[英文]谷朊粉的需求及其用途

1、Wheat-gluten uses and industry needsL.Day ab *,M.A.Augustin ab ,I.L.Batey bc and C.W.Wrigley bc& a Food Science Australia,Werribee,VIC.3030,Australia (Tel.:C 61397313233fax:C 61397313250;e-mail:li.daycsiro.aubValue-Added Wheat CRC,North Ryde,NSW 1670,AustraliacFood Science Australia,North Ryde,N

2、SW 1670,AustraliaGluten,the dough-forming protein of wheat our,is the key to the unique ability of wheat to suit the production of leavened products.The past ve decades have seen the rise of gluten as a commodity in its own right,through the large-scale industrial separation of wheat starch from glu

3、ten,plus the controlled drying of the gluten so as to retain its functional properties.The resulting Vital Dry Gluten is most widely used in bakery products.However,gluten (vital,de-vital or modiedis nding increasing use as a food ingredient to provide a range of functional properties at a more mode

4、st price than competitors such as milk and soy proteins.IntroductionGluten may be dened as the cohesive,visco-elastic proteinaceous material prepared as a by-product of the isolation of starch from wheat our.A further denition might include the genes involved in the synthesis of the gluten proteins

5、in the developing grainthe Gli-1and Gli-2loci coding for the gliadin proteins,plus the Glu-1and Glu-3loci,coding for the glutenin polypeptides (Gianibelli,Larroque,MacRitchie,&Wrigley,2001.A biological denition might include the origins of the glutenprotein complex as being derived from the stor

6、age proteins of the wheat grain(Shwery &Halford,2002.Such denitions are correct but there is more to tell.The most signicant aspect of the gluten story for the food industry is theimportance (and the potentialof gluten as a commodity,sold for a wide range of uses around the world.In its most fam

7、iliar form,gluten is traded in the dried state as Vital Wheat Gluten.In this form,the functional properties of wheat gluten may be regenerated by rehydration.In addition,many products are derived from gluten by various forms of modication,thereby suiting them to a wide range of value-added uses.The

8、proteins that form gluten are storage proteins,according to their function for the wheat grain (Shewry,1999.The grain also contains the residue of many metabolic proteins (mainly water-solublethat have been needed by the developing grain,together with the proteins providing those putative mechanisms

9、 that must carry life on into the next generation of the wheat plant when the germination process commences (Shewry,1999.This is the basic context in which we should see the storage proteins,not as the dough-forming gluten proteins,but as the grains storage proteins laid down specically to provide a

10、n essential supply of amino acids for the developing plant.In these respects,the storage proteins of the mature wheat may not differ much from those of other grains (Shwery &Halford,2002.However,the distinctive feature that makes wheat unique is the visco-elastic properties of its storage protei

11、n.When the grain is milled and mixed with water,what was merely storage proteinforms a dough with unique rheological properties,capable of retaining gas bubbles,suiting this dough to the wide range of products we have come to expect from wheat our.It is these properties that make wheat alone suitabl

12、e for the preparation of a great diversity of food productsbreads,noodles,pasta,cookies,cakes,pastries and many other foods.It is also these unique properties that account for wheat being cultivated by man in such enormous quantities throughout the world.The name given to this unique group of protei

13、ns is gluten,an enigmatic complex of proteins.Given the unique properties of wheat gluten,it is not surprising that it has been the subject of intense attention by the food industry.That interest has extended to the commercial separation of gluten from the starch and soluble proteins of our.In fact,

14、it is the cohesive properties of gluten that makes its commercial prep-aration a relatively simple process.Vital Wheat Glutenis now a signicant ingredient in the food industry and0924-2244/$-see front matter Crown Copyright q 2005Published by Elsevier Ltd.All rights reserved.doi:10.1016/j.tifs.2005.

