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Syed S H Rizvi - One of the best experts on this subject based on the ideXlab platform.
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reactive extrusion a review of the physicochemical changes in food systems
Innovative Food Science and Emerging Technologies, 2020Co-Authors: Indvi Arora, Ashto Yoo, Meena Sriram, Poonam Singha, Syed S H RizviAbstract:Abstract In recent years, the functionalization of food-based materials has generated considerable interest as a new route to develop clean label ingredients intended to replace chemically extracted or synthesized counterparts. Extrusion processing offers unique opportunities for functionalizing food ingredients for commercial utility. Extruders can function as a continuously operating bioreactor with options to vary several configurational and operational variables. Many complex structural and chemical changes are known to occur in the form of hydrolysis (Dextrinization), molecular interactions (hydrophobic and disulfide interactions, conjugation), and conformational changes in an extruder. However, understanding of the process variables (temperature, shear, residence time, moisture, feed rate etc.) and their composite effects on the conformational and biochemical changes induced in the feedstock is required to fully exploit the opportunities offered by extrusion for functionalization of food materials. This review focuses on the chemical and conformational changes that can be directed in an extruder to produce extrudates of desired attributes. It also reviews the recent advances made in extrusion technology for the targeted functionalization of selected food materials.
Kanitha Tananuwong - One of the best experts on this subject based on the ideXlab platform.
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in depth study of the changes in properties and molecular structure of cassava starch during resistant dextrin preparation
Food Chemistry, 2019Co-Authors: Kamonrat Trithavisup, Kuakarun Krusong, Kanitha TananuwongAbstract:Abstract Physical, chemical and thermal properties, as well as molecular structure of cassava-based resistant dextrins prepared under different Dextrinization conditions (0.04–0.10% HCl, 100–120 °C, 60–180 min) were determined. Increasing acid concentration, temperature and heating time resulted in the products with darker color, higher solubility, reducing sugar content, total dietary fiber and proportion of high molecular weight fiber fraction. An endothermic peak at 45–70 °C, having enthalpy of 1.66–2.14 J/g, was found from the samples processed under mild conditions (0.04–0.08% HCl, 100 °C, 60 min). However, harsher Dextrinization conditions eliminated this endotherm. Dextrinization led to 1000-fold decrease in weight-average molecular weight (Mw) of the products, comparing to the native starch. Stronger processing conditions yielded the resistant dextrins with slightly higher Mw but composing of shorter branched chains. During Dextrinization, hydrolysis was a predominant step, while transglucosidation and repolymerization played key roles in modifying molecular structure and properties, especially dietary fiber content, of resistant dextrins.
Indvi Arora - One of the best experts on this subject based on the ideXlab platform.
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reactive extrusion a review of the physicochemical changes in food systems
Innovative Food Science and Emerging Technologies, 2020Co-Authors: Indvi Arora, Ashto Yoo, Meena Sriram, Poonam Singha, Syed S H RizviAbstract:Abstract In recent years, the functionalization of food-based materials has generated considerable interest as a new route to develop clean label ingredients intended to replace chemically extracted or synthesized counterparts. Extrusion processing offers unique opportunities for functionalizing food ingredients for commercial utility. Extruders can function as a continuously operating bioreactor with options to vary several configurational and operational variables. Many complex structural and chemical changes are known to occur in the form of hydrolysis (Dextrinization), molecular interactions (hydrophobic and disulfide interactions, conjugation), and conformational changes in an extruder. However, understanding of the process variables (temperature, shear, residence time, moisture, feed rate etc.) and their composite effects on the conformational and biochemical changes induced in the feedstock is required to fully exploit the opportunities offered by extrusion for functionalization of food materials. This review focuses on the chemical and conformational changes that can be directed in an extruder to produce extrudates of desired attributes. It also reviews the recent advances made in extrusion technology for the targeted functionalization of selected food materials.
Yongcheng Shi - One of the best experts on this subject based on the ideXlab platform.
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changes in molecular size and shape of waxy maize starch during Dextrinization
Food Chemistry, 2021Co-Authors: Zhenhua Sun, Ji Kang, Yongcheng ShiAbstract:Abstract The conformational properties of pyrodextrins from waxy maize starch were investigated by high performance size exclusion chromatography with multiple detectors, and the relationships (Mark-Houwink equations) between molecular weights and intrinsic viscosities of pyrodextrins in water were established. Pyrodextrin was prepared by adjusting waxy maize starch to pH 3 or 2, heating at 170 °C or 150 °C. As heating time increased from 0.5 to 4 h, the molecular size was decreased in the order of pH 2 and 150 °C > pH 3 and 170 °C > pH 3 and 150 °C. The measured exponent α values in Mark-Houwink equation indicated that the pyrodextrins prepared at pH 3, 170 °C and 150 °C only had one compact spherical conformation (α 0.27–0.31) during Dextrinization, whereas the pyrodextrins prepared at pH 2 and 150 °C had a mixture of two shapes of molecules: compact sphere (α 0.26) and rigid coil (α 0.89) conformation.
Yoon Kil - One of the best experts on this subject based on the ideXlab platform.
