Browsing by discipline "Elintarvikekemia"
Now showing items 41-60 of 71
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(2015)Biofilms constitute a successful protection mechanism for planktonic bacterial cells to survive in hostile environments. To date, biofilm-associated infections in medical devices represent a major cause of morbidity and mortality among patients. As a potential candidate for anti-biofilm therapy, fungal hydrophobins provide new solutions to manipulate the physical and chemical properties of surfaces, which in turn may give protection against bacterial colonization. However, in practice, native hydrophobin coatings generally have no impact on bacterial surface colonization, because of the lack of being antibacterial by these fungal proteins themselves. The aim of this study was to explore the feasibility of using recombinant fusion hydrophobins to control bacterial growth. In this study, the class I hydrophobin hgfI gene isolated from the edible mushroom Grifola frondosa was in frame fused with two antimicrobial peptide genes (bac8c and p11-5), respectively, and subsequently cloned into the corresponding expression vectors with a view to obtain two recombinant fusion hydrophobins, Bac8c-HGFI and P11-5-linker-HGFI. These two chimeric genes were separately expressed in Pichia pastoris under the regulation of alcohol oxidase 1 promoter. SDS-PAGE and immunoblot analyses confirmed that these two fusion proteins were successfully expressed and secreted into the culture medium. Minimum inhibitory concentration (MIC) test demonstrated that the highly active antimicrobial peptide Bac8c became inactivated when it was fused with the hydrophobin HGFI. Interestingly, the hydrophobin HGFI gained an acquired antibacterial nature when it was fused with the antimicrobial peptide P11-5 through a 10-mer flexible polypeptide linker, with the MIC of 100 μg/ml against Escherichia coli. To the best of my knowledge, this study presents the first heterologous expression of an antibacterial fusion hydrophobin in P. pastoris. This finding in combination with surface modification mediated by hydrophobin may broaden the current approaches used for anti-biofilm therapies.
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(2014)Tämän tutkielman tarkoituksena oli validoida natriummääritysmenetelmä Tullilaboratorion käyttöön elintarvikkeiden suolapitoisuuden määrittämiseen. Uuden lainsäädännön mukaan elintarvikkeen suolapitoisuus tulee määrittää natriumpitoisuuden kautta, jolloin suolapitoisuuden analyysitekniikka muuttui kloridimäärityksestä natriummääritykseksi. Kirjallisuustutkimuksessa käsiteltiin natriumin ja suolan esiintymistä, merkitystä elintarvikkeissa ja merkitystä ihmisen terveyteen sekä sen lainsäädäntöä. Myös natriummääritysmenetelmiä tarkasteltiin, mutta pääasiassa keskityttiin ICP-OES-tekniikkaan. Kokeellisessa tutkimuksessa menetelmän validoinnissa käytettiin kahta eri varmennettua vertailunäytettä (BCR-383®, papujauhe ja ERM-BD150®, maitojauhe). Lisäksi menetelmää testattiin kahdella FAPAS-näytteellä (säilykeliha-ateria ja omenamehu). Näyte märkäpoltettiin vahvassa hapossa (69 % typpihappoa ja 30 % vetyperoksidia) ja laimennettiin 1 %:seksi typpihapoksi. Näyte analysoitiin ICP-OES-tekniikalla, jossa huuhteluliuoksena käytettiin myös 1-prosenttista typpihappoa. Menetelmän validoitavia parametreja olivat spesifisyys, herkkyys, lineaarisuus ja tarkkuus. Lisäksi määritettiin mittausalue, toteamisraja ja määritysraja ja menetelmän epävarmuus. Näytteiden tuloksia verrattiin vielä vertailuarvoon ja näytteille laskettiin z-arvot. Menetelmä oli tarkka, sen määritysrajaksi muodostui 2,5 mg/100 g. Menetelmän laajennetuksi epävarmuudeksi saatiin kaksi arvoa; 29 % pienille natriumpitoisuuksille ja 5-12 % suurille natriumpitoisuuksille (lisätty suola). Kaikkien menetelmässä käytettyjen näytteiden z-arvot vaihtelivat välillä 0,3-2,1. Menetelmä testattiin toimivaksi ja sitä tullaan jatkossa käyttämään elintarvikkeiden suolapitoisuusmäärityksissä Tullilaboratoriossa. Menetelmä myös akkreditoidaan syksyn 2014 aikana.
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(2019)Finding new plant-based protein sources is important from a sustainable development perspective. Ethanol and starch production from barley results in fiber and protein side-stream fractions that are currently utilized for animal feed. Nonetheless, it would be more profitable if the barley protein side-stream was used as a human food ingredient. The main storage proteins in barley are known as hordeins. They are polymeric proteins and have low solubility, due to their inter-chain and inter-molecular disulfide bridges and hydrophobic side-chains. In food technology applications protein solubility is an important property for emulsifying and foaming functionality. Proteins are sensitive to the surrounding environment, especially to pH, which could be used to alter the solubility. In this thesis the literature review examined barley (Hordeum vulgare) proteins, especially the hordeins, functionality and effect on food materials. The review includes previous studies concerning cereal proteins functionality in general and their effect on food materials and a discussion on protein stabilized emulsions. The aim of the study was to determine the protein composition of two barley protein concentrates, OP1 and OP2, and to evaluate protein solubility and emulsifying properties. Furthermore, the aim of the study was to compare the functionality of the concentrates. According to SDS gel electrophoresis the protein concentrates consisted mostly of hordeins, especially C-hordein and some B-hordein. Minor amounts of other proteins where also identified. The protein solubility was determined by Lowry’s method. The proteins were more soluble in sodium phosphate buffer than in deionized water. In sodium phosphate buffer at pH 3,8 the solubility of OP1 proteins was 100 mg/g ± 11 mg/g and in deionized water at pH 3,9 the solubility was 45 mg/g ± 1,1 mg/g. The solubility of the OP2 proteins in sodium phosphate buffer at pH 3,8 was 47 mg/g ± 1,5 mg/g and in deionized water at pH 3,7 the solubility was 45 mg/g ± 1,1 mg/g. In both samples the proteins solubility increased as the pH increased. Most proteins were solubilized at pH 11: the solubility for OP1 and OP2 proteins were 240 mg/g ± 11 mg/g and 140 mg/g ± 12 mg/g respectively, which is problematic regarding food products, but could be used as a treatment to improve solubility. The smallest oil droplets were formed in emulsions were the pH was adjusted to 7 with sodium phosphate buffer. The stability of emulsions was however poor in all samples because of phase separation, which was already significant after one day of storage. The phase separation was considered to be flocculation which finally resulted in creaming or sedimentation. The flocculation may have occurred due to hydrophobic interactions between the proteins on the oil/water interface. However, shaking of the emulsion causes the flocculated oil droplets to separate, forming an even emulsion. No coalescence was observed in all samples, except for OP1-emulsions with 1 % (w/v) dry matter. These results confirm that these protein concentrates can be used in food products, especially in milk type drinks that need to be shaken before usage.
