Maatalous- metsätieteellinen tiedekunta

 

Recent Submissions

  • Koivisto, Aino (Helsingin yliopisto, 2016)
    Fusarium species lower the germination of oat (Avena sativa) seeds and cause losses in yields. Fungicidal seed treatments prevent fungal diseases from spreading through seeds and soil. This study was conducted to determine how different fungicidal seed treatments affect the germination of oat seeds and the Fusarium species present in laboratory conditions applying official ISTA germination test methods on filter paper and sand. Aim was also to detect the damages fungi cause to oat seedlings as well as the effectiveness of different seed treatments and the resistance of oat cultivars to Fusarium. The germination percentages and damages were detected in two studies. In the first study, oat seeds were germinated on both filter paper and sand and treated with fungicidal seed treatments (Baytan Universal, Celest Trio and Zardex G). In the second study, oat seeds were inoculated with Fusarium culmorum and germinated on filter paper. Additionally, the effect of mould fungi on germination in several different geographical areas, years and cultivars was investigated based on the official germination tests conducted by Evira, who used samples analysed for certifying. Differences were detected between cultivars in their germination and damages caused by fungi in different geographical areas and years. In general, there were more damages in the seed lots with lower germination. The fungicidal seed treatments decreased damages clearly but increased germination only slightly. Only slight differences were observed between the researched seed treatments in their abilities to increase the germination of oat but there were greater differences in their abilities to decrease the amount of Fusarium and the damages they caused to oat seeds. The seed treatment with fludioxonil, difenoconazole and tebuconazole as active ingredients was the most effective against the damages caused by Fusarium in laboratory conditions. Additionally, the germination of oat was better with the sand germination method than on filter paper. However, there were more damages on oat seedlings germinated on sand than on filter paper.
  • Leppänen, Janette (Helsingin yliopisto, 2016)
    Maatalouden pintavalunnan ravinnehuuhtoutumat ovat yksi suurimmista hajakuormituksen lähteistä aiheuttaen vesistöjen ravinnekuormitusta. Maatalouden vesiensuojelukosteikkojen tarkoituksena on vähentää pellolta kulkeutuvia ravinteita. Kosteikon laskeutusaltaisiin kertyy hienojakoista sedimenttiä, johon on sitoutunut paljon fosforia. Sedimentillä ei ole kasviravitsemuksellista merkitystä, mutta suuren P-pidätyskapasiteetin johdosta sitä voidaan käyttää ehkäisemään P:n huuhtoutumista runsaasti P:a sisältävissä maissa. Tämän pro gradu –tutkielman tavoitteena oli selvittää kosteikkosedimentin hyödynnettävyyttä helppoliukoista fosforia sisältävän maan kunnostuksessa (esim. karjan ruokintapaikat) ja siten vähentää fosforia valumavedessä ja hillitä maatalouden vesistökuormitusta. Tutkimuskohteina oli kaksi runsaasti helppoliukoista fosforia sisältävää peltomaata (Rehtijärvi ja Ojainen), joihin on sekoitettu Liedonperän maatalouskosteikon sedimenttiä eri seossuhteilla (0; 2; 5; 10 ja 50 %). Lisäksi samoja koemaita käytettiin erillisessä sadetuskokeessa, ja tässä työssä tutkittiin maiden fosforinpidätysominaisuuksia ennen ja jälkeen sadetuksen. Sedimentti-maa -seosten hyödynnettävyyttä maan kunnostuksessa tutkittiin analysoimalla koemaiden perusominaisuudet, uuttamalla epäorgaanisen fosforin fraktiot ja heikosti kiteytyneiden oksidit sekä määrittämällä sorptio-desorptioisotermit. Kosteikon sedimentissä fosfori oli pääosin sitoutunut raudan oksideihin (NaOH-P), jonka liikkuvuus riippuu hapetus-pelkistys –olosuhteista. Rehtijärven hietamaa sisälsi suhteellisen paljon helppoliukoista (NH4Cl-P) fosforia, mutta fraktio pieneni sedimenttiä lisätessä. Ojaisten maa oli ominaisuuksiltaan samankaltainen kuin sedimentti ja vaikka sedimentin lisääminen näkyi Ojaisten maissa, eivät vaikutukset olleet Rehtijärven suuruisia. Tämä johtuu Rehtijärven alun perin suuresta fosforipitoisuudesta ja vähäisestä oksidipitoisuudesta kun taas Ojaisten maan fosforipitoisuus on pienempi, mutta oksidipitoisuus suuri. Sorptio-desorptio -kuvaajat todettiin