Orientador : Yong Kun Park / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T01:01:25Z (GMT). No. of bitstreams: 1 Lui_MariaCristinaYoun_M.pdf: 779941 bytes, checksum: aa1237e20c91ff048441111b62275d6b (MD5) Previous issue date: 2004 / Mestrado / Mestre em Ciência de Alimentos

Embora a soja em grão seja pouco consumida pela população brasileira, seus derivados protéicos são utilizados como ingredientes em diversos alimentos e a tendência é um aumento significativo do seu uso com a aprovação pela FDA e pela ANVISA da alegação funcional referente ao consumo de proteína de soja. Em paralelo, um número crescente de pesquisas sobre as isoflavonas, fitoestrógenos presentes em quantidades significativas na soja, vem demonstrando diversos efeitos benéficos destes compostos, entre os quais a sua ação antioxidante, anticarcinogênica e hipocolesterolêmica. O objetivo foi estudar as interações entre isoflavonas e proteínas da soja, seu efeito na biodisponibilidade in vitro e in vivo e o status antioxidante das isoflavonas. Os resultados sugerem que a presença da proteína reduz a quantidade e leva a um retardo no tempo de absorção das isoflavonas em relação à administração na forma livre. O efeito sobre a capacidade antioxidante do plasma e sobre a atividade e expressão gênica das enzimas CAT, GPx e SOD divergiu para a suplementação de isoflavonas ou proteínas separadamente ou em associação. / Although soybeans are not commonly consumed by the Brazilian population, soybean products are used as ingredients by the food industry and there is an increased trend in their consumption due to the approval of FDA and ANVISA on the claim regarding the health benefits of soy proteins. Therefore, many studies involving isoflavones, the phytoestrogens found in significant quantities in soybeans, have demonstrated several health benefits of these compounds, such as antioxidant capacity, and anticarcinogenic and hypocholesterolemic effects. The objective of the present study was to evaluate the interaction between isoflavones and soy proteins as well as the effect of this interaction on the in vitro and in vivo bioavailability of isoflavones and on the antioxidant status. The results indicated that the association with protein decreased the rate and proportion of absorption of isoflavones when compared to the free form. The effect of isoflavones on the plasma antioxidant capacity and on the enzymatic activity and gene expression levels of CAT, GPx and SOD was different when isoflavones were combined with soy protein compared to isoflavones alone.

<p>Detection of pathogens, toxins, hazardous chemicals, and allergens in the food industry with reliable, sensitive, efficient, and rapid results has increased the demand to develop innovative diagnostic tools. Surface-enhanced Raman spectroscopy (SERS) sensors have demonstrated to detect a wide variety of analytes using nanomaterials like metal nanoparticles. Concerns of synthetic materials that can affect the environment with disposal of sensors have opened the possibility of fabricating SERS sensors with biodegradable materials. Fabrication of electrospun nanofibers from natural polymeric materials such as soy protein isolate can be used as a SERS platform. In the first part of this research, the characteristics of SPI solutions blended with NaOH and polyethylene oxide (PEO) such as PEO Mw, zeta potential and viscosity as well operating parameters such as voltage (15, 20, and 27 kV) were studied to evaluate the best solutions for a nanofibrous SERS platform. Characteristics of electrospun nanofibers, such as surface wettability, fiber diameters, and morphology using SEM, helped determine the most feasible fibers for decoration with noble metal nanoparticles. Fibers fabricated with 12 wt% SPI + 5 wt% PEO (0.1 MDa) + 1 wt% NaOH solution showed the smallest fiber diameter and highest water contact angle measurements. Glutaraldehyde (GLA) was added as a crosslinker to partly increase nanofibers hydrophobicity. These nanofibers were decorated with Au-nanostars and Au@Ag-NPs suspended in 90% butanol and in water. Partly hydrophobic nanofibers decorated with Au-nanostars and Au@Ag-NPs in butanol showed the most feasible results for a SERS platform due to smallest fiber diameter and higher water contact angle. In the second part of this research, decorated SPI nanofibers were evaluated to study its feasibility as a SERS platform for detecting bisphenol A (BPA), a toxic chemical present in food packaging materials. However, SERS spectra were difficult to obtain due to CCD overflow (excessive number of photons) at all laser powers on SPI nanofiber mats. Optimizing other Raman spectroscopy parameters such as the exposure time and the number of averages could enhance the SERS measurements. The fabricated SPI nanofibers in this research showed that hydrophilic and partly hydrophobic nanofibers mats could be used for decoration with metal nanoparticles by suspending the nanoparticles in a hydrophobic solvent. Hydrophilic nanofiber mats with nanoparticles in a hydrophobic solvent open a new strategy for developing another type of SERS platform.</p>

No description available.