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(2016)The aim of this thesis was to define optimal packaging conditions for four fresh ready-to-cook and pre-cut vegetable mixes. The packaging conditions consisted of perforated and non-perforated film which were investigated in two different gas mixtures. One of the gas mixtures consisted of modified atmosphere which was chosen in advance and the other gas mixture consisted of normal atmosphere. The literature study focused on the negative influences of processing methods on the physiological properties of vegetables. The main principles of packaging solutions by which negative influences of fresh-cut produce could be minimized with were also mentioned. The main target of the experimental study was to examine if perforated films could be used for avoiding of in-package anaerobic respiration which is a common reason for vegetable spoilage. The respiration rates of the products were measured and with the results an optimally perforated film was defined for each product. The gas concentrations were measured electronically and the quality of the products were evaluated with sensory evaluations and microbiological determinations. Electronically measured gas concentrations were verified gas chromatographically and also the water vapour transmission properties of the films were studied. With perforated film and modified atmosphere gas concentrations remained most constant and they were mainly held in aerobic respiration level. With other packaging solutions very low oxygen levels and very high carbon dioxide levels were observed which was also noticed in the sensory evaluations where off-odours and off-flavours were discovered. With perforated film and modified atmosphere the growth of yeasts, molds and bacteria was smaller than with perforated film and normal atmosphere. The verification of the gas measurements was successful and gas concentrations which were measured both electronically and gas chromatographically were on the same range though minor differences in the accuracy of the results were discovered. The most optimal packaging solution for tested products was achieved with perforated film and modified atmosphere.
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(2015)Sterols and their conjugates are minor natural constituents in oils and fats. Plant sterols are also enriched in functional foods because of their known ability to lower serum cholesterol levels. Like other unsaturated lipids, sterols are prone to oxidize. In the literature review, thermo-oxidation reactions of free and esterified sterols were introduced and methods for the analysis of the formed products were summarized. The aim of the experimental research was to study the oxidation reactions of steryl esters. The oxidation reactions were studied at two temperatures, at 100 ºC and 180 ºC, by following the changes in the profiles of oxidation products varying in polarity and molecular size. The effects of esterification, unsaturation level of the acyl moiety in the sterol structure and temperature were studied. Solid-phase extraction (SiOH-SPE) and size-exclusion chromatography (SEC-RI) were applied for the separation and quantification of monomeric and oligomeric oxidation products. Silver coordination ion spray mass spectrometry (Ag+-CIS-MS) was applied to indicate mass ranges of the formed oxidation products. In the oxidation, sterol molecules first reacted with oxygen and then the formed monomeric oxidation products began to link with each other forming oligomers. Oligomers contributed to 17-90% and 23-78% of the oxidation products of steryl esters after 3 days and 2 hours of heating at 100 ºC and 180 ºC, respectively. Polar oligomers were the most abundant fraction at both temperatures. Non-polar oligomers were not formed in the oxidation of steryl esters. Increased unsaturation of the acyl moiety increased polymerization. Increased temperature changed the oxidation reactions and mid-polar oligomers became more dominant. Thermal reactions led to the loss of hydroxyl groups and hence the polarity of oligomers decreased. The molecular weight ranges of the most abundant oligomers and their fragments were m/z 900-1100 and 1300-1500 at 100 ºC. In conclusion, the oxidation of steryl esters begins by reactions with molecular oxygen after which the formed oxidation products begin to polymerize. This occurs both at auto-oxidation and thermo-oxidation conditions; i.e., at cooking and frying temperatures.
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(2018)Tiivistelmä/Referat – Abstract In food matrices usage of legumes is challenging due to formation of volatile compounds during storage and processing. These volatile compounds form beany flavors, which cause sensory problems in food matrices. Because the formation of volatile compounds in legume matrices is quite quick, it is supposed that enzymatic oxidation is significant when lipids are oxidized in legume matrices. The literature review of this thesis focused on the mechanisms of lipid oxidation in plants, enzymes and formation of volatile compounds in food matrices. The aim of the experimental part was to investigate how volatile compounds are formed from different faba bean and lupine cultivars by endogenic enzymes using different lipid substrates. The activity of lipoxygenase and incubation conditions were optimized at first and those conditions were used to analyse the actual samples. The main legume matrix in this study was faba bean (4 cultivars) and two lupine cultivars were also investigated. The selected legumes were pretreated by grinding the dried pods of legumes in certain particle size. Legume flours were mixed with water to prepare slurries to extract the endogenic enzymes of legume matrices. Due to lipoxygenase’s significant role in enzymatic oxidation of lipids the optimum pH-level of lipoxygenase was determined by using UV/VIS-spectrophotometer. The optimum pH-level for lipoxygenase was found at the pH 6. Optimization and formation of volatile compounds was determined by using HS-SPME-GC-MS-method. In addition, the activity of lipase and product specificity of lipoxygenase (formation of hydroperoxides) were determined. In both legume matrices the pH-optimum of lipoxygenase was at 6 and all the actual samples were measured at that pH. Quantitatively and qualitatively the widest spectrum of volatile compounds was formed when using linoleic acid as a substrate. The spectrum of volatile compounds included different alcohols, ketones, aldehydes and furans. The amounts of hexanal were at the highest when using linoleic acid as a substrate and the lowest when using α-linolenic acid as a substrate. When using trilinolein and rapeseed oil as substrates aldehydes and ketones were the only volatile compounds which were formed. Saponification of rapeseed oil improved the formation of the volatile compounds. In addition, from the saponified rapeseed oil a wider spectrum of volatile compounds were formed when compared to untreated rapeseed oil. The lipoxygenases of faba bean and lupine were shown to form different types of hydroperoxides from linoleic acid: the faba bean produced more 13-hydroperoxides than 9-hydroperoxides and lupine produced only 13-hydroperoxides. Used method when measuring the formation of free fatty acids of legume matrices did not revealed the activity of lipase. On the other hand, this result only tells that lipase activity couldn’t be measured by using this particular method and other methods could reveal lipase activity on those legume matrices. Both of the legume matrices formed different kinds of volatile compounds from different lipid substrates in certain reaction conditions. When those volatile compounds are formed in foods containing legume matrices they lower the sensory value of those foods. The formation volatile compounds in food matrices containing legumes is very plausible due to food matrices pH-level (many of them are at neutral) and usage of suitable lipid substrates and reaction conditions. Inactivation of enzymes can be obtained for example by heating, which could at the same time lower the nutritional value of foods.
