Browsing by discipline "Elintarviketeknologia"

The literature review focused on acid- and heat-induced protein gelation and the value of rice bran as a food ingredient. A protein-enriched rice bran fraction containing 24% protein, 24% fibre and 22% phytate was used in the experimental work. The aim was to investigate the effect of phytate on protein solubility and study the gelling ability and the effect of a phytate-degrading enzyme, phytase, and a crosslinking enzyme, transglutaminase, in heat- and acid-induced gelation. Phytase treatment of the protein-enriched rice bran fraction decreased the phytate content to 1%. As a result, protein solubility increased at pH 2 from 40 to 55% and at pH 4 from 40 to 47%. In addition, phytase treatment improved gel strength from 1100 to 8200 Pa and water holding capacity from 54.6% to 77.7% of heat-induced gels at pH 8. Acid-induced gelation resulted in low gel strength of 108–190 Pa and water holding capacity of 52.8–56.6%. Transglutaminase had limited crosslinking ability on the protein-enriched rice bran fraction and consequently acid induced gelation and final gel characteristics were not affected by transglutaminase treatment. Acid-induced gels showed fine and homogeneous microstructure, whereas heat induced gelation led to more dense protein and fibre network structure. Based on these results, the protein-enriched rice bran fraction has gelling ability upon heating and acidification. Phytase treatment had great technological potential in altering the protein solubility and heat-induced gelation ability of the fraction.

Substitution of animal food products and non-biodegradable plastics is of interest for addressing climate change and pollution. Plant proteins are potential raw materials with low environmental impact which can be utilized for development of protein rich foods or biodegradable plastics. Grain legumes and especially lupins are rich in proteins that could be utilized. Protein fibril is a self-assembled non-random protein structure which has a large length to width ratio. The objective of this study was to demonstrate the concept of fibrillating proteins extracted from two lupin species (L. albus and L. angustifolius) and to characterize the formed fibrils. The proteins were extracted from dried and milled lupin seeds with alkaline followed by an isoelectric precipitation. The standard extraction procedure was combined with additional process steps such as dehulling, defatting, extraction with acidic extraction media and dialysis. The extracted protein isolates were hydrolyzed into peptides in different concentrations and assembled into fibrils by heating at pH 2.0 for 24, 48 or 72 h. The fibrillated samples were analyzed with a thioflavin T (ThT) assay to indicate the β-sheet secondary protein structure. Some of the fibrillated samples were imaged with atomic-force microscopy. Samples prepared from dehulled and defatted L. angustifolius flour had the highest total protein content of 98.3 ± 0.4% on dry matter basis. ThT binding was observed in most samples indicating formation of fibrils. The binding increased significantly for samples after standard extraction process and for lower ionic strength. The fibrils appeared to form within 48 h and samples with higher protein concentration (40 mg/ml) showed massive gelation after 24 h. Studying the samples with atomic-force microscopy showed 300 nm long curly fibrils. These initial results indicate that the proteins extracted from lupin can be fibrillated.

