and water uptake of Phaseolus and winged beans. Journal of Food Science, 51, 1218–1223.

Donald A M. 2001. Plasticisation and self-assembly in starch granules. Cereal Chemistry, 78, 307–314.

Donovan J. 1979. Phase transitions of the starch-water system. Biopolymers, 18, 263–275.

Dostalova J, Houska M, Pokorny J. 1998. Relationships between processing conditions, mechanical and textural properties of cooked lentils. Polish Journal of Food and Nutrition Sciences, 7, 455−464.

Durazzo A, Turfani V, Azzini E, Maiani G, Carcea M. 2013. Phenols, lignans and antioxidant properties of legume and sweet chestnut flours. Food Chemistry, 140, 666–671.

El-Nahry F I, Mourad F E, Khalik S M A, Bassily N S. 1980. Chemical composition and protein quality of lentils (Lens) consumed in Egypt. Plant Foods for Human Nutrition, 30, 87–95.

Erskine W, Muehlbauer F J, Saker A, Sharma B. 2009. The Lentil: Botany, Production and Uses. CAB International, UK. p. 456.

Evans I D, Lips A. 1992. Viscoelasticity of gelatinized starch dispersions. Journal of Texture Studies, 23, 69–86.

Fan T Y, Sosulski F W. 1974. Dispersibility and isolation of proteins from legume flours. Canadian Institute of Food Science and Technology Journal, 7, 256–259.

FAO. 2016. FAOSTAT statistics database - Agriculture. [2017-04-23]. http://faostat3.fao.org/browse/Q/QC/E

Farooq Z, Boye J I. 2011. Novel food and industrial applications of pulse flours and fractions. In: Tiwari B K, Gowen A, McKenna B, eds., Pulse Foods: Processing, Quality and Nutraceutical Applications. Academic Press London, UK. pp. 283–324.

Ferry J D. 1980. Viscoelastic Properties of Polymers. 3rd ed. Wiley, New York, USA.

Gidley M J, Cooke D. 1991. Aspects of molecular organization and ultrastructure in starch granules. Biochemical Society Transactions, 19, 551–555.

Hedley C L, Bogracheva T Y, Wang T L. 2002. A genetic approach to studying the morphology, structure and function of starch granulesusing pea as a model. Starch-Stärke, 54, 235–242.

Hermansson A M. 1983. Protein functionality and its relation to food microstructure. Plant Foods for Human Nutrition, 32, 369–388.

Hoover H, Hughes T, Chung H J, Liu Q. 2010. Composition, molecular structure, properties, and modification of pulse starches: A review. Food Research International, 43, 399–413.

Hoover R, Manuel H. 1995. A comparative study of the physicochemical properties of starches from two lentil cultivars. Food Chemistry, 53, 275–284.

Hoover R, Ratnayake W S. 2002. Starch characteristics of black bean, chickpea, lentil, navy bean and pinto bean cultivars grown in Canada. Food Chemistry, 78, 489–498.

Hoover R, Sosulski F. 1985. Studies on the functional characteristics and digestibility of starches from Phaseolus vulgaris biotypes. Starch-Stärke, 37, 181–191.

Hoover R, Sosulski F. 1986. Effect of cross-linking on functional properties of legume starches. Starch-Stärke, 38, 149–155.

Hoover R, Sosulski F W. 1991. Composition, structure, functionality, and chemical modification of legume starches: A review. Canadian Journal of Physiology and Pharmacology, 69, 79–92.

Hsu D L, Leung H K, Morad M M, Finney P L, Leung C T. 1982. Effect of germination on electrophoretic, functional and bread baking properties of yellow pea, lentil and faba bean protein isolates. Cereal Chemistry, 59, 344.

Hu F B. 2003. Plant-based foods and prevention of cardiovascular disease: An overview. American Journal of Clinical Nutrition, 78, 544–551.

Hung T V, Liu L H, Black R G, Trewhella M A. 1993. Water absorption in chickpea (C. arietinum) and field pea (P. sativum) cultivars using the Peleg model. Journal of Food Science, 58, 848–852.

Jacobs D R, Gallaher D D. 2004. Whole grain intake and cardiovascular disease: A review. Current Atherosclerosis Reports, 6, 415–423.

Jane J. 1997. Starch functionality in food processing. In: Frazier P J, Richmond P, Donald A M, eds., Starch Structure and Functionality, Royal Society of Chemistry. Cambridge, UK. pp. 26–35.