sorptiokapasiteettia- ja indeksiä herkemmäksi menetelmäksi pieniä sedimenttieroja sisältävien maiden tutkimiseen ja jo 5 %:n sedimenttilisäys selvästi pienensi P:n desorptiota koemaissa. Oksidipinnan lisääminen tuottaa pidempiaikaisen vaikutuksen Fe- ja Al-oksidien sitoutuessa maaperään lisäten P-pidätystä. Sedimentissä olevat suolat lisäävät fosforin sitoutumista, mutta vaikutus on lyhytaikaista, sillä helppoliukoiset suolat huuhtoutuvat pois maaperästä sadetuksen kuluessa. Kosteikkosedimentillä on suuri potentiaali pidättää fosforia pintavalunnasta ja sedimenttiä pystyisi hyödyntämään runsaasti helppoliukoista fosforia sisältävien maiden fosforinpidätykseen esimerkiksi ojasuodattimen tai suodatinkerroksen rakentamisella eläinten jaloittelutarhaan. Tämän työn ja sadetuskokeen perusteella sopiva sedimenttilisäys maahan on noin 5 %.
  • Jokela, Eira (Helsingin yliopisto, 2016)
    Increasing proportion of horses is suffering from obesity and metabolic diseases. This has been associated with concentrate feeding. The aim of this thesis was to conduct a meta-analysis based on studies that examined the effect of dietary starch and NDF concentrations (g/kg DM), and starch intake (kg/day) on hindgut fermentation. Only studies that used fistulated horses or eu-thanized horses where included in the data. The inclusion criteria were that studies had to report results for diet composition, measured fermentation parameters and feed intake. Results from nine studies were used in this meta-analysis. Statistical analysis was conducted using SAS 9.3 program and Prox Mixed procedure. A linear mixed model and regression analysis was used to determine possible relationship between dietary starch concentration and NDF concentrations, starch intake and hindgut fermentation parameters. Dietary starch concentration (g/kg DM) and daily intake of starch (kg/day) increased pH (P=0,03) (P=0,04) and decreased acetate (P=0,01) (P<0,001). Increased dietary starch concentration also increased propionate (P=0,02) and low-ered the (C2+C4)/C3 ratio (P=0,02). Increase of one kilogram of starch intake lowered the hindgut pH by 0,12 units. Increase in dietary NDF concentration (g/kg DM) increased the hind-gut pH (P=0,01) and acetate (P=0,03) proportion and decreased butyrate (P=0,02) proportion. Increase in dietary NDF concentration (g/kg DM) increased pH and molar proportion of acetate in hindgut, and decreased the molar proportion of butyrate. Although data for the meta-analysis was limited and the backgrounds differ, for example diets and horse breeds, this analysis gave statistically significant results concerning hindgut fermentation parameters and diet composition. Changes in starch and NDF concentrations affect linearly to hindgut fermentation. The results of this meta-analysis emphasize that special attention should be paid to roughage-concentrate ratio when planning horses daily feeding.
  • Özge Nilay, Yurdakul (Helsingin yliopisto, 2016)
    The aim of the experimental work was to understand the rigor bonds’ effect together with protein denaturation on water-holding capacity by breaking the actomyosin bonds that were formed during rigor process and examining the dissociation of actomyosin bonds’ influence on rheological features of myofibrils in suspension. In this study the rigor bonds’ influences on water-holding capacity were compared; firstly, by dissociating the rigor bonds in one group with the addition of 10mM PPi and 2mM MgCl2; secondly, applying heat treatment at 21ºC and 44 ºC; thirdly, denaturing sarcoplasmic proteins together with the myofibrils and denaturing the myofibrils without the presence of sarcoplasmic proteins. The influence of actomyosin bonds’ dissociation on rheological features of myofibrils was investigated as well by stress sweep and frequency sweep tests. The samples that were denatured without the presence of sarcoplasmic protein showed the poorest water-holding capacity which is indicating high drip loss in PSE like conditions mainly due to myofibrillar protein denaturation. Sarcoplasmic protein precipitation with the myofibrils improved the gelling properties. The PPi addition did not affect water-holding of myofibrils (P>0.05), suggesting that the rigor bonds don’t have a significant effect on water-holding of myofibrils after temperature-induced protein denaturation.
