Gluten Free Diet Ebooks Catalog

Why Gluten Free

Why Gluten Free

What Is The Gluten Free Diet And What You Need To Know Before You Try It. You may have heard the term gluten free, and you may even have a general idea as to what it means to eat a gluten free diet. Most people believe this type of diet is a curse for those who simply cannot tolerate the protein known as gluten, as they will never be able to eat any food that contains wheat, rye, barley, malts, or triticale.

Get My Free Ebook

Gluten Free Low Glycemic Cookbook

Fun With Gluten-Free, Low-Glycemic Food Cookbook is an ebook cookbook by Debbie Johnson, former owner and executive chef of The Golden Chalice Restaurant & Gallery, a 100% gluten-free, sugar-free, low-glycemic, organic, allergy-friendly establishment. This is the first Cook-Book of its kind! Every Recipe is Completely Gluten-Free, Sugar-Free (except fruit), Digestion-Friendly, Allergy-Friendly and Low Glycemic with Meat, Poultry, Fish meals and Tree-Nut-Free, Dairy-Free, Vegan and Vegetarian Options for most recipes. The recipes in this ebook have been helpful for people with everything from celiac disease and diabetes to Ibs (irritable bowel syndrome). Also, every recipe in this book contains healing food of some type. This is according to the many books written by doctors who are experts in the field of nutrition.

Gluten Free Low Glycemic Cookbook Summary


4.6 stars out of 11 votes

Contents: 95 Page Ebook
Author: Debbie Johnson
Price: $5.98

My Gluten Free Low Glycemic Cookbook Review

Highly Recommended

The author presents a well detailed summery of the major headings. As a professional in this field, I must say that the points shared in this ebook are precise.

Purchasing this ebook was one of the best decisions I have made, since it is worth every penny I invested on it. I highly recommend this to everyone out there.

Download Now

Felicity's Gluten Free Diet Handbook

Here's just some of what you're about to learn when reading the gluten free diet handbook: The interesting history of gluten free diet sensitivity in humans. We are not designed to eat wheat! It is something we have learned to digest quite recently in our evolution and not everyone can correctly process gluten. Why gluten actually makes you sick, and why its becoming more common. What is gluten ? When you hear about what gluten does inside our body and how the internal organs cope with wheat you will finally understand where the pains come from and how you can prevent cramps or even treat them as they happen. Celiac disease and its link to gluten intolerance. Celiac disease is now wide spread through society and it is actually increasing with each generation! That means the problem is increasing and your family is at risk more than you or your parents are. Awesome alternatives to bread. Yes, you can still eat fresh bread! When I learned I had to remove bread from my gluten free diet plan, it made me pretty sad because I love sandwiches so much. Eventually I learned a few safe alternatives and now I have toast and sandwiches whenever I want to. Tips for reading food and drink labels to ensure you don't consume gluten. Now this is so important, because food companies will hide gluten in their warnings or actually call ingredients by a name that doesn't even mention gluten. You absolutely must know these so that you can take control of your diet. Read more...

Felicitys Gluten Free Diet Handbook Summary

Contents: EBook
Author: Felicity
Official Website:
Price: $34.95

Gluten Sensitive Enteropathy

Eight subjects with biopsy proven gluten-sensitive enteropathy and magnesium depletion underwent bone density testing of the lumbar spine and proximal femur with DXA (Hologic QDR-1000) (44). Four of eight had lumbar spine T-scores -2.5 or less. Five had femoral neck T-scores and five had total hip T-scores -2.5 or less. All but two had T-scores less than 0 at all three sites and only four had z-scores greater than 0 at any of the three sites. Forty-four subjects with celiac disease underwent BMD measurements of the PA lumbar spine, femoral neck, and total body with DXA (Lunar DPX-L) (45). Thirty-four of the subjects were considered as having been successfully treated. The remaining 10 were either newly diagnosed or untreated. Compared to the manufacturer's reference data, subjects with newly diagnosed or untreated celiac disease had BMDs that were significantly lower than age-matched controls at all sites. Subjects with successfully treated celiac disease had BMDs that were not...


