Master of Science / Department of Grain Science and Industry / Ekramul Haque / The effect of enzyme in temper water on wheat milling performance and flour quality was studied. Five independent variables, enzyme concentration, incubation time, incubation temperature, tempered wheat moisture content, and tempering water pH, were studied. An enzyme cocktail consisting of cellulase, xylanase, and pectinase was used at 5 different concentrations. A single pure variety of hard red winter wheat was tempered under defined conditions following an RSM central composite design which required 33 tests including 7 replicates. Each treatment had 5 levels: high, medium high, medium, medium low, and low. After tempering, the physical characteristics of the wheat kernel were determined by using the Single Kernel Characterization System. An experimental laboratory mill (Ross Mill) was used to mill wheat into flour. Thirteen streams of flour, and additional streams of bran, shorts, red dog, and germ were obtained. Product yield, protein, ash, and flour color were evaluated. The data were analyzed and compared using the software SAS and RSM Plus. The data showed that incubation time was the only significant factor affecting the tempered wheat hardness (p<0.05). The treatments affected the flour yield from the break rolls more than that from the reduction rolls. However, a maximum point for flour yield was not found. The relationship between treatments and flour yield was established with a prediction model equation. Also, the enzyme effect on the dough properties and bread making were investigated. The treatments did not affect the optimum water absorption for the flours. However, enzyme treated flours showed shorter mixing times. Regardless of the differences in mixing times, the specific loaf volumes were not significantly different for the all treatments. Bread baked from the flour milled from enzyme treated wheat did not show a positive effect on bread staling.

Master of Science / Department of Grain Science and Industry / Finlay I. MacRitchie / Ozone, a triatomic form of oxygen with a Generally Recognized As Safe (GRAS) status from the U. S. Food and Drug Administration, is a strong antimicrobial and sanitizing agent with numerous potential applications in the food industry. One of them is the improvement of wheat flour baking qualities, by replacement of the actual chlorination treatment. Following recent developments realized by the company Goemar (France) which invented and patented an ozone treatment device for wheat grain and a method for making flour from ozone-treated grains, this study aims to determine the effect of ozone treatment on wheat grain and on wheat flour, and to compare them. Three different ozone concentrations with different application times rendering three quantities of absorbed ozone have been investigated. Rheological, physicochemical and baking properties of soft wheat flours stemming from both treatments were evaluated and compared to untreated flour. Results were overall significant and showed that the treatment of flour gives more marked results than the treatment on grain for retention capacity in sucrose and volume of cakes but decreases the [alpha]-amylase activity. On the other hand, action of ozone on grain augments the maximum viscosity of the flour. Bread volume was found to be increased by both treatments in similar proportions. The treatments were also analyzed in particular and showed specific characteristics. A single treatment has not been determined to enhance all characteristics of the flour. Hence, the modification of precise features of the flour has to be related to a specific treatment.

Doctor of Philosophy / Food Science Institute / Finlay I. MacRitchie / Ozonation was studied as an alternative to chlorination for cake flour. Ozone treatment in a wooden tumbler at room temperature was conducted. Unchlorinated flour was treated with ozone at the rate of 0.06 L/min for 10 and 36 min using 5 lb of flour. Ozonation of cake flour decreased pH and increased the lightness (L value) of flour. Baking studies using a high-ratio white layer cake formulation showed that the volume of cakes significantly increased (p< 0.05) as ozonation time increased and cakes were softer than those made with chlorinated or control flours. The cell brightness and number of cells measured by image analysis (C-Cell) of cakes from ozone treated flour for 36 min exhibited similar values to those from chlorinated flour. Cakes made from flours after lipid extraction and after lipid extraction plus ozonation had low volume, indicating that lipids play a role in cake performance. Identification of volatile compounds that contribute to the odor of ozone treated flour was conducted. Volatile compounds of chlorinated, unchlorinated, defatted control, and ozonated defatted flours were analyzed using a purge and trap instrument and GC-MS. Aldehydes, alcohols, hydrocarbons and other compounds were found in unchlorinated and chlorinated flours while the volatile compounds present in ozone treated flours were mainly aldehydes and ketones. A rapid reduction in volatile compounds was detected when ozone treated flours were stored uncovered in a fume hood. Ozonation of defatted soft wheat flour produced less volatile aldehydes than ozone treated whole flour. The optimum temperature and time for ozone treatment in a metal tumbler using a response surface methodology design was studied. Time (5, 15, and 25 min) and temperature (25, 35 and 45 [degrees]C) was used with three response parameters. The optimum ozonation time was about 8 to 11 min with the temperature range between 36 and 46 [degrees]C. Ozone treatment for 5 to 25 min at room temperature showed an increase in unextractable polymeric protein, indicating a shift of protein to a higher molecular weight. Increase in Mixograph peak time, peak viscosity, and water retention capacity were observed as ozonation time increased. The ozone treatment did not affect the transition temperature and enthalpy change of the flour samples.