Constant increase in protein consumption is global trend and can be seen in consumer behavior of Finnish markets. Consumers are interested in replacing meat proteins with plant proteins, and therefore, it is important to develop locally grown-domestic products and invest in local crop research. Due to this, the current study focuses on the domestic vegetable protein (faba bean and oat) texturing by extrusion cooking and on their functionality when included in burgers. The literature section presents an overview of previous studies on extrusion of vegetable proteins and the functionality of textured vegetable proteins (TVP). In the experimental work the research materials were faba bean protein concentrate and oat concentrate with high β-glucan content. The flour concentrates were texturized with high-moisture extrusion, in different mixtures. Mixtures were prepared in the ratio of: 3:1 (FO) and 1:3 (OF) and soy protein concentrate (S) was used as a reference sample. Moisture content and water absorption capability of TVP samples were measured instrumentally. TVPs were later on applied to develop burgers based on a mixture of meat and vegetable sources. Burgers were prepared for instrumental analysis with seven different recipes, where TVP inclusion, water addition and meat content varied. TVP was included in three different percentages: 0, 25 and 50% and water was added in 0, 12.5 and 25%. In relation to TVP inclusion and water addition, the meat content varied between 25-100%. Sample with 100% meat was used as control sample (0-sample) and burgers with S inclusion as reference samples. Samples were analyzed for cooking loss, shear force and texture profile (hardness, fracturability, springi-ness, cohesiveness, gumminess, chewiness and resilience) which was measured with a compression method. Based on the results of the instrumental analysis, five different burger samples were selected and evaluated for sensorial properties (chewiness, biting force, juiciness and pasty mouthfeel). The highest TVP moisture content was in OF and lowest in FO, hence the difference between S and FO was not significant. The highest water absorption was in S and lowest in OF. 25% TVP inclusion in burgers reduced the cooking loss (p<0.05) and 50% inclusion reduced it even more (p<0.05). With 25% TVP inclusion S had higher (p<0.05) cooking loss compared to FO and OF. With 50% TVP inclusion the difference was eliminated. Water addition increased cooking loss significantly (p<0.05) with each type of TVP. The FO and OF inclusion showed to weaken (p<0.05) the textural properties of burgers and reduced (p<0.05) the shear force. The reference sample S was found to maintain the structure similar as from the meat control sample. Water addition, while replacing meat, weakened also the textural properties and shear force in each TVP included sample. Based on the results, the inclusion of FO and OF in burgers reduces the cooking loss compared to the 0-sample and the reference sample S. The texture of burgers became weaker with FO and OF inclusion, however sensory evaluation revealed them to be similar to S included sample. Therefore additional studies focusing on improving the textural properties of these TVPs are needed. Faba bean and oat concentrates with higher protein contents could be needed to obtain a texture closer to meat.

The literature review describes the characteristics, uses and probiotic potential of propionibacteria and gives an overview of proteomic methods focusing on 2-DE studies related to probiotic bacteria and P. freudenreichii. The aim of the experimental part was to use 2-DE to obtain proteome maps of two strains of P. freudenreichii and detect inter-strain differential protein expression. The influence of a number of parameters on the quality of 2-D gels was also investigated. The pH 3-7 and pH 3-11 NL proteome maps obtained displayed 305 and 356 spots, respectively, and detected the differential expression of 60 and 72 spots, respectively. The 3-11 NL proteome map showed spot over-crowding in the pH 4-6 region. Addition of 50 mM dithiothreitol (DTT) to the samples prior to isoelectric focusing (IEF) and an increase of IPG buffer concentration greatly improved spot resolution. Silver staining achieved higher spot counts than Coomassie staining. The influence of the number of lysis cycles on protein extraction was marginal, while lower protein sample loads produced superior 2-D gels. Results show that data from 2-DE proteome maps can provide an overview of inter-strain differential protein expression in P. freudenreichii. The optimal 2-DE experimental setup would include pH 4-7 IPG strips, a low protein load and inclusion of DTT in the IEF sample, as well as silver staining for spot visualisation.

Gluten free baking differentiates from traditional wheat baking by the lack of structure stabilizing gluten network. The gluten in wheat flour mixed with water creates a visco-elastic dough that makes a good quality bread. In gluten free baking the structure of bread is improved with starches and hydrocolloids. Celiac decease, gluten yliherkkyys and wheat allergy are health related reasons to avoid gluten from wheat, barley and rye. There is no method for gluten free flours to predict the quality of the baked product like there is the farinograph water absorption method for wheat flour. These topics are discussed in the literature part of this work. The aim of this research was to look into the connection between gluten free dough consistency and the quality of baked bread. In the experimental part three different dough yields were selected: 190, 200 and 210. All dough yields were used with three different mixtures in consistency measurements: 100% buckwheat, 70 % buckwheat and 30 % tapioca and addition of 1 % psyllium to the latter mixture. Two different methods were tested (forward and backward extrusion) with Texture Analyser with all different dough variations. The principle in both methods are the same: the tests measure the compression force required for a piston to extrude the dough in a sample container. The doughs consistency and behavior were studied with farinograph to see if the results were consistent. Baking test was done with different dough yields with buckwheat, tapioca and psyllium mixture. Volume, baking loss and color were determined. Texture Profiler Analysis (TPA) was done 24h and 48h after baking. A sensory analysis conducted by professional panelists was done where porosity, softness, dryness, sponginess and intensity of buckwheat taste were assessed. Backward extrusion was found to be a better method for measuring consistency of the doughs. The results showed how the increasing water amount decreased consistency and same results were obtained with farinograph. Differences between breads were found with the sensory analysis as well. Intensity of flavor and porosity increased in bread with lower water amount whereas softness and moistness increased with increasing water amount when also the bread remained softer for longer. As a conclusion it can be stated that the backward extrusion is a suitable and reproducible method for buckwheat dough consistency measurements. Water absorption, bread structure and shelf life can be predicted and optimized based on consistency.