  • Saarenmaa, Severi (Helsingin yliopisto, 2016)
    Tavoitteena työssä oli saada valmis, turvallinen ja maukas tuote uuteen tuotekonseptiin. HKScan Oyj määritti halutut ominaisuudet tuotteelle, jota tässä työssä noudatettiin (Liite 1). Tuotteen valmisteleminen vaati säilyvyyden, teknologisen- ja aistinvaraisen näkökulman tarkastelua tässä järjestyksessä, sillä säilyvyys määrittää sen, mitä ominaisuuksia teknologisesti jouduttiin hakemaan. Tuote piti saada aistinvaraisesti rakenteeltaan kuluttajille sopivaksi ja suolaisuudeltaan miellyttäväksi. Kirjallisuusosassa käytiin läpi teoreettinen puoli, jonka perusteella suunniteltiin, valmistettiin ja tutkittiin uusi lihaproteiinivalmiste. Tulokset osoittavat, että käytetyillä resepteillä ja kypsennysohjelmilla ei saavutettu 0,88 vedenaktiivisuutta, joka olisi taannut näytteiden säilyvyyden huoneenlämmössä. Esitestit ja varsinaiset kokeet jättivät näytteiden vedenaktiivisuudet yrityksestä huolimatta 0,92—0,93. Tämän lisäksi kahdella eri valmistusmenetelmällä ei löytynyt eroja aistinvaraisesti tai leikkausvoimia mitattaessa. Suolaisuuden suhteen kolmen eri suolapitoisuuden välillä ei ollut merkitseviä eroja, vaikka keskiarvoissa 1,6 % näkyi hieman suurempana suolaisuuden keskiarvona aistinvaraisissa testeissä. Myöskään leikkausvoimien välillä ei ollut merkitseviä eroja valmistuserissä. Tuotekonseptin tavoitteiden mukaisen proteiinipatukan valmistus oli tämän tutkimuksen osalta osoittautunut lähes mahdottomaksi HKScan Finland Oyj:n Vantaan tuotantolaitoksessa, jonka prosesseihin tuote piti soveltua. Työn tulokset ovat hyvä pohja jatkokehitykselle.
  • Hyttinen, Henna (Helsingin yliopisto, 2016)
    Valtaosa viljeltävistä nurmista on Suomessa nurmiheinä-nurmipalkokasviseoksia, joiden satoa korjataan säilörehuksi. Yleisimmät käytetyt kasvilajit ovat timotei, nurminata ja puna-apila. Nurmiseosta suunniteltaessa on valittava sellaisia kasvilajeja ja – lajikkeita joiden kehitysrytmi on yhtä nopea ja ne pystyvät kilpailemaan kasvutilasta yhtä tehokkaasti Tämän tutkimuksen tavoitteena oli selvittää eri nurmiheinä-nurmipalkokasviseosten botaanista koostumusta yhdellä kasvukaudella. Lisäksi tavoitteena oli vertailla kahden tai monilajisten seosten sadon määrää eri niittokerroilla. Siemenseokset sisälsivät timoteita, nurminataa, ruokonataa, englanninraiheinää, niittynurmikkaa, puna-apilaa, valkoapilaa ja sinimailasta eri suhteissa. Seoksia oli kymmenen erilaista ja yksi koejäsenistä sisälsi puh-dasta timoteita. Koe toteutettiin K-maatalouden koetilalla Hauholla vuonna 2015 satunnaistettuna ruutu-kokeena. Botaanista analyysia varten otettiin kasvustonäytteet jokaiselta ruudulta ennen niittoja. Näytteistä eroteltiin seokseen kuuluvat kasvilajit. Ennen niittoa seurattiin eri kas-vilajien kasvun kehitystä. Lisäksi jokaiselta ruudulta laskettiin kuiva-ainesato, jota käytet-tiin seosten keskinäisessä vertailussa. Timoteilajikkeet säilyivät parhaiten kahden ja kolmen kasvilajin seoksissa, kun taas use-amman kasvilajin seoksissa sen osuus aleni kaikissa sadoissa. Nurminadat ja englannin-raiheinä olivat 3-4 vuorokautta pidemmällä kasvukehityksessä kuin timoteit. Englannin-raiheinä menestyi nurmipalkokasvia sisältävässä seoksessa, mutta vielä paremmin se me-nestyi heinävaltaisessa seoksessa. Seoskasvustojen kuiva-ainesato oli suurimmillaan en-simmäisessä sadossa. Suurimman sadon ensimmäisessä sadonkorjuussa tuotti kahden kas-vilajin seos ja pienimmän kuuden kasvilajin seos. Kolmannessa sadonkorjuussa nurmipal-kokasvit ja monilajiset seokset lisäsivät sadon määrää seoksessa. Timotein osuus oli vaihteleva, varsinkin useamman kasvilajin seoksissa, silti timotei säilyi seoksissa. Englanninraiheinän hyvä niiton jälkeinen jälkikasvukyky auttaa lisäämään sadon määrää toisessa ja kolmannessa niitossa. Nurmipalkokasvien avulla voidaan lisätä kolmannen sadon määrää.