Pearl millet is a staple food in Namibia. It is milled into flour by traditional and industrial dry milling processes. This research was conducted to help determine how to improve the nutritional value and acceptability of pearl millet. The traditional milling process involves a lactic acid fermentation step which lowers the pH of kernels. The effects of the traditional Namibian and industrial “dry milling” processes on the physical and nutritional composition of pearl millet grain were compared. Additionally, the effect of steeping three different Namibian pearl millet varieties (Kangara, Kantana and Okashana 2) in lactic acid and water on the colour and the phenolic content of the flour were determined. Regarding comparing the milling processes, variety Kangara was conditioned and decorticated traditionally with a pestle and mortar and industrially with an abrasive decorticator. The traditional decorticated grain was steeped and sun dried for 24 h before hammer milling, whereas the industrially decorticated grain was roller milled. Tristimulus colorimetry and proximate analyses were conducted on the samples. Concerning acid steeping, kernels were steeped in a pH 3.5 solution and in water as a control. Colour, total polyphenol and c-glycosyl flavone contents were determined. The determination of cglycosylflavone content was particularly important because these compounds are considered goitrogenic. The traditionally milled flour was lighter in colour than industrial milled flour. However, it was significantly lower in protein, ash and c-glycosyl flavone contents in comparison to industrial milled flour. This was due to the removal of more pericarp and germ in the traditional process. The industrial dry milling process therefore produces flour with a higher nutrient content in terms of protein, fat and minerals. However, the traditional Namibian milling process makes the colour of the pearl millet flour lighter, which is probably the reason that it is more acceptable to consumers. Kernels steeped in a lactic acid solution were lighter in colour than those steeped in water. Irrespective of the steeping media, the total polyphenol content was significantly lower in steeped kernels compared to those unsteeped. A similar trend was observed for the cglycosyl flavone content. This indicates that some of these compounds may have leached out during steeping. For all varieties, kernels steeped in lactic acid had a significantly higher total polyphenol content than those in water, probably due to the dissociation of metal-polyphenol complexes in the acidic medium whereby these polyphenols became free and available for measurement. Thus, steeping in a lactic acid solution can lead to better colour improvement of kernels compared to steeping in water. Thus, lactic acid steeping can improve the sensory quality of pearl millet products. An industrial process can thus be designed to include tempering the grain with food grade lactic acid to produce sour taste and leach out the colour pigments, particularly the cglycosyl flavones hence lightening the colour of the industrial milled flour. This produces a product with high nutritional content, lighter in colour and has the sour taste that consumers find appealing. Copyright 2007, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Barrion, SC 2007, Pearl millet milling : comparison between traditional Namibian fermentation - semi-wet milling and dry milling, MSc(Agric) dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-01282009-132241 / > E1209/gm / Dissertation (MSc(Agric))--University of Pretoria, 2009. / Food Science / unrestricted

Doctor of Philosophy / Department of Grain Science and Industry / Hulya Dogan / Jon M. Faubion / The overall hypothesis underlying this study is that the nature and extent of bran interactions with the gluten protein matrix play a dominant role in both 'in-process' dough and final product quality of whole grain baked goods. Therefore, the purposeful manipulation of those interactions should be able to minimize adverse processing or product characteristics resulting from bran inclusion/presence. The approach we took was to study the effects of bran milled to different particle sizes on dough development during and after dough mixing using fundamental rheology combined with traditional cereal chemistry approaches and x-ray microtomography (XMT). The research outcomes were used to create a better picture of how the bran is effecting the dough development and to suggest strategies that allow for the control of that effect. Study-I focused on characterization of the chemical properties, empirical rheological properties and baking performance of flours and dough