15、10.003Trends in Food Science &Technology 17(20068290Viewpoint*Corresponding author.an important item of world trade(Boland,Brester,& Taylor,2005;Krishnakumar&Gordon,1995,but until halfway through the20th century,it did not exist as such.The term gluten is also used in commerce(erro-neous

16、lyto indicate the protein residue after isolating starch from corn(maize(Patil,2003;2004.However, thiscorn glutenis functionally very different from wheat gluten.Another connotation of the termglutenrelates to the family of proteins that cause dietary problems for people with coeliac disease(Feigher

17、y, 1999;Murray,1999.In this case,the termglutenincludes the storage proteins from the grains of rye, triticale,barley and possibly oats(Kasarda,2001.Thus, the termgluten-free foodsrefers to food products free from these cereal proteins,or those in which cerealprotein content is less than a dened amo

18、unt(usually 200ppm.In this review,only the properties and uses of wheat gluten are discussed.History of the commercial production of wheat glutenGluten wasrst prepared fromour almost300years ago by an Italian named Beccari,who conducted a simple water-washing experiment with wheatour(Bailey,1941.Thi

19、s discovery,which can be easily reproduced in the home kitchen,has become the basis of a major cereal industry, utilising millions of tonnes of wheat annually in North America,Europe and Australia.The present commercial process is basically an efcient repetition of Beccaris experiment.Bakers,knowing

20、 the value of the gluten component of dough,have added gluten to dough for decades. Although the enrichment of bakersour with gluten has been common practice in bread manufacture since the second half of the20th century,the purication of starch from wheatour has been practised for a much longer time

21、.For example,as far back as1840in Hull, England,Isaac Reckitt was washing starch from wheat our.In doing so,he was laying the technical foundations of the major company that bears his name (Wrigley,2002.In his own words,the procedure involvedmaking a mash of the wheat after soaking in water for many

22、 days,and when soft enough,putting the mash through sieves,the wheat starch passing through, leaving the bran in the sieves to be cast aside for pigs (Anon,1912.The gluten was afterwards separated from the starch by washing.Unfortunately,Reckitt saw no value in the gluten,and it was discarded for an

23、imal feed. The Hull site has continued as a major operation centre for the greatly diversied multinational ReckittBencki-ser.The gluten fraction continued to be discarded for some decades before its industrial potential was realised, and before procedures were developed to isolate the gluten as a fu

24、nctional mass,retaining its intrinsic properties for enhancing baking quality.The following two independent accounts describe the development of gluten manufacture for commercial exploitation.Therst of these stories begins in Wellington,New Zealand in the1930s,where a pastry cook,Harry Maltwood Will

25、iams,discovered a method of extracting gluten from our using fermentation,water-washing and the late addition of salt(Wrigley,2000.Experiments with the gluten-enriching process produced bread of increased volume and improved texture.The process for producing Procerabread was patented worldwide.After

26、 initial exploitation in New Zealand,the patent-licensing approach was extended to the larger market of Australia.Reg Bartle, one of the two who went to Australia,travelled in his own plane to visit country bakeries,resulting in introductory telegrams such asArriving Kempsey race course at3pm. Bartl

27、e,Procera.In1932,the marketing package involved the use of a band of paper to go around each loaf produced by the Procera company,indicating the payment of a royalty charge of0.1penny per loaf by the baker.The resulting 1-pound loaf sold readily for two pence at a time when a 1-pound loaf cost 2.5pe

28、nce.This marketing method amounted to the modern practice of franchising.Indeed, when theTrade Mark UsersActwas enacted in1948, Procera Australia Pty Ltd became therst major franchising company to operate in Australia.The process was also introduced to Britain,where it was known as the Procera metho

29、d.In parallel with these developments,Nigel Love(N.B. Love Mills,Sydneydeveloped a similar product;trade marked asPromaxbread.This was made from a high-proteinour,and it gave results similar to the Procera bread process.As the use of the Procera method was limited to one baker in each town or region

30、,the Promax method spread quickly with the remaining bakers.The protein-enriching Procera method involved the removal of starch,thereby producing the ongoing problem of disposing of the starchy efuent.Municipal councils complained of blocked drains and sewage difculties.These problems led to the dev