  • Nykänen, Harri (Helsingin yliopisto, 2016)
    Nowadays, the companies all over the world have increased the importance of customer measurement. However, in most cases, the measuring methods are only concentrating on the customer satisfaction. Furthermore, those companies are also developing services and products, in hopes of improving the satisfaction of their customers. Although these developments are aiming a customer orientated business, it is difficult to make profit if expanded the services and products are not projecting the final price and the customer profitability. The constant adaption of the needs of every customer leads to very inefficient result and a low productivity which won’t generate in the best possible outcome. This thesis is concentrating on the first part of the managing customer profitability, measuring how much each customer segment is using resources from the company. That is put into perspective on how much each customer segment is profitable. When both incomes and costs can be targeted to each customer group, the customer profitability can be measured. Furthermore, the customer satisfaction is compared to how much one has used resources from the company. When the company has knowledge on how to satisfy their customers, it can develop this satisfaction and additional operations can be terminated. This will improve the efficiency and productivity, leading to a better profitability. This is a public version of the final work where all confidential information concerning actual business figures has been removed.
  • Carlson, Mari (Helsingin yliopisto, 2016)
    Economic integration refers to the theoretical background which is based on the functioning of regional trade agree-ments (RTAs). Trade in context of economic integration embodies special characteristics in comparison to classical free trade. The special characteristics are contested whether they are welfare enhancing or diverting. RTAs are trade agree-ments between two or more countries and their number has been increasing during the last decades. Such agreements play an important role in international agro-food trade as already over 50% of agricultural products are traded within or between RTAs. The increase in number of RTAs and wider inclusion of agricultural trade in these agreements have revealed new agricultural trade policy measures which distort trade in agro-food products. These are so called non-tariff measures of which this study focuses on sanitary and phytosanitary (SPS) measures. The legitimate intention of such measures is to protect plant, animal and human health and prevent the spreading of harmful pathogens through international trade. This study attempted to create a theoretical framework for analysis of trade effects caused by SPS measures. The ef-fects were found to depend first of all on the burden of compliance and the nature of a SPS measure. Burden of com-pliance was divided into three dimensions of specific, uniform or universal measures according to whom the costs are due. For the nature of the SPS measures three categories were identified: cost-increasing, quantity-restricting and combining SPS measures. The developed theoretical framework was applied to analyze the case of poultry meat trade between the EU and the US in a case where the SPS measure becomes ineffective. The SPS measure of pathogen reduction treatments (PRTs) applied by the EU was identified as a combining measure. After having analyzed the trade effects in partial equilibrium framework, the changes in economic welfare for the EU poultry meat market were quanti-fied. The quantification of the economic welfare measures was made by using partial equilibrium comparative static analysis combined with Marshallian economic surplus framework. Economic surplus measures were calculated by comparing the initial welfare levels with the corresponding levels after the policy change. The analysis concentrated on short-term effects and the base year used was 2013. The calculations proceeded by defining supply and demand equations to calculate equilibrium price and quantity in the present policy regime which enabled calculations of consumer and pro-ducer surpluses. Then, the new trade policy regime was introduced by manipulating producer price. Equations defined in the first stage were used to calculate new quantities for production and consumption in the EU. Then, consumer and producer surpluses were calculated in the new trade policy regime. Finally the obtained results were compared with each other. The results of the welfare analysis show that the SPS measure concerning the use of PRTs in poultry meat has impact on producer and consumer welfare in the EU. Consumer welfare increased after the SPS measure became ineffective. The explanation is the decrease in price which lead to increase in consumption. However, producer welfare decreased as a consequence of lower price. The production of poultry meat decreased which meant that the gap between the EU production and consumption increased. This indicated that the import demand for poultry meat increased for the EU. If the imports were not restricted from the US, consumers would be able to obtain the higher welfare level than before the change in policy regime.