The Haida language, Xaad Kil is dangerously close to extinction and in need of heroic action. The purpose of this study is to find out what ancient traditions and beliefs we could incorporate into our language revitalization efforts. Drawing on archival literature and community knowledge, I found almost 100 traditional ways to support Xaad Kil revitalization. There are four main chapters: Haida foods, Haida medicines, Haida rituals and ceremonies and Haida supernatural beings that could contribute to Xaad Kil revitalization. The food chapter features two-dozen traditional foods from salmon to berries that support a healthy lifestyle for Haida language speakers and that could strengthen our connections to the supernatural world. The Haida medicine chapter features two dozen traditional medicines from single-delight to salt water that could heal, strengthen and purify the Haida language learner. The ritual and ceremony chapter features over two-dozen rituals from devil’s club rituals to labret piercing ceremonies that could strengthen Haidas and our language learning. The supernatural being chapter features twenty-three supernatural beings including Greatest Crab and Lady Luck that could bring a language learner wealth, knowledge, luck and strength. This study suggests that a Xaad kil learner and the Xaad kil language need to be pure, protected, connected, lucky, strong, healthy, respected, loved and wise. The path to these qualities is within the traditions and beliefs featured in this research. This study is significant because it shows that the language revitalization answers are within and all around us. / Graduate / 0290 / 0326 / lucybell@uvic.ca

Os isolados protéicos de soja são utilizados como ingredientes em diversos alimentos e sua utilização vêm aumentando juntamente com o aumento das pesquisas sobre os metabólitos secundários da soja, as isoflavonas. Alguns efeitos benéficos vem sendo associados às isoflavonas, entre estes a sua ação antioxidante, a redução ao risco de câncer, doenças cardiovasculares e osteoporose. O objetivo deste estudo foi o de otimizar as condições de extração das isoflavonas e de suas formas conjugadas a partir da farinha desengordurada de soja, visando o preparo de isolado protéico de soja. Os resultados mostraram que a obtenção de isolados protéicos de soja com teor aumentado de isoflavonas depende da utilização de condições brandas de centrifugação para a separação do precipitado isoelétrico, assim como da utilização de água acidificada na sua lavagem. A presença de isoflavonas no isolado resulta de três fatores, o primeiro referindo-se à associação entre isoflavonas e proteínas através de interações hidrofóbicas, eletrostáticas, e pontes de hidrogênio; o segundo à menor solubilidade das isoflavonas presentes na farinha desengordurada de soja no pH isoelétrico; e o último ao processo de carreamento (físico) das isoflavonas pelas proteínas insolubilizadas. / Soy protein isolates are used as ingredients in several food products and their use is increasing together with the increase of the researches on the secondary metabolites of soy, the isoflavones. Some beneficial effects have been associated to the isoflavones, among these their antioxidant action, prevention of cancer, cardiovascular diseases and osteoporosis. The objective of this study was to optimize the extraction conditions of the isoflavones from the defatted soy flour, seeking the preparation of soy protein isolates. The results showed that the obtention of soy protein isolates with increased content of isoflavones depends on the use of mild conditions of centrifugation for the separation of the isoelectric precipitate, as well as on the use of water acidified in the washing step. The presence of isoflavones in the isolates resulted from three factors, the first refers to the association between isoflavones and proteins through hydrophobic; and electrostatic interactions, and hydrogen bonding; the second to the decreased solubility of the isoflavones extracted from the defatted soy flour in the isoelectric pH; and the last to the carrying process (physical) of isoflavones by the precipitating proteins.