31、elopment of an industrial-scale process to provide theprotein-enrichedingredient for the Procera method in dried form(essentially as dehydrated glutenin parallel with recovering the washed-out starch that could also be dried and used in foods.These developments,devised in1938by Basil Regan and Leona

32、rd Winch of Fielders Mills(Tamworth,NSW,Australia included the problem of drying the wet gluten and retaining itsvitalnature.The result was theringorashdrier in which wet gluten pieces were rolled in dryour and subjected to heat drying.From these beginnings for the bread industry has developed the s

33、ignicant export commodity of dried gluten for Australia,and a worldwide industry for the production of dried gluten as a major trade commodity.The North American origins of commercial gluten production started with the industrial need for wheat starch,L.Day et al./Trends in Food Science&Technolo

34、gy17(2006829083not gluten(Dubois,1996.In the early1900s,it had become unprotable for the Jenks family(Lake Huron,Michiganto produceour for shipping to Detroit,due to competition from larger mills in the Midwest,so new outlets forour were sought.The process developed was designed to separate out star

35、ch,rather than specically to isolate gluten.A slackour-water dough was produced,permitting the separation of starch from gluten by gentle water washing. Initially,the gluten was discarded in favour of the starch, which sold well as laundry starch for stiffening clothing items.Initial attempts to use

36、 the gluten(in the1920s involved the use of heat-dried gluten(gum glutento bake low-carbohydrate bread for diabetics,and even later(in the 1940sfor producing monosodium glutamate by acid hydrolysis.Subsequently,the gum gluten was taken by Kelloggs to produceSpecial K(Thompson&Raymer, 1958.During

37、 these developments,Jenks and Rossman had used a harsh drying process that de-vitalised the functional properties of the gluten.It was thus useless as an ingredient to enhance baking quality.This situation changed,in the late1950s,when the Huron Milling Company adopted thenew type of drying process

38、used in Australia(quoted from Dubois,1996,based on the ringorashdrying process.This form of dry gluten retained its functional properties,when added to dough. As a result,loaf volume and crumb texture were improved.This vital dry gluten was soon exploited commercially as an additive for a variety of

39、 breads,but not as a blend with wheatour at the mill.Nevertheless,blending withour has more recently become common practice,especially in Europe where gluten fortication is essential for many low-proteinours(Spooner,1995.From these various origins, dry gluten has become an important commodity in int

40、ernational trade,both as an additive to fortifyour for bread manufacture,and as an ingredient for many food and non-food uses.The gluten industry at presentThe principle of gluten washing still remains similar to that of Beccari hundreds of years ago.Most commercial operations now use variations of

41、either the Batter Process or the Martin Process(Knight,1965.In the Martin Process, wheat dough is washed with water while it passes through a tumbling cylindrical agitator so that the starch comes out of the dough,while the protein content increases in the remaining dough.The dough is moved along th

42、e cylinder by the tumbling action,while the starch passes through small holes in the wall leaving the protein mass inside to receive further washing until it falls out at the end.On the other hand,the Batter Process involves preparing a thick suspension(batterofour.During several hours of stirring,t

43、he starch separates from the gluten,so that when the mixture is passed over ane sieve,the starch granules separate and the curds of gluten are retained on the screen. Further washing of this gluten removes further starch in a similar manner to the Martin Process.Following either process,the gluten i

44、sash dried.Various modications have been made to these basic methods,for example,the Alfa-Laval Raisio process. Modern applications also use centrifugal techniques(either conventional industrial centrifuges or hydro-cyclonesto separate the starch from the protein.In particular,hydro-cyclones serve a

45、t least in cleaning the starch,but also,in some cases,for the actual separation of the starch and gluten.Some of the newer methods process whole ground grain as the raw material,avoiding the production ofour in a dry-milling step,but cleaning bran from the protein and starch fractions creates proble

46、ms with these methods. Improved milling processes have reduced the amount of endosperm remaining in the bran and offal fractions in conventional milling,so there is little advantage to be gained in wet-milling for starch and gluten recovery. Nevertheless,modications of the traditional processes have