  • Ahola-Iivarinen, Elina (Helsingin yliopisto, 2016)
    Tiedekunta/Osasto Fakultet/Sektion – Faculty Faculty of Agriculture and Forestry Laitos/Institution– Department Department of Food and Environmental Sciences Tekijä/Författare – Author Elina Ahola-Iivarinen Työn nimi / Arbetets titel – Title The characteristics of unmodified glucan solutions and their film forming abilities Oppiaine /Läroämne – Subject Food Technology (General Food Technology) Työn laji/Arbetets art – Level M. Sc. Thesis Aika/Datum – Month and year December 2016 Sivumäärä/ Sidoantal – Number of pages 57 Tiivistelmä/Referat – Abstract In the literature review of this study, the focus was on biofilms that certain microbes produce, and their potential use in food industry. Biofilms consist of microbial cells and extracellular products, e.g., polysaccharides. Pullulan as an exopolysaccharide has many industrial applications and the aim of this study was to explore a new potential alpha-glucan, dextran, and especially its ability to form a stand-alone film. Pullulan and dextran were separately mixed in de-ionized water. The dynamic viscosities of dextran and pullulan solutions were determined. Film formation of dextran was not successful, not even with sorbitol as a plasticizer. The optical properties, water vapor and oxygen permeabilities and tensile strengths of pullulan films were studied. Additionally, Whatman42-filter material was coated with or immersed in dextran solution. Hence the changes in tensile strength and permeability values between a well-known material and dextran treated material could be detected. Pullulan films had low haze values (2.1–3.9%) and they were transparent to UVA-, UVB- and visible light. The tensile strength values of pullulan films were 47–53 MPa. For filter paper, the corresponding values were 10 MPa and application of dextran coating increased it to 15–19 MPa. All polysaccharide solutions exhibited Newtonian behavior and their relative viscosities were <10 mPa, 5% pullulan with viscosity around 20 mPa as an exception. Pullulan solutions had higher viscosities than dextran solutions. The air permeabilities were 10–50 ml/min for pullulan films, 10 ml/min for dextran-sorbitol film, 200 ml/min for dextran film and 200–500 ml/min for Whatman42 material. The oxygen permeability values for pullulan films were <0,1 cm3·μm m-2·d-1·kPa-1. Based on results in this study, pullulan films are impermeable to oxygen. As the films tolerated water vapor poorly, pullulan might be a potential component in packages made of composite materials, as individual packaging material in dry environment or possibly chemically modified to obtain better resistance to water vapor. Our results show that without additional modifications dextran does not form a continuous self-supporting films in these conditions. Säilytyspaikka – Förvaringställe – Where deposited The Digital Repository of University of Helsinki, Helda Muita tietoja – Övriga uppgifter – Additional information EKT Series 1765
  • Tamrakar, Anisha (Helsingin yliopisto, 2016)
    Cyanobacteria are well known for their ability to produce wide variety of natural products, many of which exhibit antimicrobial, antifungal, antiviral or anticancer properties. These products include peptides, polyketides, alkaloid and polysaccharides. Cyanobacteria are also infamous for its toxic blooms, which are health hazardous to human, as well as animals. In this study, new benthic cyanobacterial strains were isolated from the Varlaxudden Seashore, Porvoo, Finland. The strains were purified and identified using microscopy. In addition, Finnish cyanobacterial strains (UHCC) and Brazilian strains (CENA) were screened for bioactive compounds. The 16S rRNA gene from UHCC and CENA strains were sequenced and used for the strain identification as well as to determine phylogenetic relationships. Bioactivities of strains were tested by disk diffusion assay followed by LC-MS and HPLC analysis to detect bioactivity as well as the bioactive compounds. The isolation of strains from 48 samples resulted in 48 morphologically identified cyanobacterial strains; 36 of them were Calothrix, 5 Anabaena, 4 Nostoc and one each of Tolypothrix, Scytonema and Cyanotheca genera. Four of the Calothrix strains (VAR 5/1, VAR 20/2, VAR 30/2 and VAR 43) were successfully made axenic. The UHCC and CENA strains included in this study belonged to two different habitats and regions (temperate and tropical) and a huge diversity between the strains were observed in the phylogenetic tree. A total of 12 of the studied cyanobacterial strains exhibited antifungal and antibacterial activities. A new peptide was observed from Nostoc sp. Brazil Punan but isolation was not successful. Three Nostoc strains produced hassallidins. Nostoc sp. SMIX 1 produced an antifungal compound, puwainaphycins which included two old and four new variants. The study also revealed cyanobacterial strains showing bioactivities but the bioactive compounds remained unidentified. So, further analyses are still needed for isolation and characterization of the unidentified compounds. Therefore, this study shows that cyanobacteria are prolific source of bioactive compounds and also potential leads for drug discovery.