with different bran contents from different sources. The development of dough microstructure and the resulting crumb texture in the presence of different bran were studied using XMT. HRW and SW bran additions resulted in higher water absorptions (WA) irrespective of the flour type and bran source. Fine bran caused slightly higher WA followed by coarse and as is bran. Both HRW and SW bran decreased the dough stability of HRW flour, while it improved the stability of SW flour doughs. Macro and microstructure of baked products were significantly affected both bran type and addition level. HRW bran added to HRW flour resulted in 8-23% decrease in loaf volume while SW bran added at the same level caused 3-11% decrease. XMT indicated that bran decreased the total number of air cells significantly. SW flour resulted in harder crumb texture than that of HRW flour breads. Overall, SW bran had less detrimental effects on mixing and baking performance of HRW flour. Study-II focused on specific bran particle size and composition on small and large deformation behavior of strong and weak flour doughs. Small deformation behavior was characterized using frequency and temperature sweep tests, while the large deformation behavior was studied using creep–recovery and uniaxial extensional testing. The results revealed that the rheological behavior of bran-enriched doughs depend on type of base flour, bran type, bran replacement level (0, 5, 10%), and the dough development protocol. Weak flour doughs benefited from inclusion of bran as inherently low peak height and stability of these doughs improved in the presence of bran. Temperature sweeps indicated a slight decrease in Gʹ and G" until around 55-60°C. In the same temperature range, presence of bran increased the moduli of composite four compared to that of the control flours. Creep compliance parameters indicated that both bran source and bran replacement had significant effect on maximum compliance (J[subscript max]) and elastic compliance (J[subscript e]). Finally, the bran type affected uniaxial extensional properties, maximum resistance (R[subscript max]) and elasticity (E), significantly independent from the type of base flour.

Bread flour quality, which is directly related bread quality, varies from time to time. It is therefore almost impossible to obtain bread with consistent quality without determining the flour's suitability for bread-making and the addition of bread improvers. Rheological tests such as the farinograph and the mixograph which are commonly used by bakeries to predict flour quality are empirical in nature which makes fundamental interpretation of the results difficult. The stress relaxation test, a more fundamental rheological test, was used in combination with the mixograph to determine if the stress relaxation test can provide additional information to the mixograph on prediction of the effect of ascorbic acid and DATEM on bread-making quality of three different flour samples. In this test, an optimally developed ball of dough was compressed between parallel plates of a TA-XT2 texture analyser. The 20 g dough was compressed to a load of 1.5 N and thereafter allowed to relax at constant deformation. The relaxation time (RT) was recorded as time taken for the compression force to decay to a force of 0.65 N. Longer RT indicated better flour quality. RT was compared with the mixograph peak time and peak height as predictors of the effect of ascorbic acid and DATEM on bread quality. Test bakes were carried out, and concentrations of ascorbic acid and DATEM were varied as in the stress relaxation test and the mixograph test. At the various stages of the baking process several dough and bread properties were assessed subjectively and scored according to a standardised scoring system. The mixograph was successful in characterising untreated flours in terms of bread-making quality and the stress relaxation test did not provide additional information in this regard. The mixograph was better able to predict the effect of improvers on the stronger Lelie while the stress relaxation test was better at predicting improver effect (especially of DATEM) on the weaker flours, Tiger and Silver Queen. The mixograph predicted the improving effect of DATEM on Tiger and Silver Queen up to a peak, followed by no further improvement. The stress relaxation test predicted improvement beyond the peak, and this continued improvement was observed in the test bake and strong correlation (p<O.05) was found between effect of DATEM on RTs and these important test bake parameters: baking height, loaf volume, drop baking height and the bread score. In addition to information on mixing properties provided by the mixograph, RT seemed to be predicting dough's stability, related to its gas-retaining properties. This stability which can be enhanced by DATEM may be related to both the extensibility of dough's gluten matrix and the stability of the liquid film surrounding the gluten matrix. / Dissertation (MSc (Agric) Food Science and Technology)--University of Pretoria, 2005. / Food Science / unrestricted