The main component, besides starch, in flour is of course protein (Table 1). As discussed earlier, the gluten proteins do not give rise to any detectable endotherms during the DSC scan, but they will shift To and Tm for the thermal transitions related to starch gelatinization (116). It was found that for the two peaks obtained at water conditions where the gelatinization endotherm has the shoulder (G and M1 in Fig. 2), gluten causes a linear increase in the peak temperatures when added to wheat starch, at least at a level of addition up to 0.4 g gluten g starch. For the starch and gluten used in that investigation, the following relation was obtained for the G endotherm (116) where GS is the amount of gluten expressed as g gluten g starch. Gluten from a flour of poor baking performance affected the temperatures in the same way as the gluten from the flour of good baking performance used for Eq. (1). It was also found that the enthalpy (AH) for the G endotherm decreased with increasing...

Dermatitis Herpetiformis

Dermatitis herpetiformis was described 100 years ago by Louis Duhring as a relatively rare skin disease characterized by a rash with small blisters and intense itch. Predilection sites are on the elbows, knees and buttocks, but lesions can also be found on the scalp, axillary folds and back. The onset in young adults is usually sudden. Diagnosis is based on biopsy from the uninvolved skin immunofluorescence shows characteristic granular IgA deposits along the basement membrane. In dermatitis herpetiformis lesions, subepidermal blisters with cellular inflammatory infiltration are found. The rash is gluten-dependent and the improvement in skin lesions occurs slowly even on a strict gluten-free diet it lasts several months before the patient can stop using dapsone (diaminodiphenyl sulphane) which controls the rash in few days and, therefore, it has been used for years in the treatment of dermatitis herpetiformis 30, 31 . Even though less than 10 of patients with dermatitis herpetiformis...

Thyroid Disorders Thyrotoxicosis

Celiac disease may occur more frequently in patients with autoimmune thyroid disease and represents an associated cause of malabsorption and weight loss 24 . Recent evidence suggests that the association between autoimmune thyroid diseases and celiac disease is quite similar to that between diabetes mellitus type 1 and celiac disease 24 . In an earlier series, about 5 of patients with celiac disease were found to suffer from hyper- or hypothyroidism even though the percentages are highly variable, with clinical hyperthyroidism in celiac disease ranging from 0 up to 7 in different studies 24 . Moreover, gastric achlorydria and autoantibodies against gastric parietal cells are detectable in about one-third of patients with Graves' disease 18,24 . Hepatic dysfunction also occurs, particularly when TS is severe hypoproteinaemia and increase of AST and ALP may be present 18 .

Adrenal Insufficiency and Weight Loss

Autoimmune pathogenesis accounts for 70-90 of primary adrenal insufficiency and about 50 of patients affected have one or more other autoimmune endocrine disorders, situation referred to as polyglandular autoimmune syndrome (PGA I and II). In the more common PGA II, primary adrenal insufficiency is the principal manifestation. Other autoimmune manifestations are diabetes mellitus type 1, hypoparathyroidism, pernicious anaemia, and celiac disease. While each of these manifestations can induce weight loss 28, 29 , the weight is rapidly recovered once substitutive treatment is started 25 .

Enteropathytype Tcell Lymphoma

General Enteropathy-type T-cell lymphoma (ETL) is a neoplasm of intraepithelial lymphocytes that is often associated with celiac disease. While in some cases there is a history of celiac disease since childhood, in most cases of ETL, celiac disease is diagnosed either concurrently with or shortly before diagnosis of the lymphoma.96 Prior to diagnosis of an overt lymphoma, some patients will experience a period of refractory celiac disease and or intestinal ulcers (ulcerative jejunitis). Establishing a diagnosis from small endoscopic mucosal biopsies can be very difficult, and excision of a full-thickness intestinal biopsy specimen may be required for a definitive diagnosis. Pathology One or more ulcerating mass lesions are present in the jejunum or ileum. Occasionally, other parts of the GI tract may also be involved. Histologically, the tumor cells display a variable appearance. In most cases, the infiltrate is composed of medium-sized lymphocytes with round to irregular nuclei,...

