DOCSLIB.ORG

Nutritional Aspects of Food Extrusion: a Review

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Nutritional Aspects of Food Extrusion: a Review 916 International Journal of Food Science and Technology 2007, 42, 916–929 Original article Nutritional aspects of food extrusion: a review Shivendra Singh, Shirani Gamlath* & Lara Wakeling School of Science & Engineering, Mount Helen Campus, University of Ballarat, Victoria 3353, Australia (Received 19 February 2006; Accepted in revised form 19 April 2006) Summary Extrusion cooking, as a multi-step, multi-functional and thermal/mechanical process, has permitted a large number of food applications. Effects of extrusion cooking on nutritional quality are ambiguous. Beneficial effects include destruction of antinutritional factors, gelatinisation of starch, increased soluble dietary fibre and reduction of lipid oxidation. On the other hand, Maillard reactions between protein and sugars reduce the nutritional value of the protein, depending on the raw material types, their composition and process conditions. Heat-labile vitamins may be lost to varying extents. Changes in proteins and amino acid profile, carbohydrates, dietary fibre, vitamins, mineral content and some non-nutrient healthful components of food may be either beneficial or deleterious. The present paper reviews the mechanisms underlying these changes, as well as the influence of process variables and feed characteristics. Mild extrusion conditions (high moisture content, low residence time, low temperature) improve the nutritional quality, while high extrusion temperatures (P200 °C), low moisture contents (<15%) and/or improper formulation (e.g. presence of high-reactive sugars) can impair nutritional quality adversely. To obtain a nutritionally balanced extruded product, careful control of process parameters is essential. Keywords Carbohydrates, dietary fibre, extrusion, Maillard reaction, minerals, protein, vitamins. is able to break the covalent bonds in biopolymers, and Introduction the intense structural disruption and mixing facilitate Health and nutrition is the most demanding and the modification of functional properties of food ingre- challenging field in this era and would continue to be dients and/or texturizing them (Asp & Bjorck, 1989; in the future as well. Maintaining and increasing the Carvalho & Mitchelle, 2000). In addition, the extrusion nutritional quality of food during food processing is process denatures undesirable enzymes; inactivates some always a potentially important area for research. antinutritional factors (trypsin inhibitors, haemaggluti- Deterioration of nutritional quality, owing to high nins, tannins and phytates); sterilises the finished prod- temperature, is a challenging problem in most tradi- uct; and retains natural colours and flavours of foods tional cooking methods. Extrusion cooking is preferable (Fellows, 2000; Bhandari et al., 2001). to other food-processing techniques in terms of con- The process has found numerous applications, inclu- tinuous process with high productivity and significant ding increasing numbers of ready-to-eat cereals; salty nutrient retention, owing to the high temperature and and sweet snacks; co-extruded snacks; indirect expanded short time required (Guy, 2001). Extrusion cooking is a products; croutons for soups and salads; an expanding high-temperature, short-time process in which moist- array of dry pet foods and fish foods; textured meat-like ened, expansive, starchy and/or protenacious food materials from defatted high-protein flours; nutritious materials are plasticised and cooked in a tube by a precooked food mixtures for infant feeding; and con- combination of moisture, pressure, temperature and fectionery products (Harper, 1989; Eastman et al., mechanical shear, resulting in molecular transformation 2001). and chemical reactions (Havck & Huber, 1989; Castells Parallel to the increased applications, interest has et al., 2005). This technology has some unique positive grown in the physico-chemical, functional and nutri- features compared with other heat processes, because tionally relevant effects of extrusion processing. Preven- the material is subjected to intense mechanical shear. It tion or reduction of nutrient destruction, together with improvements in starch or protein digestibility, is clearly *Correspondent: Fax: +61353279240; of importance in most extrusion applications. Nutri- e-mail: [email protected] tional concern about extrusion cooking is reached at its doi:10.1111/j.1365-2621.2006.01309.x Ó 2007 The Authors. Journal compilation Ó 2007 Institute of Food Science and Technology Trust Fund Nutritional aspects of food extrusion S. Singh et al. 917 highest level when extrusion is used specifically to minant of protein quality in adults, according to FAO/ produce nutritionally balanced or enriched foods, like WHO/UNU (1985). Protein digestibility value of extru- weaning foods, dietetic foods, and meat replacers dates is higher than nonextruded products. The possible (Cheftel, 1986; Plahar