<p>Болести представљају један од најважнијих фактора који утичe на успешност производње сунцокрета. Црна пегавост стабла сунцокрета, коју проузрокује патогена гљива Phoma macdonaldii, представља болест која у појединим регионима распрострањења значајно смањује принос и квалитет сунцокрета. Ранија истраживања спроведена у агроеколошким условима Србије су идентификовала ову болест као широко распрострањену. Истовремено је утврђено да знатан број генотипова сунцокрета био осетљив.<br />Циљ рада је био да се установи степен отпорности инбред линија и хибрида према овој болести као и постојање извора отпорности код популација врста из рода Helianthus. Вишегодишње праћење болести на више локалитета и на већем броју хибрида за циљ је имало одређивање утицаја генотипа и спољашње средине на појаву и развој болести. Тестирана је могућност кориштења ергостерола као индикатора постојања отпорности. Праћењем концентрације фенолних једињења тестирана је реакција домаћина на присуство патогена са акцентом на период непосредно након инокулације. Други део истраживања је био фокусиран на патогена са циљем утврђивања варијабилности популације кориштењем различитих метода. Утврђена је агресивност изолата и генетска варијабилност патогена помоћу RAPD маркера. Постојање варијабилности је проверено и помоћу одгајивачких особина.<br />Тестирањем генотипова сунцокрета, применом метода вештачке инокулације у току четворогодишњег периода, утврђено је постојање статистички значајних разлика између генотипова. Од седамдесет инбред линија отпорност на највећем броју локалитета где је вршено тестирање испољиле су линије DOP-32-08, Ph-BC1-162, Ph-BC1-53, IMI-AB-12, CMS-3-8, BT-VL-2, DOP-33-08, BT-VL-24 и OD-DI-98. Реакција хибрида је варирала у односу на годину тестирања. Највећи степен отпорности су испољили хибриди Баћа и НС Брилијант. Смањење у напредовању болести у години са израженим дефицитом у падавинама је забележено код линија гајених у условима сувог ратарења. Тестирањем 181 популације 9 једногодишњих врста рода Helianthus у условима природне инфекције, утврђене су популације код свих одабраних врста код којих болест није била присутна. Утврђивањем количине ергостерола у оквиру симптома болести код биљака инбред линија у контролисаним условима утврђено је повећање количина овог једињења код осетљиве инбред линије у поређењу са линијама са одређеним степеном отпорности. Резултатима гајења 16 хибрида на већем броју локалитета у току четири године, установљено је постојање значајног утицаја средине и генотипа на појаву и интензитет<br />болести. Највећу отпорност у природним условима су испољили хибриди Баћа, НС-Х-111 и НС Фантазија. Гајењем биљака у условима различитог времена сетве, појава и интензитет црне пегавости стабла су имали тенденцију опадања са каснијом сетвом. Примена само азотних ђубрива највише је допринела порасту појаве и интензитета болести, а исти параметри су били највећи код најмање густине гајења биљака. Анализом фенолних једињења у ткиву листа, у одређеним временским интервалима, након вештачке инокулације биљака инбред линија са различитим степеном осетљивости, утврђен је повећан садржај хлорогене киселине у току прва 24 сата код узорака листа отпорне линије. Четири линије различитог степена осетљивости су инокулисане у контролисаним условима са различитим изолатима патогена. Установљено је постојање варијабилности у погледу агресивности, док су 4 четири од укупно 56 тестираних изолата испољили висок степен агресивности. Груписање изолата сличног степена агресивности према географском пореклу није установљено. Анализом генетске варијабилности помоћу RAPD маркера утврђен је висок степен полиморфизма код употребљених изолата. Од употребљених прајмера највећу информативност је имао прајмер OPE-04. Висок степен варијабилности је потврђен кластер анализом. AMOVA анализом утврђено је да се генетска варијабилност изолата гљиве односи највећим делом на варијабилност између изолата. Генетска варијабилност између изолата груписаних по регионима и агресивности је била занемарљива.<br />Слични обрасци су запажени и након утвђивања одгајивачких особина &bdquo;in vitro&ldquo;. Најбољи раст и продукција пикнида је забележена на подлози од овса. Између изолата су забележене значајне разлике у пречнику колонија и продукцији пикнида, али те разлике нису биле повезане са географским пореклом изолата.