Etiket Arşivleri: wheat

Gluten Oluşumu ve Bunu Sınırlayan-Engelleyen Etmenler ( Halef DİZLEK )

Özet

Buğday unu; nicelik ve nitelik bakımından unlu mamullerin üretimindeki en önemli öğedir. Unun içerdiği protein niceliği ve niteliği un kalitesi üzerine etki eden etmenlerin en önemlileridir. Proteinler içerisinde ise gluten proteinleri (glutenin ve gliadin) özel ve çok önemli bir yere sahiptir. Glutenin ve gliadin proteinleri hamurun yoğrulması sırasında hidrate olarak ve çeşitli kimyasal bağlarla birleşerek, hamurun özelliklerini önemli düzeyde etkileyen ve hamur içerisinde yarı sürekli bir faz oluşturan elastik ve plastik yapıdaki özü (gluteni) meydana getirirler. Gluten hamurun iskeletini oluşturur. Üstün niteliklere sahip bir unlu mamul üretiminin gerçekleştirilebilmesi, ancak hamurda gluten oluşum mekanizmasının ve bunun buğdayda, hamurda oluşumunu sınırlayan, engelleyen etmenlerin iyi bilinmesi ve bu olumsuz etmenlere karşı alınacak tedbirler ile mümkündür.
Anahtar Kelimeler: Gluten, buğday, hamur, oluşma, sınırlama, engelleme

The Formation of Gluten and Its Limiting-Preventing Factors

Abstract

Wheat flour is one of the most important component in making flour products for quality and quantity. Protein quality and quantity are unique importance in determining the functional properties of wheat flour. Among wheat proteins, gluten proteins (glutenin and gliadin) have specific and very important position. During the dough kneading, glutenin and gliadin proteins to be hydrated and associated with various chemical bonds to produce gluten. Gluten which forms bone of dough and effects dough characteristics greatly, has an elastic and plastic structure and forms semi continuous phase in dough. It is possible to produce a superior bakery product only through knowing the mechanism of formation of gluten on the dough and with a good knowledge of the factors that limit, prevent gluten formation on the wheat and dough, and taking precautions against these negative factors.
Key Words: Gluten, wheat, dough, formation, limitation, prevention


Kaynak: http://www.teknolojikarastirmalar.com/pdf/tr/02_2011_6_3_114_684.pdf

Buğday ( Wheat )

BUĞDAY ( WHEAT )

Takım: Poales

Familya: Poaceae

Cins: Triticum

Buğday, diğer tahıl tanelerine kıyasla daha geniş alanlarda ekimi yapılan bir bitkidir.

Tek yıllık otsu bir bitkidir.

Genellikle ılık ve serin iklim koşullarında yetişir.

Üretimin en fazla olduğu bölgemiz İç Anadolu Bölgesidir.

Derin ,killi ve yeterli organik maddesi olan fosfor ve kireci bulunan kumlu tınlı topraklar en iyi buğday topraklarıdır.

Ekim nöbeti açısından ise buğday ülkemizde kuru ve sulu koşullarda çeşitli kültür bitkileri ile münavemeye (nöbetleşmeye) girmektedir.

BuğdayIn Tane YapIsI

BUĞDAY TANESİNİN KISIMLARI

Kepek(Perikarp):Değirmencilikte endospermden ayrılarak hayvan yemi olarak kullanılan kabuk kısmıdır.

Endosperm:Buğdayın un elde edilen kısmıdır.

Ruşeym:Tohumun çimlenmesini sağlayan bölümüdür.Yüksek oranda yağlı madde içerir.Erken bozulmaya sebep olduğundan ayrılması tercih edilir.

BUĞDAYIN KİMYASAL BİLEŞENLERİ

BUĞDAY UNUNUN ÜRETİM ŞEMASI

Kamyondan depo zemİnİne buğday boşaltma

Helezon ve pnömatİk sİstem İle sİlo dolumu

SİLOLARDA BEKLETME

Uzun süreli olarak tahılın özelliğini bozmadan muhafaza etmesi nedeni ile çelik silolar depolama gereksinimleri için en uygun seçeneklerdir.Bu nedenle çelik silolar tahıl depolamada en çok tercih edilen yöntemdir.