Kirjallisuuskatsauksessa tarkasteltiin härkäpavun (Vicia faba) soveltuvuutta vehnäleivontaan sekä perehdyttiin härkäpapujen antimikrobisiin ominaisuuksiin. Kirjallisuuskatsauksessa tarkasteltiin myös mikroaaltokäsittelyn vaikutusta näihin ominaisuuksiin. Palkokasvit, härkäpapu mukaan lukien, sisältävät myös laajan kirjon erilaisia antimikrobisia aineita, kuten kitinaasia, glukanaasia, taumatiinityyppisiä proteiineja, defensiinejä sekä trypsiini- ja kymotrypsiini-inhibiittoreita. Kirjallisuudessa ei ole mainintaa palkokasvien kyvystä ehkäistä leivän homehtumista. Tämän tutkimuksen kokeellisen työn tavoitteena olikin tutkia härkäpavun antimikrobisten aineiden kykyä ehkäistä vehnäleivän homehtumista. Työssä tutkittiin myös, miten härkäpapu vaikutti taikinan kaasuntuottokykyyn, leivän pH:hon ja happolukuun. Tutkimuksessa käytetyistä härkäpavuista (Melody, 2013) osa mikroaaltokäsiteltiin 3 x 30 sekuntia (950 W). Käsitellyt ja käsittelemättömät härkäpavut kuorittiin ja jauhettiin hienoksi jauhoksi. Osa käsittelemättömästä jauhosta käytettiin härkäpapu-uutteen valmistamiseen. Leivontakokeissa vesi korvattiin härkäpapu-uutteella tai osa vehnäjauhosta härkäpapujauholla. Leivonnassa käytettiin mukautettua El-Dash-koeleivontamenetelmää. Taikinoiden hiilidioksidin tuottokykyä mitattiin Risographilla (National Manufacturing, USA). Happoluku ja pH mitattiin leivistä leivontaa seuraavana päivänä. Homesuspensiossa (400 solua/ml) valmistettiin homekannoista Penicillium verrucosum, Rhizopus stolonifer, Aspergillus niger ja Penicillium roquefortii ja 0,9 % NaCl-liuoksesta. 10μl suspensiota pipetoitiin kunkin leipäviipaleen päälle. Näytteet pakattiin yksittäin muovipusseihin. Seitsemän päivän inkuboinnin jälkeen (23 °C) homekasvuston halkaisija mitattiin. Härkäpapujauho ja -uute laskivat taikinan hiilidioksidin tuottokykyä. Aiemmissa tutkimuksissa fabatiinin, härkäpavun antimikrobisen peptidin, ei ole todettu vaikuttavan leivinhiivan (Saccharomyces cerevisiae) kasvuun. Härkäpapujauhot ja -uute todettiin inhiboivan homeiden Penicillium verrucosum, Aspergillus niger ja Penicillium roqueforti kasvua vehnäleivässä tilastollisesti merkitsevästi. Sen sijaan Rhizopos stoloniferiksen kasvua ne eivät ehkäisseet. Härkäpapujauhot ja -uute nostivat leivän pH:ta ja happolukua. Härkäpapu sisältää vehnäjauhoon verrattuna runsaasti fytaattihappoa, jonka on todettu nostavan happolukua. Tämän tutkimuksen perusteella härkäpapujauholla tai -uutteella voidaan mahdollisesti hidastaa leivän homehtumista ainakin joitakin homeita vastaan. Härkäpavun käytöllä voi kuitenkin olla vaikutusta hiivan toimintaan sekä leivän happolukuun.