<br />Црна пегавост сунцокрета у Србији je сталан пратилац сунцокрета. Интензит болести је значајно условљен степеном отпорности генотипова сунцокрета, агресивношћу изолата и временским условима. Патоген испољава велик степен генетске варијабилности што га чини прилагодљивим за измене у генетској структури домаћина и средини. Однос сунцокрет-Phoma macdonaldii представља динамичан систем који захтева наставак истраживања уз мониториг.</p> / <p>Bolesti predstavljaju jedan od najvažnijih faktora koji utiče na uspešnost proizvodnje suncokreta. Crna pegavost stabla suncokreta, koju prouzrokuje patogena gljiva Phoma macdonaldii, predstavlja bolest koja u pojedinim regionima rasprostranjenja značajno smanjuje prinos i kvalitet suncokreta. Ranija istraživanja sprovedena u agroekološkim uslovima Srbije su identifikovala ovu bolest kao široko rasprostranjenu. Istovremeno je utvrđeno da znatan broj genotipova suncokreta bio osetljiv.<br />Cilj rada je bio da se ustanovi stepen otpornosti inbred linija i hibrida prema ovoj bolesti kao i postojanje izvora otpornosti kod populacija vrsta iz roda Helianthus. Višegodišnje praćenje bolesti na više lokaliteta i na većem broju hibrida za cilj je imalo određivanje uticaja genotipa i spoljašnje sredine na pojavu i razvoj bolesti. Testirana je mogućnost korištenja ergosterola kao indikatora postojanja otpornosti. Praćenjem koncentracije fenolnih jedinjenja testirana je reakcija domaćina na prisustvo patogena sa akcentom na period neposredno nakon inokulacije. Drugi deo istraživanja je bio fokusiran na patogena sa ciljem utvrđivanja varijabilnosti populacije korištenjem različitih metoda. Utvrđena je agresivnost izolata i genetska varijabilnost patogena pomoću RAPD markera. Postojanje varijabilnosti je provereno i pomoću odgajivačkih osobina.<br />Testiranjem genotipova suncokreta, primenom metoda veštačke inokulacije u toku četvorogodišnjeg perioda, utvrđeno je postojanje statistički značajnih razlika između genotipova. Od sedamdeset inbred linija otpornost na najvećem broju lokaliteta gde je vršeno testiranje ispoljile su linije DOP-32-08, Ph-BC1-162, Ph-BC1-53, IMI-AB-12, CMS-3-8, BT-VL-2, DOP-33-08, BT-VL-24 i OD-DI-98. Reakcija hibrida je varirala u odnosu na godinu testiranja. Najveći stepen otpornosti su ispoljili hibridi Baća i NS Brilijant. Smanjenje u napredovanju bolesti u godini sa izraženim deficitom u padavinama je zabeleženo kod linija gajenih u uslovima suvog ratarenja. Testiranjem 181 populacije 9 jednogodišnjih vrsta roda Helianthus u uslovima prirodne infekcije, utvrđene su populacije kod svih odabranih vrsta kod kojih bolest nije bila prisutna. Utvrđivanjem količine ergosterola u okviru simptoma bolesti kod biljaka inbred linija u kontrolisanim uslovima utvrđeno je povećanje količina ovog jedinjenja kod osetljive inbred linije u poređenju sa linijama sa određenim stepenom otpornosti. Rezultatima gajenja 16 hibrida na većem broju lokaliteta u toku četiri godine, ustanovljeno je postojanje značajnog uticaja sredine i genotipa na pojavu i intenzitet<br />bolesti. Najveću otpornost u prirodnim uslovima su ispoljili hibridi Baća, NS-H-111 i NS Fantazija. Gajenjem biljaka u uslovima različitog vremena setve, pojava i intenzitet crne pegavosti stabla su imali tendenciju opadanja sa kasnijom setvom. Primena samo azotnih đubriva najviše je doprinela porastu pojave i intenziteta bolesti, a isti parametri su bili najveći kod najmanje gustine gajenja biljaka. Analizom fenolnih jedinjenja u tkivu lista, u određenim vremenskim intervalima, nakon veštačke inokulacije biljaka inbred linija sa različitim stepenom osetljivosti, utvrđen je povećan sadržaj hlorogene kiseline u toku prva 24 sata kod uzoraka lista otporne linije. Četiri linije različitog stepena osetljivosti su inokulisane u kontrolisanim uslovima sa različitim izolatima patogena. Ustanovljeno je postojanje varijabilnosti u pogledu agresivnosti, dok su 4 četiri od ukupno 56 testiranih izolata ispoljili visok stepen agresivnosti. Grupisanje izolata sličnog stepena agresivnosti prema geografskom poreklu nije ustanovljeno. Analizom genetske varijabilnosti pomoću RAPD markera utvrđen je visok stepen polimorfizma kod upotrebljenih izolata. Od upotrebljenih prajmera najveću informativnost je imao prajmer OPE-04. Visok stepen varijabilnosti je potvrđen klaster analizom. AMOVA analizom utvrđeno je da se genetska varijabilnost izolata gljive odnosi najvećim delom na varijabilnost između izolata. Genetska varijabilnost između izolata grupisanih po regionima i agresivnosti je bila zanemarljiva.<br />Slični obrasci su zapaženi i nakon utvđivanja odgajivačkih osobina &bdquo;in vitro&ldquo;. Najbolji rast i produkcija piknida je zabeležena na podlozi od ovsa. Između izolata su zabeležene značajne razlike u prečniku kolonija i produkciji piknida, ali te razlike nisu bile povezane sa geografskim poreklom izolata.