47、 remained the preferred choice for most of the gluten produced worldwide.甲U+ a MN电子枪approximately75%protein,up to8%moisture,and varying amounts of starch,lipid andbre.The starch andbre become entrapped in the cohesive matrix of the protein and become more difcult to remove as the protein content inc

48、reases.The amount of starch varies,and more extensive washing can reduce the starch andbre content and increase the protein content.The extra water needed for this creates its own problems by producing a larger amount of efuent from the process,and increasing the total biological oxygen demand(BODof

49、 that efuent.Consequently,gluten of higher protein content is only produced as a special order and at a premium price.cdsO O 乙Gluten is a modestly priced food protein,much cheaper than casein and soy isolates,whilst being greatly preferred to protein sources that are only suited to animal food.Its p

50、rice advantage(see Table1for price comparison in Australiaoffers signicant scope for value addition by modication.On occasions,threatened market surpluses of gluten have stimulated manufacturers to explore ways of converting gluten into products with different properties.A common example is the crea

51、tion of a gluten product that is water-soluble,or at least dispersible in water.Deamidation,the most common method for this purpose,may be achieved with either acid or alkali treatment(Batey&Grass,1981;Wu, Nakai,&Powrie,1976.Removal of the amide group from some of the many glutamine residues

52、(to form the corresponding carboxylic acid,glutamic acidchangesTable1.Current prices of food protein ingredients in Australia(September2005,in US dollarsIngredient Protein content(%approx.Price per tonne($a Price per tonne protein($a Wheat gluten7540005333yx 0 A B · E参考答案一、选择题 题号 1 2 3 4 5 6 7

53、8 9 10 11 12 13 14 15 答案 C BD AB AC ACD D B D B D C C BC CD BD二.填空(本大题共3小题,共22分。把答案填在答题纸的横线上16.42.12 17.(10.518;(23.0;(3A ,C ,E ;(4b ; 18.(1略 (22.0,3.75;(3AC ;三.计算题(本大题共3小题,共35分。解答应写出必要的文字说明、方程式和重要的演算步骤。并画出相应的受力图只写出最后答案的不能得分。有数值计算的题,答案中必须明确写出数值和单位19.(1电子在电场A 中加速运动,由动能定理:210101022U q mv U qv m=-=(2电子

54、在加速电场中作类平抛运动,水平方向为匀速直线运动,则粒子在电场中偏转时间:0Table 2.Usage of gluten in different regions of the world (as percentage of total usage for the regionUsesNorth America Europe Australia Japan Total world Baking 8317543063Flourfortication 166914Meats1925a 5Breakfast cereals 1122Noodles 10Sausages 12Pet food 121

55、3138Other243238aIncludes gluten used for synthetic sh products.L.Day et al./Trends in Food Science &Technology 17(2006829086L. Day et al. / Trends in Food Science & Technology 17 (2006 8290 87 gluten on people with coeliac disease and others with wheatprotein allergies, particularly because

56、there is an increasing trend towards the incorporation of gluten into foods that do not traditionally contain wheat proteins. Many researchers have been trying to understand the mechanism of coeliac disease and to reduce allergenicity of the proteins by modifying the allergen structure in such a way

57、 that the allergenic epitopes are no longer recognised by the immune system. Until now, the technological approach to decrease allergenicity has largely been empirical. The main reason for this is a lack of detailed knowledge about the integral allergen and epitope structure and their genetic backgr

58、ound, thus hampering the design of more rational, generic strategies for processing. Scientic knowledge about coeliac disease, including knowledge about the proteins that cause the problem and the grains that contain these proteins, is still incomplete. Any consideration of new uses of gluten or of

59、modied gluten, particularly in non-cereal based food products, should include the impact of the application on people with intolerances to gluten. Current food uses of wheat gluten The most common usage of gluten in western countries has traditionally been, and continues to be, in baked goods of various types. However, with an increasing awareness of wheat gluten's un