  • Hjelt, Anniina (Helsingin yliopisto, 2016)
    Stickiness of food powders is a major issue in food industry because it causes problems during processing and it deteriorates the perceptible quality. The literature review presents different stickiness testing methods and the reasons and mechanisms for stickiness. The aim of the experimental work was to investigate stickiness of milk powders. Five different spray-dried milk powders were studied. Powders were characterized by measuring the moisture content, water activity, particle size composition, surface fatty acid composition and water sorption. Stickiness was investigated with a viscometer and with penetration test. Glass transition temperatures (Tg) were also determined. The results were analyzed with the PLSR (Partial Least Squares Regression). LF WMP contained much more surface fatty acids (42.7 mg/g) than WMP (12.4 mg/g) though the bulk fat content was same in both powders. According to the BET-sorption models, lactose-free powders adsorpt more water than conventional powders. The glass transition temperatures were much higher in lactose-containing powders (RH 0 %, 84–87 °C) than in the lactose-free powders (RH 0 %, 32–40 °C). Fat content did not affect the Tg because fat is not a water adsorbing component. Critical relative humidity is for lactose-free powders from 6 to 10 % and for lactose containing powders 40 to 42 % at room temperature (25 °C). Viscometric method was used to determine stickiness curves. Lactose-free samples became sticky at much lower temperatures than lactose-containing samples. When comparing the Tg and Tsp of skim milk powders, Tsp was 11–17 °C higher then Tg in SMP and in LF SMP the difference was 34–51 °C. In the PLSR model the coefficient of determination R2 was 90.3 %, adjusted coefficient of determination R2 adj. was 80.7 % and the coefficient of prediction Q2 was 59.9 %. Only lactose content was important according to the variables important in projection (VIP) in the PLSR model. The experimental work indicated that viscometric method is an applicable way to determine powder stickiness curve. Glass transition temperature determination is also reasonable way to predict powders stickiness and sticky point temperature is slightly above the Tg. The study showed that sugar content affected more to stickiness than fat content.
  • Vainio, Mika (Helsingin yliopisto, 2016)
    The literature review dealed with fat replacers in frankfurters. Manufacturing, properties and usages of microcrystalline cellulose were described. Also other fat replacers that are at the moment in use are described, such as hydrocolloids and proteins from vegetable. The literature review also described different methods that have been used to measure properties of frankfurters. The aim of the experimental work was to find out the influence of two different types of microcrystalline cellulose, Vivapur® 105(i) and Arbocel® M80(ii), on the properties of frankfurters, and can they been used as a fat replacer. Three different concentrations of microcrystalline cellulose (MCC) (1 %, 3 % and 5 %) Were studied and compared to the control sample. Measured properties of frankfurters were pH, water holding, cooking loss, firmness and bite force. Also amount of free water was measured with NMR. Although adding MCC decreased pH of frankfurter closer to the isoelectric point, it did not affect as lowering water holding. Both MCC(i) and MCC(ii) increased significantly (p<0,05) firmness of the frankfurters when measuring was made with warm samples, excluding MCC(i) 3 % concentration. Effect was not as visible in the measurements of bite force.