Drying Tempering and Cooling

Fujio and Lim (33) found that heat-treated gluten was an amorphous biopolymer, thus exhibiting glass transition behavior as observed with DSC. The state transition affects diffusion and deformation. Product deformation due to moisture removal continues until a point where the material transitions into the glassy state. Once the structure becomes immobile, moisture removal may continue, but the final product texture and integrity may be compromised. Another condition detrimental to final product quality is the formation of moisture gradients, since they can result in breakage as the gradients equilibrate. External drying conditions, such as relative humidity and temperature, can be adjusted to prevent transition to the glassy state and to prevent moisture gradients from forming.

Predominantly Extranodal Group

A subset (10-25 ) of primary intestinal lymphomas has a T-cell phenotype, also known as enteropathy-type intestinal T-cell lymphoma. This disease tends to occur in adults with a history of gluten-sensitive enteropathy or celiac disease, although it can occasionally be found in patients without a history of enteropathy. Patients usually present with weight loss, abdominal pain, and jejunal involvement, and are typically diagnosed at the time of emergency surgery for small bowel perforation. The clinical course is often aggressive with associated poor survival rates, and death usually occurs from intestinal perforation due to chemotherapy-refractory malignant ulcers. Postmortem examination often reveals multiple jejunal ulcers that are associated with perforation, and a distinct mass may be absent. Histologic studies show that the uninvolved intestine may have blunting of villi, as is commonly seen in celiac disease. Tumors are found diffusely and contain a mixture of small, medium, and...

Test Methodology 104 Fecal Fat Analysis

A D-xylose absorption test is an indirect but specific method for assessing mucosal absorption of the small intestine. D-Xylose is not normally present in blood or urine and digestive enzymes are not necessary for its metabolism. Normally, approximately 60 of D-xylose taken in an oral dose will pass through the intestinal mucosa and, over time, into the circulatory system, eventually to be excreted into urine. Low absorption of xylose will occur in disorders of the small intestine, such as intestinal malabsorption, Crohn's disease, celiac disease, AIDS, pellagra, and ascariasis.

Changes in the Gastrointestinal Tract

Diseases involving the GI tract contribute to delayed gastric emptying (GE) and delayed small-bowel absorption. Such diseases include linitis plastica, pathologies of the small bowel, such as lymphomas, lymphangectasia, sarcoidosis, Whipple's disease, celiac disease, viral enteritis, and haemangiomas of the gut. These processes influence malabsorption by lymphatic infiltration of the mucosal and submucosal tissues. Less obvious aetiologies of delayed GE and malabsorption include cirrhosis, psoriasis, ileitis, and ulcerative colitis 12 . Human studies 13 document the association of gastroparesis and abnormal small-bowel function, which contribute to the malabsorption associated with non-GI tumours, which ultimately leads to malnutrition and cachexia. These GI processes are independent of tumour site, size, or overt constitutional changes 14 , but are clinically manifested in advanced cancer, after weight loss, following chemotherapy or abdominal radiation 14 .

Nonhodgkin Lymphoma Eatl Enteropathyassociated Tcell Lymphoma

The understanding of celiac-associated lymphomas has improved in recent years 40 . It was shown that celiac-associated lymphomas were of single histogenetic type. Immunohistological and molecular studies then indicated that these tumors are of T-cell origin. It appears likely that enteropathy associated T-cell lymphoma derives from intraepithelial lymphocytes (IEL) monoclonal HML-1 antibody stains lymphoma cells (CD 103+ lymphocytes expressing integrin-a E-fi 7 characteristic for mucosal associated lymphocytes). The lymphoma cells are usually pleomorphic and manifest a cytotoxic CD3+, CD4 CD8-phenotype 41, 42 , A monomorphic small cell variant has been described in which the cells are CD3+, CD4-, CD8+ and CD56+. To assess the clonality of duodenal mucosal T cells in coeliac patients, the analysis of TCR rearrangements by multiplex polymer chain reaction (PCR) on DNA extracted from duodenal biopsies of patients with complicated and noncomplicated celiac disease was recently performed...