et al., 2003). Many researchers cause might be the denaturation of proteins and inacti- have reported the positive and negative effects of the vation of antinutritional factors that impair digestion. extrusion process on the nutritional quality of food and The nutritional value in vegetable protein is usually feed mixtures using different extruder conditions (tem- enhanced by mild extrusion cooking conditions, owing perature, feed moisture, screw speed and screw confi- to an increase in digestibility (Srihara & Alexander, guration) and raw-material characteristics (composition, 1984; Hakansson et al., 1987; Colonna et al., 1989; particle size). Reviews of various chemical changes Areas, 1992). It is probably a result of protein denatur- affecting the nutritional quality of food during extrusion ation and inactivation of enzyme inhibitors present in cooking have been published by Cheftel (1986), Asp & raw plant foods, which might expose new sites for Bjorck (1989), Camire et al. (1990) and Areas (1992). enzyme attack (Colonna et al., 1989). All processing However, none of the publication offers a comprehen- variables have different effects in protein digestibility. sive review of all nutritional aspects. The findings are summarised in Table 1. The present paper reviews the updated and more Among the process variables, the feed ratio has the advanced mechanisms and new concepts about the maximum effect on protein digestibility, followed by nutritional changes during the extrusion process. The process temperature in the extrusion of fish–wheat flour effect on proteins and amino acid profile, carbohydrates, blend. Tripling the ratio of fish to wheat increases the dietary fibre, vitamins, mineral content and some non- digestibility of the extrudates by 2–4% (Bhattacharya nutrient healthful components of food are discussed. et al., 1988; Camire et al., 1990). Increase in extrusion This paper also indicates the gaps in the available temperature (100–140 °C) enhances the degree of inac- extrusion literature and some of the future opportunities tivation of protease inhibitors in wheat flour, and for research to make extrusion processes more efficient consequently, the protein digestibility values are in terms of retention of nutritional quality of food. increased. Extrusion, even at 140 °C, does not have any adverse effect on protein digestibility, which might be attributed to the lesser residence time of food dough Nutritional changes within the extruder. The effect of other process varia- bles, such as length to diameter ratio and screw speed on Protein protein digestibility values appears to be insignificant Every animal, including humans, must have an adequate (P ¼ 0.05) (Bhattacharya et al., 1988). Increased screw source of protein in order to grow or maintain itself. speed may have increased the protein digestibility of Proteins are a group of highly complex organic com- extruded corn-gluten, because the increase in shear pounds that are made up of a sequence of amino acids. forces in the extruder denatures the proteins more easily, Among the twenty-two amino acids that make up most thus facilitating enzyme hydrolysis (Bhattacharya & proteins, isoleucine, leucine, lysine, methionine, phenyl- Hanna, 1985). alanine, threonine, tryptophan, and valine are consid- An advantage of extrusion cooking is the destruction ered as essential amino acids. of antinutritional factors, especially trypsin inhibitors, Protein nutritional value is dependent on the quantity, haemagglutinins, tannins and phytates, all of which digestibility and availability of essential amino acids. inhibit protein digestibility (Bookwalter et al., 1971; Digestibility is considered as the most important deter- Lorenz & Jansen, 1980; Armour et al., 1998; Alonso Table 1 Effect of processing parameter on protein digestibility Processing parameter Protein digestibility Food source References Process temperature › with increasing Corn gluten–whey Fapojuwo et al. (1987), extrusion temperature blends, sorghum and Bhattacharya & Hanna (1985), fish–wheat blends Bhattacharya et al. (1988) Feed ratio › with increasing Fish and wheat flour Bhattacharya et al. (1988) & animal protein Camire et al. (1990) Screw speed Insignificant effect Fish and wheat flour Bhattacharya et al. (1988) › with increasing Corn gluten–whey blend Camire et al. (1990) screw speed Length to diameter ratio Insignificant effect Fish and wheat flour Bhattacharya et al. (1988) ›, increase. Ó 2007 The Authors. Journal compilation Ó 2007 Institute of Food Science and Technology Trust Fund International Journal of Food Science and Technology 2007 918 Nutritional aspects of food extrusion S. Singh et al. et al.,
Load more

Recommended publications
  • Food Extrusion Processing: an Overview