Jenkins P J, Donald A M. 1998. Gelatinisation of starch: a combined SAXS/WAXS/DSC and SANS study. Carbohydrate Research, 308, 133–147.

Jenner A. 1985. The Amazing Legumes. The Saskatchewan Pulse crop development Board, Regina, Saskatchewan, Canada.

Johari A, Arora S, Potaliya M, Kawatra A. 2015. Role of lentil (Lens culinaris L.) in human health and nutrition. Annals of Agri Bio Research, 20, 291–294.

Jood S, Bishnoi S, Sharma A. 1998. Chemical analysis and physico-chemical properties of chickpea and lentil cultivars. Nahrung, 42, 71–74.

Joshi M, Adhikari B, Aldred P, Panozzo J F, Kasapis S. 2011. Physicochemical and functional properties of lentil protein isolates prepared by different drying methods. Food Chemistry, 129, 1513–1522.

Joshi M, Adhikari B, Aldred P, Panozzo J F, Kasapis S, Barrow C J. 2012. Interfacial and emulsifying properties of lentil protein isolate. Food Chemistry, 134, 1343–1353.

Joshi M, Aldred P, McKnight S, Panozzo J F, Kasapis S, Adhikari R, Adhikari B. 2013. Physicochemical and functional characteristics of lentil starch. Carbohydrate Polymers, 92, 1484–1496.

Kadam S S, Salunkhe D K. 1989. Milling. In: Salunkhe D K, Kadam S S, eds., Handbook of World Food Legumes: Nutritional Chemistry, Processing Technology and Utilization. vol III. CRC Press, New York, USA.

Kato A, Nakai S. 1980. Hydrophobicity determined by a fluorescence probe method and its correlation with surface properties of proteins. Journal of Agricultural Food Chemistry, 46, 2671–2677.

Kaur M, Sandhu K S, Lim S. 2010. Microstructure, physicochemical properties and in vitro digestibility of starches in different Indian lentil (Lens culinaris) cultivars. Carbohydrate Polymers, 79, 349–355.

Kaur M, Singh N. 2007. Characterization of protein isolates from different Indian chickpea (Cicer arietinum L.) cultivars. Food Chemistry, 102, 366–374.

Kaur M, Singh N, Sandhu K S. 2007. Preparation and characterization of protein isolates from different lentil (Lens culinaris) cultivars. Journal of Food Science and Technology, 44, 327–329.

Kaushik P, Dowling K, McKnight S, Barrow C J, Wang B, Adhikari B. 2016. Preparation, characterization and functional properties of flax seed protein isolate. Food Chemistry, 197, 212–220.

Khan M A, Rana I A, Ullah I, Jaffery S. 1987. Physicochemical characters and nutrient composition of some improved lines of lentils grown in Pakistan. Journal of Food Composition and Analysis, 1, 65–70.

Kim H, Behall K M, Conway J M. 2005. Short-term satiety and glycemic response after consumption of whole grains varying in the amount of β-glucan in overweight adults. In: North American Association for the Study of Obesity 2005 Annual Meeting. Obesity Research, 13, A219.

Kinsella J E. 1979. Functional properties of soy proteins. Journal of the American Oil Chemists’ Society, 56, 242–258.

Kinsella J E. 1982. Relation between structure and functional properties of food proteins. In: Food Proteins. Proceedings of the Kellogg Foundation International Symposium on Food Proteins Held at University College. Cork, 21–24 September, 1981. Applied Science Publishers, Republic of Ireland. pp. 52–103.

Knuckles B E, Kuzmicky D D, Gumbmann M R, Betschart A A. 1989. Effect of myo-inositol phosphate esters on in vitro and in vivo digestion of proteins. Journal of Food Science, 54, 1348–1350.

Kon S. 1979. Effect of soaking temperature on cooking and nutritional quality of beans. Journal of Food Science, 44, 1329–1335.

Kumar S K, Barpete S, Kumar J, Gupta P, Sarker A. 2013. Global lentil production: Constraints and strategies. SATSA Mukhapatra - Annual Technical Issue, 17, 1–13.

Kuntz I D. 1971. Hydration of macromolecules III: Hydration of polypeptides. Journal of American Oil Chemist Society, 93, 514–516.

Ladjal-Ettoumi Y, Boudries H, Chibane M, Romero A. 2016. Pea, chickpea and lentil protein isolates: Physicochemical characterization and emulsifying properties. Food Biophysics, 11, 43–51.

Leach H W, McCowen L D, Schoch T J. 1959. Structure of the starch granule I. Swelling and solubility patterns of various starches. Cereal Chemistry, 36, 534–544.