Test Methodology 103 Schilling Test

This step distinguishes between pernicious anemia and other causes of malabsorption. Step 2 repeats the doses of B12 from Step 1, but adds intrinsic factor along with the oral dose of labeled B12. The 24-hour urine collection is repeated for measurement of the radiolabeled B12. If the labeled B12 in the urine from Step 2 is 7.5 , then the malabsorption has been corrected by the addition of the intrinsic factor and the diagnosis is pernicious anemia. If the results are

Gastrointestinal and Respiratory Epithelium

Avidine Biotine Peroxydase

Stomach and the intestines have a non-stratified epithelium rapidly renewed from the bottom of the intestinal crypts or glands. Like many other simple epithelia, these epithelial cells do not show hyaluronan except for a little in the basolateral surfaces of some cells at the bottom of the crypts (Fig. 3d) (34). However, the enterocytes become positive for hyaluronan and CD44 in the immunological injury caused by Crohn's disease and celiac disease (Kemppainen et al., unpublished data). Introduction of allergens increases hyaluronan in the gut lumen (35). Likewise, transformation of the colon epithelial cells is frequently accompanied by the expression of hyaluronan, while normal colon epithelium is virtually hyaluronan free (Fig. 3g and h) (23). In colon cancer cells, the level of hyaluronan is a strong, unfavorable prognostic indicator of the patient survival (36). The emergence of hyaluronan expression on gastric cancer cells (Fig. 3e) shows a similar negative correlation with the...

Scientific Foundations

Gluten, a natural chemical present in flours, makes the dough elastic. It also ensures removal of the carbon dioxide released during fermentation. Subsequently, the amount of gluten used for making bread determines its final volume. Kneading (pressing and working a mass of dough with the hands) makes the gluten work better in forming a bigger framework to trap the released carbon dioxide.

Rheological Comparison Between Synthetic And Food Polymers

Polymer Glass Transition

The glass transition temperature (Tg) is a function of product composition, molecular weight of the continuous structural matrix, degree of branching, degree of cross-linking, crystallinity, and degree of plasticization. For un-cross-linked molecules, the drop in modulus is about three decades near Tg. The magnitude of drop in modulus in the glass transition region decreases as the degree of cross-linking or molecular entanglement increases, which is the case for low-moisture gluten samples. As shown in Figure 2, for a gluten sample equilibrated in 65 relative humidity (RH), the drop in modulus is less than two decades (13). The degree of viscosity drop at a constant (T - Tg) has been used as an index of ''fragility.'' Unfortunately, organic glass usually is more fragile than inorganic glass. Thus, there is minimal opportunity for applying this concept in stabilizing food systems. A high-crystallinity sample has lower modulus drop at Tg due to Figure 2 Typical DMTA plot for gluten (RH...

Clinical Presentation

Anemia with an elevated MCV. macrocytic anemia, is most often a manifestation of folate or vitamin B,, deficiency. The presence of macrocytic anemia. with or without the symptoms previously mentioned, should lead to further testing to determine Bp and folate levels. An elevated methylmalonic acid (MMA) level can be used to confirm a vitamin B,2 deficiency. Folate deficiency anemia is usually seen in alcoholics, whereas B 2-deficiency anemia mostly occurs in people with pernicious anemia, a history of gastrectomy, diseases associated with malabsorption (e.g bacterial infection, Crohn disease, celiac disease), and strict vegans (rare).