Paçal İşlemİ

Buğday çeşidinin çok оlması, elde edilen unda da farklılıkları ortaya çıkarmaktadır. Un fabrikalarında birçok çeşit ve özellikteki buğdaylar öğütülürken üretileсek un kаlitesinin sürekli aynı özellikte olması istenir. Her zaman aynı kаlitede ve özellikte buğday bulunamaması vе іstenіlen kalіtede un imal edilmesi için birkaç buğday çеşidi paçal yapılır. Bu nedenle laboratuarlarda yapılan çalışma sonuсu farklı kalіtedekі buğdaylar bellі oranlarda karıştırılır. Bu karıştırma işlеminе pаçаllаmа denіr.

ÇÖP SASÖRÜ

Kullanım Amacı: Özellikle tahılların öğütülmeden önce ve diğer granül ürünlerin kaba ve ince atıklarından ayrıştırılması için tane iriliğine göre elenmesi prensibi ile calişmaktadır.

TAŞ AYIRICI

Tahıl işleme tesislerinde öğütülmemiş tahıldan, taşın kuru sistemle ayrılması için etkin ve verimli olarak kullanılan bir makinedir. 

TRİYÖR

Buğdayın sığmayacağı fakat kırık ve ot tohumlarının sığabileceği gözeneklere sahip baskılı saclar ile buğdayın kırık ve ot tohumlarından temizlenmesi için kullanılır. hava akımı ile de makine içinde oluşabilecek muhtemel toz alınmaktadır.

KABUK SOYUCU

Kullanım Amacı: Özellikle un fabrikalarında buğday veya diğer tahılların üzerindeki tozların temizlenmesi, küçük toprak parçalarının parçalanarak buğdaydan ayrılması  ve kabuk soyma işlemini gerçekleştirmede kullanılır.

Çalışma Prensibi: Tahılın yoğun bir baskı ile kendi kendine sürtünmesi, tahılın rotor üzerine yerleştirilmiş çelik metal çapalara sürtünmesi ve dışa silindirik olarak sarılmış özel malzemeden örme olarak yapılmış aşındırmaya uygun profildeki örgü gömleğe sürtünmesi yoluyla temizlenmekte ve soyulma işlemi gerçekleşmektedir.

YIKAMA VE KURUTMA ÜNİTESİ

Buğdayı su içerisinde ilerleterek dışında bulunan toz vb. istenmeyen maddelerin uzaklaştırılmasını sağlar. Ürün girişinde bulunan ve birbirlerine ters çalışan iki helezonla buğdayın ön yıkama işlemini ve kalmışsa taş ayrımı sağlar. Dik kısmında(soba) panjur saclarla ince bir kepek ayrıştırılarak nispeten kurutma sağlanmış olur.

Kurutma işlemi süratli bir şekilde yapılır.

TAVLAMA

Buğdayın öğütülmeden önce özellikle sertlik derecesine göre tanenin nem düzeyini ayarlamak ve öğütmeye en elverişli hale getirmek için taneye su verme işlemine tavlama diyoruz.
Buğdayın tavlanmasında amaç, buğday tanesinin fiziksel yapısını, nem miktarını istenilen düzeye getirerek öğütmeye elverişli duruma getirmek ve unun ekmekçilik kalitesini yükseltmektir. Böylece kırma valslerinde yapılan kesme ve taneyi açma işlemlerinde kabuğun ufalanması önlenir. Tavlanmamış buğday kabuğu kırılgan bir yapıya sahip olduğundan başlangıçta kırma valslerinde buğdayın açılması esnasında kabuğun ufalanmasına sebep olacaktır.

İkinci kez siloya dolum: Buğdaya su verilir ve 12 saat süre ile yumuşaması beklenir.Böylelikle buğdayın dinlenmesi de sağlanmış olur.

ÖĞÜTME

Kırma valslerde buğday patlatılarak irmik kabuktan ayrılır.Oluşan karışım pnömatik fan yardımı ve pnömatik devre sistemi ile hava  kilitlerinden geçerek eleklere taşınır.

Eleme

 Valsten geçen irmik ve un elekler aracılığıyla birbirinden ayrılır. Elekler kapalı bir sistem içerisinde hareket eden farklı gözenek yapılarının üst üste yerleştirilmesi ile oluşmuştur.