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(2019)D-vitamiini on välttämätön rasvaliukoinen vitamiini, jonka tärkeimpiä fysiologisia tehtäviä on muun muassa ylläpitää veren kalsiumpitoisuutta ja vaikuttaa luuston vahvuuteen. Pääasiassa D-vitamiinia saadaan auringon valon avulla, kun ihon 7-dehydrokolesterolia syntetisoidaan kolekalsiferoliksi (D3-vitamiiniksi). Lisäksi D-vitamiinia saadaan myös ravinnosta. Kolekalsiferolia esiintyy eläinkunnan tuotteissa kuten eri kalalajeissa ja kananmunan keltuaisessa ja toista yleisintä D-vitamiinimuotoa, ergokalsiferolia (D2-vitamiinia), esiintyy sienissä. D-vitamiinipitoisuudet elintarvikkeissa ovat kuitenkin erittäin pieniä, ja se luo haasteita D-vitamiinianalytiikalle. Tämän tutkimuksen tavoitteena oli kehittää aiempia menetelmiä herkempi ja nopeampi tapa määrittää D3-vitamiinipitoisuuksia kaloista, kun yleisesti D-vitamiinianalytiikassa käytössä olevaan nestekromatografiin yhdistetään massaspektrometri. Samalla tässä tutkimuksessa oli tarkoitus selvittää perimän vaikutusta kirjolohien vaihteleviin kolekalsiferolipitoisuuksiin. Tutkimus toteutettiin Luonnonvarakeskuksen (Luke) toimeksi antamana. Tutkittavana oli sekä saman perimän omaavia kirjolohia että verrokki kirjolohia, joiden perimässä oli vaihtelua. Menetelmässä käytettiin yleisesti D-vitamiinianalytiikassa käytössä olevia esikäsittelymenetelmiä: saippuointia, uuttoa ja kiinteäfaasiuuttoa. Tarkoituksena oli kehittää määritysmenetelmä kvadrupolilentoaika-massaspektrometrille, mutta koska herkkyys tällä laitteella ei riittänyt näin pienille pitoisuuksille, jatkettiin menetelmän kehitystä kolmoiskvadrupolimassa-analysaattorilla. Näin saatiin määritettyä kirjolohien kolekalsiferolipitoisuudet, kun käytössä oli APCI-ionisaatiolähde ja MRM-menetelmä massa-analysaattorin pilkkoutumisreaktioissa. Kolmoiskvadrupolille kehitetyllä määritysmenetelmällä saatiin erinomainen toistettavuus. Tutkittujen kirjolohien kolekalsiferolipitoisuus oli noin 3 µg/100 g, mikä vastaa muiden tutkimusten tulostasoa. Vaihtelua eri kirjolohiryhmien välillä ei huomattu, mutta koska näytemäärä jäi tutkimuksessa melko pieneksi, on vaikea tehdä varmaa johtopäätöstä siitä, ettei perimällä olisi vaikutusta kirjolohien D3-pitoisuuksiin. Vaikka kolekalsiferolipitoisuudet saatiin hyvin määritettyä kirjolohinäytteistä, on menetelmässä vielä kehitettävää. Isot vaihtelut rinnakkaisissa sekä matalat takaisinsaantoprosentit viittaavat siihen, että kirjolohi näytematriisina on erittäin haastava. Esikäsittelyn eri vaiheisiin ja erityisesti kiinteäfaasiuuttoon tulisi vielä kiinnittää huomiota, jotta varmistettaisiin D-vitamiiniyhdisteiden kunnollinen eluoituminen ja näytteiden puhtaus niin, että näytemateriaalista tulevat häiriöt eivät vaikuttaisi määritykseen massaspektrometrillä.
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(2015)The literature review introduced properties of native cellulose and common water-soluble cellulose derivatives, pathways to develop antimicrobial packaging from cellulosic materials, mechanisms of existing antimicrobial packaging systems and characterization of antimicrobial films. Special emphasis was given to potential of cellulose betainates (CB) as inherently antimicrobial, low-toxic materials for development of antimicrobial films. The aim of this study was to investigate overall potential of CB as antimicrobial films. CB together with commercial cationic starch (CS) and chitosan (CH) added with different amounts of sorbitol were prepared into films by solution casting. Mechanical properties, moisture and oxygen barrier attributes, and microscopic characteristics of aforementioned films were determined. In addition, antimicrobial potential of CB were tested against Listeria innocua and Escherichia coli compared to CS and CH by agar diffusion assay for films and measurements on optical density at 600nm for aqueous polysaccharide solutions. CB forms self-standing films with relatively low mechanical strength and stiffness while possessing good flexibility and medium barrier properties against water vapor and oxygen. CB films is antimicrobial against E. coli but not against L. innocua according to agar diffusion assay. Based on growth inhibition ratio (GIR%) from solution-phase tests, L. innocua was also more resistant than E. coli against CB at concentrations below 512 µg/ml. CB exhibited similar antimicrobial activity to that of CH within 512–1280 µg/ml. However, an increase in viscosity of CB solution at higher concentration (2560 µg/ml) as well as excessive microorganism (~108cfu/ml) in initial inoculum led to decrease in their antimicrobial efficacy. In conclusion, CB is antimicrobial against E. coli in film, and potential to exert similar antimicrobial potency as that of chitosan in solution with adequate quantities. Therefore, CB is a promising candidate as for fabrication of antimicrobial films. However, the antimicrobial mechanism, antimicrobial spectrum of CB and the applicability of CB films require further explorations.