Kirjallisuuskatsauksessa perehdyttiin erityisesti palkokasveista löydettyihin homeenkasvua estäviin proteiineihin. Kirjallisuuskatsauksessa tarkasteltiin myös härkäpapua palkokasvina, leivän homehtumista sekä perinteisiä ja vaihtoehtoisia menetelmiä leivän säilyvyyden parantamiseksi. Härkäpavun jauholla, uutteella ja proteiineilla on havaittu homeenkasvua estävä vaikutus leivässä, mutta sen vesiuutteen proteiinifraktioiden homeenestokykyä ei ole raportoitu aiemmin. Kokeellisen työn tavoitteena oli tunnistaa homeenkasvua estäviä fraktioita härkäpavun vesiuutteesta ja siitä eristetystä proteiinista. Homeenestokykyä tutkittiin käyttäen yleisiä leipien pilaajahomeita, jotta leivässä homeenkasvua estävät härkäpavun vesiliukoiset proteiinifraktiot voitaisiin tunnistaa. Tutkimuksessa kahdelle härkäpapulajikkeelle (Kontu, Suomi ja Alex, Espanja) tehtiin vesiuutto ja vesiuutteen proteiinit saostettiin ammoniumsulfaatilla (75 %). Vesiuutteet ja vesiuutteista saostettu proteiini fraktioitiin geelisuodatuskromatografialla (Sephadex G100). Näytteiden proteiinipitoisuus määritettiin spektrofotometrisesti ja proteiinikoostumus elektroforeettisesti SDS-PAGE:lla. Homeenestokyky määritettiin maljakokeissa käyttäen neljää yleistä leipähometta (P. paneum, P. roqueforti, P. albocoremium ja A. niger). Tämän työn perusteella härkäpavun vesiuutteesta oli mahdollista erottaa geelisuodatuksella homeenkasvua estäviä proteiinifraktioita ja härkäpavun proteiinifraktioiden havaittiin estävän P. paneumin ja P. roquefortin kasvua in vitro. Pieniä proteiineja tai paljon globuliinia sisältävillä fraktioilla ei havaittu homeenestokykyä. Vaikka saostaminen ei vaikuttanut fraktioiden homeenestokykyyn, ammoniumsulfaattisaostuksessa menetettiin globuliinien vesiliukoisuus ja vesiuutteen A. nigerin estokyky. Näytteiden homeenestokyvyn havaittiin riippuvan proteiinikonsentraatiosta ja homelajista, mutta Kontu ja Alex eivät eronneet toisistaan proteiinikoostumukseltaan ja homeenestokyvyltään. Työn perusteella härkäpavun proteiinifraktioilla on merkitystä härkäpavun homeenestokyvyssä ja niiden toiminnallisuutta homeenkasvun estäjinä tulisi tutkia myös elintarvikkeissa kuten leivässä.

The aim of this master’s thesis was to study the effects of flaking conditions on the quality properties of oat flakes and to simulate the flaking process in laboratory conditions. The review of literature deals with oat processing focusing on oat flaking and oat flake quality properties. The flaking process includes groats steaming and tempering, which plasticizes the groats when moisture is absorbed. Then the groats are flattened by a flaking roller mill. Increasing tempering temperature and time results in higher water absorption. Increasing tempering time also increases the amount of fines. Flake breakage in the process reduces the flake yield resulting in more costs. There are no published studies that evaluate the impact of steaming on flake quality properties. The aim of the experimental part of this thesis was to study the effects of flaking moisture on flake strength and quality. Kilned and unkilned groats were flaked in a laboratory-scale flaking machine. Laboratory-scale flaking was carried out with a standardized flake thickness 0,7-0,8 mm. In addition, the properties of five commercial oat flakes were analyzed. There was significant variation between the different commercial oat flakes in their both water hydration capacities and amount of fines. The results implied that flaking conditions have an effect to these flake quality properties. Oat flakes were significantly thicker with higher flaking moisture. The roll gap was tightened to produce the same flake thickness. Both the bulk density and the amount of fines decreased with higher flaking moistures. There were no significant changes in the pasting properties of flakes made of kilned groats compared to kilned groats. Increasing flaking moisture reduces the amount of fines. In addition, water absorption increased with high flaking moistures. Even a three-percent increase in flaking moisture improved the quality of oat flakes. Increasing flaking moisture in between 12-20 % had a beneficial effect on quality properties of oat flakes.