    FOOD EXTRUSION PROCESSING: AN OVERVIEW By Bon-Jae Gu, School of Food Science, Washington State University. Ryan J. Kowalski, School of Food Science, Washington State University. Girish M. Ganjyal, School of Food Science, Washington State University FS264E FS264E | Page 1 | extension.wsu.edu WSU EXTENSION | FOOD EXTRUSION PROCESSING: AN OVERVIEW Food Extrusion Processing: An Overview cereals, pellet products, pet foods, and pre-gelatinized flours, Summary among others (Singh et al. 2007). It is a system that encompasses multiple unit operations such as mixing, Extrusion processing is a commonly used processing kneading, cooking, forming, and cutting all into a single piece technology in the food industry with a wide number of of equipment. This results in having a relatively simple process applications. It is a processing system that utilizes a single with high efficiency and low cost compared to other screw or a set of screws to force food materials through a small processing methods (Fellows 2009). opening. While food is being forced through the extruder, foods are cooked by the high pressure, high shear, and high temperature environment created by the screws, encased in the barrel. Upon exiting, materials often puff due to the release of pressure and conversion of water into steam. The entire process is continuous and capable of happening in less than a minute. The most commonly used extruders in the food industry include single-screw and twin-screw systems, with twin-screw systems more widely used because of their flexibility. A brief overview of extrusion processing systems is provided in this publication, including applications of extrusion in the food industry, different parts of the extruder, and the concept of extrusion as a multiple input and multiple output processing system.
    [Show full text]
  • Precooked Bran-Enriched Wheat Flour Using Extrusion
    JFS S: Sensory and Food Quality Precooked Bran-Enriched Wheat Flour Using Extrusion: Dietary Fiber Profile and Sensory Characteristics H. GAJULA,S.ALAVI,K.ADHIKARI, AND T. HERALD ABSTRACT: The effect of precooking by extrusion processing on the dietary fiber profile of wheat flour substituted with 0%, 10%, 20%, and 30% wheat bran was evaluated. Depending on the level of bran, total dietary fiber (TDF) and soluble dietary fiber (SDF) in uncooked flours ranged from 4.2% to 17.2% and 1.5% to 2.4%, respectively. Precooking by extrusion significantly increased SDF in flours (by 22% to 73%); although in most cases it also led to a significant decrease in TDF. Cookies and tortillas produced from uncooked and precooked flours with 0% and 20% substituted bran were evaluated for consumer acceptability using a 9-point hedonic scale. With a few exceptions, all cookies had scores ranging from 6 to 7 (“like slightly” to “like moderately”) for each attribute, including overall acceptability, appearance, texture, crumbliness, and flavor. Tortillas were rated for the same attributes except for crumbliness, which was replaced with chewiness. In most cases, tortilla scores ranged from 5 to 7 (“neither like nor dislike” to “like moderately”). Consumer acceptability scores of cookies from uncooked flour did not change significantly with increase in bran substitution from 0% to 20%. However, consumer scores for tortillas did decrease significantly with increase in bran level. Extrusion precooking of the flours did not improve the consumer acceptability of cookies and tortillas; however, it did improve their dietary fiber profile by increasing the SDF significantly.
    [Show full text]
  • Extrusion-Cooking of Starch
    Chapter 13 Extrusion-Cooking of Starch L. Moscicki, M. Mitrus, A. Wojtowicz, T. Oniszczuk and A. Rejak Additional information is available at the end of the chapter http://dx.doi.org/10.5772/52323 1. Introduction The extrusion technology, well-known in the plastic industry, has recently become widely used in food industry, where it is referred to as extrusion-cooking. It has been employed for the production of so called engineered food and special feed. Generally speaking, extrusion-cooking of vegetable raw materials consists in the extrusion of grinded material at baro-thermal conditions. With the help of shear energy, exerted by the rotating screw, and additional heating by the barrel, the food material is heated to its melting point, than is conveyed under high pressure through a series of dies and the prod‐ uct expands to its final shape. That results in much different physical and chemical proper‐ ties of the extrudates in comparison to raw materials used. Food extruders – processing machines (see fig. 1), belong to the family of HTST (High Tem‐ perature Short Time) equipment, with a capability to perform cooking tasks under high pressure. This aspect may be explained for vulnerable food and feed as an advantageous process since small time span exposures to high temperatures will restrict unwanted dena‐ turation effects on e.g. proteins, amino acids, vitamins, starches and enzymes. Physical tech‐ nological aspects like heat transfer, mass transfer, momentum transfer, residence time and residence time distribution have a strong impact on the food and feed properties during ex‐ trusion-cooking and can drastically influence the final product quality (Mościcki et al., 2009, Moscicki, 2011, Mościcki, 2011).