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(2018)Kirjallisuuskatsauksessa käsiteltiin yleisellä tasolla hyönteisten turvallisuutta elintarvikkeena, kotisirkan ja jauhomadon koostumusta sekä niiden proteiineja ja proteiinien toiminnallisia ominaisuuksia. Lisäksi kirjallisuusosassa käsiteltiin lyhyesti proteiinien ja rasvojen hapettumista tämän tutkimuksen näkökulmasta. Tutkimuksen tavoitteena oli tutkia prosessoinnin vaikutusta jauhomadon ja kotisirkan proteiinien hapettumiskäyttäytymiseen emulsiossa sekä vaikutusta lipidien hapettumiseen. Lisäksi tavoitteena oli optimoida kotisirkan ja jauhomadon proteiinien uuttomenetelmä. Proteiinien uuttoa optimoitiin eri menetelmillä ja parhaaksi uuttomenetelmäksi osoittautui molemmille hyönteisille uutto-olosuhteet, jossa uuttoliuoksen pH oli 10 ja NaCl -pitoisuus 0,1 M. Jauhomadon proteiinien uuttoon tarvittiin lisäksi rasvanpoisto ennen proteiinien uuttoa. Molempien hyönteisten proteiineja käsiteltiin lämmöllä (+60 °C) ja entsyymillä (transglutaminaasi). Lisäksi jauhomadon proteiinit käsiteltiin uuton yhteydessä sulfiitilla (Na2S2O5) ruskistumisen estämiseksi. Näistä kaikista käsitellyistä proteiineista sekä molempien hyönteisten käsittelemättömistä liukoisista proteiineista valmistettiin emulsiot, joiden hapettumista seurattiin mittausajankohtina 0, 1, 3 ja 7. Proteiinien hapettumista tutkittiin seuraamalla tryptofaanin hajoamista sekä karbonyylien ja dityrosiinin muodostumista fluoresenssispektroskopisella menetelmällä. Lipidien hapettumista tutkittiin seuraamalla konjugoitujen dieenien muodostumista spektrofotometrisesti. Emulsioiden ulkonäköä seurattiin hapettumiskokeen aikana ja emulsioiden partikkelikoko tutkittiin mittausajankohtana 0. Kotisirkan entsyymikäsitellyistä proteiineista valmistetussa emulsiossa proteiinien hapettumista oli havaittavissa, mutta lipidien hapettuminen oli vähäistä. Jauhomadon entsyymikäsitellyistä proteiineista ja kotisirkan lämpökäsitellyistä proteiineista valmistetuissa emulsiossa proteiinien ja lipidien hapettuminen oli vähäistä. Jauhomadon lämpökäsitellyistä proteiinista valmistetussa emulsiossa konjugoituja dieenejä muodostui enemmän kuin muihin näytteisiin. Tässä emulsiossa muodostui karbonyylejä, mutta tryptofaanin hajoamista ei ollut havaittavissa. Sulfiittikäsittely vaikutti altistavan jauhomadon proteiinit hapettumiselle emulsiossa.
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(2018)Kokeellisissa tutkimuksissa puolukkamehu on alentanut korkeaverenpaineisen rotan systolista verenpainetta, parantanut verisuonten endoteelin toimintaa sekä vaikuttanut suotuisasti matala-asteisen tulehduksen merkkiaineisiin. Tämän tutkielman kirjallisuusosassa selitettiin keskeisimmät verenpaineen säätelymekanismit, ja selvitettiin marjojen terveysvaikutuksia sekä niiden taustalla olevia fenolisia yhdisteitä. Kokeellisen osan tavoitteena oli selvittää puolukkamehun vaikutuksia verenpaineen nousun aiheuttamiin vaurioihin rottien munuaisissa. Korkeaverenpaineiset ja terveet normaalipaineiset rotat saivat juotavakseen puolukkamehua kahdeksan viikon ajan. Puolukkamehun vaikutuksia munuaisiin tutkittiin määrittämällä immunohistokemiallisesti verenpainetta säätelevän angiotensiinikonvertaasientsyymin (ACE1), endoteelin prostasykliiniä säätelevän syklo-oksigenaasi 1:n (COX1) ja DNA:n hapettumisesta kertovan 8-hydroksi-2-deoksiguanosiinin (8-OHdg) suhteelliset pitoisuudet munuaisissa. Lisäksi laskettiin veren keskipaine, plasman Na/K ja Na/Ca suhteet sekä virtsan Na/K. Puolukkamehu laski veren keskipainetta korkeaverenpaineisilla rotilla (p=0,007). Keskipaine ottaa huomioon myös diastolisen verenpaineen, mikä yksittäisenä arvona on epätarkka kuvaamaan vaikutusta verenpaineeseen. Kohonneen verenpaineen aiheuttamat muutokset munuaisissa jäivät vähäisiksi. Puolukkamehu ei vaikuttanut merkitsevästi munuaisten ACE1, COX1 ja 8-Ohdg -pitoisuuksiin korkeaverenpaineisilla rotilla eikä myöskään terveillä kontrolleilla. Puolukkamehu kuitenkin nosti COX1-pitoisuutta eläinmallista riippumatta, kun puolukkaryhmät yhdistettiin. ACE1 ja 8-OHdg -pitoisuuksiin ryhmien yhdistämisellä ei ollut vaikutusta. Tutkimus osoitti, että puolukkamehu alentaa korkeaverenpaineisten rottien keskiverenpainetta. Lisäksi puolukkamehu vaikuttaa suotuisasti prostasykliinien muodostumiseen mitattuna sitä tuottavan COX1-entsyymin suhteellisella määrällä munuaisten verisuonten endoteelissa. Puolukkamehu ei tämän tutkimuksen mukaan vaikuta munuaisten ACE1-entsyymin määrään, joten verenpaineen alenemisen taustalla on muita mekanismeja, kuten vaikutus verisuonia laajentavien prostasykliinien tuotantoon
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(2016)Olive oil is one of the most thoroughly analyzed vegetable oils. A lot of research has been done to examine the health effects of the consumption of olive oil. Also the authenticity of olive oil has been of major concern and has led to numerous research projects and investigation. The EU Commission´s regulation No. 1348/2013 determines the maximum acceptable levels of several components in all categories of olive oil. The most significant differences between refined olive oil and non-refined extra virgin olive oil (EVOO) appear to be in the natural UV-absorption at wavelength 270 nm and in stigmastadiene concentration, consequently, also in the maximum accepted levels of these two parameters. Cheaper refined olive oil and other vegetable oils are produced on a large scale which raises the risk of adulteration by cutting more valuable EVOO with refined vegetable oils. To detect the mixing of EVOO with refined vegetable oils, measuring the K₂₇₀-value and determining the stigmastadiene concentration seem to be very efficient methods. Both UV-absorption at wavelength 270 nm and