<br />Crna pegavost suncokreta u Srbiji je stalan pratilac suncokreta. Intenzit bolesti je značajno uslovljen stepenom otpornosti genotipova suncokreta, agresivnošću izolata i vremenskim uslovima. Patogen ispoljava velik stepen genetske varijabilnosti što ga čini prilagodljivim za izmene u genetskoj strukturi domaćina i sredini. Odnos suncokret-Phoma macdonaldii predstavlja dinamičan sistem koji zahteva nastavak istraživanja uz monitorig.</p> / <p>Diseases are a major constraint in sunflower production. Phoma black stem, caused by pathogenic fungus Phoma macdonaldii, is widely distributed disease known in some regions for extensive damage to sunflower yield and quality. Previous research conducted in Serbia and testing for resistance with isolates of pathogen coming from this region identitified disease as common. At the same time, reports on resistance to this disease suggested majority of tested genotipes to be susceptible.<br />Aim of this research was to quantify level of resitance in selected inbreed lines and hybrids as well as to find sources of resistance in species from genus Helianthus. Multiyear monitoring of disease on different hybrids and locations was conducted to determine significance of genotype and environment influence on incidence and severity od disease. Usage of ergosterol as indicator of resistance was also tested. Host reaction to disease was monitored by quantification of total soluble phenols and different phenolic compounds known to be impacted during disease progress in other host-pathogen systems. In this part of research emphasis was particularly on period of time following the inoculation. Secound part of research was focused on pathogen. Aim was to determine variability of pathogen population using several methods. Four inbreed lines varyng in level of susceptibility were used for determination of isolate aggressiveness and RAPD markers were used for genetic variability determination. Distinctions among isolates were define using cultural characteristics.<br />Results of sunflower genotypes survey after application of artificial inoculation methods during 4-year period confirmed presence of significant differences in resistance to phoma black stem among tested genotypes. Out of 70 tested sunflower, inbred lines with the highest level of resistance on majority of localities were DOP-32-08, Ph-BC1-162, Ph-BC1-53, IMI-AB-12, CMS-3-8, BT-VL-2, DOP-33-08, BT-VL-24 и OD-DI-98. Resistance of hybrids varied in each year with the highest level of resistance manifested by hybrids Baća and NS Brilijant. Differences between irrigated and rainfed trials were found in year characterized with drought periods after inoculation with decreased disease severity in rain fed experiment. Total of 181 populations of 9 Helianthus species was surveyed for disease incidence. Among the populations of each species ones without symptoms of disease were found. Positive correlation was found between quantity of ergosterol and level of resistance in selected sunflower inbred lines. Disease incidence and severity data of 16 hybrids from number of locations during 4-year period showed significant influence of both genotype and environment. Highest level of resistance had hybrids Baća, HS-H-111 and NS Fantazija.<br />Crop production practices influenced disease incidence and progress. Plants in experiment with different sowing times expressed different disease intensity. Both disease incidence and severity decreased along sowing timeline. Solely application of nitrogen fertilizers most enhanced disease intensity, and the same parameters were highest in plots with lowest plant density.<br />Analysis of phenolic compounds in leaf tissue revealed a significant increase in concentration of chlorogenic acid in first 24 h after inoculation of resistant genotype. In susceptible genotypes that parameter remained unchanged. Patterns of reaction of four inbred lines to disease revealed differences in aggresiveness, with 4 out of 56 tested isolates regarded as highly aggressive. Isolates with similar aggressiveness did not cluster according to geographic origin. Genetic variability analysis using RAPD markers on colected isolates revealed significant level of polymorphism, with primer OPE-04 as the most informative one. High level of genetic variability was confirmed after cluster analysis. Genetic variability among groups with similar agressiveness and geografic origin was insignificant while variability among isolates inside each group was significant according to AMOVA analysis. Similar patern was observed after determination of culturing characteristics &bdquo;in vitro&ldquo;. Pathogen growth and development was best on oat agar medium. Testing warious isolated for growth and production of picnidia revealed significant difference without corelation to geographic origin.