    [Show full text]
  • Food Extrusion - Karwe M
    FOOD ENGINEERING – Vol. III - Food Extrusion - Karwe M. V. FOOD EXTRUSION Karwe M. V. Cook College, Rutgers University, New Jersey, USA Keywords: Extruded products, extrusion equipment, flavor formation, Maillard browning, nutritional changes, physico-chemical changes in starch, protein, and lipids, process modeling, scale-up, single-screw extruder, twin-screw extruder Contents 1. Introduction 2. Extruded Products 2.1. Products for Human Consumption 2.2. Pet Food and Animal Feed Products 3. Extrusion Equipment 3.1. Single-Screw Extruders 3.2. Twin-Screw Extruders 3.3. Extrusion Equipment Size 4. Extrusion Variables and Process Parameters 5. Process Modeling and Scaling 5.1. Process Modeling 6. Scale-Up 7. Physico-Chemical Changes During Extrusion 7.1. Changes in Starches 7.2. Changes in Proteins 7.3. Changes in Lipids 8. Flavor Formation and Loss During Extrusion 9. Effect of Extrusion on Nutritional Quality 10. Other Applications of Extrusion Processing Acknowledgments Glossary Bibliography Biographical Sketch SummaryUNESCO – EOLSS The process of screw extrusion is used in the food and agricultural industries to make a variety of products.SAMPLE The process combines maCHAPTERSny operations as one, is flexible, can be used to make different types of products, and produces few or no effluents. This article gives an overview of the status of food extrusion research and applications. 1. Introduction Extrusion is defined as a process in which material is pushed through an orifice or a die of given shape. The pushing force is applied using a piston or a screw. In food applications, screw extrusion is predominant. ©Encyclopedia of Life Support Systems (EOLSS) FOOD ENGINEERING – Vol.
    [Show full text]
  • Effects of Extrusion-Cooking on the Nutrient and Anti-Nutrient
    Journal of Applied Pharmaceutical Science 02 (05); 2012: 158-162 ISSN: 2231-3354 Effects of Extrusion -Cooking on the Nutrient and Received on: 06-05-2012 Revised on: 12-05-2012 Accepted on: 17-05-2012 Anti-Nutrient Composition of Pigeon Pea and Unripe DOI: 10.7324/JAPS.2012.2533 Plantain Blends Anuonye J. C., Jigam A. A and Ndaceko G. M ABSTRACT The effects of extrusion cooking on the nutrient and anti-nutrient composition of raw and extruded blends of pigeon pea and unripe plantain flours were evaluated. Pigeon pea seeds were cleaned and processed into flour while unripe plantain was peeled, sliced, dried and milled into flour separately and sieved to pass 0.85mm mesh. The moisture content of the flours was determined. Unripe plantain flour was added to pigeon pea flour at 25% levels of substitution. The moisture content of the blends was adjusted to 25% levels. The blends were Anuonye J. C. extruded using a Brabender laboratory single-screw extruder (Duisburg DCE 330 model) at Food Science and Nutrition 0 Department, Federal University of 120rpm and temperature of 100 c. The proximate composition, minerals, amino acid profile and some vitamins of raw and extruded samples were determined. Antinutrients (Phytate, Technology Minna. saponnis, oxalate, tannin, trypsin inhibitor, lectin and hydrogen cyanide content) of raw and extruded samples were also estimated. Results of proximate composition, showed a significant (P<0.05) increase in fat content (1.97%) and energy value (1420 kj/100g), while marginal decrease was noticed in protein (22.98%), ash (3.72%) and crude fibre (7.04%).