Ambalajlama ve depolama

Unların çuvallara doldurulmasını sağlayan sistem çuvalı sallayarak unun çuvala dolmasını sağlamaktadır.Daha sonra çuvalların ağzı dikilmektedir.

KAYNAKÇA

http://www.unihracati.com/un-uretimifabrikalarda-un-ur%D0%B5timini-8-asamada-incele%D1%83ebiliriz.html

http://www.hatap.com/

Oriental Fermented Foods

ORIENTAL FERMENTED FOODS

MOLD MODIFIED FOODS

Reason for studying oriental fermented foods:

Different from western foods interms of taste, texture, flavor and appearance.

Different from western foods interms of microbiological standpoint: mixed culture of yeast, bacteria, and mold.

Since it is cheap and nutritious, large number of people consume.

There are too many things to modernize plants.

Oriental foods are receiving increasing attention of western consumers. hİghly nutritive because;

Complementary effect of proteins from plant and animal sources

İncreased protein efficiency ratio and digestibility

Synthesis of vitamins

Shorter cooking time

Desirable enzymes are produced

The lipoxygenase enzyme is responsible for the “beany” flavor commonly noted in soymilk. The

reaction catalyzed by the enzyme involves water, the unsaturated oil, and oxygen and the end-

product hexanal is one of the compounds responsible for the beany flavor.

Soy sauce

-dark -brown liquid with a salty taste and district pleasent aroma

– made by fermenting soybean, wheat and salt with a mixture of mold , yeast, and bacteria.

-During fermentation

Proteins …. peptidies, aminoacids, sugar alcohols, acids

carbohydrates are also hydrolysed

chemical hydrolysis is tried in U.S.A but taste of product is not the same

soy sauce is used as a seasoning agent in preparation of food

Japan leads the soy sauce industry in the world

Shoyu’ is the Japanese name for soy sauce.

In Japan the total production is about 1.04 million kiloliters (kl),

The annual consumption of shoyu per capita is about 8.3 l,

The consumption volume in Japan is decreasing slightly, but that in American and European area is increasing.

Raw Materials and their treatment

Soy Beans: defatted soybean

Soy bean ® washed ® soaked overnight ® drained ® steamed (at 10lb/ in2 for several hrs)This will

effect the future enzymatic action on soy proteins

Wheat:

Wheat ® roasted ® coarsely crushed. Adds color and flavor to resulting soy sauce and destroys

surface microorganisms and facilitates enzymatic hdrolysis

Reason of using wheat:

The mold grows better and produces more enzymes on a mixture of wheat -soybean than any of them alone

Addition of roasted crushed wheat reduce the growth of undesirable microorganism

Cooked soybean : 60 % moisture good for bacterial growth

Soybean-wheat mixture : 45 % moisture good for mold growth but not bacteria

wheat serves as a precursor of sugar, alcohols, organic acids and flavor compounds.

Wheat is rich in glutamic acid

Salt

NaCI ® gives salty taste, surpress undesirable organisms

Soy sauce koji:

Koji: is a japanese name gives to a preparation consisting of mold growth on cooked cereals or/and soybeans.

– serves as an enzyme source.(like malt in alcoholic fermentations)

Soy sauce koji is made from a mixture of roasted wheat and steamed soybeans with

A koji starter ® Aspergillus oryzae or A. soyae (Called tane koji)

Aspergillus oryzae

Aspergillus oryzae on wheat

Preparation of tane koji:

Polished rice is soaked in water overnight ® drained ® steamed for 1 hr ® mixed with 2% of wood ash, for trace elements ® inoculate with A. oryzae spores ® Spread out in tray 1,5 cm ® cover with damp clothes ® incubate at 30C for 5 days (green to yellowish spores of A. oryzae mycellium ® spores are harvested ® dried at 50 C and stored at 15 C. [ 25×107 viable spore/gm of tane koji]

A good soy sauce has 18% salt, 4.6-4.8 final pH

Price is determined by:

Nitrogen yield

Total soluble nitrogen

Amino nitrogen/total soluble nitrogen ® ratio (>50% is good)

Glutamic acid and salt are principle flavoring constituents

Sugars present are glucose, arabinose, xylose, maltose, galactose, glycerol and mannitol (also alcohols)

Organic acids: lactic, succinic and pyroglutamic

Color is due to non-enzymatic browning

SAFETY OF ORIENAL FERMENTED FOODS

Scientist can not find aflatoxin and aflatoxin producing cultures in oriental fermented foods unless they intentionally contaminate with these cultures.