The effects of initial particle moisture content, wood-cement ratio and density on physical (thickness swelling and water absorption) and mechanical properties (MOE, MOR, IB and edgewise compression) were investigated. Five initial particle moisture content levels - 0-6%, 8-15%, 25-30%, 40-50% and 60-80%; three wood-cement ratios - 1:1, 1:1.5 and 1:2; and three density levels at each wood-cement ratio - 1:1 -0.472 g/cm³, 0.528 g/cm³ and 0.622 g/cm³, 1:1.5 - 0.636 g/cm³, 0.707 g/cm³ and 0.809 g/cm³; and 1:2 - 0.763 g/cm³, 0.847 g/cm³ and 0.939 g/cm³ were used. Combinations of the above variables gave 45 treatments. Three replicate boards were made for each treatment thus giving a total of 135 panels for the study. A total of 135 test specimens were used for each property tested. Results from the tests were compared to the German and ISO Standards for similar boards and to the Canadian Waferboard Standard. Initial particle moisture content was highly significant in the development of physical and mechanical properties of magnesite cement-bonded particleboard. Increasing initial particle moisture content from 0-6% to 60-80% resulted in the reduction of the physical and mechanical properties of the boards. The highest initial particle moisture content of (60-80%) yielded the lowest physical and mechanical properties. For manufacture of boards of favourable mechanical properties, an initial particle moisture content of not more than 15% is recommended. On the other hand, a higher initial particle moisture content (>40%) is considered desirable if board thickness and water absorption are to be minimized. All the mechanical properties tested consistently increased by increasing wood-cement ratio and density and were highest at 1:2 wood-cement ratio and density level 3 of each wood-cement ratio. Thickness swelling and water absorption were consistently reduced by increasing wood-cement ratio and density. In both physical properties tests, the 1:2 wood-cement ratio and density level 3 yielded the lowest values. Thirty-two of the forty-five treatment combinations of initial particle moisture content, density and wood-cement ratio pass the MOE requirement of the German Standard DIN 52 362 for Portland cement-bonded particleboard; forty-one treatments met the minimum MOE Canadian Waferboard Standard requirements, while no treatment meet the MOR requirements for this Standard. Eleven of the forty-five treatments met the minimum IB Canadian Waferboard Standard requirements. All the 45 treatments pass the ISO building board requirements in thickness swelling, while 18 treatments pass the water absorption requirements for this Standard. Most of the treatment combinations compare favourably with results obtained in tests conducted in Europe for cement-bonded particleboard. / Forestry, Faculty of / Graduate

Orientadores: Florencia Cecilia Menegalli, Delia Rita Tapia Blacido / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-14T13:43:25Z (GMT). No. of bitstreams: 1 AndradeMahecha_MargaritaMaria_M.pdf: 13503554 bytes, checksum: 744c46669728d982aa8ab0cda3d79f8a (MD5) Previous issue date: 2009 / Resumo: O interesse em filmes biodegradavéis éuma tendência mundial que tem aumentado de modo significativo nos ?timos anos motivando assim, estudos relacionados com o desenvolvimento e caracterização de filmes a base de macromoléculas naturais. O objetivo deste trabalho foi elaborar biofilmes a partir de farinha de biri (Canna indica L.) e avaliar o efeito de quatro variaveis de processo: concentração de glicerol (15 ¿ 35%), temperatura de processo (70 ¿90 °C), temperatura de secagem (35 ¿ 55 °C) e umidade relativa de secagem (30 ¿ 70%) sobre as propriedades mecânicas (força, deformação, tensão, elongação e módulo secante), ópticas (cor, brilho e opacidade) e a solubilidade em água dos biofilmes. Na primeira etapa do trabalho, foram obtidos farinha e amido a partir de rizomas de biri cultivados no estado de São Paulo (Brasil). Estes materiais foram caracterizados quanto à composição centesimal, propriedades físicas e térmicas, análiise de microestrutura por microscopía eletrica de varredura (MEV), distribuição de tamanho dos grânulos de amido e análise estrutural por espectroscopia de absorção no infravermelho (FTIR). Numa segunda etapa, filmes