  • Kangas, Essi (Helsingin yliopisto, 2016)
    Ruokablogien lukemisen yleistymisen myötä blogeista on tullut tärkeä tuotetiedon lähde. Tämän tutkimuksen tavoitteena on tutkia, miten ruokablogien lukeminen vaikuttaa ruokaan liitettävään ostokäyttäytymiseen. Tarkoituksena on selvittää erityisesti, miten ruokablogien sisältämä sähköinen kuulopuhe (eWOM) vaikuttaa ruokablogissa mainittujen tuotteiden ostouseuteen yhdistämällä aikaisemmista eWOM-tutkimuksista saatua tietoa. Ruokablogien lukemisen vaikutuksen tutkimisessa käytettiin hyväksi aikaisempia eWOMia koskevia tutkimuksia sekä Kotlerin ja Armstrongin (2006) kuluttajan ostopäätösprosessia. Tutkimuksen empiirisessä osassa hyödynnettiin kvantitatiivista tutkimusotetta E-lomakkeella toteutetulla survey-kyselyllä. Kvantitatiivinen tutkimusote mahdollisti tutkimuskysymysten tarkastelun suuremmalla otoksella. Tutkimuksen perusjoukkona olivat Helsingin yliopiston läsnä olevat opiskelijat, joilla oli tiedot opiskelijarekisterin tietokannassa. Ruokablogien sisältämän eWOMin vaikutusta ostokäyttäytymiseen arvioitiin tutkimusta varten kehitetyllä eWOM-mittaristolla, joka luotiin faktorianalyysien perusteella. Faktorianalyysin pohjalta muodostettujen summamuuttujien vaikutusta ruokablogissa mainittujen tuotteiden ostouseuteen analysoitiin varianssianalyysillä. Taustatekijöiden analysoinnissa käytettiin ristiintaulukointia jakauma- ja frekvenssitarkastelujen lisäksi. Ruokablogien lukemisen yleisimpiä tarkoituksia olivat ruokablogit reseptien, inspiraation ja tiedonlähteenä. Yleisimmin ruokablogista saatavaa tietoa olivat tieto resepteistä, tuotteista ja niiden käyttötavoista sekä tieto muiden kokemuksista. Ostouseusryhmien ääripäiden välillä todettiin olevat tilastollisesti merkitsevää eroa ruokablogin lukemisen useuden suhteen. Ruokablogien lukemisen sekä tuotearvosteluiden ja -suositusten vaikutus ostoaikomukseen erosivat tilastollisesti merkitsevästi kaikkien ostouseusryhmien välillä ja vaikutukset ostouseuteen olivat suuret. Lukijakommenttien vaikutus ostoaikomukseen erosi tilastollisesti merkitsevästi ei kertaakaan ruokablogista tuttua tuotetta ostaneiden sekä ei kertaakaan ostaneiden ja vähintään kolme kertaa ostaneiden välillä ja vaikutus ostouseuteen oli keskisuuri. Tutkimuksessa havaittiin, että lukijat kokevat tuotearvostelut ja -suositukset eri tavalla kuin lukijakommentit, mutta molemmilla tekijöillä on vaikutusta ruokablogissa mainittujen tuotteiden ostouseuteen.