    [Show full text]
  • Protein-Protein Interaction of Soybean Protein from Extrusion Processing
    PROTEIN-PROTEIN INTERACTION OF SOY PROTEIN ISOLATE FROM EXTRUSION PROCESSING A Thesis presented to the Faculty of the Graduate School at the University of Missouri-Columbia In Partial Fulfillment of the Requirements for the Degree Master of Science by ANGELA CHIANG Dr. Fu-Hung Hsieh, Thesis Supervisor DECEMBER 2007 © Copyright by Angela Chiang 2007 All Rights Reserved The undersigned, appointed by the dean of the Graduate School, have examined the thesis entitled PROTEIN-PROTEIN INTERACTION OF SOY PROTEIN ISOLATE FROM EXTRUSION PROCESSING presented by Angela Chiang, a candidate for the degree of Master of Science, and hereby certify that, in their opinion, it is worthy of acceptance. Fu-Hung Hsieh, Ph.D., Department of Food Science Andrew D. Clarke, Ph.D., Department of Food Science Gang Yao, Ph.D., Department of Biological Engineering ACKNOWLEDGEMENTS It has been a long way for the past two years. I would not have this fulfilling journey without the support and encouragement from many people. I would like to thank Dr. Fu-Hung Hsieh for giving me the opportunity to conduct this research with his professional guidance. His understanding in the hardships of students traveling aboard is most appreciated. I would also like to thank my thesis committee members, Dr. Andrew D. Clarke and Dr. Gang Yao for their professional advice in my research and thesis. Special recognition is also extended to Harold Huff for his assistance and knowledge in extrusion processes. Thank you to JoAnn Lewis for always having the answers to the questions I have through these two years. Special thanks to my friends, including Atreyee Das, Hsin-Ming Lu, and Yu-Wei Lin, Chia-En Wu for their assistance, encouragement and companionship throughout the master study.
    [Show full text]
  • Role of Extrusion Technology in Food Processing and Its Effect on Nutritional Values G
    International Journal of Modern Science and Technology Vol. 01, Issue 01: April 2016. Page 1-4. http://www.ijmst.co/ ISSN: 2456-0235 Mini Review Article Role of extrusion technology in food processing and its effect on nutritional values G. Baskar*, R. Aiswarya Department of Biotechnology, St. Joseph’s College of Engineering, Chennai – 600 119. India. *Corresponding author: Email id: [email protected] Abstract Extrusion cooking is a multi-functional thermal/mechanical process, which has drawn wide attention in agro-food processing industries. This process has various beneficial effects like destruction of antinutritional factors, gelatinization of starch, increased soluble dietary fiber and reduced lipid oxidation. On the other hand, Maillard reaction also influence in the nutritional value of the food by the interaction between protein and sugars. The raw material and their composition along with the process condition also influence the nutritional value of the food. The extrusion cooking is widely applied for cereal and protein processing such that the mild extrusion condition (low temperature, low residence time and high moisture) improves the nutritional quality of food largely. In case of high extrusion condition such as high temperature <200ºC, low moisture content (<15%) with the presence of high reactive sugars adversely affects the nutritional quality of food. In order to obtain a nutritionally balanced food control of process parameters along with the physico-chemical changes should be monitored properly at timely basis. This review also suggests the recent development in food industries regarding the extrusion technology. Keywords: Extrusion cooking; Maillard reaction; Nutritional value; Temperature. Introduction and significant nutrient retention. This process Proper nutrition involves intake of involves high temperature and short time as food carbohydrates, fats and proteins at an appropriate materials are cooked in a tube by the level for balancing the body with fiber, vitamins, combination of pressure, moisture and minerals and energy.