a partir de farinha de biri foram elaborados segundo um Delineamento Composto Central Rotacional 24 (DCCR). Os resultados obtidos foram analisados estatisticamente empregando a metodologia de superfície de resposta (RSM) que juntamente com a função de desejabilidade (D) permitiu a obtenção das condiçoes de processo ótimas (concentração de glicerol de 17%, temperatura de processo de 90 °C, temperatura de secagem de 44,8 °C e umidade relativa de 36,4%). Nas condições ótimas os biofilmes apresentaram altos valores de resistência mecânica (7,0 MPa), baixa solubilidade (38,3%) e valores de elongação satisfatórios (14,6%). Na útima etapa do trabalho, foram elaborados biofilmes de farinha e de amido de biri para determinar o efeito das fibras, proteínas e lipídios sobre as propriedades dos filmes de farinha. Os biofilmes foram caracterizados com base em suas propriedades mecânicas, ópticas, microestrutura e analise estrutural por MEV e FTIR. Os biofilmes de farinha apresentaram maior flexibilidade em termos de elonga?o (14,6%), maior permeabilidade ao vapor de ?ua (5,3 ?0,2 x 10 ¿10 g.m/m2.h.Pa) e menor resistência mecânica e rigidez (7,0 N e 231,7 MPa) quando comparados com os biofilmes de amido de biri (1,4%; 18,6 N; 1772 MPa e 3,2 ± 0,01 x 10 -10 g.m/m2.h.Pa, respectivamente). A partir das análiises MEV, observouse que os biofilmes de farinha apresentaram imperfeições na sua superfície e uma seção transversal menos densa e com pequenas fissuras quando comparados com os biofilmes de amido. Os espectros de FTIR evidenciaram a presença De grupos OH, CH2 e amida III em ambos os biofilmes enquanto que o grupo amida I só foi evidenciado nos filmes de farinha. Em relação às propriedades ópticas, os filmes de farinha apresentaram cor amarelada enquanto que os filmes de amido apresentaram-se mais claros e menos opacos / Abstract: The focus in biodegradable films is a global trend and has received a significant attention in recent years, thus motivating studies related to the development and characterization of films based on natural macromolecules. The objective of this study is to develop edible films from biri flour (Canna indica L.) and evaluate the effect of four process variables: glycerol concentration (15 - 35%), process temperature (70 - 90 °C), drying temperature (35 ¿ 55 °C) and drying air relative humidity (30 ¿ 70%), on both mechanical (puncture force, deformation, tensile strength, elongation at break and secant modulus), and optical (color, brightness and opacity ) properties, as well as on water solubility of films. In the first stage of this work, flour and starch were obtained from rhizomes of biri cultivated in the S? Paulo State (Brazil). The evaluation of such materials dealt with proximate chemical composition, physical and thermal properties, microstructural analysis by Scanning Electron Microscopy (SEM), size distribution of starch granules and structural analysis by Fourier Transform Infrared (FTIR) spectroscopy. On the second stage, edible films from the biri flour were prepared according to a Central Composite Rotational Design 24 (CCRD). The results were statistically analyzed using the response surface methodology (RSM), which along with the desirability function (D) allowed to obtain the optimum process conditions (17% for glycerol concentration, 90 °C for process temperature, 44,8 °C for drying temperature and 36,4% for air drying relative humidity). In optimum conditions the films showed high values of tensile strength (7,0 MPa), low solubility (38,3%) and satisfactory values of elongation at break (14,6%). On the last stage of this work, the films were prepared from flour and starch biri in order to determine the effect of fiber, protein and fat on the properties of the flour biofilms. The films were characterized based on their mechanical and optical properties, microstructure and structural analysis by means of SEM and FTIR. The results showed that flour films have greater flexibility in terms of elongation at break (14,6%), high water vapor permeability (5,3 ?0,2 x 10 -10 g.m/m2.h.Pa) and lower tensile strength and secant modulus (7,0 N and 231,7 MPa) when compared with the starch films (1,4%; 18,6 N; 1772 MPa and 3,2 ?0,01 x 10 -10 g.m/m2.h.Pa respectively). From SEM analysis it was observed that the flour films have flaws in its surface and a cross section less dense, with small cracks compared with the starch films. FTIR spectra showed presence of OH groups, CH2 and amide III in both films, while the amide group I was only observed in flour film. Optical properties showed that the flour films were yellowish while the starch films were clearer and less opaque / Mestrado / Mestre em Engenharia de Alimentos