  • Zhang, Angel (Helsingin yliopisto, 2016)
    The enzymatic degradation of plant cell walls has being extensively explored during the past decade chiefly due to the current and potential uses of plant biomass found in several industries. In this process, the effective removal of the hemicellulosic portion is of paramount importance. For this purpose, hemicellulases have been intensively studied and produced from bacterial and fungal sources. Within this group of enzymes, mannanases, which are mostly used during the processing of softwood, have been found in several industrial applications. Currently, white rot basidiomycetes have gained increasing attention due to their ability to fully decompose wood. One of these fungi, Dichomitus squalens, has been regarded as an effective wood degrader; nonetheless, its enzymatic arsenal and catalytic potential have only recently been explored. In the present study, six mannan acting enzymes were selected from the genome of D. squalens and heterologously produced using the methylotrophic yeast Pichia pastoris. Four of these enzymes, consisting of two β-1,4-endomannanases, one β-1,4-mannosidase and one α-galactosidase, were successfully produced. The biochemical characterization of the concentrated enzymes using synthetic p-nitrophenyl substrates corresponding to their predicted activities showed optimal pH ranging from 3 to 5 and optimal temperatures ranging from 50 to 60 °C. In addition, three of the enzymes, namely MAN1, MND1 and GAL2, showed high thermostability retaining the majority of their enzyme activities after an incubation of 60 minutes at 60 °C. In contrast, MAN2 lost all of its activity after an incubation of 30 minutes at 60 °C. Furthermore, MAN1 and GAL2 showed optimal enzyme activities of 1922.2 (± 26.6) and 903.7 (± 7.4) U/mL respectively, with specific activities of 11.1 (± 1.0) and 27.9 (± 0.5) U/mg respectively. The four enzymes had a molecular mass ranging from 47 to 110 kDa, without showing evidence that any of them formed dimers or more complex structures. The results of the present study revealed the function of four putative mannan degrading enzymes from D. squalens and provided evidence of its mannolytic capacity. Future studies with other cell wall degrading enzymes or the synergistic effects of characterized enzymes of this species may further reveal its potential as a source of industrial enzymes.
  • Tonteri, Elina (Helsingin yliopisto, 2016)
    Johdanto: Kohonnut verenpaine lisää riskiä sairastua sydän- ja verisuonitauteihin ja se on maailmanlaajuisesti merkittävin yksittäinen terveitä elinvuosia vähentävä riskitekijä. Verenpaineeseen vaikuttavat sekä perinnölliset tekijät että ympäristötekijät, kuten ravinto. Kaakaon sisältämillä flavonoideilla, flavanoleilla, saattaa olla edullinen vaikutus verenpaineeseen. Useissa kokeellisissa tutkimuksissa kaakaon ja tumman suklaan on havaittu alentavan verenpainetta. Monet aiheesta tehdyt tutkimukset ovat kuitenkin olleet kestoltaan melko lyhyitä. Tavoite: Tämän tutkimuksen tarkoituksena oli selvittää, onko tumman suklaan säännöllisellä nauttimisella (49 g/vrk) 8 viikon ajan vaikutusta verenpaineeseen henkilöillä, joiden verenpaine on lievästi koholla, kun suklaalla korvataan tavanomaisia välipaloja. Kontrollijaksolla tutkittavat vähensivät välipalojaan 49 g tummaa suklaata vastaavan energiamäärän verran, mutta eivät saaneet mitään vähentämiensä välipalojen tilalle. Aineisto ja menetelmät: Tutkittavat (n=22) olivat iältään 33 - 64 vuotiaita miehiä ja naisia, joiden verenpaine oli lievästi koholla. Tutkimusasetelma oli satunnaistettu vaihtovuorokoe. Tutkittavilla oli kaksi 8 viikon koejaksoa: suklaa- ja kontrollijakso. Suklaajaksolla tutkittavat nauttivat 49 g suklaata/vrk ja vähensivät välipalojaan suklaan sisältämän energiamäärän verran. Kontrollijaksolla tutkittavat ainoastaan vähensivät välipalojaan, mutta eivät saaneet mitään tilalle. Toistettujen mittausten varianssianalyysin avulla selvitettiin, oliko systolisen tai diastolisen verenpaineen muutoksessa tai tutkittavien painon muutoksessa eroa suklaa- ja kontrollijakson välillä. Kovariaatteina huomioitiin alkuverenpaine, alkupaino sekä natriumin ja kaliumin saanti. Tulokset: Tummalla suklaalla ei ollut vaikutusta tutkittavien verenpaineeseen. Suklaajakson alussa tutkittavien systolinen/diastolinen verenpaine oli 141,6 ± 11,5/ 89,5 ± 8,4 mmHg ja lopussa 141,8 ± 14,2/ 88,5 ± 9,4 mmHg. Kontrollijaksolla tutkittavien paino laski keskimäärin yhden kilon, mutta suklaajaksolla tutkittavien painossa ei havaittu muutosta. Ero painon muutoksessa kontrolli- ja suklaajakson välillä oli tilastollisesti merkitsevä (p = 0,027). Johtopäätökset: Tämän tutkimuksen perusteella välipalojen korvaaminen tummalla suklaalla päivittäin 8 viikon ajan ei vaikuta verenpaineeseen henkilöillä, joiden verenpaine on lievästi koholla.