    [Show full text]
  • Effect of Extrusion Cooking on the Nutritional Properties of Amaranth, Quinoa, Kañiwa and Lupine
    ISSN 0355-1180 UNIVERSITY OF HELSINKI Department of Food and Environmental Sciences EKT Series 1632 Effect of extrusion cooking on the nutritional properties of amaranth, quinoa, kañiwa and lupine Lakshminarasimhan Sundarrajan Helsinki 2014 Tiedekunta/Osasto Fakultet/Sektion – Faculty Laitos/Institution– Department Faculty of Agriculture and Forestry Department of Food and Environmental Sciences Tekijä/Författare – Author Lakshminarasimhan Sundarrajan Työn nimi / Arbetets titel – Title Effect of extrusion cooking on the nutritional properties of amaranth, quinoa, kañiwa and lupine Oppiaine /Läroämne – Subject Food Sciences (Food Bioprocessing) Työn laji/Arbetets art – Level Aika/Datum – Month and year Sivumäärä/ Sidoantal – Number of pages M.Sc. Thesis January 2014 98 Tiivistelmä/Referat – Abstract Amaranth, quinoa, kañiwa and lupine are good sources of protein, fat, dietary fibre and bioactive compounds. The literature review deals with the nutritional properties and the stability of bioactive compounds and the effect of extrusion cooking on amaranth, quinoa, kañiwa and lupine. The main aim of this study was to (1) chemically characterize amaranth, quinoa, kañiwa and lupine, and (2) to determine the effect of extrusion cooking on the nutritional properties and the stability of bioactive compounds. Extrudates were processed using twin screw extruder at two different extrusion temperatures (140 and 160 °C) containing two different contents of tested flour mixtures (20 and 50%). The raw materials and the extrudates were stored at -18 °C and chemically characterized to determine fatty acid composition, tocopherol composition and total phenolic acid content. Fatty acid composition was determined using GC while tocopherol composition was detected using HPLC. The total phenolic acid content was analyzed using Folin-Ciocalteu method.
    [Show full text]
  • Effects of Fiber Content and Extrusion Conditions on Quality of Pasta
    EFFECTS OF FIBER CONTENT AND EXTRUSION CONDITIONS ON QUALITY OF PASTA A THESIS SUBMITTED TO THE GRADUATE SCHOOL OF NATURAL AND APPLIED SCIENCES OF MIDDLE EAST TECHNICAL UNIVERSITY BY SEZIL SOLTA CIVELEK IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN FOOD ENGINEERING SEPTEMBER 2019 Approval of the thesis: EFFECTS OF FIBER CONTENT AND EXTRUSION CONDITIONS ON QUALITY OF PASTA submitted by SEZIL SOLTA CIVELEK in partial fulfillment of the requirements for the degree of Master of Science in Food Engineering Department, Middle East Technical University by, Prof. Dr. Halil Kalıpçılar Dean, Graduate School of Natural and Applied Sciences Prof. Dr. Serpil Şahin Head of Department, Food Engineering Prof. Dr. Serpil Şahin Supervisor, Food Engineering, METU Assoc. Prof. Dr. İlkay Şensoy Co-Supervisor, Food Engineering, METU Examining Committee Members: Prof. Dr. Servet Gülüm Şumnu Food Engineering, METU Prof. Dr. Serpil Şahin Food Engineering, METU Assoc. Prof. Dr. İlkay Şensoy Food Engineering, METU Prof. Dr. Behiç Mert Food Engineering, METU Assoc. Prof. Dr. Özge Şakıyan Demirkol Food Engineering, Ankara University Date: 09.09.2019 I hereby declare that all information in this document has been obtained and presented in accordance with academic rules and ethical conduct. I also declare that, as required by these rules and conduct, I have fully cited and referenced all material and results that are not original to this work. Name, Surname: Sezil Solta Civelek Signature: iv ABSTRACT EFFECTS OF FIBER CONTENT AND EXTRUSION CONDITIONS ON QUALITY OF PASTA Solta Civelek, Sezil Master of Science, Food Engineering Supervisor: Prof. Dr. Serpil Şahin Co-Supervisor: Assoc.
    [Show full text]
  • DEVELOPMENTS in FOOD EXTRUSION Introduction Extrusion
    DEVELOPMENTS IN FOOD EXTRUSION Introduction Extrusion is a process which combines several unit operations including mixing, cooking, kneading, shearing, shaping and forming. Extruders are classified according to the method of operation (cold extruders or extruder-cookers) and the method of construction (single- or twin- screw extruders). The principles of operation are similar in all types: raw materials are fed into the extruder barrel and the screw(s) then convey the food along it. Further down the barrel, smaller flights restrict the volume and increase the resistance to movement of the food. As a result, it fills the barrel and the spaces between the screw flights and becomes compressed. As it moves further along the barrel, the screw kneads the material into a semi-solid, plasticised mass. If the food is heated above 100ºC the process is known as extrusion cooking (or hot extrusion). Here, frictional heat and any additional heating that is used cause the temperature to rise rapidly. The food is then passed to the section of the barrel having the smallest flights, where pressure and shearing is further increased. Finally, it is forced through one or more restricted openings (dies) at the discharge end of the barrel as the food emerges under pressure from the die, it expands to the final shape and cools rapidly as moisture is flashed off as steam. A variety of shapes, including rods, spheres, doughnuts, tubes, strips, squirls or shells can be formed. Typical products include a wide variety of low density, expanded snack foods and ready-to-eat (RTE) puffed cereals. Cold extrusion, in which the temperature of the food remains at ambient is used to mix and shape foods such as pasta and meat products.