Orientador : Cesar Francisco Ciacco / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos e Agricola / Made available in DSpace on 2018-07-15T18:25:15Z (GMT). No. of bitstreams: 1 SalcesRuiz_Franz_M.pdf: 5204043 bytes, checksum: c560e5f4711d26bd722e4936f7d60b23 (MD5) Previous issue date: 1984 / Resumo: A desidratação. da batata doce após a colheita ou determinado período de armazenamento tem sido preconizada como uma al tentativa tecnológica para o melhor aproveitamento deste tubérculo. Este trabalho teve como objetivo estudar o processo de desidratação de batata doce usando rolos secadores (Drum-Dryer). O efeito dos parâmetros operacionais nas propriedades tecnologia dos flocos foi investigado com auxilio da Metodologia de Resposta de Superfícies (Response Surface Methodology - RSM). As análises de variança mostraram um ajuste altamente significativo pa-ra a maioria dos modelos matemáticos que relacionaram o efeito dos parâmetros operacionais e as propriedades tecnológicas dos flocos. O teste indicou que os modelos para o rendimento, porcentagem de retenção de vitamina C, porcentagem de carotenóides, viscosidade inicial e o Índice de solubilidade em água foram altamente significativos, ao nível de 0,01%. Os modelos para cor, viscosidade máxima e viscosidade a 509C e o índice de absorção em água foram significantes ao nível de 0,14, 0,26, 0,90 e 15,00%, respectivamente. Estes resultados mostraram que o Índice de absorção em água não variou significativamente em função das variáveis experimentais. A representação gráfica dos modelos matemáticos, como respostas de superfície (curvas de nível), permitiu estudar como as variáveis independentes (parâmetros operacionais) afetaram as 1fespostas (características tecnológicas). O rendimento foi afetado principalmente pela abertura entre os rolos e a concentração de sólidos, sendo pouco afetado pela pressão. de vapor, O rendimento máximo foi obtido para concentrações entre 16 e 20% de sólidos e aberturas em to~no de 0.30mm, em uma grande faixa de pressão. de vapor. A porcentagem de retenção de vitamina C e carotenó1des foi afetada, principalmente, pela pressão de vapor e a concentra ção de sólidos no purê, A maior retenção de vitamina C (81%) e corotenóides '(98%), ocorreu para pressões de cerca de 80lb/po12, entre 15-17% de concentração de sólidos e aberturas entre 0,10 e O,20mm. As curvas de nível mostraram que a viscosidade inicial e a viscosidade máxima foram controladas, essencialmente, pela abertura entre os rolos. A pequena influência da pressão de vapor nestas duas variáveis indicou que mesmo as pressões mais baixas testadas (40 lb/pol ) foram suficientes para uma extensiva gelatinização do amido. O efeito das variáveis operacionais sobre a viscosidade a 509C foram semelhantes aos observados para a viscosidade máxima. A pressão e abertura entre os rolos foram as variáveis de maior influência no índice de absorção de água. As curvas de nível mostraram a existência de um efeito de compensação entre a temperatura dos rolos e a espessura do filme. Filmes finos provocaram uma gelatinização mais efetiva do amido que aquelas obtidas com filmes mais espessos. Conseqüentemente a absorção de água dos produtos obtidos co~ pequenas aberturas foi superior àquelas obtidas com aberturas maiores, nas mesmas condições de pressão de va-por. As curvas de nível do índice de solubilidade em água mostraram um comportamento oposto ao apresentado pelas curvas do índice de absorção em água. Os máximos valores do índice de solu-bilidade em água, foram obtidos a altas pressões entre 65-76 lb/po12l, concentrações intermediárias (entre 18 a 23%) e aberturas pequenas menores que O,20mm), Provavelmente, o aumento do índice de solubilidade em água foi devido à desintegração dos grânulos de amido, que solubilizando diminuíram o índice de absorção em água. O maior efeito no índice .de solubilidade em água foi devido a abertura entre os rolos. O maior efeito sobre a cor foi devido a variações na abertura. Aumentos na abertura até cerca de O,30rnrn, em uma ampla faixa de pressão de vapor e concentrações de sólidos, resultaram em alto DE. Estes resultados em conjunção com aqueles de retenção de carotenóides indicaram que não existe uma relação entre a cor observada e o conteúdo deste composto. Estudos com batata doce armazenadas a 209C e 90% de umidade relativa mostraram que o tempo de armazenamento, até 5 se-manas, teve uma influência positiva na cor e rendimento dos flocos. Estes resultados .foram provavelmente devido ao aumento na concentração de sólidos solúveis totais durante este período de armazenamento / Abstract: Dehydration of sweet potato after harverst or storage was recommended as a technoloical