the concentration of stigmastadiene appear to rise during the refining processes of lower class virgin oil (lampante) and also when refining vegetable oils. The aim of this master´s thesis work was to compare different methods and possible natural marker compounds in detecting the addition of refined vegetable oil in extra virgin olive oil. A thorough research was done to investigate the effects of mixing ordinary olive oil (OO), which consists of refined olive oils and virgin olive oils, with EVOO. Also mixtures of refined sunflower oil and EVOO were analyzed. The mixtures were then analyzed with GC-MS to determine the concentration of stigmastadiene. As the result, a mixture of 15–30 % of refined oil to EVOO raised the K₂₇₀-value above the regulation´s maximum accepted level of 0.22. Mixtures of 5 % of refined oil to EVOO raised the stigmastadiene concentration to levels of 0.09–0.27 mg kg⁻¹, thus clearly above the regulation´s maximum accepted level of 0.05 mg kg⁻¹. Both methods are relatively fast and non-laborious. They can be used as a combination to screen oils in order to detect possible adulteration and to proceed to further investigation when necessary.
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(2019)Sourdough baking is a process used for thousands of years and it’s still used to this day. Sourdough is a mixture of flour and water that has been fermented with lactic acid bacteria (LAB) and yeasts and it’s used to leaven the bread. Some of sourdough LAB produce exopolysaccharides (EPS) from sucrose in their metabolism. Dextran, which consists of α-(1→6) linked glucosyl units is the most common EPS. EPS produced by LAB have been widely studied to have different positive impacts on bread texture. The aim of this thesis was to screen the sourdough samples for EPS producing LAB and to analyze the structures of those EPS as accurately as possible. In the experimental part LAB were isolated from the sourdough samples and grown on MRS agar containing sucrose. All EPS forming colonies were then isolated from the plates and purified to obtain pure strains. The EPS produced by the strains were hydrolyzed enzymatically by dextranase and glucosidase after which their monosaccharides and enzyme resistant oligosaccharides were analyzed by HPAEC-PAD. The structures of the EPS were also analyzed with NMR. 13 EPS producing strains were isolated from the sourdough samples. Based on the HPAEC-PAD results all samples were found to be dextran because the enzymes were able to hydrolyze them. From the enzyme resistant oligosaccharide chromatograms it was seen that there were four different chromatographic profiles so there were four different EPS structures. NMR results confirmed that all EPS were dextrans. The NMR results also confirmed that there were four different structures among the EPS samples. All EPS had α-(1→3) linked branches. Two samples also had α-(1→2) linked branches. This research gave information about the EPS production by the sourdough’s LAB and also the structures of those EPS.
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(2020)Uusille elintarvikkeille tai niihin käytetyille uutuusvalmistusaineille on tuottajien määritettävä hyllyikä eli varastointiaika, jonka aikana tuotteessa ei tapahdu laadun muutoksia. Tuotteen hyllyikä on lyhyempi kuin todellinen laadunheikkenemisaika, koska pienestäkin laadun muutoksesta vastaa tuottaja. Hapettuminen on suurimpia huolenaiheita, koska sen seurauksena syntyy primaarisia ja sekundaarisia hapettumistuotteita, jotka voivat pilata tuotteen väriä, makua ja rakennetta. Tämän tutkimuksen toimeksiantaja on kehittänyt uuden valmistusaineen. Valmistusaine on kaura-rypsiöljypohjainen kuivattu emulsio, jonka hapettumisnopeus on hyllyiän määrittämiseksi tarpeen selvittää. Tutkimuksen tavoitteena oli selvittää rasvojen hapettumiskestävyyttä kaura-rypsiöljyseoksessa ja arvioida uuden valmistusaineen hyllyikä. Lisäksi tavoitteena oli selvittää, vaikuttavatko valmistusaineeseen lisätyt antioksidantit tai valmistustavan muutos rasvojen hapettumisnopeuteen. Tutkimusta varten valmistettiin kuivaamalla yhteensä neljä valmistusainetta. Yhteen uusista näytteistä lisättiin tokoferoliseosta ja yhteen rosmariiniuutetta. Toisen valmistustavan näyte valmistettiin eri tavalla kuin muut näytteet. Lisäksi käytössä oli yksi näyte, joka oli ollut kuusi kuukautta tehdastiloissa ennen varastointikokeen alkua. Rasvojen hapettumista seurattiin nopeutetussa varastointikokeessa 12 viikon ajan 40 ℃:ssa. Näytteistä määritettiin alussa ja 2, 5, 8 ja 12 viikon kuluttua rasvahappokoostumukset kaasukromatografilla, peroksidiluku, haihtuvat yhdisteet kiinteäfaasimikrouutto-kaasukromatografialla ja tokoferolit sekä -trienolit suuren erotuskyvyn nestekromatografialla. Tutkimusta varten valmistettujen uusien näytteiden rasvahappokoostumuksissa ei tapahtunut muutosta varastointikokeen aikana. Tokoferolien ja -trienolien kokonaispitoisuudet pienenivät noin 32 %, ja peroksidiluvut nousivat noin kaksinkertaiseksi tasoon 13-15 mekv/kg. Kaikkiin näytteisiin muodostui haihtuvia hapettumistuotteita (heptanaalia, 2-pentyylifuraania, heksaanihappoa ja nonanaalia). Eniten kaikissa näytteissä oli heksanaalia ja 3,5-oktadien-2-onia. Kaikissa uusissa valmistusaineissa hapettuminen oli rajallista, ja käytetyt antioksidanttilisäykset eivät merkittävästi parantaneet säilyvyyttä. Sen sijaan valmiiksi vanhentuneessa näytteessä hapettuminen oli voimakasta kahdeksannen säilytysviikon jälkeen. Tutkimuksen tulosten perusteella uuden valmistusaineen rasvojen hapettumiskestävyys on hyvä ja hyllyiäksi voi arvioida jopa 7-12 kuukautta. Tutkimuksessa osoitettiin myös, että lisätyt antioksidantit tai erilainen valmistustapa ei lisännyt valmistusaineeseen hapettuvuuden kestoa.