Processing procedures such as cooking, salting, acid formation, antibiotics production, and low moisture are the probable reasons for the safety of oriental fermented foods.

Mycotoxins – the yellowish colonies are of Aspergillus flavus, a producer of aflatoxin.  The green colonies are of  Penicillium, another mycotoxin-producing genus (ochratoxin, patulin, penitrem, PR toxin).

TEMPEH

“Tempeh” is a fermented soybean product and meat substitute that originated in Indonesia.

It is probably the first “fast food” in that it can be deep-fried in 3–4 min or cooked in 10 min.

In the first step the soybeans are soaked in water or acidified water at room temperature.

During this stage a partial germination of the soybeans may occur depending on the amount of O2 available to the seed, and acid is produced by bacteria growing in the soak water.

Depending on the temperature during soaking, bacteria reach 108–1010 colony-forming units per ml after 24–36 h.

The pH drops from 6.5 to 4.5 due to the growth of the acid-producing bacterial species – e.g., Lactobacillus casei, Streptococcus faecium, Staphylococcus epidermidis, and Klebsiella pneumoniae that are present naturally on the soybeans.

The acid helps to prevent the growth of undesirable microorganisms, but any partial seed germination can affect the protein properties of the soybean and the subsequent fungal growth phase.

The bacteria that grow in the steeping water produce vitamin B12, a significant nutrient in tempeh.

The most desirable bacterial species for this stage is K. pneumoniae, but other pure bacterial starter cultures can perform the same function.

The soaked beans are de-hulled and carefully cooked to avoid overcooking or undercooking of the beans.

The soybeans are then drained, cooled below 35 °C, and dusted with wheat flour to provide a good source of fermentable carbohydrate, and inoculated.

The desirable fungal species for successful tempeh production, whether arising from environmental inoculation or from pure starter inoculation, are Rhizopus oligosporus

Tempeh must be consumed fairly quickly.

Defects include:

(1) black patches due to fungal sporulation,

(2) slime due to excessive bacterial growth because of too little O2 or a temperature of 42 °C,

(3) a yellow color due to growth of toxic fungi.

The yellow color indicates that the tempeh is highly toxic and it should not be eaten.

During the fungal growth phase the O2 level must be controlled at a reduced level, otherwise the fungus will grow too quickly and form black spore masses that degrade the quality of the tempeh.

The traditional way to control O2 is to wrap the inoculated beans in banana leaves, but a modern innovation is the use of microperforated polyethylene plastic.

The fungus grows and mycelia knit the beans into a firm cake to give the characteristic meaty texture.

The enzymes from the fungi transform the soybeans making them more nutritious by hydrolyzing the protein and complex carbohydrates and increasing the levels of the vitamins – riboflavin, niacin, pantothenic acid, and vitamin B6.

MISO (Bean paste)

Most popular fermented soybean good in Japan.

Fermentation principles similar to soy sauce.

Miso: like peanut butter (smooth, some chruncy) light-yellow to reddish-brown.

Bean paste (miso) is used as flavoring agent.

Freeze dried miso is getting common in western countries.

® use in dips, salad dressing, sauces

contains > 10% salt. So can be kept for a while without refrigeration

TOFU

Soy cheeses (soya cheeses) are a curd made from soymilk (soybean milk), called tofu in English.

Tofu is made in a similar process to making cheese from milk.

The soymilk is curdled by adding coagulants (CaSO4, MgCl2, glucono-delta- lacton (GDL)).

Curds are then pressed into cakes of various types.

Soft tofu is not pressed and is eaten as it is.

Medium-soft tofu is the most popular in everyday use.

Firm tofu is used in processed foods which are fried, grilled, fermented, and dried.

SUFU

Sufu is mostly sold in the west, more common under the name, Preserved Bean-curd.

sufu virtually means spoiled tofu, due to the strong flavour and pungent aroma.

Sufu resembles the dairy equivalent in cheese, Parmesan or Camembert and is sometimes referred to as Chinese cheese.

Sufu may satisfy cravings for cheese for individuals following a vegan diet.