alternative for the better exploitition of this tuber. The objetive of this project was to study the dehydra-tion process of sweet potato with a double Drum-Dryer. The Res-ponse Surface Methodology was used to study the re1ation between.the process parameters (roll temperature, roll spacing and total solids content in the puree)and some technological properties of the flakes obtained. The analyses of variance indicated that the mathemat1ca1 models expressing the relation between the processing .parameters and the techno10gica1 propert1es were we adjusted. The F va1ue 1ndicated that the mathematica1 models for yie1d, as-corbic acid and caroten01d retentions, initlal v1scosity and water solubility index were s1gn1ficant at the 0.01% level. The models for color, maximum vlscosity, viscosity at S09C and water absorp- tion index were sign1ficant at the 0.14, 0.26, 0.90 and 15.00% 1eve1s, respective1y. These resu1ts showed that the model for water absorption index was not significant1y affected operational parameters. The effect of the operat10na1 parameters on the techno10- by the g1ca1 properties, of the f1akes was a1so studied by .contour plóts. The yie1d was ma1n1y affected by the spac1ng between the rolls and total sol1ds concentrat10n. The steam pressure d1d not have a significant effect on the yie1d. The maximum y1e1d was obtained at 16 to 20% of the total 801ids concentrat10n and around 0.30mm ro11 spacing. The ascorbic acid and carotenoid retentions were ma1n1y affected by the steam pressure and total so11ds concentrat10n of the puree, The maximum ascorbic actd (Bl%) and carotenoid (98%) retentions were obtained at about 80 psig, 15-17% solids concentra tion.and roll spacings between 0,10 and 0.2G mm. The contours plots showed that the inicial viscosity and maximum viscosity were affected essentially by the roll spacing. The small influence of steam pressure on the initial viscosity in dicated that even the low stearn pressure used led to extensive starch gelatinization. The effect of the processing pararneters on the viscosity at 509C was similar to that observed with the maximum viscosity, The pressure and the roll spacing were the variables that influenced the water absorption index. The contour plots showed a compensation effect between the surface temperature and film thickness. Thin films caused more effective starch gelatinization than thick ones, at the sarne roll surface temperature, Consequen-tly the water absorption of the products obtained with the smallest spacing was higher than that obtained with a larger roll spacing. On the other hand the maximum water solubility index values were obtainàd with a higher steam pressure (ranging from 60 tô 80 psig), total solids concentration from 17 to 23% and a rollcing below 0.20 mm, Flakes with high DE were obtained at 0.30 mm roll spacing spa- whith wide ranges of steam pressures and total solids concentra-tions, The storage of sweet potatoes at 209C and 90% relative humidity showed that storage up to 5 weeks had remarkable effects on the color and yield. These results were probably due to the increase in the soluble solids content .during the storage period / Mestrado / Mestre em Tecnologia de Alimentos

Orientador : Ahmed A. El-Dash / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos e Agricola / Made available in DSpace on 2018-07-17T12:40:24Z (GMT). No. of bitstreams: 1 Vilela_EvodioRibeiro_D.pdf: 7890313 bytes, checksum: 81fb45f3c3d3129430775794930c5abc (MD5) Previous issue date: 1983 / Resumo: Grãos de guandu (Cajanus Cajan, Millsp.), variedade Kaki, foram inicialmente caracterizados fisicamente com relação à suas dimensões, distribuição por tamanhos empeneiras e dessecados afim de verificar a proporção de cotilédones, casca e embrião. Foram determinados na farinha integral, casca e cotilédones os teores de proteína, lipídeos, cinzas, fibra, amido e minerais. O grão de guandu estudado possui 87,1% de cotilédones, 12,1% de casca e 0,6% de embrião. Os cotilédones apresentaram um processo de produção de farinha foi desenvolvido utilizando um moinho de rolos. Os grãos, inicialmente com 13% de umidade, foram condicionados com umidades variando até 16% e tempos de 15 até 120 minutos, afim de facilitar a separação da casca por peneiragem. Antes da passagem no moinho de rolos os graos foram quebrados em moinho de disco e a casca separada por ventilação. As farinhas e subprodutos da moagem foram analisados quanto à sua composição química. Determinou-se também nas farinhas o teor de amido danificado. Dois tipos de farinhas foram obtidos, uma farinha de quebra com 15,76% de proteína e 46,78% de amido e uma farinha de redução com 24,11% de proteína e 38,22% de amido. O