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(2018)The aim of this study was to determine the chemical hazards associated with the packaging materials of liquid packaging board with polyethylene coating on both sides, and if these chemical hazards would transfer to the liquid packaging board and to milk packaged in it. Consumers’ exposure to chemical hazards resulting from the packaging materials of the liquid packaging board used in the packaging of milk was assessed. Additionally, the process of safety assessment of new packaging materials of liquid packaging board was developed and described. A multinational manufacturer of food contact materials bears a great responsibility for the consumer safety and conformance of its products which is why conducting this study was important. A core made of recycled fibre and a tape used in the packaging of liquid packaging board were assessed for their chemical risk in this study. The core consists of adhesives and core board made of recycled fibre. Adhesive tapes consist of backing material and adhesive. Sometimes a primer is used between the backing material and adhesive. The chemical composition and potential sources of contamination were discussed in the literary review. Non-Intentionally Added Substances (NIAS) and substances known to cause alterations in the sensory properties of liquid packaging board and food in adhesive tapes and core board were analysed. Additionally, non-targeted screening methods were employed to detect unpredicted NIAS in the packaging materials, liquid packaging board and a food simulant for milk. The concentrations of NIAS were compared with specific migration limits in the European Commission Regulation (EU) 10/2011 on plastic materials and articles intended to come into contact with food. They were also compared with the values of acceptable and tolerable daily intakes if provided by the European Food Safety Authority (EFSA). The analytical methods that were used for qualitative and quantitative analyses were GC-MS and GC-FID. Predicted and unpredicted NIAS were detected from the packaging materials using the chosen methods. Some of the substances were found to transfer to liquid packaging board and to the food simulant. The migration to the food simulant was not be analysed for some of the NIAS. Additional information on the transfer of these substances to food is still needed. Substances for which adequate toxicological information was available did not pose a threat to consumer safety based on the exposure assessment. Furthermore, a process for the risk assessment of new packaging materials was successfully developed.
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(2013)Increasing the use of biodegradable packaging materials could reduce the need of petroleumbased plastics. Hemicelluloses are a potential source of renewable raw material for packaging purposes. The literature review focused on polysaccharide-based packaging materials and properties of food packaging materials. In addition, crosslinking polysaccharides with citric acid and ammonium zirconium carbonate (AZC) were discussed. The objective of the experimental study was to prepare self-standing films from spruce galactoglucomannan (GGM), and to study their properties. The aim was to enhance the mechanical and permeability properties, and make the films less sensitive to moisture, via crosslinking. Crosslinking was carried out in solution and sorbitol was used as plasticiser. The films were prepared by a casting method and dried at room temperature. Tensile strength, elongation at break and Young’s modulus were measured by tensile testing. In addition, oxygen permeabi lity, water vapour permeability and water solubility of films were measured. The effect of moisture on films was investigated with sorption isotherm and humidity scanning dynamic mechanical analysis. Citric acid did not function as a crosslinking agent, but acted more as a plasticiser increasing elongation. The heating required for the crosslinking reaction should be performed in dry film instead of solution. Crosslinking with AZC resulted in strong films, with tensile strength up to 52 MPa. Sorbitol addition decreased the tensile strength and Young’s modulus, but increased the elongation, as expected. Crosslinking and sorbitol addition both decreased water vapour permeability, resulting in a better water vapour barrier. The deviations in oxygen permeability measurements were high, but it looks like crosslinking with AZC results in better oxygen barrier. In high relative humidity (RH) the film with AZC absorbed less water vapour and the storage modulus decreased slower than in the non-crosslinked film. Thus, crosslinking with AZC made the properties of GGM films less susceptible to changes in RH. AZC appears to be a promising crosslinking agent for hemicellulose films, therefore the suitability for food packaging applications should be further studied.