Cereal side streams, such as rice bran and dried distiller´s grain with solubles (DDGS) are formed in large quantities in industrial processes. These side streams contain considerable amounts of protein that could be better valorized. Deep eutectic solvents (DES) have been applied in various biomass fractionation studies and could be potentially used as protein extraction solvents. The literature review of this master´s thesis covered the characteristics of rice bran and DDGS, existing extraction methods and DESs. The aim of this work was to study the effect of water content of two DESs (choline chloride:urea, molar ratio 1:2 and sodium acetate:urea, 1:2) on the protein extraction from rice bran and DDGS. Protein extraction yield, protein content in dialyzed and freeze-dried extracts and protein fragmentation were studied. DDGS protein extraction yields with ChCl:urea at 30-50% water contents (56-57%) were significantly higher (p<0.05) than by NaOH (46%) and water (36%), which were used as reference solvents. With NaAcO:urea the water content did not affect the yields significantly and the yields did not differ from those of the reference solvents. In case of rice bran, a low water content produced higher yields and with NaAcO:urea at a water content of 10% the yield was 70%, which was significantly higher than with the reference solvents. Protein contents were measured by two methods, which gave conflicting results. According to BCA assay, the highest protein concentration from DDGS was obtained with NaOH, but according to elemental analysis with the DESs. In case of rice bran, the protein concentrations were extremely low with both methods. Based on these results, rice bran protein extraction using DESs does not appear feasible, whereas DDGS protein could be extracted more efficiently using the DESs than the reference solvents. Neither of the DESs at any water contents degraded protein to a significant extent.

Gelatin-based confections are one type of gummy confections. Their main ingredients are water, sucrose, glucose syrup and gelatin, which causes gel-like texture. The literature review focused on the raw materials, the manufacturing process and the properties of gelatin- and starch-based gummy confections. The aim of this study was to find out how invert sugar, when it replaces sucrose and glucose syrup, affects structural properties and short-term shelf life of gelatin-based confections. In addition, changes in the sensory quality were observed. In the experimental research, the gelatin-based confections were manufactured on a laboratory scale according to simplex-centroid mixture design, where the total sugar content was constant, but sucrose, glucose syrup and invert sugar mass fractions were varied. Measurements for the samples were rheological properties, sugar content and dry matter content of confection paste and mechanical properties (hardness, stickiness and relaxation parameters), dry matter content, water activity and water sorption of confections. In addition, a few samples were manufactured with coloring and flavoring agents for sensory observation. The results were analyzed with the PLSR (Partial Least Squares Regression). Finnsugar Ltd.'s product development department offered the topic of this study and raw materials, but all the experiments were carried out in the Department of Food and Environmental Sciences in the University of Helsinki. The PLSR model contained five components, and the coefficient of determination R2 was 74.1%, the adjusted R2 was 63.3% and the coefficient of prediction Q2 was 43.6%. The model determined all response variables well, but predicted some of them poorly. Almost all response variables regression models were statistically significant at 5% significance level, but some of the models were incomplete (plof<0.05). The variables important in projection (VIP) in the PLSR model were mass fraction of invert sugar, mass fraction of glucose syrup and their interactions with mass fraction of sucrose. The PLSR model was best for rheological properties of confection pastes and mechanical properties of confections, and poorest for water activity and dry matter content of confections. Even at low mass fraction of invert sugar viscosity of confection paste decreased. Invert sugar also reduced hardness of confections, and speeded up their structures recovery after compression. Sensory observation shows the positive effects of invert sugar, such as softness of structure and stronger taste. The present study showed that the sugars have interactions, which also affect properties of the gelatin-based confections, and invert sugar content alone is not the significant factor. Based on the results of this study it seems that invert sugar affected stronger most of the response variables if it replaced relatively more glucose syrup than sucrose.