Effect Of Variables

Effect Shearing Starch

Studies by Attenburrow et al. (73) have monitored the changing acoustic emission amplitude of crushing starch and shown a marked reduction in intensity with increasing moisture content. Nicholls et al. (72) reported the decrease of acoustic events with increasing relative humidity when crushing extruded granules of gluten wheat starch and waxy maize starch (Fig. 14). Seymour and Hamann (89) also found a general decrease in the acoustic emission parameters, sound pressure and sound intensity, with increasing water activity. Figure 14 Acoustic emission produced when crushing extruded granules as a function of conditioning relative humidity O gluten, A wheat starch, waxy maize starch. (From Ref. 72 with kind permission from Academic Press.) Figure 14 Acoustic emission produced when crushing extruded granules as a function of conditioning relative humidity O gluten, A wheat starch, waxy maize starch. (From Ref. 72 with kind permission from Academic Press.) Figure 15 Shearing and breaking...

Microstructure Of Breads A Wheat Breads

During development of a wheat kernel, protein bodies within the endosperm cells fuse to form the protein matrix (66, 67). In the milling process, the outer layers of the grain and the germ are separated from the starchy endosperm, the flour. In the flour particles, gluten forms a network around the starch granules. During the mixing of bread dough, wheat-endosperm-storage proteins become hydrated and interact to form gluten, an extensive and gas-retentive film. The unique visco-elastic properties are derived from the mixture of glutenin and gliadin (68) Hydrated glutenin is an elastic material hydrated gliadin is viscous liquid. In wheat bread dough, the gluten forms the continuous phase in which starch granules, lipid, added yeast cells, and cell wall fragments are dispersed. Although the structural properties of gluten have a great effect on the final texture of bread, the other components affecting the distribution of water in the dough, such as starch and cell walls, have a direct...

Effects Of Raw Materials On Final Product Quality

Variations in raw materials are due to environmental conditions and varietal differences. Environmental conditions affect protein content, rheological properties, and final product quality. The protein content of wheat is closely linked to the environment (2). Frost adversely affects wet gluten yields and mixograph results (3). Additionally, sprouting in wheat increases checking of pasta (4). Genetic differences affect rheological properties of gluten and final product quality. Medium to strong glutens have high gluten indices, SDS sedimentation, and gluten viscoelasticity, which are all linked to genotype (2). The differences in macromolecular components of different varieties of durum wheat affect the cooking quality of pasta (5, 6). The relationship between raw material differences and final product quality is complex due to both the environmental and genetic effects.

Viscoelastic Properties of Biscuit Doughs

Biscuit dough is a complex material resulting from the mixing of various ingredients, such as wheat flour, water, sugar, and fat. During the mixing process, specific interactions between these constituents (and especially gluten proteins) develop, giving their structure to the dough. In the following, the viscoelastic behavior of a biscuit dough is characterized in small-amplitude oscillatory shear experiments. These measurements permit one to follow the development of the structure during the kneading process and to check the influence of the process parameters on dough quality.

Test Methodology 101 Vitamin Testing In The Clinical

Vitamin B12 deficiency may result from infestation of intestinal parasites such as Diphyllobothrium latum that compete for the vitamin, stomach removal surgery or ileal resection, celiac sprue, Crohn's disease, or drugs such as alcohol, neomycin, or para-acetylsalicylic acid. celiac sprue - malabsorption syndrome resulting from intolerance to dietary wheat proteins

Matrix Properties

Studies have been carried out to define the base material properties without the complication of the gross structure, using specimens of simple geometry obtained by hot pressing or extrusion or a combination thereof. Mechanical properties as a function of water content have been studied in wheat starch, amylopectin, and gluten and mixtures of these components with themselves and with sugars, poly-ols, and lipids (70-80). With the addition of glucose to starch, the fall in modulus occurred at a lower moisture content corresponding to a depression of the glass transition of starch due to monomer plasticization (Fig. 8). The magnitude of the fall in modulus and its value at low moisture fell with increasing glucose content. The modulus difference between glassy and rubbery states is less than for a purely amorphous polymer, and the rubbery modulus is indicative of partially crystalline material (79). The increase in moisture was also accompanied by a change in the failure mode, with a...