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(2018)The literature review introduces the rapeseed chemical composition, the rapeseed protein isolate as a novel food ingredient, and protein oxidation. Rapeseed is an economically important oilseed crop since it is one of the largest sources of vegetable oil in the world. Rapeseed expeller is a protein-rich by-product of canola oil extraction. The main use of this protein-rich by-product is animal feed. However, it could be potentially utilized in the food industry, for example, as a source of protein in plant protein products, as a texture-improving ingredient in bakery products or as an alternative for animal proteins. We need more protein for human nutrition, and thus it is important to find new plants that can be used as protein sources. This way we can reduce environmental stress. Because the production process of rapeseed protein expeller already exists, it is a good new potential protein source. Protein and lipid oxidation are significant factors when food and nutrition quality are examined. The objective of this study was to optimize the protein extraction method and to examine the oxidation of rapeseed proteins and the lipid oxidation in two different rapeseed expellers. A few parameters, including extraction solvent (0.1 M and 1 M NaCl), pH (8 and 10), extraction time (4 h and overnight) and the removal of oil, were tested and the parameters that gave the biggest acquisition of soluble proteins were chosen for the experiment. The oxidation of rapeseed protein expeller was measured based on the loss of tryptophan fluorescence and the formation of carbonyls and dityrosine by using fluorescence spectrometry and based on the formation of hexanal by using the headspace gas chromatography method. Protein oxidation was measured in two different ways: in the rapeseed protein expeller during three months and in the extracted protein solution during seven days. The chosen extraction parameters were pH 8, 0.1 M NaCl solution and overnight extraction. The soluble protein amounts of the two rapeseed expeller samples were different after extraction, but this could be explained by the batches’ slightly different chemical compositions, especially their different cruciferin and napin ratios. During both the 7-day and 3-month oxidations, the tryptophan fluorescence decreased. During the 3-month oxidation, the formation of carbonyls increased and no hexanal was detected in any of the rapeseed expeller samples which were measured with headspace gas chromatography. The temperature and preservation time had a considerable effect on the protein oxidation in both the 7-day and 3-month oxidation tests, when only the loss of tryptophan was considered as an oxidation marker. The results revealed that fluorescence spectroscopy is a potential method for investigating the protein oxidation in the rapeseed protein expeller by using the loss of tryptophan and the formation of carbonyls as oxidation markers.
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(2017)The literature review introduced the chemistry of sterols and presented the sterols found in microalgae, and placed emphasis on the analytical methods used for studying sterols in microalgae. A brief discussion about application of microalgae-derived sterols was also included. The aim of this work was to learn about the sterol compositions in microalgae: Euglena gracilis and Selenastrum sp.. The common analytical methods of sterols are not suitable when applied to microalgae. Traditional alkaline hydrolysis may lead to an underestimation of total sterol content, because it cannot break acetal bond in steryl glycoside (SG). Additional acid hydrolysis for determining SG may lead to isomerization or decomposition of Δ7-sterols, which are the main sterols in green algae. A combination of alkaline hydrolysis and enzymatic hydrolysis was performed in this study. Firstly, sterol contents were determined using two methods: direct saponification and accelerated solvent extraction followed by saponification. Secondly, sterol classes: free sterol (FS), steryl ester (SE), and SG were determined by fractionation using solid phase extraction, followed by alkaline hydrolysis (FS and SE) and enzymatic hydrolysis (SG). Sterols were quantified using an internal standard and determined by GC-FID as their trimethylsilyl ether derivatives and identified by GC-MS. Euglena gracilis contained three major sterols: ergosterol and corbisterol, and Selenastrum sp. contained Δ7-ergosterol, chondrillasterol, and Δ7-chondrillasterol. Sterol contents ranged from 0.68-3.24 mg/g dry matter in Euglena gracilis, of which ergosterol constituted 68-93%. Sterol content in Selenastrum sp. was > 9 mg/g dry matter, with 36% Δ7-ergosterol, 12% chondrillasterol, and 52% Δ7-chondrillasterol. Comparison between the two extraction methods showed that ASE had a lower sterol yield than direct saponification. In E. gracilis, SE compromised 20-24%, FS 60-65%, and SG 11-12%. In Selenastrum, SE compromised only 1%, FS 74%, and SG 25%. The findings suggested that data on sterol composition ought to be viewed with caution. Underestimation of total sterol content may result from missing remarkable amounts of SG in certain microalgae species.
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(2014)Rye bran contains dietary fiber, and lipids. Unsaturated fatty acids make rye bran products vulnerable to oxidation and formation of off-flavor. High level of dietary fiber gives rye bran a rough feel in the mouth. Therefore, extrusion was chosen to make rye bran products more appealing to consumers. The literature review covered flavor of rye, lipids in rye, lipid oxidation in cereals, extrusion of cereals, and principles of the HS-SPME-GC-MS method. The aim of this thesis was to study stability of lipids of rye bran during the extrusion process using different extrusion parameters, and the stability of extrudates during storage. Four experiments were carried out. The first three were to analyze the effect of extrusion die temperature (80, 100, 120 and 140 °C), water content of the rye bran feed (13, 16, 22, and 30%) and particle size of the rye bran (633 ± 13 and 15 ± 1 ?m). In the last experiment, five most interesting samples were selected from the previous three experiments and reproduced. A stabilization of relative humidity was conducted. HS-SPME-GC-MS analysis was run after stabilization to determine effects of the parameters on the initial quality of extrudates, and then every two weeks till the 10-week time point. In total of 88 (max.) volatile compounds were detected. Among them, 30 volatiles were selected for further study based on peak areas at first, mainly lipid oxidation and Maillard reaction products (MRPs): aldehydes, furans and pyrazines. PCAs analyzing the extrudates were run with the 30 compounds as variables. Ten volatiles appeared to have a significant effect on the PCA model. From the first experiment, extrusion temperature of extrusion die had a small effect on the oxidation stability. The indicator of oxidation, hexanal, of all samples had almost the same level at initial point (around 3.0 * 107 counts/s). The increasing tendency during storage was also similar. MRPs were more likely to appear in the extrudates produced at higher temperature (140 °C). From the second experiment, water content had great impact on the oxidation and MRPs. MRPs were better released at 2-week time point and then decomposed or reacted with other compounds. The initial state of oxidation was similar, but during the storage, the lower the water content was, the better the oxidative stability the extrudates had. Comparing the results of the experiment 2 and 3, the level of MRPs was much higher when the particle size of the bran was small, while the oxidative stability was improved in the third experiment, especially in the 16% water content samples. In conclusion, water content and particle size of rye bran had significant influence on the initial state of the extrudates. Samples produced with lower water content and bran with finer particle size had better oxidative stability and higher level of MRPs. This will be important in the developing of extruded rye bran products.