Lee H C, Htoon A K, Uthayakumaran S, Paterson J. 2007. Chemical and functional quality of protein isolated from alkaline extraction of Australian lentil cultivars: Maltida and Digger. Food Chemistry, 102, 1199–1207.

Liener I E, Kakade M L. 1980. Protease inhibitors. In: Liener I E, ed., Toxic Constituents in Plant Feedstuff. Academic Press, New York. pp. 7–71.

Liu Q. 2005. Understanding starches and their roles in foods. In: Cui S W, ed., Food Carbohydrates: Chemistry, Physical Properties, and Applications. CRC Press, New York, USA, pp. 357–406.

Magdassi S, Kamyshny A. 1996. Surface activity and functional properties of proteins. In: Magdassi S, ed., Surface Activity of Proteins: Chemical and Physicochemical Modifications. Marcel Dekker, New York. pp. 1–38.

Matsumura Y, Mori T. 1996. Gelation. In: Hall G M, ed., Methods of Testing Protein Functionality, Blackie Academic and Professional, London, U.K. p. 106.

McClements D J. 2005. Food Emulsions: Principles, Practice and Techniques. 2nd ed. CRC Press, New York, USA.

Neves V A, Lourenco E J. 1995. Isolation and in vitro hydrolysis of Globulin G1 from lentils (Lens culinaris, Medik). Journal of Biochemistry, 19, 109–120.

Noda T, Takahata Y, Sato T, Ikoma H, Mochida H. 1996. Physicochemical properties of starches from purple and orange fleshed sweet potato roots at two levels of fertilizer. Starch-Stärke, 48, 395–399.

Nygaard D F, Hawtin G C. 1981. Production, trade and uses. Lentils. Commonwealth Agricultural Bureau, Slough, UK, pp. 7–13.

Obanni M, Bemiller J N. 1997. Properties of some starch blends. Cereal Chemistry, 74, 431–436.

Osborne T B, Campbell G F. 1898. Proteins of lentils. Journal of the American Chemical Society, 20, 362.

Parker R, Ring S G. 2001. Aspects of the physical chemistry of starch. Journal of Cereal Science, 34, 1–17.

Peleg M. 1988. An empirical model for description of moisture sorption curves. Journal of Food Science, 53, 1216–1217.

Philanto A, Korhonen H. 2003. Bioactive peptides and proteins. Advances in Food and Nutrition Research, 47, 175–181.

Quast D G, da Silva S D. 1977. Temperature dependence of hydration rate and effect of hydration rate and effect of hydration on the cooking rate of dry legumes. Journal of Food Science, 42, 1299.

Rathod R P, Annapure U S. 2017. Physicochemical properties, protein and starch digestibility of lentil based noodle prepared by using extrusion processing. LWT-Food Science and Technology, 80, 121–130.

Ratnayake W S, Hoover R, Warkentin T. 2002. Pea starch: Composition, structure and properties - A review. Starch-Stärke, 54, 217–234.

Reddy N R, Pierson M D, Sathe S K, Salunkhe D K. 1984. Chemical, nutritional and physiological aspects of dry bean carbohydrates - A review. Food Chemistry, 13, 25–68.

Renkema J M S, Lakemond C M M, Jongh H H J, Gruppen H, Vliet T V. 2000. The effect of pH on heat denaturation and gel forming properties of soy proteins. Journal of Biotechnology, 79, 223–230.

Salunkhe D K, Kadam S S. 1989. Handbook of World Food Legumes: Nutritional Processing Technology and Utilization. CRC Press, Boca Raton, FL.

Sandhu K S, Lim S. 2008. Digestibility of legume starches as influenced by their physical and structural properties. Carbohydrate Polymer, 71, 245–252.

Sarko A, Wu H C. 1978. The crystal structures of A-, B- and C-polymorphs of amylose and starch. Starch-Stärke, 30, 73–78.

Sathe S K, Deshpande S S, Salunkhe D K. 1982. Functional properties of lupin seeds (Lupinus mutabilis) proteins and protein concentrates. Journal of Food Science, 47, 491–497.

Schmidt R H. 1981. Gelation and coagulation. In: Pour-El A, ed., Protein Functionality in Foods. American Chemical Society, Washington D.C., USA. pp. 131–148.

Schoch T J, Maywald E C. 1968. Preparation and properties of various legume starches. Cereal Chemistry, 45, 564–573.

Shekib L A, Zoueil M E, Youssef M M, Mohamed M S. 1986. Amino acid composition and In vitro digestibility of lentil and rice proteins and their mixture (Koshary). Food Chemistry, 20, 61–67.