Farinogram Weakness

Alveogram Values

The dough-making process encompasses various phases, which in practice overlap (9). The first phase is the moistening of the flour particles, where adsorption of water onto particle surfaces induces high adhesion forces (10). Then solubilization and swelling of albumins, globulins, arabinoxylans, and damaged starch granules are followed by the restructuring of a gliadins and glutenins network. This last step involves a continuous overlap of molecular buildup and breakdown, proceeding simultaneously during mixing. Therefore, consistency increases up to a maximum and then falls off. This continuous degradation explains why energy expended during mixing is involved not only in dough structural buildup, but also in heat and irreversible structural breakdown (11). In bread doughs, gas-holding ability is generally associated with the formation of a continuous gluten network (12). The most critical factors in the mixing stage are flour quality, amount of water added, and magnitude of work...

Small Bowel

An interesting correlate is the association of cholera pandemics and Vibrio cholera toxin stimulation of IgA plasma cells 37 . Helicobacter pylori has been shown to have a significant association with small intestinal lymphoma 38 , Primary small intestinal lymphoma or extranodal lymphoma represents a group of heterogeneous disorders with varied histological findings of histiocytic, lymphocytic infiltration or undifferentiated lymphoma. A true histiocytic lymphoma may occur late in Celiac disease. The variants of this disorder, small intestinal lymphoproliferative disorders, have groups which are characterized by serological abnormalities of the alpha heavy chain of IgA 39 . Alsabti et al. 40 studied normal family members of 8 patients with a-chain disease. Both patients and family members demonstrated increased circulating B lymphocytes, decreased T lymphocytes and defective cellular immune responses. These findings, and serologic abnormalities of a-chain in multiple members of four...


Protein occurring in wheat giving firmness to risen dough in bread-making. Those allergic to gluten suffer from coeliac disease, resulting in poor absorption of dietary components and in the consequent malabsorption syndrome. Gluten-free products are available for such people.

Cereal Proteins

In the baking industry, the type of wheat flour dictates to a large extent the nature of the final baked product. Breads, for example, are usually prepared from hard wheat flour, while biscuits and cakes are prepared from soft wheat flour. Moreover, it has long been recognized that the gluten network in wheat flour dough is largely responsible for the dough's unique functional properties and that some wheat flours produce better breadmaking doughs than others (26). Pragmatically, gluten can be defined as the viscoelastic mass remaining after dough is washed in water or dilute salt solution to remove starch and water-soluble components. Besides lipid and residual starch (10-15 ), about 75 of dry gluten consists of prolamins, so most research has focused on this component. The wheat prolamins are usually divided into two groups (a) the a, p, y, and m gliadins, which are monomers with relative molecular weights (Mr) ranging from 30,000 to 74,000 and having no interchain disulphide bond,...


After mixing, the dough is formed into the desired shape for the final product. Loaves of bread may be formed or pieces may be cut from a large sheet. To form a large sheet of dough, the dough is passed through sets of rollers that gradually reduce the thickness. The gradual thickness reduction further develops the gluten structure without tearing the dough. Important sheeting parameters include reduction ratio and roller speed. Oh et al. (27) found that reduction ratio and roll speed affect the surface of cooked pasta. Cooked-noodle surface was firmer for slower roll speeds and for greater reduction ratios, implying that high pressure results in a smooth surface. Once the large dough sheet is formed, it can be cut into the desired shape for the final product. Alternatively, pieces may be cut from the large dough mass and formed into the final product's shape, such as loaves of bread. Forming takes the developed dough and shapes it into the desired form for the final product.

Water Relations

Transport of water between crust and crumb takes place during the storage of bread, and drying of the crumb will enhance all other negative changes occurring during storage (161, 171). However, a transport of water, or redistribution of water, between starch and gluten has also been suggested to be involved in the staling of bread (163). As a means to investigate the state of water during staling, measurements of unfreezeable water have been performed using DSC. The amount of ''bound'' or unfreezeable water can be determined for starch (and other macromolecules) using DSC (172). The experimental conditions involve keeping the sample for a certain period of time at a temperature well below the freezing point of water, and then from the ice melting endotherm during heating calculate the amount of water frozen during the treatment (152). With knowledge about the total amount of water present, the percentage of unfreezeable water can be calculated.