Salting does five things:

it imparts a salty taste to the sufu,

it prevents the growth of undesirable organisms,

it stops the growth of the mold,

it releases the proteolytic enzymes bound to the mold mycelia so they can penetrate into the tofu to transform it, removes some water from the tofu blocks.

Salting can be by dry salting or brine salting.

Dry salting: takes longer, does not result in a consistent product(6–12 days),16%, washed with water.

Brining is done with a saturated salt solution, or an alcoholic brine solution in which the blocks are immersed for 4–5 days, resulting in final moisture levels of 50–65% with 12% salt.

The ethanol has two effects: first, during ripening lipolytic enzymes release free fatty acids that combine with ethanol to produce aromatic esters,

it seems to interfere with protein degradation when compared with salted sufu.

Ang-kak

Chineese originated food colorant

Washed and sterilized rice is inoculated with Monascus purpureus

In 3 days begin to redden and 3 weeks color will turn to deep purplish red

Dry at 40 C

Pigments, monoscoribrin and monoscoflavin will accumulate in the m.o. solubilise reacting it with water soluble proteins


Cereals and Cereal Products ( H.-D Belitzand W.Grosch )

Cereals and Cereal Products Food Chemistry (2nd Ed), 1999 H.-D Belitz and W. Grosch

Major cereals include wheat, rye, rice, barley, millet and oats. „ the most important staple foods of mankind

Production: 60% of cultivated land in the world

Cereals: caryopsis huskless (bared seed)—wheat, rye whusk—oat, barley, rice

Chemical composition of cereals

Celiac Disease (celiac sprue, or gluten-induced enteropathy) „ Wheat, rye and barley (Triticeae sp) „ Prolamin fractions „ Loss of villous structure of the intestinal mucosa Degenerative changes of epithelial cells Severely impaired nutrient absorption function „ Affects both infants and adolescents 0.05% in central Europe 0.33% in Ireland

Individual constituents—Proteins Low in Lysine and methionine

Osbone Fractions of cereals „ 1907 T.B. Osborne separated wheat proteins on the basis of their solubility into four fractions. „ 1.Water extracted: water-soluble albumins 2.Salt extracted: salt-soluble (e.g. 0.4 mol/L NaCl globulins 3.Ethanol extracted: 70% aqueous ethanol-soluble prolamins* *the only aa composition can be correlated to the botanical genealogy 4.Acid extracted: 0.5 mol/L acetic acid soluble glutelins (I) LMW (dissolved in 50% 1-propanol at 60oC with l dithioerythritol) (ii) HMW (ppt. At 60% 1-propanol)

Wheat gluten proteins Monomeric gliadins Polymeric glutenin ω-gliadins α-type γ-type LMW HMW (ω-5, ω-1, ω-2) gliadins gliadins subunits subunits S-poor S-rich HMW Intermediate LMW group group MW group Figure Classification of wheat gluten proteins based on structural homologies and genetical relationships

Protein components of wheat gluten –prolamins:glutelins (2:3) „ In hydrated form, prolamins—dough viscosity glutelins —dough elasticity „ Occur at 9 different complex loci in wheat genome HMW glutenin subunits: Glu-A1, Glu-B1 and Glu-D1 LMW glutenin subunits, ω- and γ-gliadin: Gli-A1, Gli-B1 and Gli-D1 α- and β-gliadin: Gli-A2, Gli-B2 and Gli-D2 „ The relative importance of different alleles for gluten quality: Glu-1>Gli-1>Gli-2

Wheat gluten „ the storage proteins of wheat „ composed of two main groups of proteins—gliadin (a prolamin) and glutenin (a glutelin) „ easy to isolate in relatively pure form (insoluble in water) „ responsible for the cohesive, viscoelastic property of wheat flour dough and the ability of gas retention during dough fermentation, and partly for the setting of the dough during baking „ In hard wheat, 80% of protein is gluten protein; in soft wheat, less than 50% of protein is gluten protein

„ Gliadins added to the glutenins soften the gluten formed „ Gliadins act as plasticizer

Chemical properties of gluten proteins –amino acid composition „ high in glutamic acid (about 35% of the total protein), presented as its amide (glutamine) in protein „ low in the basic amino acids (lysine) „ high in proline (about 14% of the total protein); involved in a ring structure, not form an α-helix „ high levels of amino acids with hydrophobic side chains and relatively low amounts of sulfur- containing amino acids