Silverio J, Fredriksson H, Andersson R, Eliasson A C, Åman P. 2000. The effect of temperature cycling on the amylopectin retrogradation of starches with different amylopectin unit-chain length distribution. Carbohydrate Polymers, 42, 175–184.

Singh S, Singh H D, Sikka K C. 1968. Distribution of nutrients in the anatomical parts of common Indian pulses. Cereal Chemistry, 45, 13–18.

Sopade P A, Obekpa, J A. 1990. Modelling water absorption in soybean, cowpea and peanuts at three temperatures using Peleg’s equation. Journal of Food Science, 55, 1084–1087.

Sumner A K, Nielsen M A, Youngs C G. 1981. Production and evaluation of pea protein isolate. Journal of Food Science, 46, 364–372.

Suschetet M. 1975. Influence of tannic acid on the hepatic content of vitamin A in rats fed a vitamin A-containing diet or vitamin A-deficient diet. Comptes rendus des seances de la societe de biologie et de ses filiales, 169, 970–978. (in French)

Swanson B G. 1990. Pea and lentil protein extraction and functionality. Journal of the American Oil Chemists’ Society, 67, 276–280.

Tang J, Sokhansanj S. 1993. Moisture diffusivity in Laird lentil seed components. Transactions of the ASAE, 36, 1791–1798.

Tester R F. 1997. Starch: The polysaccharide fractions. In: Frazier P J, Richmond P, Donald A M, eds., Starch Structure and Functionality. Royal Society of Chemistry. Cambridge, UK. pp. 163–171.

Tester R F, Morrison W R. 1990. Swelling and gelatinization of cereal starches. I. Effects of amylopectin, amylose, and lipids. Cereal Chemistry, 67, 551–557.

Tharanathan R N, Mahadevamma S. 2003. Grain legumes - A boon to human nutrition. Trends in Food and Science Technology, 14, 507–518.

Timilsena Y P, Adhikari R, Barrow C J, Adhikari B. 2016. Physicochemical and functional properties of protein isolate produced from Australian chia seeds. Food Chemistry, 212, 648–656.

Tolstoguzov V B. 1997. Protein-polysaccharide interactions. In: Damodaran S, Paraf A, eds., Food Proteins and their Applications. Marcel Dekker, New York. pp. 171–198.

Turfani V, Narducci V, Durazzo A, Galli V, Carcea M. 2017. Technological, nutritional and functional properties of wheat bread enriched with lentil or carob flours. LWT-Food Science and Technology, 78, 361–366.

Urbano G, Porres J. M, Frias J, Vidal-Valverde C. 2007. Nutritional value. In: Yadav S S, McNeil, D L, Stevenson P C, eds., Lentil: An Ancient Crop for Modern Times. Springer, The Netherlands. pp. 47–93.

Utsumi S, Kinsella J E. 1985. Structure-function relationships in food proteins: subunit interactions in heat-induced gelation of 7S, 11S, and soy isolate proteins. Journal of Agricultural and Food Chemistry, 33, 297–303.

Vandenberg A. 2009. Postharvest processing and value addition. In: Erskine W, Muehlbauer F J, Sarker A, Sharma B, eds., The Lentil: Botany, Production and Uses. CAB International, UK. p. 391.

Vidal-Valverde C, Frias J. 1992. Changes in carbohydrates during germination of lentils. Zeitschrift für Lebensmittel-Untersuchung und Forschung, 194, 461–464.

Vojdani F. 1996. Solubility. In: Hall G M, ed., Methods of Testing Protein Functionality. Blackie Academic and Professional, London. pp. 11–60.

Wang B, Timilsena Y P, Blanch E, Adhikari B. 2017. Characteristics of bovine lactoferrin powders produced through spray and freeze drying processes. International Journal of Biological Macromolecules, 95, 985–994.

Wang N, Daun J K. 2006. Effects of variety and crude protein content on nutrients and anti-nutrients in lentils (Lens culinaris). Food Chemistry, 95, 493–502.

Wang W, Nema S, Teagarden D. 2010. Protein aggregation - Pathways and influencing factors. International Journal of Pharmaceutics, 390, 89–99.

Williams P C, Erskine W, Singh U. 1993. Lentil processing. Lens Newsletter, 20, 3–13.

Wood J A, Harden S. 2006. A method to estimate the hydration and swelling properties of chickpeas (Cicerarietinum L.). Journal of Food Science, 71, 190–195.