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Efeito da concentração de acido, umidade e temperatura na hidrolise de amido de mandioca por extrusão termoplastica visando a produção de alcool
[s.n.], 2018Co-Authors: Yoon KilAbstract:Orientador : Ahmed A. El-DashTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de AlimentosResumo: Tem-se conhecimento que a produção de álcool a partir de amido de mandioca tornou-se economicamente inviável, devido ao processo requerer um alto consumo de energia e uso de grande quantidade de água e de enzima ?-amilase e amiloglicosidase na etapa de gelatinização, liquefação e sacarificação do amido. Entretanto, a extrusão termoplástica é considerada uma tecnologia que permite a gelatinização e dextrinização de materiais amiláceos a seco com baixo consumo de energia. Portanto, o objetivo do presente trabalho foi estudar o efeito de variáveis de extrusão (umidade de matéria-prima (13,3 - 26,7 %); temperatura de extrusão (93 - 227ºC) e concentração de ácido (0,006 - 0,074 N)) em propriedades fisico-quimicas do amido de mandi oca, além de definir condições de extrusão que permita uma maior produção de álcool com um menor consumo energético. Outras variáveis fixas no processo de extrusão foram a taxa de compressão (1: 3), a velocidade da rosca (100 rpm) o diâmetro da matriz (4 mm) e a taxa de alimentação (65 g/min). Para definir as condições adequadas do processo foi usado a RSM (metodologia de superfície de resposta), avaliando algumas propriedades fisico-quimicas dos produtos extrusados, tais como viscosidade da pasta a frio e a quente, índice de absorção da água, índice de solubilidade em água, teor de açúcar redutor, taxa de expansão e dureza. A modificação da estrutura do amido também foi estudada com o auxilio de difração de raio-x, calorimetria diferencial de varredura (DSC), microscopia eletrônica (SEM) e a distribuição de peso molecular (PM) do amido examinado pela cromatografia liquida de permeação em gel de alta pressão (HPLC). A energia mecânica desenvolvida no processo foi avaliada em função do torque. O efeito da concentração de ácido foi significativo nas propriedades físicas, químicas estudadas, enquanto que a umidade e temperatura de extrusão também contribuíram significativamente, (p ? 0,05) exceto na viscosidade de pasta a quente. O valor de torque foi influenciado significativamente pela umidade e pela temperatura. Sendo que a primeira variável apresentou o maior efeito. De uma maneira geral, o torque diminuiu com aumento destas variáveis. O efeito da concentração de ácido no rendimento em álcool apresentou uma influência altamente significativa (p = 0,023). O rendimento em álcool na presença de ácido alcançou o máximo de 93,4 % (com média de 93,7 %), enquanto que o amido extrusado sem ácido produziu o máximo de 93,4 % (com média de 87,6 %). O amido cozido por método tradicional produziu um rendimento de 92.4%. E o amido cru produziu um rendimento de 41.4 % de álcool, sob as mesmas condições de fermentação. Para determinar as condições de extrusão recomendadas, as áreas das curvas de superfície de resposta que representam a menor viscosidade (dispensa o uso de ?-amilase) e o menor torque (menor consumo energético) foram sobrepostas com acurva de nível de rendimento em álcool. Desta manei r a podemos encontrar as condições operacionais onde o rendimento em álcool é máximo e o consumo de energia e insumos são mínimos. Várias alternativas de condições operacionais de extrusão foram identificadas sendo que a mais favorável foi nível de 24 % de umidade, na faixa de temperatura entre 168 - 214 ºC e 0,062 - 0,074 de concentração de ácidoAbstract: It is well know that the production of alcohol from cassava starch his not economically feasible without a subsidy. This is due to the fact that the process is highly energy consuming because of the wet gelatinization of the starch and the enzime consumption required for liquefaction and saccharification. Thermoplastic extrusion technology, however, permits dry gelatinization and the Dextrinization of starch using a low energy consumption. Therefore, the objective of the present work was to study the effect of certain extrusion variables (moisture content of 14.3-26,7%, temperature of 93-227°C, and acid concentration of 0,006-0074 N) on the gelatinization characteristics of the cassava starch in order to define the extrusion conditions which would permit the highest alcohol yield with the minimum energy consumption. The other extrusion variables were held constant, i.e., screw speed (100rpm), screw compression ratio(3:1), die diameter (4mm), and feeding rate(65g/min). Surface Response Methodology(SRM) was used to evaluate the effect of processing variables on the physical and chemical properties of the extruded starch, i.e, paste viscosity at room temperature and at 95°C, water absorption index and water solubility index, reducing sugar content, degree of expansion, and hardness. Also, the alteration in starch granular structure was studied using x-ray diffraction, differential scanning calorimetry, scanning electron microscopy and determining the product molecular weight distribution by high-performance gel permeation chromatograph(HPLC). The mechanical energy consumed during the process was avaluated as a function of torque. The effect of acid concentration on starch characteristics was highly significant to changes in the extruded starch with the exception of the hot viscosity. Although the torque value was influenced inversely by both moisture content and temperature the effect of the former was greater. The alcohol yield of the extruded starch was influenced significantly(p=0.023) by the concentration of acid. When acid was used, the yield reached 98,7% (average 93,7%), while a failure to use it yielded only 93.4% (average 87.5%). The alcohol yield reached only 93.4% (average 87.5%). The alcohol of starch gelatinized by a conventional method was 92.4%, while that of raw starch was only 41.4%. To define the recommended extrusion conditions to permit the highest alcohol yield at a minimum cost, a graph was made superposing the areas of the RSM curves representing the minimum viscosity (reducing or eliminating the consumption of representing highest alcohol yield. Various alternatives of extrusion operational conditions were established. The recommended conditions were defined as cassava starch extruded at a moisture level of 24%, a temperature of 168-214°C and with an acid concentration of 0.062-0074 NDoutoradoDoutor em Tecnologia de Alimento