amido de guandu foi isolado da farinha e foram desenvolvidos a milogramas para ambos, em várias concentrações. O apresentaram maiores teores de proteína, gordura e amido do que na casca. À exceção do fósforo, todos os minerais tiveram teores maiores na casca do que nos cotilédones. O amido foi caracterizado também pelo inchamento e solubilidade em várias temperaturas. Tanto o amido como a farinha apresentaram uma viscosidade sempre crescente com o aquecimento e agitação, e valores baixos de inchamento e solubilidade (ambos em torno de 20), características de grânulos de alta resistência. A farinha de guandu foi extrudada com teores de umidade inicial de 20, 22, 24 e 26i, temperaturas de 160, 180 e 2000C e taxas de compressão da rosca de 2:1, 3:1 e 4:1. As seguintes características foram avaliadas em ambos experimentos: o teor que durante o processamento, produção de extrudados, teor de umidade após a extrusão, densidade, dureza e absorção de dos produtos extrudados, solubilidade da proteína, índice de solubilidade e viscosidade das farinhas extrudadas. O efeito conjugado das variáveis temperatura e taxa de compressão da rosca foi analisado através de superfícies respostas utilizando um modelo de regressão de 2ª ordem. O teor de umidade inicial da farinha, nas condições pesquisadas, não afetou as características dos produtos. Os extrudados apresentaram uma superfície rugosa e uma estrutura interna aberta bastante porosa. A temperatura foi a variável que mais afetou as características como umidade após a extrusão, densidade, dureza e proteína solúvel. O teor que durante o processamento, a expansão das amostras, a absorção de água, e as viscosidades a 25, 95 e 500C das farinhas extrudadas, tiveram, entretanto, suas variações influenciadas também pela taxa de compressão / Abstract: Grains of pigeon pea (Cajanus cajan, Mill.) Variety Kaki, was initially characterized physically with respect to its size, distribution of sizes empeneiras and dried in order to verify the proportion of cotyledons, bark and embryo. Were determined in wholemeal, bark and cotyledons the levels of protein, fat, ash, fiber, starch and minerals. The grain of pigeonpea has studied cotyledons of 87.1%, 12.1% and 0.6% from the bark of embryo. The cotyledons showed a production process was developed using a flour mill rolls. The grains, initially with 13% moisture, were conditioned with humidity ranging up to 16% and up to 120 times of 15 minutes in order to facilitate the separation of the shell by peneiragem. Before the passage of the mill rolls the grains were broken in the disk mill and shell separated by ventilation. And by-products of flour milling were analyzed for their chemical composition. It was also in the content of starch flour damaged. Two types of flour were obtained, a meal break with 15.76% and 46.78% of protein and starch of a meal reduction with 24.11% and 38.22% of protein from starch. The starch was isolated from pea flour and have been developed for both the milogramas in various concentrations. The show higher levels of protein, fat and starch than in the shell. With the exception of phosphorus, all mineral levels were higher in bark than in cotyledons. The starch was also characterized by swelling and solubility in various temperatures. Both the starch such as flour had an ever increasing viscosity with heat and agitation, and low values of swelling and solubility (both around 20), characteristics of granules of high resistance. The pigeon pea flour was extruded with levels of water content of 20, 22, 24 and 26i, temperatures of 160, 180 and 2000C and rates of compression screw of 2:1, 3:1 and 4:1. The following were evaluated in both experiments: the content that during processing, production of extruded, moisture content after extrusion, density, hardness and absorption of the extruded products, solubility of the protein, index of solubility and viscosity of extruded flour. The combined effect of varying temperature and rate of compression screw was analyzed by using a surface answer the regression model of 2nd order. The initial moisture content of flour under the conditions studied, did not affect the characteristics of the products. The extruded had a surface rugosa and a very open porous internal structure. The temperature was the variable that most affected the characteristics as humidity after extrusion, density, hardness and soluble protein. The content that during processing, the expansion of the samples, the water absorption, and the viscosities of 25, 95 and 500C of extruded flour, have, however, its variations also influenced by the rate of compression / Doutorado / Ciência de Alimentos / Doutor em Ciência de Alimentos