Chemical properties of gluten proteins „ low level of charges of gluten proteins results in low repulsion forces within the proteins, thus, the protein chains can interact with each other quite readily (by H-bonding, hydrophobic interactions), a condition that appears to be necessary for dough formation, gluten structure stability, the rheological and baking properties of flour

Physical properties of gluten — Gliadins „ a large group of proteins with similar properties, average MW~40,000, monomeric proteins (single chain) associated by H-bonding and hyrophobic interactions, extremely sticky when hydrated, little or no resistance to extension, and appear to be responsible for the dough’s cohesiveness (viscosity)

Physical properties of gluten — Glutenins „ a heterogeneous group of proteins, MW~100,000 to several million, average MW~3 million, polymers by inter-molecular disulfide bonds (multichain), resilient and rubbery but prone to rupture when hydrated, apparently gives dough its property of resistance to extension (elasticity)

The importance of gluten proteins to breadmaking quality „ Breadmaking quality, as indicated by loaf volume, increased linearly with flour protein content for all cultivars „ But, gradients of regression lines (“protein responses”) differed amongst cultivars. „ Breadmaking performance vs the glutenin polymer size distribution: higher proportions of glutenin polymers of greater molecular size have higher breadmaing performance

Structure of wheat gluten „ Protein composition of wheat gluten: know well „ Type and extent of polymerization or aggregation of subunits or on other interactions in native gluten: little information available „ Dough rheology: construction now „ Genetic modification ‘gluten composition, quantity ‘ gluten polymerization or aggregation ‘dough rheology ‘ dough property ‘baking property ‘storage quality Need to be correlated with more information with lots of studies on a molecular level

Enzymes present in cereal kernels –amylases „ α-amylase:minimal activity in mature kernels; increases abruptly during sprouting or germination

Enzymes present in cereal kernels –lipases, lipoxygenases „ Oxidize linoleci acid to 9-hydroperoxy acids and cooxidizes carotenoids at a slow rate

„ Addition of lipoxygenase (type II)-active soy flour (1%) –increases mixing tolerance, improve dough rheology, increases bread volume

Enzymes present in cereal kernels –glutathione dehydrogenase „ Catalyzes the oxidation of glutathione (GSH) in the presence of dehydroascorbic acid (DHAA) as H-acceptor „ Relatively high in activity in wheat flour

„ Small amount (2-6 g AA/100 kg flour) caused a pronounced increase in both dough strength and bread volume (Jorgensen, 1935) „ Inhibit the SH/SS interchange, which starts immediately on dough making and leads to depolymerization of gluten proteins weakening of gluten is limited <> X X <> X X

Other nitrogen compounds –glutathione, cysteine „ Free state as thiol compd (GSH, CSH) „ Oxidized forms (GSSG, CSSC) „ Protein-bound forms (GSSProt, CSSProt) „ During dough making GSH+ProtSSProt’ProtSSG+ProtSH If HM gluten proteins are cleaved, the viscosity of the dough drops. „ GSH: predominantly in germ and aleurone layer „ GSSG and CSSC are rheologically inactive, however, they are converted to rheologically active thiols by reduction or SS/SH interchange.

Enzymes –microbial phytase „ 70% phosphorus in wheat is bound to phytin (1% of the kernels), formation of water-insoluble salts in the intestinal absorption of calcium and iron ions „ Can be hydrolyzed during dough making by microbial phytases— nutritionally and physiologically desirable

Distribution of Carbohydrate in wheat

Carbohydrate—Wheat starch „ 65~70% (14% moisture) of flour of 80% extraction, 75~80% (db) of endosperm (endosperm is about 83% of wheat kernel) „ one starch granule per amyloplast „ often divided into two types A-type: large lecticular B-type: small shperical „ About 25% amylose, 75% amylopectin „ Lipid (predominantly lysolecithin in wheat) complexed within the starch granules retard swelling and increase starch gelatinization temperature; thus influence the baking behavior of cereals and the properties of the baked products

Functionality of starch as related to bread products „ dilute gluten to desirable consistency „ furnishes sugar through amylase action „ furnishes surface suitable for strong union with gluten „ becomes flexible but does not disintegrate during partial gelatinization „ sets structure to the final loaf of bread