<br />In conclusion, phoma black stem occurence on sunflower in Serbia is common. Disease incidence and severity depend on host resistance, isolate aggressiveness and environmental conditions. As a result of high level of genetic variability pathogen is addaptable to changes in host susceptibility and environment. Pathosystem sunflower-Phoma macdonaldii is highly dinamic and requires continuation of research and monitoring.</p>

The present study was aimed at extending our knowledge of the antioxidative properties of the milk protein products, whey protein isolate (WPI) and sodium caseinate (NaCas), in oil-in-water (O/W) emulsions rich in polyunsaturated fatty acids (PUFAs). In particular, the objective was to contribute to our understanding of the compositional and processing factors that influence the oxidative stability of protein-stabilised O/W emulsions. Linoleic acid (approximately 60 %) was used as the lipid for the oil phase (10.6 %). The emulsion samples were usually incubated at 50 °C to accelerate lipid oxidation. Lipid oxidation indicators were lipid hydroperoxides and headspace hexanal, determined by solid phase microextraction (SPME) combined with gas chromatography (GC). WPI- or NaCas-stabilised emulsions were prepared using a wide range of protein concentrations (0.5, 1.0, 2.0, 3.0, 4.0, 7.0 or 10.0 %) at two droplet sizes (d32 = 0.31 and 0.65 µm). In general, higher lipid oxidation levels were found for the larger droplet size. Increasing protein concentration led to a decrease in the lipid oxidation rate. The greatest decrease in lipid hydroperoxide levels (values after 4 h) occurred at up to 4.0 % protein concentration. The greatest decrease in hexanal levels (values after 24 h) occurred at up to 4.0 % protein concentration in WPI emulsions (0.31 µm). The hexanal levels were more independent of the protein concentration in the other emulsion types. The hexanal level decreased at protein concentrations > 4.0 % in NaCas emulsions (0.31 and 0.65 µm) and at protein concentrations > 7.0 % in WPI emulsions (0.65 µm). The difference between lipid hydroperoxide generation in emulsions with small and large droplet sizes decreased with increasing protein concentration. This effect was more pronounced in NaCas emulsions. In general, NaCas was a better inhibitor of lipid oxidation than WPI, but WPI appeared to be the better antioxidant at some droplet size/protein concentration combinations. The protein in the continuous phase, i.e. the unadsorbed protein, played an important role in lipid oxidation. In principal, the lipid hydroperoxide and hexanal levels showed the same development over the continuous phase protein concentration as over the protein concentration in WPI and NaCas emulsions (d32 = 0.31 µm). A low NaCas level in the continuous phase already led to a relatively low hexanal level, whereas a higher WPI level was required. When NaCas solution was added to a WPI emulsion or WPI solution was added to a NaCas emulsion, a synergistic antioxidative effect was observed. The high molecular weight fractions (molecular weight = 12000-14000) of WPI and NaCas contained pro-oxidative metal ions that contributed to lipid oxidation in the emulsions. An enrichment of NaCas emulsions with the low molecular weight fraction of NaCas (with a molecular weight = 12000-14000) notably inhibited lipid oxidation. An enrichment of WPI emulsions with the low molecular weight fraction of WPI (with a molecular weight = 12000-14000) also seemed to inhibit lipid oxidation, but the effect was not significant. The protein solutions were enriched with these fractions before emulsion preparation. Pure WPI solution or mixed WPI/NaCas (1:1, weight/weight) solution with 1.12 or 2.24 % protein concentration was heated at 84 °C for up to 40 min, cooled and then used to prepare emulsions. Lipid oxidation was generally not affected by the heat treatment or the degree of whey protein denaturation. However, at the lower WPI concentration, more hexanal was produced for the longer heating times (20, 30 and 40 min) and this appeared to be