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(2016)Term cocoa flavanols refers to all flavanolbased compounds found in cocoa including procyanidins. Procyanidins are polymerized compounds formed from cathecin and epicathecin flavanols. Cocoa flavanols contribute to the bitterness in chocolate but they are also proven to be heart and vascular health promoting. In autumn 2013 after EFSA’s positive scientific opinion European commission approved Barry Callebaut’s health claim ”cocoa flavanols help maintain endothelium vasodilation, which contributes to normal blood flow” considering ACTICOA™ cocoa powder. Because cocoa flavanols can contribute to human health it is important to know how chocolate manufacturing process affects them. The aim of the study was to define which processing steps in chocolate manufacturing are mostly responsible of the reduction of cocoa flavanols. Both dark and milk chocolate making processes were examined. In addition, raw chocolate manufacturing was compared to a standard chocolate manufacturing by analysing samples of raw chocolate made from the same Arriba Nacional-cocoa bean variety. The effect of alkalising process was also evaluated by comparing two chocolate samples that differ only in the cocoa powder used, which was either alkalised or non-alkalised. Additionally, these samples were compared with a sample, in which cocoa powder was enriched ACTICOA™-powder, in order to detect its beneficial effects on the flavanol content of the end product. The samples were collected throughout the manufacturing process of chocolate, ranging from fermented cocoa beans to milk chocolate. Samples included differently processed chocolates (dark chocolates containing 70 % and 47 % of cocoa and 35 % milk chocolate) and their conching, refining and cocoa mass samples. Two other 70 % chocolate samples with altered recipes and two raw chocolate samples were also analysed. NIST SRM 2384-baking chocolate was analysed to check the reliability of the results. In addition the amount of cocoa flavanols in Crump-powder was determined. According to the results the greatest loss in the amount of cocoa flavanols occurs at refining step, when almost half of the remaining flavanols were lost. In processing fermented beans to cocoa mass as well as in conching step, the losses are around 20 percent. Processes (tempering etc.) after conching doesn’t seem to have major effects on cocoa flavanols. By replacing 10 % of the chocolate’s cocoa (the cocoa powder fraction) with ACTICOA™-powder the total flavanol amount increased 150 % compared to chocolate containing alkalized powder. The effect of non-alkalized powder wasn’t as remarkable, the increase was only 16 %. The most critical prosessing step for cocoa flavanols in traditional chocolate manufacturing is refining, during which particularly trimers and larger procyanidins are lost. Instead of changing the chocolate manufacturing process more flavanol preserving, it would be more efficient to use cocoa ingredients that are processed in flavanol preserving manner, such as ACTICOA™-powder to ensure the health beneficially sufficient amount of flavanols in chocolate.
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(2017)Potato (Solanum tuberosum L.) is a plant that belongs to the group of nightshades (Solanaeceae). Enzymatic browning occurs in potato tuber when it is peeled or bruised. Polyphenols in tuber (e.g. chlorogenic acid and tyrosine) are oxidised into o-kinones by polyphenol oxidase. When kinones polymerise, melanins are formed. These compounds cause the brown colour in potato tubers. Sulfites are used as food additives in potatoes preventing enzymatic browning reactions. The maximum permitted usage levels in European Union are 50 mg SO2/kg in peeled potatoes, 100 mg SO2/kg in cooled and frozen potatoes and 400 mg SO2/kg in dried potato products (No 1333/2008). The allergy threshold limit for sulfites in food products is 10 mg SO2/kg (No 1169/2011). The objectives of this study were 1) to determine the sulfite content in various potato products on the market, 2) to examine the binding of sulfite on potato in the relation with temperature, time and concentration, 3) to examine sulfite content in different potato varieties and 4) to compare the HPLC results with the rapid determination methods. The objectives in the literature review were to study the use of a potato as a food component, industrial peeling of potatoes, enzymatic browning reactions, sulfites and their analytical methods. In this study, a modified RP-IP-HPLC-PC (Reversed Phase Ion-Pair High Performance Liquid Chromatography Post-Column) method was used. For rapid determination methods, two kits were used: Merck MQuantTM Sulfite Test and Neogen ALERT® for Sulphites in Seafood. 18 food products were selected to this study (6 mashed potato flours, 3 fresh products and 9 frozen). Box-Behnken Experimental Design was carried out prior to the examination of sulfite binding in different potato varieties (Belana, Nicola, Siikli, Gala, Jelly, Melody, Bellarosa, Afra and Puikula). Sulfite was found in four mashed potato flours and three fresh potato products. In flours, the content of sulfites were below the maximum limit, but over the allergy threshold limit (10 mg SO2/kg). However, sulfite was labelled. In fresh products, the content of sulfite in the first product was below the allergy threshold limit, the second product fell under the maximum limit but the third product exceeded it. In the first product sulfite was not labelled but in the other two ones it was. In Box-Behnken Experimental Design, results were analysed with one-way ANOVA. Concentration (%) had the biggest influence on sulfite binding on potato (p = 0,000) and then time (s) (p = 0,0079). Temperature (°C) didn’t have any statistical significance (p = 0,3513). According to the results, the best measurement point was 1 %, 60 s, +5 °C. The peeled potato varieties were sulfite treated in these conditions. Statistical analysis was carried out with one-way ANOVA and then Tukey HSD. According to the results, there was a statistical significance (p = 0,000) in sulfite binding in different potato varieties. Sulfite was bound most in Puikula (67,0 ± 8,8 mg SO2/kg) and least in Gala (19,7 ± 5,3 mg SO2/kg). The most difference within the varieties in sulfite binding were with Belana, Gala and Puikula. Jelly had a difference only with Gala. In rapid determination methods, ALERT® was more accurate than MQuantTM. ALERT® could be applied on the surface of the sample contrary to MQuantTM that needed 3 or 5 times dilution before measurement. ALERT® is a good choice for semiquantitative rapid method. MQuantTM, however, is not suitable for rapid measurement of sulfites in potato products.
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