Stages of starch granular dispersion in baked goods „ Swollen Scottish short-bread „ Gelatinized Biscuits Cakes „ Disrupted Bread „ Dispersed Wafers „ Enzymatic degraded

Polysaccharides other than starch –Pentosans „ water soluble ( absorb 15~20 times more water) and water insoluble pentosans „ Rye flour: 6~8% (15~25% water soluble); wheat flour: 2~3% (1~1.5% water soluble) „ water soluble pentosan: absorb 15~20X water, form highly viscous solutions consists mainly of a linear arabinoxylan and highly branched arabinogalactan „ water insoluble pentosan: swell extensively in water, responsible for the rheological properties of dough and the baking behavior of rye, and increases the crumb juiciness and chewability of baked products (optimal starch:pentosan=16:1,w/w) „ in wheat bread

„ Polymerization caused by enzymic phenol oxidation lack of solubility of most pentosans

Polysaccharides other than starch — β-glucan (lichenins) „ Barley: 3~7%, Oats: 2.2~4.2%; wheat and rye: 0.5~2% „ Linear D-glucopyranose joined by β-1,3 and β-1,4 linkages „ Proivde a high viscosity to water solutions „ Barley β-glucan can interfere in wort filtration in beer production

Polysaccharides other than starch — Glucofructans „ wheat flour contains 1% water-soluble, non-reducing oligosaccharides, predominates in durum wheats

Sugars

Lipids „ Cereal kernels contain relatively low levels of lipids oat: 6~8%, wheat: 1.6% „ Stored mainly in the germ, smaller extent in the aleurone layer „ Not differ significantly in their fatty acid composition among cereal lipids

Wheat total lipid (3~4%) Germ (30%) Aleurone (25%) Endosperm (45%) (Rich in TG, GI, PhL) Non-starch lipid (29%) Starch lipid (16%) (TG, Digalactosyl diacylglycerides) (FFA, Lysophatidylcholine) Figure Lipid distribution in various fractions of wheat kernels

Lipids „ Rheological dough properties are affected by nonstarch- bound lipids „ Free lipid: 90% of total nonpolar lipids and 20% of total polar lipids „ By kneading, glycolipids become completely bound to gluten extent of binding of TG depends on dough handling (intensive oxygen aeration, addition of lipoxygenase increase free lipids)

Gas-holding capacity and baking volume are positively influenced by polar lipids, while negatively influenced by nonpolar lipids *Polar lipids get concentrated in the boundary layer gas/liquid and stabilized the gas bubbles against coalescence *Lipid vesicles seal the pores which are formed in the protein films on kneading

Lipids—carotenoids and tocopherols „ Carotenoids: Wheat flour 5.7 mg/kg, durum wheat 7.3 mg/kg corn 0.6~57.9 mg/kg

The Cereals An Overview

THE CEREALS: an overview

Grasses: members of the Grass family
Critically important food sources for humans and animals
Cereals are basic foods for humankind.
wheat, rye, oats, barley, rice, maize, sorghum and millet
Cereal crops are energy dense, containing 10,000 -15 000 kJ/kg, about x10-20 times > than most fruits and vegetables
important sources of dietary protein, carbohydrates, the B complex of vitamins, vitamin E, iron, trace minerals, and fibre
Important for development of early civilisations (agriculture)

OVERVIEW OF CEREALS

Cereals not grown in deserts (dry and arctic) and mountain regions
Grain Characteristics
CEREALS: WHEAT & RICE PRODUCTION BY REGION
OVERVIEW OF CEREALS: STRUCTURE
WHEAT
RICE (Oryza Sativa)
RICE: a major crop in Asia
RICE: STRUCTURE
MAIZE: (Zea Mays) (Corn)
MAIZE
TYPES OF MAIZE
OATS: AN IMPORTANT EUROPEAN CROP
OATS: DISTRIBUTION & USES
OATS: DISTRIBUTION & USES
RYE: INTRODUCTION
RYE: WORLD DISTRIBUTION
RYE: PRODUCTION & CONSUMPTION
RYE: ERGOT
SORGHUM: A SEMI-ARID CROP
SORGHUM DISTRIBUTION
SORGHUM: (Sorghum Bicolor)
MILLETS