connected with the physical instability of the emulsions. Greater oxidative stability was found at the higher protein concentration and when the proteins were mixed, pointing to a possible synergistic antioxidative effect of WPI and NaCas. The addition of the free radical source 2,2’-azobis(2-amidinopropane) dihydrochloride (AAPH) greatly increased the oxygen uptake and the generation of lipid hydroperoxides in the emulsions. The oxidative stability increased with increasing protein concentration (1.0, 4.0 and 7.0 %). NaCas had a greater antioxidative effect than WPI. The inhibition of oxygen uptake appeared to be largely influenced by the free-radical-scavenging activity of the system, determined by the protein type and the protein concentration, as the radicals were produced linearly over time and oxygen was consumed linearly over time. It can therefore be concluded that free-radical-scavenging activity represents a major antioxidative mechanism of the milk proteins. Oxygen was consumed much faster in emulsions than in protein solutions when the same level of AAPH was incorporated. In a WPI (1.0 % protein) emulsion, much lower levels of protein hydroperoxides than of lipid hydroperoxides developed. This pointed to a much greater reactivity of linoleic acid than of the milk proteins with oxygen. In contrast, the exposure of WPI to oxidising linoleic acid in an emulsion (1.0 % protein) or to AAPH in aqueous solution led to oxidative damage of the whey proteins, indicated by the loss of amino acids. The loss of specific amino acids was different for proteins in the continuous phase or cream phase of an emulsion or in WPI solution. The present study confirms the antioxidative potential of WPI and NaCas and gives new insights into their functionality as oxidative stabilisers in O/W emulsions.

The application of current soy protein films are limited due to their low mechanical strength and high moisture sensitivity compared to synthetic materials. This research studied several methods to improve the mechanical properties [tensile strength (TS), elongation at break (EAB), Young’s modulus of elasticity (YM)] of solvent cast soy protein isolate (SPI) films. Drying times were significantly reduced through the use of a heated casting surface. Neutral (pH 7) SPI films were prepared but were found to have lower TS, EAB and YM than control films prepared under alkaline conditions. Cellulose was extracted from soybean wastes and transmission electron microscopy (TEM) verified the existence of nano-sized fibres. Composite SPI films were prepared using either extracted cellulose fibres or titanium dioxide (TiO2) nanoparticles and their mechanical and barrier properties (water vapour, and oxygen permeability) were evaluated under different relative humidity (RH) conditions. In general, TS and YM decreased and EAB increased with increasing RH. Films with 5% (w/w) added cellulose exhibited significant (p-value < 0.05) improvements in TS and YM but decreased EAB. TiO2 composites possessed similar TS, YM, and EAB values to control films. Barrier properties were comparable across all samples, and decreased with increasing RH. Samples were characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Preliminary work investigating synthesis of filler materials using cross-linked sodium alginate particles increased the TS and YM of SPI films to a similar extent as extracted cellulose. A method for electrospinning cellulose using ionic liquids was developed, but requires further process optimization to be used for fibre/filler synthesis. / OMAFRA; Hannam Soy Utilization Fund

The present study was aimed at extending our knowledge of the antioxidative properties of the milk protein products, whey protein isolate (WPI) and sodium caseinate (NaCas), in oil-in-water (O/W) emulsions rich in polyunsaturated fatty acids (PUFAs). In particular, the objective was to contribute to our understanding of the compositional and processing factors that influence the oxidative stability of protein-stabilised O/W emulsions. Linoleic acid (approximately 60 %) was used as the lipid for the oil phase (10.6 %). The emulsion samples were usually incubated at 50 °C to accelerate lipid oxidation. Lipid oxidation indicators were lipid hydroperoxides and headspace hexanal, determined by solid phase microextraction (SPME) combined with gas chromatography (GC). WPI- or NaCas-stabilised emulsions were prepared using a wide range of protein concentrations (0.5, 1.0, 2.0, 3.0, 4.0, 7.0 or 10.0 %) at two droplet sizes (d32 = 0.31 and 0.65 µm). In general, higher lipid oxidation levels were found for the larger droplet size. Increasing protein concentration led to a decrease in the lipid oxidation rate. The greatest decrease in lipid hydroperoxide levels (values after 4 h) occurred at up to 4.0 % protein concentration. The greatest decrease in hexanal levels (values after 24 h) occurred at up to 4.0 % protein concentration in WPI emulsions (0.31 µm). The hexanal levels were more independent of the protein concentration in the other emulsion types. The hexanal level decreased at protein concentrations > 4.0 % in NaCas emulsions (0.31 and 0.65 µm) and at protein concentrations > 7.0 % in WPI emulsions (0.65 µm). The difference between lipid hydroperoxide generation in emulsions with small and large droplet sizes decreased with increasing protein concentration. This effect was more pronounced in NaCas emulsions. In general, NaCas was a better inhibitor of lipid oxidation than WPI, but WPI appeared to be the better antioxidant at some droplet size/protein concentration combinations. The protein in the continuous phase, i.e. the unadsorbed protein, played an important role in lipid oxidation. In principal, the lipid hydroperoxide and hexanal levels showed the same development over the continuous phase protein concentration as over the protein concentration in WPI and NaCas emulsions (d32 = 0.31 µm). A low NaCas level in the continuous phase already led to a relatively low hexanal level, whereas a higher WPI level was required. When NaCas solution was added to a WPI emulsion or WPI solution was added to a NaCas emulsion, a synergistic antioxidative effect was observed. The high molecular weight fractions (molecular weight = 12000-14000) of WPI and NaCas contained pro-oxidative metal ions that contributed to lipid oxidation in the emulsions. An enrichment of NaCas emulsions with the low molecular weight fraction of NaCas (with a molecular weight = 12000-14000) notably inhibited lipid oxidation. An enrichment of WPI emulsions with the low molecular weight fraction of WPI (with a molecular weight = 12000-14000) also seemed to inhibit lipid oxidation, but the effect was not significant. The protein solutions were enriched with these fractions before emulsion preparation. Pure WPI solution or mixed WPI/NaCas (1:1, weight/weight) solution with 1.12 or 2.24 % protein concentration was heated at 84 °C for up to 40 min, cooled and then used to prepare emulsions. Lipid oxidation was generally not affected by the heat treatment or the degree of whey protein denaturation. However, at the lower WPI concentration, more hexanal was produced for the longer heating times (20, 30 and 40 min) and this appeared to be connected with the physical instability of the emulsions. Greater oxidative stability was found at the higher protein concentration and when the proteins were mixed, pointing to a possible synergistic antioxidative effect of WPI and NaCas. The addition of the free radical source 2,2’-azobis(2-amidinopropane) dihydrochloride (AAPH) greatly increased the oxygen uptake and the generation of lipid hydroperoxides in the emulsions. The oxidative stability increased with increasing protein concentration (1.0, 4.0 and 7.0 %). NaCas had a greater antioxidative effect than WPI. The inhibition of oxygen uptake appeared to be largely influenced by the free-radical-scavenging activity of the system, determined by the protein type and the protein concentration, as the radicals were produced linearly over time and oxygen was consumed linearly over time. It can therefore be concluded that free-radical-scavenging activity represents a major antioxidative mechanism of the milk proteins. Oxygen was consumed much faster in emulsions than in protein solutions when the same level of AAPH was incorporated. In a WPI (1.0 % protein) emulsion, much lower levels of protein hydroperoxides than of lipid hydroperoxides developed. This pointed to a much greater reactivity of linoleic acid than of the milk proteins with oxygen. In contrast, the exposure of WPI to oxidising linoleic acid in an emulsion (1.0 % protein) or to AAPH in aqueous solution led to oxidative damage of the whey proteins, indicated by the loss of amino acids. The loss of specific amino acids was different for proteins in the continuous phase or cream phase of an emulsion or in WPI solution. The present study confirms the antioxidative potential of WPI and NaCas and gives new insights into their functionality as oxidative stabilisers in O/W emulsions.