During mixing, dough development begins as raw materials are combined and macromolecules are hydrated. Icard-Verniere and Feillet (26) measured specific mechanical energy during mixing and found that mixing has three stages, differing in torque. First, flour particles are hydrated, which is marked by a low, constant torque. Hydration increases the mobility of the macromolecular chains, which enables the proteins to polymerize. Second, dough development occurs as sulfhydral groups react to form disulfide bonds. This stage is marked by sharply increasing torque. Last, the torque remains constant at a maximum value, indicating fully developed dough. Overmixing the dough results in breakdown of the gluten matrix. However, optimal mixing produces dough with even hydration and a strong gluten structure.

Staling Of Bread

The staling of bread is defined as ''almost any change, short of microbiological spoiling, that occurs in bread during storage which makes it less acceptable to a consumer'' (58). The staling of bread has been recognized as a problem during centuries, and the typical changes occurring in crumb and crust during storage of bread are well known. It seems that the changes in the crust can be explained from a change in Tg because of water uptake from the crumb or from the surroundings (161). As the moisture content increases in the crust, this could be expected to influence Tg so that it decreases and approaches room temperature (162), thus causing the change from crisp to rubbery texture. In the center of the crumb, the moisture content will decrease during storage (161), but Tg will still be well below room temperature at the moisture content of bread (162). The increase in crys-tallinity of starch, occurring in parallel with other changes during staling, points to the involvement of...


Shear, heat, and air incorporation are important parameters to control during extrusion. Shear is applied to the material to promote dough formation as the screw rotates. Excessive shear breaks down the dough and produces excessive viscous heating. Often heat is applied to aid in the aggregation of proteins by the formation of disulfide bonds (29). When calculating the amount of heat to add, one must account for both the external heat applied and heat due to friction from the screw shear. Overheating the dough results in overworked dough and the gluten denatures (28, 30). An additional concern with extrusion is air incorporation. Air produces weak spots in the extrudate that may result in breakage, so a vacuum is used to remove air (1, 28, 30, 31). Extrusion is an efficient method for the production of a variety of food products, but care must be taken to control shear, heat, and air incorporation.


Commercial low-moisture baked goods, such as cookies, crackers, and hard pretzels, derive their characteristic textural crispness from the glassy solid state of their crumb structures (1-4). In polymer science terms, products of this class can be described as rigid foams consisting of air cells surrounded by a glassy matrix with ''fillers,'' or discontinuous inclusions. The matrix of a crisp cookie is a continuous sucrose-water glass with embedded ungelatinized starch granules, undeveloped gluten, and fat. Similarly, the matrix of a cracker or pretzel is a continuous glassy network of (partially) gelatinized starch, (partially) developed gluten, amorphous sucrose, and included fat. To achieve the kinetically metastable state of a glass, such products are deliberately formulated and processed so that the possibility for glass-to-rubber transitions within the matrix is minimized i.e., the glass transition temperature (Tg) is brought well above ambient temperature. Thus, variations in...

Glass Transition

A glass transition expresses the transition between a glassy, brittle state and a rubbery state. As will be discussed later, the glass transition temperature (Tg) is important for storage stability and retaining of crispness. The Tg can be evaluated from the diffuse steplike transition in heat capacity observed in DSC, and then either the initial, midpoint or endpoint temperature of the transition can be used to define Tg (77, 78). Another suitable method is DMTA, where Tg can be defined and measured in different ways from the elastic modulus (E'), loss modulus (E ), or tan 5 ( E E') measured as a function of temperature. The cereal components that have been of most interest in this connection are starch and gluten, but doughs and baked products have also been investigated.