    [Show full text]
  • Extrusion-Cooking Modifies Physicochemical and Nutrition
    foods Article Extrusion-Cooking Modifies Physicochemical and Nutrition-Related Properties of Wheat Bran Chiara Roye 1,* , Muriel Henrion 2,Hélène Chanvrier 2, Karlien De Roeck 1, Yamina De Bondt 1 , Inge Liberloo 1, Roberto King 3 and Christophe M. Courtin 1 1 Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition, Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 20, 3001 Leuven, Belgium; [email protected] (K.D.R.); [email protected] (Y.D.B.); [email protected] (I.L.); [email protected] (C.M.C.) 2 Société des Produits Nestlé S.A., Nestlé Research and Development Orbe, Route de Chavornay 3, 1350 Orbe, Switzerland; [email protected] (M.H.); [email protected] (H.C.) 3 Société des Produits Nestlé S.A., Nestlé Research, Vers-chez-les-Blanc, 1026 Lausanne, Switzerland; [email protected] * Correspondence: [email protected]; Tel.: +32-(0)-16-37-42-22 Received: 7 May 2020; Accepted: 28 May 2020; Published: 4 June 2020 Abstract: The potential of extrusion-cooking to change the physicochemical characteristics of wheat bran, increase its nutritional value and decrease its recalcitrance towards fermentation was investigated in this study. The conditions in a twin-screw extruder were varied by changing screw configuration, moisture content and barrel temperature. The former was not previously investigated in studies on bran extrusion. Extrusion-cooking resulted in an increased water-holding capacity and extract viscosity of bran, suggesting shear-induced structure degradation and structure loosening due to steam explosion at the extruder outlet. Modelling showed that the extent of these modifications mainly correlates with the amount of specific mechanical energy (SME) input, which increases with an increasing number of work sections in the screw configuration and a decreasing moisture content and barrel temperature.
    [Show full text]
  • Physical And/Or Chemical Modifications of Starch by Thermoplastic Extrusion
    3 Physical and/or Chemical Modifications of Starch by Thermoplastic Extrusion Maria Teresa Pedrosa Silva Clerici Federal University of Alfenas-UNIFAL-MG Brazil 1. Introduction Starch makes up the nutritive reserves of many plants. Starch biosynthesis is a complex process, which may be summarized as during the growing season, the green leaves collect energy from the sun, this energy is transported as a sugar solution to the starch storage cells, and the sugar is converted into starch in the form of tiny granules occupying most of the cell interior. The conversion of sugar into starch takes place through enzymes (Corn Production Source, 2011; Tester et al., 2006). Starch granules are composed of two types of alpha-glucans, amylose and amylopectin, which represent approximately 98–99% of the dry weight. The ratio of the two polysaccharides varies according to the botanical origin of the starch and classifies starch as the ‘waxy’ starches contain less than 15% amylose, ‘normal’ 20–35% and ‘high’ amylose starches greater than about 40% (Tester et al., 2006; Wurzburg, 1989). Amylopectin is a much larger molecule than amylose with a molecular weight and a heavily branched structure built from about 95% ( 1- 4) and 5% ( 1- 6) linkages. Amylopectin unit chains are relatively short compared to amylose molecules with a broad distribution profile. They are typically, 18–25 units long on average (Tester et al., 2006; Wurzburg, 1989). Nutritionally, starch is consumed as an energy source, and it is the most abundant energy source in the human diet as it is present at high amounts in cereals, roots and tubers, which products range from breads, cookies, pastes to consumption as snacks, porridges, or as processed cooked grains (white rice, corn grain) or whole grains (whole grain of rice, wheat, popcorn, etc.).
    [Show full text]